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1. pre 47k iN pla br pin I Figure 3 2 External Wiring for Temperature Measurement The circuit functions similarly to a dual slope procedure In the first step the capacitor is charged by the pin DIS Afterwards the transistor Pl is opened start Now the TDC measures the time until the capacitor is discharged over the resistor Rrer down to the lower trigger level of the Schmitt trig ger at the SNS input of the TDC stop Then the capacitor is charged again During the charging time the result of this time difference measurement is calculated and stored in the Timel Register After charging the capacitor the same process is repeated using the other transistors The calculated time differences are stored in the Time2 and in the Time3 Register The number of resistors to be measured can be selected in the TEMP Register TDC501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 12 of 37 When operating with 4 resistances the fourth measurement result is calculated not immediately after measuring since only 3 Time Registers are available The result in Timel Register has to be read out then the calculation of the fourth result is started automatically and written into the Timel Register For calculating a time difference the CPU needs 34 calibration clock periods Thus the fourth result is written to the Timel Register 34 calibration clock periods a
2. by delaying the stop signal OFF with la auto noise i OFF tCAL1 tRES Figure 3 1 Influence of the Auto Noise Unit on the Characteristic of the TDC If the automatic generation of the calibration values is switched on then the same offset remains during the generation of the calibration values belonging to the measured value so that the offset is out counted during the following time difference calculation automatically if Time Registers are read externally by the microcontroller if original data are read see Chapter 3 3 and no additional error occurs If the calculation of the time difference is executed automatically then after the cali bration a new offset is adjusted automatically In this case no HEX 08 is needed TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 11 of 37 3 2 Temperature Measurement Unit In many applications of the TDC501 a temperature measurement is necessary By very simple eco nomical and nevertheless exact methods it is possible to attribute a temperature measurement to a time difference measurement The TDC501 has a temperature measurement unit which enables execution of highly exact tem perature measurement with simplest external wiring An example of the external wiring of the temperature measurement unit using external bipolar transistors as switches can be seen in Figure 3 2 DIS SNS Lal N Rig Rt Ron Rad IE Bas TDC501 Pr
3. face is made exclusively by the pins STRB READ DO D7 and BITS The processor interface has two registers for configuration purposes In the MODE Register general functions e g the measurement mode and the auto noise unit are adjusted In the TEMP Register the temperature measurement and the number of used ports is configured A two stage output multiplexer formats the data depending on the selected bus width BIT8 0 gt 4 bit mode Data bus is 4 bits wide BITS 1 gt 8 bit mode Data bus is 8 bits wide The data bus is connected through only during the low phase of the STRB input Otherwise it is high z If the bus is adjusted to 4 bits wide BIT8 0 the upper 4 bits of the bus are high z all the time To make sure that they don t float it is recommended to pull them to GND 3 4 4 Instruction Set The TDC501 provides very few instructions Whether an instruction is to be executed as read in struction or as write instruction is selected by the pin READ If this pin is set to 1 the TDC is read Setting this pin to 0 a write operation is executed The execution of an instruction is controlled by the pin STRB An instruction is always executed during the low phase of the pin STRB TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 19 of 37 Read instructions consist of low strobes at the STRB input and the READ pin set to 1 Selection of the data source to be r
4. Example Setting the MODE Register to D7 DO 10100101 means measurement range 0 selected internal auto noise unit enabled and measurement without automatic generation of calibration values after a time measurement read the TDC original data conditionally TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 20 of 37 3 4 5 2 Write TEMP Register The TEMP Register is 4 bits wide It can be written in one write cycle in 8 bit mode as well as in 4 bit mode For decoding the TEMP Register the input DO has to be set to 0 and the input DI has to be set to 1 during the write cycle The remaining two bits are for configuration of the temperature measurement unit The bits of the TEMP Register have the following meaning Data Bits Function D3 D2 D1 DO Table 3 2 TEMP Register 3 4 5 3 Initialization Instruction INIT HEX 00 or HEX 08 The INIT write instruction is the initialization instruction of the TDC501 It is initiated by setting the lower three bits to 0 during the write cycle Bit 4 selects whether the random number generator of the auto noise unit is incremented when initializing or not If this bit is set to 1 the random number generator is incremented The remaining bits are not used in the 8 bit mode In both in the 8 bit and in the 4 bit mode this instruction needs only one cycle After initialization the TDC is ready for measurement Some registers and the RD
5. TDC501 has a temperature measurement unit A temperature measurement can easily be real ised using the following components A capacitor is charged and then discharged using a tempera ture dependent resistor and thereafter using a reference resistor By division of the two measure ment results for discharge a factor is received which is linearly dependent on the resistance rela tion This method is especially suited for high precision temperature measurement at low current consumption Except for the temperature dependent resistor and the reference resistor no other requirements are made on the used components 2 2 3 Generating Calibration Values In default mode after reset the TDC will automatically generate two calibration values after time measurement and then calibrate the measurement values using the internal 16 bit CPU The auto matic generation of calibration values and the computing of calibrated measurement values measurement results can be disabled to allow fastest measurement rate The generation of calibra tion values can be done separately without having a start stop event too The temperature measurement is always executed with the generation of calibration values and the computing of calibrated measurement time values The generation of calibration values is always done in measurement range 1 2 2 4 Processor Interface For communication with a microcontroller the TDC has a processor interface Its data bus can be
6. bit CPU Coarse Count 12 16 TDC_Val t a 2 o a lao lee a SY E 16 MUX a i en 28 Time3 Load 5_ ES em 5 a L gt ta Load 3 E a 8 ia gt ral y Si E ms z E A NO lt on MUX a 2 5 mm 28 Time 2 Load 4 i A g 2 E from ALUI 2 Control Bits Load 1 E Cal Clock Load 5 2 Load 4 1 28 A Status In Control gt Time g Load 3 AS Unit Load 2 Login m gt Load 1 Control Bits m from CPU Link E RDY Figure 3 4 Structure of the 16 Bit CPU TDC501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 17 of 37 Using the 16 bit CPU the microprocessor attached to the TDC501 is relieved of the calculation of the time difference This leads to computing time saving in the processor Small and low priced processors can be used A further advantage of the CPU is in the current saving which is of par ticular interest for battery operated devices The calculation of the time difference is executed in the TDCS501 in a fraction of the time and with a fraction of the current which a 4 or 8 bit processor would need With the help of the internal CPU it is possible to execute a complete temperature measurement in lt 0 5ms without interaction with the processor The CPU has a 16 bit ALU with output registers which provides the following functions 16 16 bits addition 16 16 bits subtraction A B or B A 1 bit SHIFT
7. by setting bit 7 in the MODE Register to 1 When the auto noise unit is enabled an off set adjusted by the random number generator is preserved during the whole burst measurement and can be changed as usual by an INIT HEX 08 instruction 4 2 2 Separate generation of calibration values without previous measurement To be able to execute an external time difference calculation in spite of a switched off automatic generation of calibration values e g in burst mode the TDC provides the possibility to generate calibration values separately without a previous measurement This mode is selected by setting bit 6 Calibrate in the MODE Register to 1 Since the generation of the calibration values is executed always in the measurement range 1 the values of bit 4 and bit 5 MODE and CAL_DIS of the MODE Register are ignored Note The generation of calibration values is executed correctly if and only if the pin MDIS is set to 0 TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 28 of 37 4 3 Temperature measurement The temperature measurement is controlled by the TEMP Register The TEMP Register has four adjustments e switched off e measurement with 3 resistors e measurement with 2 resistors e measurement with 4 resistors As already described in chapter 3 2 the temperature measurement is put down to a resistance ratio measurement The resistors which are to be measured discharge a capaci
8. count_reg is stored in the original data re gisters G Regl 3 and the status of the chain is stored in the fine quantisation register By correct controlling of the chain generation of appropriate additional information and correct subsequent processing the time difference can be determined exactly to one gate delay The value in the fine quantisation register has a high redundancy Therefore it is freed from this redundancy in the Compress Unit and stored in the original data registers F Regl 3 The ALU1 assembles the TDC original values finecount FC and calibration value CAL which represent the time differences measured by the fine quantisation unit in number of gate delays LSBs from F Regs and G Regs TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 15 of 37 The complete measuring record of original values before their composition by the ALU1 looks as follows F Register Mode 0 F Regl finecountl FC1 F Reg2 finecount2 FC2 F Reg3 calibration valuel CAL1 Calibration value2 CAL2 is directly read from the Compress Unit Note The coarse count is directly read by the CPU Mode 1 F Regl finecount FC F Reg2 calibration valuel CAL1 F Reg3 calibration valuel CAL1 Calibration value2 CAL2 is directly read from the Compress Unit Burst Mode F Regl 1 measurement value F Reg2 2 measurement value F Reg3 3 measurement value Measurement value4 is directly read
9. from the Compress Unit Separate generation of calibration values without measurement F Regl calibration valuel CAL1 F Reg2 calibration value2 CAL2 G Register Mode 0 G Regl finecountl FC1 G Reg2 finecount2 FC2 G Reg3 calibration valuel CAL1 Calibration value2 CAL2 is directly read from Count_Reg Mode 1 G Regl finecount FC G Reg2 calibration valuel CAL1 G Reg3 calibration valuel CAL1 Calibration value2 CAL2 is directly read from Count_Reg Burst Mode G Regl 1 measurement value G Reg2 2 measurement value G Reg3 3 measurement value Measurement value4 is directly read from Count_Reg Separate generation of calibration values without measurement G Regl calibration valuel CAL1 G Reg2 calibration value2 CAL2 If the fine quantisation unit or the coarse counter overflows this is indicated by a flag The flag is accessible via the status register and the pin TIMO timeout If a timeout occurs the measurement is aborted and the TDC goes into the wait state TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 16 of 37 3 4 16 Bit CPU and Processor Interface 3 4 1 16 Bit CPU If enabled the 16 bit CPU calculates the calibrated measurement time values measurement re sults using the original measurement and calibration values according to the formulas in Chapter 3 3 1 and Chapter 3 3 2 Figure 3 4 shows the structure of the 16
10. least sig nificant byte of the Timel Register it is possible to stop reading even if not all registers have been read e g measurement procedure with only one measurement It is also possible for example after an INIT with a subsequent measurement to read the Timel Register by sending 4 strobes then execute the second and the third measurement without interme diate INIT instructions and then read the Time2 and Time3 Registers by sending 8 strobes Reading out the Time Registers in the 4 bit mode functions like the reading in the 8 bit mode In 4 bit mode 7 strobes are necessary per time value In doing so always the least significant nibble is put on the data bus first With the 8 strobe 0 is read After the 8 strobe the value of the next Time Register can be read with 7 further strobes Reading out all Time Registers will take 23 STRB strobes in total 3 4 6 3 Reading the Original Data With the selection of the TDC s original data as read source within the MODE Register finecount FC 16 bits wide calibration value CAL 16 bits and coarse count CC 12 bits are put on the data bus in the following order TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 25 of 37 Burst Mode Sep Calibration without Meas l value FC1 FC 1 meas value CAL1 CALI CAL2 CAL2 CAL2 Table 3 7 Reading Order of Original Values Note If the automatic generation of calibration values is
11. of the 16 bits input word 16 1 bit multiplication REG IN lt 0 comparison With these basic functions it is possible to build a word parallel CPU which controls the necessary functions The CPU has 5 registers e Two 16 bit wide internal value registers which store intermediate results for later calculations e Three Time Registers which store the calibrated measurement time values as measurement re sults These registers are 28 bits wide and are written to by the ALU at the end of a calculation process Due to the three Time Registers it is possible to measure and calculate up to three time differences without having to read out the TDC As long as no new initialization instruction of the microproces sor is received the Time Registers are written in the order Timel to Time3 If the registers are full then further starts and stops are ignored The TDC original values are overwritten with each meas urement The Time Registers can also be read after each individual measurement of course Addition and subtraction take one clock cycle each The division needs 24 clock cycles A complete time calculation needs 34 calibration clock cycles The control unit of the CPU generates the RDY flag which signals that the Time Registers contain valid data If no calculation of the time differences is executed because the generation of the calibration values is disabled via the MODE Register CAL_DIS 1 the RDY flag is set to 1
12. the MODE Register NOISE EN to 1 Exceptions e During temperature measurements the automatic generation of the calibration values can not be disabled e Inthe burst mode the auto noise unit is enabled only if bit 7 of the MODE Register is set to 1 TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 30 of 37 5 Typical instruction sequences and timing diagrams Figure 5 1 shows the timing diagrams of a write and a read instruction as well as some typical in struction sequences to control the TDC501 The following points are to be noticed 1 During the write cycle of the TDC the pin READ and the data which are to be written must be stable before the falling edge of STRB During the read cycle the pin READ must be 1 before the falling edge of STRB STRB is used as clock for the read and write pointer So no spikes may occur on this signal line With each write access the read pointer is reset and each read access resets the write pointer 5 The write instruction INIT resets both the read pointer and the write pointer Thus writing and reading sequences can be interrupted at any time The minimum pulse width of 30ns for STRB shown in Figure 5 1 applies to all read and write instructions The only exception is the initialization instruction when the auto noise unit is en abled This special initialization instruction needs a minimum pulse width of 60ns A basic initializ
13. ASIC Design Center VERTRIEBS GMBH pd Date 2005 07 19 MSC Vertriebs GmbH ASIC Design Center Industriestra e 16 76297 Stutensee Author UW AP Phone 497249 910 205 Fax 497249 910 268 Email uw msc ge com Competence in electronics User Manual TDC501 Page 2 of 37 Contents t TINFRODUCTHON Gas tiie essential i lie 4 2 SONVERVIEW hh Ba era 5 2 1 FEATURES ae ana na DR 5 2 2 GENERAL DESCRIPTION a een een 6 2 2 1 Time Difference Measurement uecseesesssnsssesssssensnnnennnnsnsnensnnnnnnnsnnnnnsnsnsnnennensennensnanenn 6 2 2 2 Temperature Measurement u a ek 7 2 2 3 Generating Calibration Values uses secon 7 2 2 Processor Interface mi Oo 7 2 3 BLOCK DIAGRAM a a ee Nenn ee 8 Sie BUNG HONAL DESCRIPTION 22 a e e Es eh 9 3 1 INPUT UNIT o as a 9 SL LE PAULO Noise dandome 9 3 2 TEMPERATURE MEASUREMENT UNIT ccccsessscscccececeesenseaececececsesensnsececeeceseseeessaaeeeeeseesenenens 11 3 3 MEASUREMENT UNIT A ia 13 3 3 1 Mode 0 Function Measurement Range O ooooonnocccnnccccnoncccnoncnononcnonancnnonnccnnncnonnnaninnnos 13 3 3 2 Mode 1 Function Measurement Range Du es 14 3 3 3 Principle Function of the Fine Quantisation Unit 000 0 eeecceceeccecsseceesneceseeeeenneeeenaees 14 34 16 BIT CPU AND PROCESSOR INTERFACE anna naeh ehe 16 34 1 A man samhe homhiomhimhmhhemmhenomhaamhnmhaih 16 AN A a anas gae ae SC ca ase ee HS cts os ease AET SE E Gas Sains NAA EN Haigh hs s 18 324 3 Proc
14. Quiescent current consumption 150 nA Current of the measurement unit 10mA Aus 5000 sec 200 uA Current consumption of the CPU 5000 100 nA 500 pA Current consumption of the precounter OnA Current consumption of the calibration clock input 10uA MHz 1MHz 10 pA Total current consumption to be expected approx 710 pA 6 3 Package and Pin Configuration lt 13 6 7 gt ag gt 107 02 8 23 22 So Top View o yo O 2 as Y 1 0 0 35 0 8 E 510 15 M o bas Figure 6 1 Package TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 35 of 37 D1 STRB n __ Strobe Processor Interface active low Poren je a Bee a be BIDIR ma MS Data Bus 6 pa BIDIR 4 mA IMSB3 Data Bas SSS s p BDR ma MS Data Bas SSS 9 b BIDIR ma IMSB 6 Data Bas SSS mojo BDR ma ISB Data Bus 3 pr ENI Ham mill Bor ie de er OUT OUT MU A AUN O I mo ss T 5 SchmitTrigger Input for Temp 20 mD on PIPA Configuration 2r fres AN est Input must be 2 VDD Li Fo Fo Em iii AA mm ai 24 NSTA N Invert Start Input O pos Edge 25 STA N Start Input 26 stp N Stop nut 2 NSTP N 0 invertStopInput 0 pos Ed
15. S501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 22 of 37 3 4 6 Reading the TDC After a measurement is completed the RDY flag is set to 1 and the TDC501 can be read As al ready mentioned when reading data from the TDC it is only necessary to put an appropriate num ber of low active strobes on the pin STRB Depending on the selection in the MODE Register and the data bus width the data of the TDC are put on the data bus It is only to be made sure that pin READ is set to 1 before pin STRB is set to 0 After a measurement the TDC501 expects that it is read out Therefore it is not necessary to an nounce the read access by a write instruction Three sources can be read Time Register TDC original data absolute or conditional w Status Register The data source is selected via the MODE Register Source MODE Register Bits TDC_Val Force TDC_Val TDC original data absolute 1 Status Regier JO____ TDC original data conditional O AA Ca Table 3 3 Read source selection within the MODE Register Note Neither a read access on the Time Registers nor the reading of the original data resets the RDY flag This can only be done by the start event of a new measurement or an INIT or a reset on the pin RST 3 4 6 1 Reading the Status Register The TDC501 has a 7 bits wide Status Register which reflects the actual state of the TDC If the Status Register is selected as rea
16. TDC501 Page 21 of 37 original data registers contain the new calibration values A further generation of the calibration values can be started with a new INIT instruction Note If the TDC was initialized by an INIT or by a reset at the pin RST before the generation of the calibration values was selected in the MODE Register then the generation of the calibration values is started immediately after writing the MODE Register Ifthe TDC mode measurement range O with the auto noise unit switched on automatic genera tion of calibration values and reading the original values absolute or conditional is selected then immediately after the instruction INIT HEX 08 the random number generator is incre mented the RDY flag is cleared and the TDC waits for a start stop event After the correct measurement of the start stop event the RDY flag is set to 1 Now the original data registers contain the new measurement and calibration values and all further starts and stops are ignored A further measurement in the same mode can be started with a new INIT instruction Note The original data of this measurement contain an offset generated by the auto noise unit This offset can be counted out externally by using the formula in Chapter 3 3 1 Ifthe TDC mode measurement range 1 with the auto noise unit switched on automatic genera tion of calibration values and reading the Time Registers is selected then immediately after an instru
17. Y and the TIMO flag are cleared After an INIT the TDC original data of a previous measurement can t be read any more The values of the Time Registers however are not cleared and can be read even after an INIT The Time Registers are overwritten only if the time difference calculation for a new measurement is executed Examples If the TDC mode temperature measurement is selected via the TEMP Register then immedi ately after an INIT the RDY flag is cleared and the execution of the temperature measurement is started if the calibration clock is running After a correct execution of the temperature meas urement the RDY flag is set to 1 and the Time Registers contain new data A further tem perature measurement can be started with a new INIT Note If the TDC was initialized by an INIT or by a reset at the pin RST before the temperature measurement was switched on in the TEMP Register then the temperature measurement is started immediately after writing the TEMP Register If the TDC mode separate generation of calibration values without previous measurement is selected by setting the appropriate bits in the MODE Register then immediately after an INIT the RDY flag is cleared and the execution of the generation of the calibration values is started if the calibration clock is running After a correct execution the RDY flag is set to 1 and the TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual
18. already approx 150ns after the TDC has received a stop Then the original data can be read This is independent of whether the original values are to be read conditionally or absolutely The CPU is operated with the calibration clock TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 18 of 37 3 4 2 Data Formats The original data of a TDC measurement finecount FC calibration values CAL and coarse counter value CC are of the type unsigned integer The value of the coarse counter is 12 bits wide all other values are 16 bits wide The values are multiples of a LSB FC and CAL or multi ples of the calibration clock period CC The data of the three Time Registers are fixed point numbers with a width of 28 bits They have 12 bits pre decimal positions and 16 bits post decimal positions The measurement results in the Time Registers are the calibrated measurement values representing the measured time differences in mul tiples of the calibration clock period Example e Timel result is HEX 01A56B Calibration clock period 500ns gt The Time measurement result is decimal 26 338546 gt The measured time difference is 26 338546 Calibration clock period 13169 273ns 3 4 3 Processor Interface The processor interface is used for communication with a microprocessor For the operation of the processor interface it is not necessary for the calibration clock to run The controlling of the inter
19. asurement improvement Auto Noise Unit Power consumption lt 5uA at 10 measurements sec in measurement range 0 independent of measured time difference Package PQFP44 with 0 8 mm pitch Measurement range depends on period of calibration clock TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 6 of 37 2 2 General Description The TDC501 is a general purpose chip for high precision time difference measurement The pat ented measurement principle of the TDC501 is integrated in a fully digital device Supplied with 5V the TDC501 achieves a typical resolution of 220ps It has an internal measuring channel which can be used for two measurement purposes time difference measurement and temperature measure ment The block diagram of the TDC is to be found in Chapter 2 3 2 2 1 Time Difference Measurement During the time difference measurement the time difference between the rising falling edge of a start signal and the rising falling edge of a stop signal at the start stop input pins of the chip is de termined The triggering edges of the start and stop signals can be selected separately for each pin The TDC501 provides three Time Registers in which the measurement results are stored There are two measurement ranges available Measurement range 1 4ns 14us In this measurement range only the TDC s fine quantisation unit is used for measurement The measurement range depends on the resolution Th
20. ation of the TDC501 can be realised in two ways 1 Power On Reset at pin RST By setting this pin to 1 for at least 60ns SV typ the TDC is reset to its default state The MODE Register and the TEMP Register are set to their default values the write and read pointers are reset and the RDY flag as well as the TIMO flag are cleared After power on reset the TDC is ready for measurement and the temperature measurement is switched off The results in the Time Registers are not cleared by a power on reset whereas all original data registers are cleared 2 Start Up Instruction Sequence With the following start up sequence the TDC501 can be set to a defined state from any status 1 Instruction Dummy READ Effect write pointer reset 2 Instruction Write MODE Register Effect Configuration of the MODE Register 3 Instruction Write TEMP Register Effect Configuration of the TEMP Register After the third instruction the TDC is configured and can be initialized by an INIT TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 31 of 37 1 Timing Write Data lt 7 0 gt Don t Care x Valid Value ES Don t Care STRB ee gt 30 ns READ Don t Care Don t Care 2 5 ns 2 2 ns 2 Timing Read High Z High Z Data lt 7 0 gt Value STRB lt gt 30 ns gt READ Don tCare N Don t Care Sns 3 5 gt 5na gt lt 17ns lt _ gt l
21. ature Range Tsg 65 150 Table 6 2 Absolute Maximum Ratings TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 33 of 37 6 2 Current consumption The TDC s current consumption is one of the most important criteria if it is to be used in battery operated devices The TDC501 is a chip with fully static CMOS logic which only needs current when switching The current consumption depends on the period of activity of the measuring unit and the internal CPU If no measurements calculations or I O activities take place the chip only needs its quiescent current The current consumption in the active state depends strongly on the operating voltage Following currents can be expected Quiescent current Current of the measuring unit during measurement Current of the CPU Current of the precounter coarse counter Current of the calibration clock input approx 150 nA at 5V typ approx 10 mA at 5V approx 100 nA per calculation sec at 5V approx 250 nA per measurement second and per MHz at 5V and measurement over the full measurement range approx 10 uA MHz at 5V The current consumption of the measurement unit drops squarely to the supply voltage the current consumption of the remaining components drops linearly to the supply voltage Examples 1 Measuring in measurement range 0 with calibration 3 6V operating voltage 10 measure ments sec and 1MHz continuous cali
22. bration clock The average time measurement is about 1ms In the measurement range 0 the measuring unit is active for 4 calibration clocks on the average in dependent of the measured time difference Calculation of the current consumption Quiescent current consumption 150nA 0 72 108 nA Current of the measurement unit 10mA 4us 10 sec 0 72 208 nA Current of the CPU 10 100nA 0 72 720 nA Current of the precounter 250nA 10 1 1ms 1us 21 0 72 439 nA Current of the calibration clock input 104 A MHz 1MHz 0 72 7 2 uA Total current consumption to be expected approx 8 7 uA It can be seen clearly that in this case the current consumption of the TDC501 is determined to be approximately 85 of the calibration clock input Since the TDC501 needs a clock only during measurement and calculation the active period of the calibration clock could be limited to approx 15ms by using a gated calibration clock So the current consumption could be reduced of down to approx 1 5uA TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 34 of 37 2 Measuring in measurement range 1 with calibration 5V operating voltage 5000 meas urements second and 1MHz continuous calibration clock The average measuring time measurement is about lus The average active period of the measuring unit per measurement with calibration is about 4 us Calculation of the power consumption
23. canned at the same position i e to the same LSB and so the measured time difference has always the same quantisation error Changing the offset of the characteristic for each single measurement by delaying the stop signal according to Figure 3 1 causes sampling at different positions of the characteristic In order to be able to execute an averaging when measuring constant time differences the TDC provides an auto noise unit which is part of the input unit The auto noise unit is enabled by setting pin NOEN to 1 or by setting bit 7 in the MODE Register to 1 exception burst mode The auto noise unit changes the offset of the characteristic by delaying the stop signal The offset delay is generated by a 10 bit pseudo random number generator The step up of the pseudo random number generator and thus the generation of a new offset occurs with the initialization of the TDC501 with the INIT instruction HEX 08 Thus it can be decided with an INIT instruction whether a new offset is adjusted HEX 08 or not HEX 00 So the user has all flexibility using this option TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 10 of 37 quantisation stage width resolution Measurement value calibration value CAL2 with auto noise My N bie different offsets generated m T CAL2 by auto noise unit D FC with auto noise FC CAL1 with auto noise CALI offset enlargement
24. conditional readout of original data means that after measurement if the generation of calibra tion values is not switched off in the MODE Register the time difference calculation is executed and the result is stored in the Timel Register Before the CPU has finished the calculation it is not possible to read out the original data At the end of the calculation the RDY flag is set to 1 and the TDC original data can be read the Timel Register could be read as well An absolute read of original data can be executed immediately after a stop or possibly following generation of calibration values RDY is set to 1 immediately after the stop after approximately 150ns 5V typ or after the generation of calibration values In this case the Time Registers contain invalid data Important note When the auto noise unit is enabled the original data FC and CAL contain an offset generated by the random number generator which can be counted out externally according to the formulas in the Chapters 3 3 1 and 3 3 2 TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 26 of 37 4 Measuring features of the TDC501 In the following some additional information is given on the different measurement modes de scribed in the preceding chapters The TDC501 is conceived as general purpose chip and so it pro vides a wide set of measurement possibilities which cover most applications 4 1 Measuring in the measurement rang
25. ction INIT HEX 00 the RDY flag is cleared and the TDC waits for a start stop event In this mode the random number generator is not incremented After the correct measurement of the start stop event the RDY flag is set to 1 and the Timel Register contains new data Now up to two further start stop events can be measured without a further INIT and without having to read the TDC During the following measurement the RDY flag is reset to 0 and set to 1 again when the new measurement result is written to the respective Time Register After the measurement of max three start stop events the TDC must be initialized in order to be able to execute further measurements Note If you want to stop the TDC after e g only one measurement even if further start stop events occur then the RDY output can be connected to the MSDI input After the first meas urement the RDY output is set to 1 and switches the inputs off so that new starts do not effect the TDC Executing an INIT initializes the TDC The TDC can be initialized from any state via the data bus by the following sequence of instruc tions Instruction dummy read to reset the write pointer to Timel Register Instruction write MODE Register Instruction write TEMP Register Instruction INIT I After instruction 4 the TDC is ready for measurement or depending on the selected mode executes a temperature measurement or a separate calibration values generation TDC
26. d source via the MODE Register then in the 8 bit mode the status register is read in one cycle In the 4 bit mode two STRB strobes are necessary in which always the low order nibble is put on the data bus first TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 23 of 37 NOISE_EN D5 DO RDY shows status of pin RDY _ Table 3 4 Status Register The bits TIME and TIME2 in Table 3 4 indicate how many Time Registers contain valid data written into after the last INIT Thus these bits give a good overview of the present status of the TDC The bits TIME and TIME are to be interpreted as follows TIME2 TIME1 e No Time Register has been written e When temperature measurement with 4 ports this state is reached again when measurement is done and the data of port 4 are in the queue for calculation If measurement with automatic time difference calculation is selected this state is reached again after the 4 measurement Nevertheless the data of the first three measurements are available in the three Time Registers which is to be detected by the RDY flag set to 1 Only Timel Register has been written When temperature measurement with all 4 ports this state is reached again if after the end of measurement Time Register has been read and the 4 value is stored in this register 1 Joo e Timel and Time2 Registers have been written e Timel Time2 and Time3 Registers have been w
27. disabled this values are invalid When reading the original data in the 8 bit mode the least significant byte and in the 4 bit mode the least significant nibble of the original value are put on the data bus first When e g a finecount value in the 4 bit mode is read 4 low active STRB strobes are necessary When reading the coarse count value however only 3 strobes have to be sent If the coarse count value is read in the 8 bit mode then the most significant nibble is set to 0 If a complete original data measurement record for a measurement in the measuring range 0 is to be read in 8 bit mode then for this 10 strobes are to be provided in total independent of whether an automatic generation of calibration values is se lected or not If the MODE Register is set to read the original data then a further measurement can only be started after an INIT exception Burst mode Similar to the reading of the Time Registers in this mode the read pointer is reset to the first original value by a write instruction e g INIT So the reading of data can be started after a measurement immediately after the RDY flag has been set to 1 The TDC original data can be read out both conditionally and absolutely This is selected via the MODE Register e A conditional readout is selected if bit 2 TDC_Val of the MODE Register is set to 1 e An absolute readout is selected if bit 2 and bit 3 TDC_Val and TDC_Val Force are set to 1 A
28. e 0 As already mentioned the TDC501 has two measurement ranges The measurement range 0 is the so called extended measurement range It is used for long time differences Range 0 is selected by setting bit 4 MODE in the MODE Register to 0 and the pin MODE to 0 The temperature measurement always takes place in the extended measurement range As shown in Figure 3 3 of Chapter 3 3 1 in this measurement range the calibration clock is used Due to this measurement principle the minimum measurable time difference is 2 periods of the calibration clocks If the TDC is operated at its lower voltage limit of 2 7V then the calibration clock should not exceed 2 MHz preventing malfunction of the TDC This results in a minimum measurable time difference of lus worst case The maximum measurable time difference in range 0 results from the minimum usable calibration frequency The minimum calibration frequency results from the condition that the double period of the calibration clock must be lt 2 LSBs Otherwise an overflow will occur when generating the calibration values The minimum resolution at 5 5V is approx 160ps This results in a maximum calibration clock period of Ya 160ps 216 5 2us Since the precounter coarse counter is 12 bits wide the maximum measurable time difference is 5 2us 212 20ms worst case In addition to the long measurable time difference the constantly small power consumption is re markable Th
29. e maximum range of the fine quantisation unit is 2 LSBs This means the maximum measurable time difference is 2 resolution The minimum measurable time difference in this range is about 4ns Measurement range 0 400ns 25ms In this measurement range an internal coarse counter is used as precounter in order to be able to measure large time differences The fine quantisation unit is started by the triggering edge on the start input It is stopped on the next positive edge of the calibration clock Simultaneously the coarse counter is started This coun ter operates with the positive edge of the calibration clock The fine quantisation unit is started again by the triggering edge on the stop input and is stopped by the next positive edge of the cali bration clock This edge also stops the coarse counter By using this precounter principle very large time differences with the full resolution of the TDC can be measured The measurement range depends on the calibration clock Using a 12 bit coarse counter and a calibration clock of down to 150 kHz allows a maximum measurable time difference of about 25ms Due to the principle this measurement range has a minimum measurable time differ ence of two calibration clock periods typical at SV 25 C Measurement range depends on period of calibration clock TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 7 of 37 2 2 2 Temperature Measurement The
30. e measured time difference in periods of the calibration clock for ex ample in microseconds if one uses a crystal accurate 1 MHz clock The calculation of measurement results is executed by the internal 16 bit CPU if the automatic gen eration of the calibration values is enabled and in addition the Time Registers are selected to be read Since one needs calibration values for the calculation of the time difference two values are generated which represent one and two periods of the calibration clock immediately after the measurement of the calibration clock If the automatic generation of the calibration values is switched off via the MODE Register no val ues for CAL1 and CAL2 are generated and the internal CPU does not execute a time difference calculation the Time Registers remain unchanged TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 14 of 37 3 3 2 Mode 1 Function Measurement Range 1 Since in the mode above time differences which are smaller than 2 calibration clock periods cannot be measured there is a second mode which is qualified for measuring very small time differences This mode is selected by setting pin MODE to 1 or by setting bit 4 of the MODE Register to 1 In this mode the coarse counter is not active The fine quantisation unit is active the whole time FC between start and stop Therefore the maximum measurement range is 2 LSBs In this mode calibration va
31. e reason is that for each time measurement the internal measurement unit is active for only 4 calibration clock periods on the average independently of the time difference to be measured For battery applications this fact is of extreme importance Within measurement range O each time difference is measured with the full resolution of the TDC The absolute accuracy however depends on the frequency accuracy of the calibration clock Using high precision oscillators as calibration clocks one could increase theoretically the absolute accu racy into the area of the resolution 4 2 Measuring in the measurement range 1 Within this range only the internal fine quantisation unit is used Range 1 is selected by setting bit 4 in the MODE Register or the pin MODE to 1 Due to the measurement principle the minimum measurable time difference is about Ans 5V typ The maximum measurable time difference is 2 LSBs It strongly depends on the resolution Based on a minimum resolution of 160ps at 5 5V worst case the maximum measurable time difference is 160ps 216 10us TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 27 of 37 In this measurement range the maximum measuring rate can be achieved When switching off the automatic generation of the calibration values then the TDC original data are available for reading approx 150ns after the stop This is indicated by the RDY flag In 8 bit mode two strobes w
32. ead is done via the MODE Register Write instructions consist of low strobes at the STRB input and the READ pin set to 0 The desti nation of the write instruction is decoded using the lower bits of the data bus The timing diagrams for read and write instructions as well as some instruction examples are re presented in Figure 5 1 of Chapter 5 3 4 5 Writing the TDC The TDC has the two writeable registers MODE and TEMP and an initialization instruction in two versions 3 4 5 1 Write MODE Register If during a write instruction the data input DO is set to 1 then a write access on the MODE Re gister is executed This register is 7 bits wide so that in the 8 bit mode this register can be written in one cycle In the 4 bit mode two cycles are needed Only in the first cycle the data input DO has to be set to 1 Thus first the low order nibble is to be written in the 4 bit mode The bits of the MODE Register have the following meaning D7 NOISE EN 0 enable disable auto noise unit_ D6 Calibrate 10 enable disable separate generation of calibration values DS CAL DIS O enable disable automatic generation of calibration values D4 MODE 0 mode 0 range0 _mode I rangel D3 TDC_Val Force O absolutereadingofTDC original data D2 TDC Val O conditional reading of TDC original data DI Status O readstatusregister_ iii Do select MODE Register U Table 3 1 MODE Register
33. essor Interface io a n nal NS A dae ode un 18 3 4 4 Instruction Set 324 22 ne naniB snkathhunhinbinnsnlinbehlengtke 18 345 Witnes the EDEN essen 19 DAS AL Write MODE Resisier sei ea Eee 19 349 Write LEMPIRAS 20 3 4 5 3 Initialization Instruction INIT HEX 00 or HEX 08 een 20 346 Reading the TDCi ea ui 22 3 4 6 1 Reading the Status Register es ns Ne eo sn 22 34 62 Reading the Time Register nasse einlesen 24 3 4 6 3 Reading the Original Data nee Re nn 24 4 MEASURING FEATURES OF THE TDC5S01 ooooocccnnnnncncconanannnonnnananonnonnncononnnnnnccnonnancononnnnoncnnns 26 4 1 MEASURING IN THE MEASUREMENT RANGE s cccsssssseceessssececsesseeecseseeaeesenesueeecssseeeesesnaes 26 42 MEASURING IN THE MEASUREMENT RANGE Lau ana 26 ZA BUM teen A Te E oe I S Tae sos has 27 4 2 2 Separate generation of calibration values without previous measurement eeeeeeee 27 43 TEMPERATURE MPASUREMENT nes as 28 44 ADDITIONAL OPTIONS PFOR ALEMODES e ries sca iaucehadiacetadactunesnaiandessaasessdiahacacasaadiangnaidasensseces 29 5 TYPICAL INSTRUCTION SEQUENCES AND TIMING DIAGRAMS see 30 TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 3 of 37 6 BPPENDRE SS Einlesen 32 6 1 ELECTRICAL SPECIFICATIONS ccssssccssccccssssssnsccecescesesesenseaeeececcesesesenseaeceseeseseeessaaeeeseseeseeeens 32 6 1 1 Recommended Operating Conditions u a Boe ee 32 6 1 2 Absolute Maximum Rat
34. fter the register has been read The readout of the fourth result is done via 4 further strobes 8 bit mode or via 7 further strobes 4 bit mode after reading the Time3 Register since the read pointer returns automatically on the Timel Register The temperature measurement is executed always in the measurement range O with coarse counter with a following automatic generation of the calibration values and calibration by the 16 bit CPU This makes it possible for example to execute a temperature measurement between time measure ments in the measurement range using the start stop inputs and no automatic calibration meas urement without having to change the configuration of the TDC In the application example above external bipolar transistors are used as switches These transistors are specially qualified because of their very small differential collector emitter on resistance Using the circuit application above a measurement error of only 0 1 o of the resistance relation can be achieved If a minor accuracy e g 3 measurement error is tolerable the TDC offers the possi bility to minimize the number of external components by using directly the ports Pl P4 as switches In order to configure the ports for this mode the pin PMOD must be set to 1 In this mode the ports P1 P4 are high z during the charging phase of the capacitor During the measure ment phase the ports are set to 0 The ports Pl P4 have a guaranteed ou
35. ge CN Ti E AS 30 Mmo n __ Measurement Disable disabled 31 MODE IN Mode Selection of Measurement Range 732 NOEN IN Auto Noise Unit Enable 1 enabled a AA MAA O 3 op II eo AAA O sejak mn Shock Input Schmitt Triggen APA SSA ler m EA RT 2 Power On Reset active high aig 2 Selecion 478 Bit Mode 0 4 Bit Mode 744 ReaD m Read not Write Processor Interface Note In brackets pinout of version 9416E2001 Table 6 3 Pin Configuration TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 36 of 37 6 4 Application Examples using 4 8 Bit Processors 6 4 1 TDC501 with 4 Bit Interface with uPD753xx Processor Measuring in measurement range 0 Start Input LCD Unit TDC 501 uPD753xx Stop Input Wiring for Temperature Measurement P20 P23 P11 INT1 P60 P61 P62 Figure 6 2 Application Example 1 Notes Including external components for temperature measurement Configuration 4 bit data interface Start and Stop inputs trigger on rising edges Calibration clock is generated externally The auto noise unit is disabled Pin NOEN GND can be activated by setting bit 7 in MODE Register to 1 e All unused outputs are to be left open TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 37 of 37 6 4 2 TDC501 with 8 Bit Interface with AT89C51 Process
36. ings sieh iR iss 32 6 2 CURRENT CONSUMPTION dead A CRA aaa SA ee he 33 6 3 PACKAGE AND PIN CONFIGURATION ccccsessesseceeecececsesenseaecececeeseeenenececeseeseseeeseaaeceseeeeseneneas 34 6 4 APPLICATION EXAMPLES USING 4 8 BIT PROCESSORS sc scccscscceesessssececesecseeesessnseeeeeeeesenenens 36 6 4 1 TDC501 with 4 Bit Interface with uPD753xx ProcessoOr ceeecceceseeeeeteeeesteeeenaees 36 6 4 2 TDC501 with 8 Bit Interface with AT89C51 Processor occcononooonoonncncononnnnanananonononnnns 37 TDC501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 4 of 37 1 Introduction MSC Vertriebs GmbH has many years of experience in the development of high precision Time to Digital Converters TDCs MSC s first TDC was developed in 1990 and implemented in a cost effective Gate Array technology Similar to the terms ADC DAC etc MSC established the term TDC Time to digital Converter and patented the measurement principle of the TDC501 which is described in this manual The TDC501 is implemented in a 1 0um CMOS process technology featuring 2 7V 5V operation The chip is delivered in a QFP44 0 8mm fine pitch package Supplied with 5V the TDC501 achieves a typical resolution of 220ps This resolution cannot be achieved using conventional time measurement components The integrated measurement principle together with the technology used allows high precision time difference measurement at
37. ith a period of 60ns are needed for reading out the data and one strobe for ini tializing the chip So the entire measurement time is approx measured time difference 330ns 5V typ When measuring small time differences a measuring rate of up to 2 Mio sec can be achieved 4 2 1 Burst mode If very high measuring rates are to be realised then the processor or the hardware used must be able to select and initialize the TDC501 respectively Since smaller low priced processors are not able to achieve this the TDC provides a so called burst mode available in the measurement range 1 This mode allows to write measurement values to all 3 original data registers So in this mode the TDC can execute up to four measurements without being read or initialized after each measurement Between the measurements there is only a dead time of approx 150ns 5V typ which the TDC501 needs for storing the original values Between the measurements no processor activity is needed In this mode the RDY flag becomes active after the 4 measurement After a burst the 4 measurement values are read conditionally or absolutely in the original data format A new burst measurement can be started with the INIT instruction This mode is activated when e Bit 4 and bit 5 in the MODE Register are both set to 1 e and pin NOEN is set to 1 Even though pin NOEN is set to 1 in this mode the auto noise unit is not enabled This unit is en abled only
38. low power consumption In addition the TDC provides 4 ports for high precision temperature measurement The integration of the TDC501 in battery powered appli cations has become to a common procedure The TDC501 is perfectly suited for measurement of time differences Applications like distance measurement using laser phase measurement ultrasonic positioning temperature measurement etc have been implemented successfully with this TDC many times Go ahead and discover the world of our TDCs TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 5 of 37 2 Overview 2 1 Features Channels one channel with edge sensitive Start and Stop inputs programmable edge sensitivity of the inputs Resolution 5V typ 220ps Measurement ranges 5V typ range 1 short time measurement Ans 14us range 0 long time measurement 400ns 25ms Temperature measurement up to 4 ports available Burst mode up to 4 fast start stop measurements Calibration clock external oscillator clock required 150 kHz 5 MHz Calibration automatically after measurement or stand alone ALU calibration of the measurement values Voltage range 2 7V 5 5V Temperature range 40 C 85 C Processor interface 4 8 bit selectable status flags for interrupt generation Internal memory up to 4 uncalibrated measurement values up to 3 calibrated measurement values Configuration software and hardware configurable Me
39. lues CAL1 CAL2 are generated automatically after time measurement when desired and a time calculation is executed according to the following formula Ti el ith OFF 2 Call Cal2 ime u Cal2 Call MA un Note If the time difference is to be calculated by the internal CPU then this time must be smaller than two clock periods of the calibration clock Example If a 1 MHz calibration clock is used then the internal CPU cannot calculate time differences beyond 2us Thus the calibration clock has to be selected properly In order to achieve high precision accuracy when measuring in the measurement range 1 the calibration clock should be selected in such a way that the time difference to be meas ured is in the range of the calibration clock period length In doing so be sure that the time of two periods of the calibration clock is smaller than 2 LSBs Otherwise the fine quantisation unit would overflow during the generation of the calibration values 3 3 3 Principle Function of the Fine Quantisation Unit Within the fine quantisation unit a new digital measurement principle is applied which is based on the utilization of gate delays This measurement principle is a patent of MSC During the time between start and stop an impulse is sent through a closed chain of simple logical basic elements whereby the number of all the runs through the whole chain is taken in account in the count_reg When turning off the actual status of the
40. ment with P1 or P4 Time2 measurement with P2 Time3 measurement with P3 A special feature applies to P4 Since the TDC501 has only three Time Registers the result of P4 remains in the original data registers without being calculated After the result of Pl stored in the Timel Register is read the calculation of P4 is started and the result is written automatically into the Time Register After reading the Time3 Register the read pointer automatically returns to the Timel Register So the result of P4 can be read Note The temperature measurement is only executed correctly if bit 3 in the MODE Register TDC_Val Force is set to 0 and pin MDIS is set to 0 TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 29 of 37 4 4 Additional options for all modes Two options can be operated together with every other mode e The automatic generation of calibration values after a measurement e The auto noise unit The automatic generation of calibration values is enabled if bit 5 of the MODE Register CAL_DIS is set to 0 This is default If this option is enabled after each time measurement a calibration measurement follows automatically The TDC executes two measurements of one and two periods of the calibration clock and stores the calibration values in the appropriate original data registers The auto noise unit can be enabled either by setting pin NOEN to 1 or by setting bit 7 in
41. nput Unit The input unit receives the incoming start stop signals and generates as a function of the selected mode the appropriate start stop signals for the fine quantisation unit The start stop inputs have a disable pin MSDI Setting this pin to low enables the measurement unit to receive start stop signals Setting this pin to high disables the start stop inputs If the meas urement pins are disabled after a start signal has been received a stop signal will not reach the measurement unit In this case the measurement unit continues measurement and will if the inputs are not enabled again generate a timeout overflow This can be used for gating stop signals without affecting the measurement 3 1 1 Auto Noise Unit The typical average LSB width of the TDC501 is 220ps SV typ In single shot mode a standard deviation of the measurement values about 1 4 LSBs including the calibration error can be reached By multiple measurements and arithmetic averaging a standard deviation of approx 0 01LSB can be achieved To increase accuracy of measurement in such a way the characteristic of the TDC501 has to be sampled at as many positions as possible This is not achieved by measuring constant time differences e g clocks generated by quartz oscillators etc Example When measuring a crystal accurate clock it is not possible to achieve a substantial accuracy im provement by averaging since the characteristic of the TDC is almost always s
42. or Measuring in measurement range 1 Start Input Stop Input Vcc P1 0 P11 P12 P13 5 PLA PLS TDC 501 P1 6 P1 7 P3 0 RXD P3 1 TXD P0 4 P0 1 P05 P0 6 P0 7 PSEN ALE PROG P0 2 P3 2 INTO Figure 6 3 Application Example 2 Notes Configuration 8 bit data interface Start and Stop inputs trigger on rising edges Calibration clock is generated externally Auto noise unit is enabled NOEN Vcc In the burst mode the auto noise unit is enabled only if bit 7 of the MODE Register is set to 1 e All unused outputs are to be left open TDCS501RefManEngV 12 doc Version 1 2 Author UW AP
43. ritten Table 3 5 Function of Timel and Time2 Important note If the Status Register is selected as read source within the MODE Register no time difference cal culation can be executed by the internal CPU So before the start of a measurement the Status Register may not be selected for reading if a calculation of the time difference is to be executed The status of RDY and TIMO can be determined during such a measurement by reading the appro priate pins TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 24 of 37 3 4 6 2 Reading the Time Registers The three 28 bits wide Time Registers of the TDC501 are selected for reading when the three bits TDC_Val Force TDC_Val and Status of the MODE Register are all set to 0 In accordance with Table 3 6 in the 8 bit mode 4 STRB strobes are necessary to read out one Time Register For each Time Register the least significant byte is put on the data bus first If all Time Registers are to be read 12 STRB strobes are needed STRB Value 1 Timel 0 7 Timel 8 15 Timel 16 23 Timel 24 27 4 MSBs set to 0 Time 0 7 6 Time2 8 15 8 EIN 1 Time2 16 23 Time2 24 27 4 MSBs set to 0 Time3 0 7 Time3 8 15 Time3 16 23 Time3 24 27 4 MSBs set to 0 0 1 Table 3 6 Reading of the Time Registers in 8 bit mode Since the read pointer is reset automatically after any write instruction e g INIT to the
44. switched to 4 bit or 8 bit by setting a pin This bi directional data bus allows the configuration of the TDCS501 as well as the readout of the measurement results No further hardware is required to communicate with standard microprocessors Two interrupt sources are available RDY This flag signals the end of a measurement and that valid data is in the registers TIMO This interrupt signals measuring range exceeding of the fine quantisation unit or over flow of the coarse counter The interrupt sources can also be determined by reading the status register TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 8 of 37 2 3 Block Diagram amp Y Q S A S a E 2 E is E Z an ca A A i ry Y AU T MdO nd onuoy dad vl El El E A gt oo og ooN a ES J9ISIS9Y NAO A O E 42 10u00 an NO A ALU 1 13ND g T 3ou d i i Measurement soy Junoy Lg Unit im S 2 d a aN SAN to on 5 2 19 UNO 95180 2 5 So Ea SE 2 Z za N VEN a gt ES gt as 9 S 3 Th eS th Yyyy AA AAA A l Ban 233 jalg Figure 2 1 Block Diagram al DO ZS 2 z 3 TDC501RefManEngV12 doc Version 1 2 Author UW AP User Manual TDC501 Page 9 of 37 3 Functional Description 3 1 I
45. t gt 1 5ns 3 Write MODE Register 4 Bit Mode Data lt 3 0 gt gt 1M0 M1 M2 gt M3 M4 M5 M6_ gt Don t C STRB lt gt 30 ns gt READ DontC Don t C 4 Read Timel Register 8 Bit Mode Data lt 7 0 gt a 5 gt ni gt Time1 lt 7 0 gt Time1 lt 15 8 gt Time1 lt 23 16 gt Time1 lt 27 24 gt 28 31 0 STRB READ oe Figure 5 1 Timing diagrams 5V typ TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 32 of 37 6 Appendix 6 1 Electrical Specifications 6 1 1 Recommended Operating Conditions Operation of the chip outside the recommended range will affect the device reliability and a perma nent function of the chip cannot be guaranteed min max min max Input Voltage Vi 0 vD 0 VD V Ambient Temp Ta 4 85 0 m C Input Low Voltage VIL_ __D__ O3VDD o os NV pos ttigger Voltage Vp 18 4 12 24 N neg trigger Voltage rise time falltime me 0 200 o 2 m Schmitt Trigger ttf 0 10 0 10 m Note Outside this range TTL level specifications can not be guaranteed Table 6 1 Recommended Operating Conditions 6 1 2 Absolute Maximum Ratings Operation of the device outside the specified ranges may damage the chip Symbol Power Supply VDD EEE VO Voltage vivo 05 WDD 0 5 IOL min 9 0 mA Operating Temperature Range Topt 40 85 Storage Temper
46. tor The discharge time down to the trigger level of a Schmitt Trigger is measured with the TDC s measurement unit As suming that the resistor at port Pl is the reference resistor the measured time differences for the unknown resistors at the other ports divided by the measured time difference for the reference re sistor result in a function which is linearly dependent on the unknown measurement resistors Using this method it is advantageous that the absolute value of the capacitor and the operating vol tage do not affect the result of measurement Only fluctuations during the actual measurement time would affect the results negatively Since the differential internal resistance of the switching transistors affects the result of measure ment the output buffers of the TDC501 are capable of driving external bipolar transistors directly Even with simplest bipolar transistors an accuracy of far under 1 parts per thousand can be achieved For less accurate measurements however the port pins can be used directly The temperature measurement is always executed in the measurement range 0 independently of the adjustment of the MODE Register followed by an automatic generation of the calibration values and the calculation of the measurement result for each port When all of the measurements and calculations are completed the RDY Flag is set to 1 Then the results of the Time Registers are to be read in the following order Timel measure
47. tput current of Io 24mA at VDD 5V The temperature measurement is a pure relation measurement Neither the absolute value of the capacitor nor that of the calibration clock affects the accuracy Only the short term stability of these two values is important TDCS501RefManEngV 12 doc Version 1 2 Author UW AP User Manual TDC501 Page 13 of 37 3 3 Measurement Unit After the start stop signals have been processed by the input unit or generated by the temperature measurement unit they arrive at the fine quantisation unit and the coarse counter The fine quantisation of the measurement results depends on the selected mode 3 3 1 Mode 0 Function Measurement Range 0 This is the default mode of the TDC The coarse counter is enabled The measurement is executed in accordance with Figure 3 3 cal a gt FC FC2 car Ir Start p Stop Run Coarse Count FC1 FC2 Time C C _ _ ime oarse Cal Call Figure 3 3 Measuring in Measurement Range 0 As shown in Figure 3 3 the fine quantisation unit is active only during the times FC1 FC2 CALI and CAL2 These values together with the value of the coarse counter represent the original data of the TDC Thus the power consumption of the chip in this mode is relatively independent of the measured time difference With the above formula for calculation of time one obtains a measure ment result that represents th

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