71M651x Power Meter IC
Contents
1. the security enable bit is reset whenever the chip is reset Hardware associated with the bit permits only ones to be written to it Thus pre boot code may set SECURE to enable the security feature but may not reset it Once SECURE is set the pre boot code is protected and no external read of program code is possible The SECURE_E fuse must be blown to enable SECURE set If SECURE_E is not blown SECURE may not be set The SECURE_E fuse may not be overridden with FOVRIDE Specifically wnen SECURE is set e The ICE is limited to bulk flash erase only e Page zero of flash memory the preferred location for the user s preboot code may not be page erased by either MPU or ICE Page zero may only be erased with global flash erase Note that global flash erase erases CE program RAM whether SECURE is set or not e Writes to page zero whether by MPU or ICE are inhibited If the emulator clock is disabled with ECK_DIS the emulator is indeed locked out This would provide some measure of security but since the bit is reset when external reset occurs the tamperer could break in to the MPU before the MPU sets the ECK_DIS bit Once the meter cover has been penetrated components can be altered When the FLASH is programmed is the complete FLASH erased first ensuring that no residual program is left before a new image is programmed Yes If customers use the unused FLASH as non volatile storage for total energy consumption for example t2. ADC decimation filter are completely cleared between samples Also sufficient time for the ADC modulator to settle to the new multiplexed value is provided before the filter begins calculating the new value Does TDK have a patent on the single ADC with MUX TDK Semiconductor has a patent that is filed and pending 12 20 2004 3 30 PM 10 29 71M651x Power Meter IC FAQ Can see the raw ADC samples The CE creates an interrupt at the 2 520Hz rate which tells the 80515 MPU when new ADC data is available By using RTM mode data transfer and an external processor or a host PC running LabView software it is possible to capture raw data The SSI interface may also be used to get access to raw data samples Can you explain the input stage of the ADC i e how we can measure the 250mV swing What is the common reference point for each phase The common reference point is the V3P3 supply The input looks like a small capacitor that switches between the input and V3P3 Can the reference voltage of the ADC be made flexible in the range from 0 125V to 0 5V Also it should be possible to amplify its value First the dynamic range of the current input is 2000 1 The current internal Vref is designed with 10ppm temperature stability In case the range is to be increased beyond the specification the CE Engine input sample gain can be modified The 71M6511 13 have not been tested with external reference since the internal reference is alread
3. a delay in time phase error between each sample For instance if V and are sampled they will be sampled at different times how is the delay between the samples accounted for Is this done automatically by the firmware It is important that the and V samples of a given phase have zero relative delay The samples are initially shifted apart in time due to the single converter Our baseline code automatically corrects for this shift with an all pass filter on the voltage side This correction is robust giving the proper correction at 50 and 60Hz as well as higher harmonics The all pass filter is controlled by a single constant Minor adjustments to the constant permit delay compensation for phase mismatches in voltage and current sensors What is the sampling rate of the ADC of the 71M6511 and 71M6513 and up to what harmonic can these chips measure measurement accuracy The front end sample rate of the ADC i e the speed of the modulator in the delta sigma ADC is 5MHz One full cycle of 13 multiplex states occurs at 2 520Hz i e each channel is sampled at 2 520Hz The system meets all known harmonic accuracy specifications including IEC 65053 22 5th harmonic and the harmonic specifications published by some manufacturers that cover the range up to the 21st harmonic Although only one ADC is used in the 71M651x devices to reduce crosstalk between channels how is the cross talk between samples reduced The contents of the
4. accumulations with capacity left over This is especially true in the single element residential case What is the main use of the RAM in the 71M6513 6511 devices The 71M651X have 2kB RAM for the 80515 MPU used for metering and data storage 1kB RAM CE Data Compute Engine Data Storage 4kB RAM CE program Compute Engine program Is there any information on the SFRs that are implemented and how to use them other than what is in the files reg805151 h and sfrs c The SFRs are described in the Software User s Manual How can update flash without using the ICE To read values from the CE it is better to switch the CE off using the CEO command through the serial port and then read the information This causes the information to be consistent Power Fail Circuitry Reset and Watchdog In the TDK 71M6153 and 71M6511 devices is the MPU involved in servicing the power fail interrupt or is this implemented fully in hardware What is the reaction time to a power fault The part has a hardware monitor to observe the power supply Its reaction time is a few us The demo code does not have any fault detection in the CE although it could certainly be added Do the 71M651x devices have integrated Power On Reset circuitry Yes the 71M651x devices have on chip power fault detection and reset circuitry This is implemented by using the on chip comparator for generating the Reset pulse for external devices The trip point is programmed ext
5. amount of adjustment must be decided in advance and is read from a table whose x axis is temperature and y axis is the amount of adjustment The accuracy and range limitation are shown below Range limitation The gain of the voltage and current paths are varied by multiplying by an integer gain constant The gain will be zero when the constant is zero Typically the constant is 2 for current and for voltage The maximum value for either constant is 2 Thus the adjustment range is from 0x to 2x CE demo software limitation Accuracy limitation 1 The temperature sensor measures the temperature deviation from room temperature It is accurate to 1 degrees at temperature extremes It is repeatable to 1 degree estimated at room temperature Thus a probable temperature tolerance is TempError degrees 1 T Troom 0 16 This is a CE hardware limitation 2 The typical value of the gain constant is 16384 Thus the resolution of one step 1 LSB is 0 0122 This is CE demo software limitation 12 20 2004 3 30 PM 15 29 71M651x Power Meter IC FAQ 3 The temperature of the 651X IC is assumed to be the same as the temperature of the component being compensated The self heating of the 651X IC is estimated to be less than 3 degrees Compensation accuracy depends on the predictability of the component being compensated 12 20 2004 3 30 PM 16 29 71M651x Power Meter IC FAQ Calibration Do I have to follow the calibration pr
6. changed in the B02 version so they can generate interrupts This approach permits the CE to select an active phase and perform de bounce filtering on it In fact the CE demo code already does this in the frequency determining FLL module The question of how the accuracy might be disturbed due to the extra processing performed each mains cycle in the 80515 MPU is a good one and a sound reason why other approaches should be considered first Approach 2 The CE can be programmed to accumulate cycle counts during each XFER interval The demo code creates XFER intervals at approximately a 1Hz rate corresponding to an exact number of crystal clocks and interrupts the 80515 MPU when the interval has expired The XFER interrupt handler is the primary interrupt handler in the 80515 MPU demo code It reads the CE accumulators and updates the 80515 MPU Wh and Varh registers It could also be programmed to update its RTC with the count of main cycles occurring during the interval The advantages of this approach are twofold There is no 50 60Hz processing overhead and the load on the MPU is reduced Approach 3 Two new bits have been added to the B02 version of the 6513 These bits allow the MPU to easily add or subtract 1 second from the hardware RTC The intent is that they permit the RTC to be calibrated and temperature corrected in a way not affecting the meter accuracy The best approach for mains locked RTC is to use the cycle count accumulated in approach
7. general DIO The five LCD outputs SEG3 SEG7 are shared with the SSI interface and are not general DIO The 71M6511 has no general DIO pins The four COM pins COMO COM3 and the 15 dedicated segment outputs SEGO SEG2 SEG8 SEG19 are to be used to drive LCDs only The 24 multi use pins SEG24 DIO4 SEG31 DI011 SEG34 D1014 SEG37 DI0O17 can be either LCD outputs or general DIO The five LCD outputs SEG3 SEG7 are shared with the SSI interface and are not general DIO Do the digital I O pins in the TDK 651x devices have enough capability to drive LEDs directly Yes but a current limiting resistor will be necessary to drive LED s 12 20 2004 3 30 PM 20 29 71M651x Power Meter IC FAQ Are the LCD I Os on the TDK 71M6511 6513 capable of driving dot matrix displays 2 line x 16 characters No The LCD can drive up to 168 individual dots 5 25 dots per character Can the 71M6515x devices use 3 common 33 DC for display bright contrast The 71M651X chips support this mode There is also a voltage DAC for adjusting the contrast How many LCD segments can the TDK 71M651x devices drive The 71M6513 can use up to 42 segment pins that along the 4 COM pins can drive up to 168 LCD segments The 71M6511 can use up to 32 segment pins that along with the 4 COM pins can drive up to 128 LCD segments The 71M6515 does not drive an LCD Can programmable pulse outputs with separate pulse dividers and pulse widths implemented The user can use
8. larger than the register should hold However when the register gets updated e g every minute the minute register is updated the register will go back to a legal number range Generally entries to the RTC should be checked for validity before they are written to the RTC registers What is the max value that can be held in the RTC before it wraps around The maximum RTC value is 255 years i e the year 2255 Do the 71M651x devices provide the 32K RTC clock as a buffered output The RTC clock is an output option of TMUXOUT want to implement a 1ps timer Having looked at the timer c code the T0 T1 timers have a 10ms granularity and need to be manually restarted using the appropriate api call know from previous experience with 8051 52 that T0 T1 timers can be 8 bit reloadable TxM1 M0 10 in TMOD SFR Is this implement in the timer API Otherwise will have to change the timer API which may affect other functions within the LAPIE Each instruction needs 12 clock cycles so a timer with 1 works at 5 12 MHz speed meaning 2 4 microseconds We recommend using timers for intervals of more than 100 microseconds The current timer interval of 10ms is useful for running the APIs and to verify if there is any activity on any I O ports There is a second timer T2 mentioned in the reg80515 h file Do have access to T2 No T2 does not exist in the 71M651X and there is no MDU Multiply Divide unit Is drift in the watch crystal co
9. the one of general purpose I O ports and can program to generate desired pulse output How does the voltage boost work Please explain the various pins VDRV VLCD of the 6511 and 6513 VDRV is an output that generates AC when the LCD_BSTEN bit 0x2020 bit 7 is set If the AC from VDRV is applied via a small capacitor e g 33nF and a diode to a large reservoir capacitor e g 220nF this large capacitor builds up 5VDC An example for this circuit is implemented in the Demo Boards See the Demo Board User s Manuals for the schematics VLCD is an input If the 651X drives 3 3V compatible LCDs the voltage at this input should be 3 3V If it drives 5V LCDs either 5VDC generated by the VDRV pin or any other 5V source should be applied to VLCD 12 20 2004 3 30 PM 21 29 71M651x Power Meter IC FAQ Other Interfaces SSI 12C SPI UART RTM Optical Does the UART speed rely on the MPU clock divider in the TDK 71M651x device Not until the MPU can t service the port fast enough We are presently running 9600 baud at 1 8 of 5MHz The clock speed of MPU drives the UART baud rate What is the maximum speed of the two communications ports What is the limitation on the optical port What are the available divide ratios for the baud rate generator We have run the COM ports at 38 4kbaud and believe they can go faster with more care in the 80515 MPU program The two COM ports are the same with the exception that the optical port has an analog
10. to power the meter at 240V RMS or higher The voltage divider on the 71M651x demo boards seems to be much larger than would be required even to support a 480V AC phase voltage while staying within the 250mV pk maximum voltage on the IC Does the accuracy diminish as the maximum and minimum values are approached on the voltage and current inputs 600V RMS is also the full scale voltage assumed by the resistor divider In other words 600V RMS corresponds to 250mVpk at the ADC The current scaling maps 210A RMS to 250mVpk The ADC is extremely linear from 250mVpk on down Full scale ADC clipping occurs at around 330mV depending on the exact value of the reference It is better to design the voltage divider to take 20 above the rated voltage to take care of thermal drifts Is the 71M6511 6513 able to support the use of resistive shunts to directly measure current What is the smallest input voltage at which 0 1 to 0 2 accuracy can be supported The 71M6511 613 Demo Boards were designed for use with a current transformer CT input and have to be modified and rerouted for a current shunt input to prevent quantization noise at the super low end shunt voltage input Also the CE program has to be modified to amplify the current gain 8x With these modifications the 71M6511 6513 has been tested with a shunt connection and its accuracy has been tested over the range of 125 to 0 1Amp The accuracy was within 0 1 to 0 2 down to 0 3A and lowe
11. 053 23 The 71M6511 and 71M6513 devices were designed with IEC62053 in mind and exceed its accuracy requirements for both active energy and reactive energy Can the 71M651x devices handle both 50Hz and 60Hz line frequencies Yes our demo code works properly with both 50Hz and 60Hz lines It also works properly with frequencies above and below This is necessary to meet the 2 frequency tolerance required in some specs Can the TDK 71M6513 generate 2 additional output pulse selected sources Yes The 71M6513 can generate additional pulse outputs Four outputs configured as Import W Export W Cap VAR Ind VAR are quite feasible It would be implemented with changes to both the CE and 80515 MPU code No hardware changes need be made The 71M6511 3 measures both V and I and does the power calculation But can the V and measurements be displayed directly Yes The demo code can be used to display the voltage and current 12 20 2004 3 30 PM 6 29 71M651x Power Meter IC FAQ Pulse Frequency and Width Can the Wh and VARh pulse outputs be changed to measure other functions Yes Can the pulse widths be adjusted Yes The variable PULSE_WIDTH can be used to program pulse widths other than the default 50ms What is the variable range of pulse rate of 71M6513 and is the step is fixed or random The pulse rate is programmable using the WRATE constant The scaling is up to the programmer In the TDK 71M6511 and 71M6513 can the Wh and VA
12. 1 6511H can easily be verified by connecting a DMM between the BT1 header and the battery Power sags and brown outs can be simulated by modulating the 5V power supply and verifying that all functions RTC XRAM are properly maintained while the main power is down Note Revisions A and B02 of the 71M6513 6513H or 71M6511 6511H will loose the RTC while power is down even if a battery is attached How can I test power consumption of the chip on the Demo Board When power consumption is measured it should be noted that the shunt regulators will cause relatively high con sumption when using the supplied 5V power supply This is due to their function similar to zener diodes e causing a voltage drop of 5V 3 3V across a low ohmic resistor Once a regulated power supply is used and adjusted close to 3 3V the total power consumption of the Demo Board will drop rapidly giving a good indication of the chip s potential performance A few components around the 71M6513 6513H or 71M6511 6511H will contribute to the power consumption as will the operation mode of the chip See the section Power Saving Measures located in the appendix of the Demo Board User s Manual for a detailed description of how power can be saved How can access the I O memory using the serial commands that come with the Demo Board The following command lets you read and write all l O memory locations gt RI20 reads hex value at address 2020 LCD_BSTEN gt RI20 0E w
13. 2 to determine when the hardware RTC time needs to be corrected This way the hardware RTC can be used to keep track of hours days months years etc This also provides a seamless method for bridging power outages Is there an interrupt available with the output of the energy pulse Are there interrupt priorities Yes there definitely are interrupt priorities and the 80515 MPU code is entirely interrupt driven The CE pulse output can be configured as an interrupt What is the range of pulse rates available from the Wh and VARh test LEDS The pulse generators are implemented entirely within the CE and are therefore easily customizable Since the CE sample rate is 2 520Hz the maximum pulse rate is half that or 1 260Hz The demo generators are 32 bit rollover enabled integrators whose output is their sign bit They naturally provide a 50 duty cycle The pulse width could be modified with further CE code The pulse rate is entirely programmable within the lt 1 260Hz upper limit 12 20 2004 3 30 PM 28 29 71M651x Power Meter IC FAQ In the 71M6513 can the V l samples be re aligned for each phase since they may be 7 degrees apart or are all the samples aligned for all 3 phases or is each phase sample set V I independently Each V pair is phase aligned to itself and not to the other two pairs The uncorrected phase error is actually 2 13th of the 2 520Hz period or 1 1 degrees at 50Hz What is the accuracy of the frequency measurem
14. A TDK 71M651x Power Meter IC TDK SEMICONDUCTOR CORP B DECEMBER 2004 TDK 71M651x Power Meter IC Frequently Asked Questions 12 20 2004 3 30 PM meter support tsc tdk com This product is sold subject to the terms and conditions of sale supplied at the time of order acknowledgment including those pertaining to warranty patent infringement and limitation of liability TDK Semiconductor Corporation TSC reserves the right to make changes in specifications at any time without notice Accordingly the reader is cautioned to verify that the data sheet is current before placing orders TSC assumes no liability for applications assistance TDK Semiconductor Corp 6440 Oak Canyon Rd Irvine CA 92618 TEL 714 508 8800 FAX 714 508 8877 http www tdksemiconductor com 2004 TDK Semiconductor Corporation 12 16 2004 rev 1 1 1 29 71M651x Power Meter IC FAQ Contents Contents A ie 2 Metering Methods and CONNECtIONS oocooocccnnnnoccnnnoccccnononnnononnnn narran 3 Pulse Frequency aid WidWitiiiroiinata rre llana lar 24 estate Pinilla ta 7 Metering Accuracy and Harmonica miccional pena ia cid 8 Sensors and Analog Front End iii oo 8 Multiplexer and AD Ci A ee 10 Memory and Memory Secufity 2 enve anata he ei aces 12 Power Fail Circuitry Reset and Watchdog c rcscccceecsccecnndatceseeduedecsatecegeuedendeensiereedecdeednapetesnsanedteneieceaceedeessieenssecd ndveppueeedneese 13 Temperature COMpenS atm dis 15 CA
15. Also the chip temperature is measured This application uses a 3 pole Gaussian low pass filter with the following characteristics 119dB 50Hz 3dB 0 28Hz Settling time to 0 1 3 0 seconds Settling time to 1ppm 4 3 seconds The resulting circuit had 4 stable digits of display 12 20 2004 3 30 PM 27 29 71M651x Power Meter IC FAQ Miscellaneous Is there a zero crossing for mains locked RTC and can one of the input pins be used as a comparator to interrupt the MPU on each zero crossing in the 71M651x devices Will this load the ADC voltage input leading to inaccuracies Since the built in RTC is based on the watch crystal a mains based RTC will be a second RTC implemented entirely in 80515 MPU code unless approach 3 is used Approach 0 Yes one of the comparators could be used as a 60 50Hz MPU interrupt This approach requires that the 80515 MPU performs de bouncing and that one selected phase is hardwired to the comparator Accuracy effects are also of concern Approach 1 There are direct 71M6513 outputs that can be issued by the CE Presently the CE demo code uses them as Wh and VARh pulse outputs One of them could certainly be converted to a glitch free 60 50Hz output and be configured to interrupt the 80515 MPU Note that these two outputs are one of the few functions that don t work in our A01 silicon version Also the specification states that when configured as outputs DIO pins can t interrupt the MPU this is being
16. LI ATOM araiciisiita itsio 17 CE Featuresis oia iio pisa 18 RIG Clock and Tie iii A A A AA EA cad daa cia caia 19 Digital Ozand LEDO e ie 20 Other Interfaces SSI I2C SPI UART RTM Optical 0 cccecceececeeeeeceee eect cece eeeeeae cess eee ceaaaeeeeeeeseseaeseeeeesecaeaeeeeeeeseeseaeeeeees 22 ICE Programming Debugging and FirMWare oooonnccnnonicnnoconcnnnoncncnano cnn crono nn 22 Tamper DISE ile p aerae EEE E E S A EEE EA E A E EAE E E E E E E E E E 24 AEN E EE E T AE A e 24 Voltage Power Requirements Battery OperatiON ooononccnninociconoccccnononcnonononcnnnon cnc canon nr rnnnn cnn nao rn nnn rr rana nn r nan r nr r EAEE rra nan EE EEEE 24 Demo Board Questions 20 A id 25 Scale and Other DC Appi A ONS a a r r raa nn nn conca a e aE aa a e E a a eraa aee eia 27 MiscellanedUs 3 A A A a a a eNe 28 12 20 2004 3 30 PM 2 29 71M651x Power Meter IC FAQ Metering Methods and Connections Can the IB input in the TDK 71M6511 be used to implement a 3 wire single phase meter or is the accuracy of this input restricted The IB input offers full accuracy and can be used to implement a 3 wire single phase meter for the second current input The multiplexer function has to be modified by selecting the proper meter equation in order to accept this input When connecting Neutral to V3P3A what are the consequences concerning isolation of the IA B C and VA B C sense inputs with other parts of the 651x i e is there a chance tha
17. Rh pulses from the CE be programmed to provide ve VARh and ve VARh Are the ve and ve signs associated with the phase angle and hence the quadrant in which the power vector is Yes this is possible and is a useful quantity in four quadrant metering The power measurement is classified as positive reactive power based on the sign of measured reactive power which is also called lagging reactive power Similarly if the sign is negative the reactive power is also known as negative reactive power These quantities are programmable by the user for pulse output Can the Wh VARh output pulse rate of the TDK 71M6513 and 71M6511 be altered to implement an integer value Yes The output pulse rate can be altered by modifying the WRATE cal constant with the on board 80515 MPU 12 20 2004 3 30 PM 7 29 71M651x Power Meter IC FAQ Metering Accuracy and Harmonics What does the 63rd harmonic become in a 50Hz system and is it detectable In a 50Hz system the 63rd harmonic is 63x50Hz 3 150Hz Our exact sampling frequency is 32 768Hz 13 2520 6Hz The aliased signal will be 629 4Hz and will be detectable Sensors and Analog Front End What is the maximum AC voltage that can be applied to the power supply on TDK 71M651x Demo Boards The maximum AC voltage can be applied to the demo board is 600V RMS with respect to Neutral This limit is set by the 1000V rating of the C6 capacitor on the demo board The value of the capacitor is sufficient
18. X 5 7703 10 16384 3600 WRATE 3 2Wh WRATE CE register location 2D is 1024 For the 71M6511 6511H WRATE is 2334 so that the equation becomes Kh IMAX VMAX 4 11021 10 16384 3600 2334 1 0Wh How would conduct EMI testing on the Demo Board The Demo Board is not a reference design and it is not optimized for EMI As a starting point the Demo Board may be operated in an EMI laboratory in order to test electromagnetic emissions and susceptibility The layout of the Demo Board is not optimized for EMI emissions Similarly the Demo Board does not have provisions for protection against high energy bursts Tranzorbs MOVs capacitors and the like must be added to properly protect the Demo Board ESD discharges directly to the Demo Board surface and or LCD must be avoided As in a finished meter product a certain distance e g one inch between the viewing window and the display has to be maintained for ESD immunity How can test power down brown out and battery operation with the Demo Board 12 20 2004 3 30 PM 25 29 71M651x Power Meter IC FAQ Power down brown out and battery operation can easily be simulated and evaluated with the Demo Board A 3 6 volt battery should be connected at the two pin header labeled PT 1 and the corresponding jumper at JP8 should be connected between the pins VBAT and BATTERY With the 5V power supply removed the battery current drawn by the 71M6513 6513H or 71M651
19. and would offer much lower long term drift Accuracy should be quite good The best result would come from allocating one or more of the six primary inputs as a zero reference input The V3 input can t be used because it is referenced to VBIAS and will likely have a different offset 2 Sensor offset This effect could be quite significant in the case of Hall sensors or if a pre amplifier is utilized There is little that could be done here to fight offset 3 Numerical calculation offset Truncation of 2 s complement words generates a negative offset This offset can be predicted and cancelled within the CE code What is the common reference point for each phase for inputs to the ADC of the TDK 71M651x devices The common reference point is the V3P3 supply The input stage of the ADC looks like a small capacitor that switches between the input and V3P3 Can the EQU setting in the 71M651x devices be used to momentarily switch from 3 phase to 1 phase measurement and then back again Yes one could change the equation specified by EQU on the fly The customer would have to decide what to do with the lost 3 phase data The demo code measures power in each phase The three individual phase powers are manipulated according the EQU defined for operation The demo code could be modified to permit individual phases to be output Can the TDK 71M651x devices measure reactive current Yes Assuming that the current is 90 degrees out of phase with the v
20. comparator on its RX and a tri statable output driver on its TX Software setup for both ports is slightly different The available baud rates are 2400 4800 9600 19 2 38 4 76 8 153 6 but the 80515 MPU may not be able to keep up with baud rates above 38 4kbaud The 115 2kbaud family is not available What is the speed of I2C on the DIO04 and DIO05 The 1 C speed is 78kHz What are the choices for a digital interface to the 71M6513 11 devices 1 SPI master output only The RTM output permits 4 selected 32 bit words to be output each CE code pass The code passes are at 2 520Hz rate resulting in an average throughput of 322kbps Each group of 4 words can be output at 5MHz bit rate with a long pause until the next code pass During the gap the 80515 MPU could select a different list of output words This is the fastest and easiest way to output 16 bytes For customers who want to output a specific collection of data each frame time the 80515 MPU could be programmed to sequence the desired words out through the RTM The control interface could be implemented in 12C serial port or be output on general I O pins using the bit bang scheme 2 C Master only The clock rate is 78kHz If the external processor wants to receive values for temperature frequency Wh VARh Vh and Ph it needs 6 32 192 bits each frame At a 1Hz frame rate this is easily within the capability of the 1 C interface Being unable to implement slave mode may be a probl
21. em if the processor wants to talk to other IC devices 3 Bit banged parallel In block mode this could be as fast as 100kHz word rate 16 bit word If a handshake is used for each word the rate probably drops to 10kHz There is a concern here that the 71M651X couldn t recognize a write strobe fast enough to recognize the data 4 Serial port This port can run faster than 9 600 baud But even at 9 600 baud it is fast enough to transfer 192 bits per frame What is RTM RTM stands for Real Time Monitor RTM is programmed through the debug board to monitor Compute Engine RAM data Please refer data sheet for more RTM timing info RTM data can be connected to a DSP or other external equipment to obtain and analyze raw sample data ICE Programming Debugging and Firmware Is the debug port that appears on the 71M6511 and 71M6513 demo boards a JTAG port 12 20 2004 3 30 PM 22 29 71M651x Power Meter IC FAQ The debug port is not a JTAG port per IEEE 1149 The debug port is used for connecting a PC COM port serial port to the chip via the Debug Board This will give the user an option for observing and altering internal parameters of the meter device by connecting a terminal or by using PC terminal software Does the ADM51 ICE function well when connected to the 71M651x demo boards during live measure ments Yes There is no change to the accuracy with the ICE connected or disconnected The same is true of the Debug Board I
22. ent The frequency measurement in the Demo code can be considered ideally accurate within the constraints of crystal accuracy with zero mean AC noise added The AC noise is 0 25 pp and is averaged away during Watt and VAR measurements When the 71M651x devices store the V l samples are they the phase shifted versions with the INTERP compensation already applied Yes Is there any way to improve speed on the voltage and current estimates Yes the XFER rate is 1Hz in the demo setup PRESAMPS 42 SUMCYCLES 60 The rate is highly programmable however since it is the 2 520Hz sample rate divided by the product of PRESAMPS and SUM_CYCLES where PRESAMPS can be 42 50 84 or 100 and SUM_CYCLES can be any value from 1 to 63 The concept is that accumulation should occur in two steps a fast accumulator that accumulates one or two cycles and provides info to the CREEP discriminator followed by a slower accumulator which slows the 8051 interrupt rate substantially CE code can be modified for voltage sag swell Perhaps this could be done at the same time as CREEP or perhaps the XFER rate could be increased If an entirely different circuit is needed there is still plenty of code space data RAM and code cycles available in the CE In the 6515 data sheet a zero cross function is mentioned Can this be used for synchronizing the RTC to the 50Hz 60Hz mains period The main purpose of the zero cross detection is to announce the presence of vol
23. ernally with a pair of resistors Do the TDK 71M651x devices have the capability to reset without external stimulation The chip has internal detection of power_ok and power_not_ok states It uses an external resistor divider so customers can select the trip voltage This should be more economic than a large external RC time constant Are there any limitations on the reset circuit No the reset circuit works well on the demo boards properly resetting the chip on both fast and slow power up sequences 12 20 2004 3 30 PM 13 29 71M651x Power Meter IC FAQ Is the watchdog timer implemented in hardware Yes the robust watchdog timer is implemented in hardware with a fixed 1 5s timeout The generic 80515 MPU programmable watchdog timer is also present Do the 71M651x devices have a robust watchdog timer Yes The 71M6511 6513 parts have a 1 5s independent watchdog timer that cannot be turned off by firmware Thus there is no WD enable flip flop that can be turned off by an ESD event Any circuit state that causes firmware to loose control or any slow down of the clock will be caught and will force a reboot of the chip Although the WD timer can t be turned off by firmware it can be disabled by connecting the V1 pin power fault detect to 3 3V This is essential for initial system debug Do the TDK 71M651x devices power up with the watchdog timer enabled The chip powers up with the watchdog disabled It will be enabled in the power
24. es TDK have any EMI test data for the 71M651x power meter chips No EMI testing has been done on the ICs themselves EMI always has to be tested in a complete system However TDK has performed ESD testing and all pins of the wattmeter chips surpass TDK s 2000V ESD specification Do the Demo Boards meet conductive and radiated emission testing The revisions A of the 71M6511 and 71M6513 Demo boards have been tested for conductive and radiated emissions in compliance with FCC Class B part 15 Voltage Power Requirements Battery Operation Can the V3P3D V3P3A devices be powered in battery back up mode so that the MPU can respond to a key press and briefly display data on the LCD or perform some communications via the serial interface It is possible to implement this procedure The current Demo Board does not support it directly However the MPU can be programmed to run in low power mode using one of the DIO pins to sense the power fail Upon power fail the MPU is powered by battery and the firmware will shut down the CE ADC LCD boost and other circuitry in order to save power The V3P3D V3P3A pins must be tied together and GNDA and GNDD must be tied together How low can the battery voltage be in the 71M651X devices The minimum voltage of operation we suggest is 3 00V even though the 651x has lot of margin below 3V V1 has to be tied to battery backup to prevent a reset 12 20 2004 3 30 PM 24 29 71M651x Power Meter IC FAQ Dem
25. hen in order to ensure that this figure is accurate before a power failure occurs could this mean that certain FLASH locations will be written to excessively over the lifetime of the meter Yes the 20 000 times write limit does limit the use of flash memory for TOU data The optimum plan would be to store as much data as fits in the battery backed XRAM and then transfer it to flash when it is full This should minimize the amount of flash memory used If the customer can t fit his requirements into the flash the data can be 12 20 2004 3 30 PM 12 29 71M651x Power Meter IC FAQ stored in the EEPROM which typically has 1M write cycles Also note that the data is written on a special event occurrence such as power failure or season change in TOU time of use metering Are there any methods for checking the contents of the RAM FLASH in the TDK 71M651x devices to ensure that no corruption has occurred during power fail i e some form of checksum Yes this would be a boot up procedure implemented in 80515 MPU firmware Why do the 71M651x devices not provide an external memory bus access to expand memory 64K of memory is OK for a standard meter but a pre payment meter typically requires 128K due to the different country support proprietary Synchronous Smart card protocols and encryption 3DES and AES The extra pins are expensive both in power consumption and price The CE is powerful enough to perform all the multiplications and
26. hronized to the start of the period in the 71M6513 and 71M6511 Is a zero crossing detector used The demo firmware accumulates V h and calculates average VRMS over the last 1 second interval This is the same technique used for the power calculation Thus ripple rejection depends on a sufficiently long measurement interval The compute engine has a frequency locked loop for generating a square wave of the same frequency as the fundamental input signal This square wave signal is used by the measurement module of the compute engine for signal processing routines 12 20 2004 3 30 PM 3 29 71M651x Power Meter IC FAQ What method is used to calculate the reactive power in the TDK 71M651x devices In the TDK 71M651x devices the CE demonstration code calculates reactive power by phase shifting the voltage waveform by 90 degrees The phase shift circuit shifts all frequencies 90 degrees but has a 1 f frequency response The CE then precisely measures fundamental frequency and scales the phase shift circuit so it has unity gain The result is an accurate VAR calculation for fundamental frequencies from 45 to 65 Hz This single frequency technique is consistent with IEC62053 23 and with clause 3 1 5 in IEC62052 11 which states Standards for reactive power apply for sinusoidal currents and voltages containing the fundamental frequency only The advantage of this technique is that the VAR measurement will not see reactive power when unity power fact
27. ly if the sign is negative the reactive power is also known as negative reactive power These quantities are programmable by the user for pulse output Do the TDK 71M651x have the ability to measure DC power Apart from the small DC input offsets are there any other limitations The TDK 71M651x products do have the ability to measure DC power particularly if not measuring 3 phases of DC power The issue here is to separate the apparent DC power caused by the sensor and ADC offsets from the actual DC power to be measured Some offset sources are given below 1 ADC offset This is probably the most significant DC error Typical values observed in the 71M6511 13 are around 1 to 2mV Our ADC is auto zeroed which means the offset is caused by layout dependent parasitic capacitance rather than MOSFET threshold mismatch Offset in auto zeroed systems should have a significantly tighter standard deviation and significantly lower drift over time If the customer calibrates and subtracts the DC offset he should be able to get a system that is probably 10x better and equivalent to around 0 1mV offset Even better would be using one of the ADC inputs as a zero reference Since the 6511 6513 uses no buffer amplifiers the offset of each of the six inputs is the same This technique would 12 20 2004 3 30 PM 4 29 71M651x Power Meter IC FAQ provide an offset canceling method that would not require calibration and would be more stable over temperature
28. mpensated by the temperature sensor in the TDK 651x devices What should the maximum drift of the 32K crystal in PPM be in order to maintain 0 1 accuracy Yes it is possible to compensate for temperature drift For this the MPU firmware has to be modified to generate compensating coefficients by observing the real time clock on the TMUXOUT pin Meter accuracy is directly proportional to clock rate Thus 0 1 meter error occurs when the crystal is 1000PPM in error Many production calibration procedures adjust the V and scale to achieve correct meter reading These procedures automatically correct for time base error What is the accuracy of the 32K crystal and RTC on the Demo Board over time long term stability How is accuracy controlled The accuracy over time is guaranteed by the crystal manufacturer Ecliptec corp www ecliptek com specifies 3ppm year for their EC38T Series We are careful to avoid premature aging of the crystal by minimizing its power dissipation 12 20 2004 3 30 PM 19 29 71M651x Power Meter IC FAQ Digital I O and LCD Outputs Can all the SEG pins and COM pins be used as DIO pins in the TDK 71M651x devices No The 71M6513 has four general DIO pins DIOO DIO3 that are fully configurable as DIO The four COM pins COMO COM3 and the 19 dedicated segment outputs SEGO SEG2 SEG8 SEG23 are to be used to drive LCDs only The 18 multi use pins SEG24 DIO4 to SEG41 DIO21 can be either LCD outputs or
29. ntinuously without resetting the CE in the 71M651x devices Yes The on chip 80515 MPU can make on the fly changes to the CE data RAM This is required for temperature correction of calibration data What are the limits on the Phase correction in the TDK 71M651x devices The demo code contains constant delay all pass filters that adjust the voltage delay by 11 13 of one ADC sample time 7 25 degrees 60Hz 6 04 degrees 50Hz The all pass delay is controlled by a parameter that can be adjusted to compensate for additional phase errors such as caused by the CT s 5 degrees If the delay is caused by high frequency roll off for instance a better compensation method might be an additional single pole network which would flatten the frequency response as well as the delay How should the CROSS and V_CROSS constants of the CE data memory be set in the TDK 71M6511 and 71M6513 devices The values of CROSS and V_CROSS should be set to zero Is the INTERP compensation already applied to the V l samples that are stored in TDK 71M651x devices Yes The compute engine aligns the current input to the voltage input based on the INTERP parameter 12 20 2004 3 30 PM 18 29 71M651x Power Meter IC FAQ RTC Clock and Timers Does the RTC support leap years Yes Do have to be careful when writing data to the RTC registers What happens if enter a number gt 31 for the day of month Some wrap around will appear when the number is
30. o Board Questions What program is pre installed on the 71M6513 IC with the demo board The program pre installed in the 71M6513 6511 IC that comes with the board is the demo program that is released at the time of shipment filename 651X_demo hex The release date of the program can be determined by typing the command gt il letter i followed by the digit one using the serial interface Is the voltage on the demo boards 5V even though the IC runs on 3 3V Yes It is 5V and is regulated down to 3 3V on the demo board What are the two rates for the fast slow switch SW1 that controls the Wh VAR pulse outputs in the TDK 71M651x devices FAST is 0 23 Wh 828Ws per pulse This will allow the user to test the meter for low currents SLOW is 3 68 Wh 13 248Ws per pulse This allows for meter testing at high currents However the current Demo Board code does not read the position of switch SW1 Recent 6511 Demo Boards are shipped with SW1 removed What Kh is programmed into the Demo Boards for the TDK 71M651x devices The 71M6513 6513H Demo Boards have a Kh of 3 2 Wh per pulse if they are operated with an external CT current transformer that has a winding ratio of 2 000 1 These values can be derived by reading the values for IMAX and VMAX i e the RMS current and voltage values that correspond to the 250mV maximum input signal to the IC which should be 208A and 600V and inserting them in the equation for Kh Kh IMAX VMA
31. o design a single phase power meter with anti tamper features that use monitoring the power of both the phase and neutral line currents How can implement this The basic requirement is to have two current inputs for monitoring both power line currents phase and neutral The power KWh and KVARh will be calculated based on the line with the higher current When the line currents differ by more than 6 25 the power measurement is changed to the higher current line and vice versa There is no problem in using both a CT and a shunt for single phase meters The channel for current input with shunt has to have 8x gain in the Compute Engine program and necessary care is taken in PCB layout design to avoid crosstalk 12 20 2004 3 30 PM 9 29 71M651x Power Meter IC FAQ In general terms it can be said that the Compute Engine provides two individual registers for kWh for phase and neutral current inputs based on the Wh register info The MPU code can be used for verifying the tamper conditions based on the register information Two registers for KVARh and 7h are also provided The new single phase meter demo code provides the following 7 register values e Vo lo Wh register phase current e Vo lo VARh register e Vo l Wh register neutral current e Vo l VARH register e lo2h Phase current register 1 2h Neutral current register Voh Voltage Register Multiplexer and ADC When the ADC is multiplexing between inputs there will be
32. ocedure specified in the Demo Board User s Manuals The procedures in the Demo Board User s Manuals based on energy collection are a good starting point for evaluating the 6511 and 6513 chips Users may define their own calibration procedures which could involve measuring voltage current and phase angle directly and then determining the calibration factors It is also possible to generate improved calibration procedures that take into account varying phase angles at different currents This would require that the MPU feeds different calibration factors to the CE RAM depending on the current that the meter encounters Are the Wh and VARh outputs intended to be Pulse outputs for calibration purposes No The Wh and VARH results are the 71M651x device pulse generator outputs that can be used drive other pulse counters Is there any auto correction in the VREF or would this need to be implemented in the MPU by the customer using the Temp measurement The reference circuit VREF is built to be as intrinsically flat over temp as possible Additional curvature correction is sometimes added but this increases the variation in the temperature curve and results ultimately in worse accuracy than digital correction This design is based on a band gap reference circuit What is the minimum 0000 and maximum FFFF input gain for V I_CAL in dB in the 71M651x devices The voltage CAL is nominally 16384 It can vary from 0 to 32767 The result fr
33. oltage the CE can certainly be programmed to measure this An alternative way to do this is to use the relation Reactive Current Reactive Power Voltage Can the 71M6513 device vary pulse rate between 1 600pulse kWh and 30 000pulse kWh What is the maximum rate of pulse output and duty cycle of the TDK 71M6513 device Yes variable pulse rate is possible The limitation is the maximum pulse rate rather than the number of pulses per kWh The meter has a maximum power handling capacity of 144kW This would correspond to 480V 100A 3ph or the equivalent The 71M6513 limitation is that its maximum pulse rate must be less than 1 2 of the 2 520Hz ADC sample rate Thus a 3 phase 480V 200A meter must have a K gt 0 228kWs pulse or 0 063 Wh pulse which is equivalent to 15 8k pulses kWh If the meter full scale is lower e g 277V 10A 3 phase the value of K gt 6 5Ws pulse or 1 83mWh pulse which is equivalent to 546k pulses kWh Pulse rates faster than 1 260Hz would either require a hardware change or non uniform spacing or would need a special CE firmware What is the formula equation of VARSUM VARSUM is the sum of the received and delivered reactive power in four quadrant metering which could also be defined as the sum of lagging and leading reactive powers 12 20 2004 3 30 PM 5 29 71M651x Power Meter IC FAQ Do the 71M651x devices have the ability to measure reactive current Yes reactive energy meters are described in IEC62
34. om CAL is a sample stream that has been scaled by V_CAL 16384 The dB range is therefore 6dB to infinity If the customer s baseline design requires a V_CAL less than 1000 the cal step size will be larger than 0 1 which may be too coarse The current cal is nominally 16384 and scales the current stream by l _CAL 16384 The same digital range as for the voltage applies Thus the dB range is 6dB to infinity What value is to be used for calibration KVAR Although a range for KVAR is given the entry should stay at 1931 hex QUANT These two values are the same the UART interface treats all numbers as hex unless they are preceded with a or sign My calibration system tells me that the accuracy after calibration is changing from 0 08 to 0 25 and then back to 0 08 What is going on If the integration time over several pulses is relatively low and if the calibration system is not synchronized to the pulses it may sometimes catch a pulse in its time window and sometimes miss it Make sure to use either a synchronized calibration system or a reasonably long integration time calibrated the 651X chip but now the results are worse than before What is going on Make sure the calibration system applied 60 phase shift and not 60 300 It is customary to use the angle by which the voltage leads the current This means that there is a positive phase for inductive circuits since current lags the voltage in an inductive circ
35. or harmonics exist This is not true of tracking delay VAR measurements Alternatively VAR could be calculated from Wh and VAh but typically the performance at low currents is inferior because of noise in the VAh calculation What are the V h 1 h Values How do I use them The accumulated volt squared and current squared values are used by the MPU to calculate RMS voltage and current from the previous measurement interval The MPU divides by the number of samples and takes the square root These values are also used to calculate VAh V h and 1h are also useful quantities to provide the amount of time the meter has run continuously without disruption For example a meter with 220V input running for 31 days a month continuously will result in a count of 31 24 220 220 What is the maximum phase compensation allowed in TDK 71M6511 or 71M6513 devices The maximum phase compensation allowed is 7 degrees The compensation can be provided by the INTERP constant in the CE data memory In the TDK 71M6511 and 71M6513 can the Wh and VARh pulses from the CE be programmed to provide ve VARh and ve VARh Are the ve and ve signs associated with the phase angle and hence the quadrant in which the power vector is Yes this is possible and is a useful quantity in four quadrant metering The power measurement is classified as positive reactive power based on the sign of measured reactive power which is also called lagging reactive power Similar
36. perature of the external components with 100 accuracy Think of a meter containing the 6513H chip sensing a substrate temperature of 60 C This could be because the external components have been heated up equally to 60 C or because the PCB that the 6513H is mounted on is exposed to sunlight but the other components are cold Thus planning of component placement airflow and consideration of component thermal characteristics may be needed to provide accuracy How would a typical application in the 71M651x devices compensate for the thermal drift of external components The 71M651x devices can compensate for temperature variations in components by measuring its own temperature and by responding to scale factors written in its CE memory by the on chip 80515 MPU A typical temperature compensation program in a single phase meter might be as follows 1 The 80515 MPU requests the CE to measure temperature once per second The frequency of this request is controlled completely by the 80515 MPU In the example we assume the 80515 MPU requests temperature each time it receives an XFER_BUSY interrupt 2 Based on the temperature measurement the 80515 MPU determines which parameters need to be adjusted In this example let s assume the 80515 MPU adjusts the gain of the voltage and current ADC outputs as well as the phase shift of the current sensor The MPU would compensate for voltage and current gain by modifying the value of CAL_IO and CAL_VO The
37. r than 0 3A if the integration time was increased This would correspond to an input amplitude of roughly 0 3mV RMS Does TDK recommend types of current transformers and voltage shunts and what accuracy should they have This is up to the meter manufacturer and desired meter specifications The meter itself provides the signal that must be within 250mV at the inputs of the 71M651X devices How can adjust the offset between 1S and 1L Is this done in the IC or on the board Offset is automatically removed within the IC as long as the analog inputs are within 0 25V of the 3 3VDC supply to the IC There is no additional offset adjustment required What are the evaluation conditions for the 71M6511 such as turns of the CT input current at IA and calibration values TDK recommends using a CT with 2000 1 ratio with a 1 7Q load resistor This will result in 250mV at the input for 200 Amperes 12 20 2004 3 30 PM 8 29 71M651x Power Meter IC FAQ Can a Rogowski coil be directly connected to the TDK 71M6513 What does the input impedance to the ADC look like Yes a Rogowski coil can be connected When using a di dt device such as a Rogowski coil there may be the need to roll off high frequencies so the entire signal stays within the 250mV range Phase shift due to the roll off can be compensated in the CE The ADC input impedance is a 1pf switched capacitor at 5MHz This gives an equivalent input impedance of 200kQ2 I want t
38. rites hex value OE into address 2020 My CT has only a turn ratio of 1000 1 How can modify my Demo Board to accommodate this The basic scaling conditions for the demo board are VMAX 600V and IMAX 208A 208A would generate 104mA with a 1 2 000 turns ratio These 104mA would generate 176mV RMS across resistors R24 R25 1 7Q total or 250mV peak at the IA input you are using a 1 1 000 turns ratio you would generate 208mA at 208A This means you should decrease the resistors R24 R25 and so forth so the combined resistance is 0 850 12 20 2004 3 30 PM 26 29 71M651x Power Meter IC FAQ Scale and Other DC Applications Can the 71M6513 IC be used for DC applications Yes the inputs are useable for both AC and DC What offset and noise figures can be expected for a DC application 1 The 71M651X chips use single converter technology This means that all channels have the same offset How ever care must be taken to match input impedance between ground sense and signal sense The typical input impedance is 70kOhms 2 A typical offset of 2mV has been observed and this offset is tightly matched between parts 3 We have not characterized the broadband noise since it is not important for power meter applications 4 TDK has developed a scale application In this application rather than processing the differential voltage with an instrumentation amplifier the DC voltage applied between two input channels is measured and then subtracted
39. s the LCD API flexible i e will it support the full range of displays that can be supported by our hardware or are there some restrictions am planning to design our own proprietary display Would the LCD API be configurable to suit this The TDK 71M6511 13 devices can drive the segment and back plane lines of the LCD directly Within each chip each addressable segment is independently controlled Thus to the extent permitted by the number of segment drivers the part should be able to interface to any custom LCD The structure inside the LCD API needs to be modified for the current segment mapping Is Keil s C compiler assembler linker required for the 71M6151x devices How about other tools We are using Keil s C tools Other tools can potentially be used but we have not tested any The ultimate goal is to generate a hex file that is compatible to upload to the MPU flash memory of the device What is the utility we can use to re flash the 71M651X part after re compiling the DSP code and firmware code respectively We use the Signum ICE model ADM51 for flash uploading during development A Flash Download Board will be available for programming of production units 12 20 2004 3 30 PM 23 29 71M651x Power Meter IC FAQ Tamper Detection Do the 71M651x devices support tampering detection Yes the 80515 MPU code can be programmed for tampering detection based on the technique and sensor used for detection EMI EMC Do
40. t some of the inputs outputs could be connected to Neutral due to an internal failure e g LCD pins or serial interface which would cause a hazard This is a quite common methodology with most of the metering chips for measurement If another signal faults by connecting to neutral high current could result from this but only to the extent it is provided by the power supply which is limited to a few 50mA The ESD diodes in the 651x part ensure that all pins will be just a few volts from each other Thus if one of the pins is tied to neutral and neutral is hot there could be a hazard This is not unique to the TDK 71M6511 and 71M6513 Any part that uses resistive dividers for voltage sense must have one of its pins connected to neutral What technique is used to introduce the 90 degree phase shift when measuring VAR in the 71M651x devices Our baseline CE code uses a bilinear integrator to shift voltage 90 degrees for VAR measurements An all pass filter along with 1 fo multiplication provides the accurate VAR measurement Is using V and I the most efficient method for calculating Apparent Power VAh in the TDK 71M6513 or 71M6511 devices Apparent power measured in VAh can be calculated from V and I However it is more accurate for low currents to use Wh and VARI i e SQRT Ws x Ws VARs x VARs This method of computation is less sensitive to broadband noise than V and I How is the measurement of Vrms and Irms sync
41. tage for the external microcontroller It is also used by the measurement module of the compute engine for signal processing routines 12 20 2004 3 30 PM 29 29
42. uit The phase is negative for a capacitive circuit since the current leads the voltage 12 20 2004 3 30 PM 17 29 71M651x Power Meter IC FAQ CE Features Do the 71M651x devices implement something in the CE to filter out the ripple control signal No In CE code at the end of each complete cycle does the CE interrupt the MPU in order to fetch the energy values from the CE RAM What is the cycle time and will it vary if additional code is added Is it possible to make the CE code interrupt the MPU at other intervals or is the MPU responsible for accumulating the fractions of energy The MPU receives a CE_BUSY interrupt after each CE code pass The other interrupt occurs once at the end of each sum interval and is called XFER_BUSY The rate of this interrupt can be varied and is set at 1 second in the demo configuration SUM_CYCLES and PRE_SAMPS The energy is always accumulated by the CE but when the CE generates XFER_BUSY it stores the energy in registers accessible to the MPU Upon receiving the XFER interrupt the MPU reads the accumulated energy and updates its display EEPROM and whatever else is required for housekeeping The XFER_BUSY handler of the MPU code does a number of calculations including the calculation of RMS voltage and current and the measurement of load angles Is the Compute Engine CE code modifiable by the customer Yes it is The code is stored in Flash memory Can CE calibration values be changed co
43. up boot sequence Once enabled it can t be disabled without a full chip reset When does the TDK 71M651x MPU exit from reset The MPU will exit from reset 4100 cycles of the 32kHz clock after ResetZ is taken High Does the TDK 71M651x reset input pin have a Schmitt trigger No Is the reset timer count value 4100 programmable No This time is necessary to ensure the PLL is settled and stable Is there is default setting of the MPU clock divider MPU_DIV which is always used at power on reset for example 000 CKCE or can the POR setting be defined in boot up code MPU_DIV hardware default is 000 For low power the MPU should reprogram MPU_DIV as soon as possible 12 20 2004 3 30 PM 14 29 71M651x Power Meter IC FAQ Temperature Compensation How much can the 71M6511 compensate the thermal drift of external components The question is very hard to answer since the external component characteristics are unknown 10 PPM C 651XH or 50 PPM C 651X is achieved when compensation is limited to the 71M651x device itself using the internal temperature sensor The 651XH has a double trimmed bad gap with predictable behavior over temperature 10 PPM over the temperature range that makes reading of the internal temperature sensor more accurate The 651X has a single trimmed band gap with 50 PPM deviation from nominal over temperature In a system design the temperature sensor inside the 71M6511 cannot always determine the tem
44. y beyond the industry standard requirement What is the ADC s speed when transmitting data to the MCU in the 71M6511 6513 devices The ADC samples 32 768 13 2 520 samples per second Is there a limitation to high frequency modulated signals that the TDK71M651x devices can detect due to the sampling rate of the ADC The 6513 has a sample rate of 2520 Hz Thus the highest frequency that can be detected must be below 1260Hz 12 20 2004 3 30 PM 11 29 71M651x Power Meter IC FAQ Memory and Memory Security Could the disabling of the emulator clock ECK_DIS 1 in the application that is downloaded to the 71M651x devices provide some security against tampering When enabled the security feature limits the ICE to global flash erase operations only All other ICE operations are blocked This guarantees the security of the user s MPU and CE program code Security is enabled by MPU code that is executed in a 32 cycle pre boot interval before the primary boot sequence begins Once security is enabled the only way to disable it is to perform a global erase of the flash followed by a chip reset Global flash erase also clears the CE program RAM The first 32 cycles of the MPU boot code are called the pre boot phase because during this phase the ICE is inhibited A read only status bit PREBOOT identifies these cycles to the MPU Upon completion of the pre boot phase the ICE can be enabled and is permitted to take control of the MPU SECURE
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