Zetex ZXLD1362EV3 User's Manual
Contents
1. in production to support existing designs and production Obsolete Production has been discontinued Datasheet status key Draft version This term denotes a very early datasheet version and contains highly provisional information which may change in any manner without notice Provisional version This term denotes a pre release datasheet It provides a clear indication of anticipated performance However changes to the test conditions and specifications may occur at any time and without notice Issue This term denotes an issued datasheet containing finalized specifications However changes to specifications may occur at any time and without notice Europe Americas Asia Pacific Corporate Headquarters Zetex GmbH Zetex Inc Zetex Asia Ltd Zetex Semiconductors plc Kustermann park 700 Veterans Memorial Highway 3701 04 Metroplaza Tower 1 Zetex Technology Park Chadderton Balanstrake 59 Hauppauge NY 11788 Hing Fong Road Kwai Fong Oldham OLY 9LL D 81541 Munchen USA Hong Kong United Kingdom Germany Telefon 49 89 45 49 49 0 Telephone 1 631 360 2222 Telephone 852 26100 611 Telephone 44 161 622 4444 Fax 49 89 45 49 49 49 Fax 1 631 360 8222 Fax 852 24250 494 Fax 44 161 622 4446 europe sales zetex com usa sales zetex com asia sales zetex com hq zetex com 2006 Published by Zetex Semiconductors plc ZXLD1362EV3 User Guide issue 1 TIT 11 01 20082. whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user B A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness Reproduction The product specifications contained in this publication are issued to provide outline information only which unless agreed by the company in writing may not be used applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned Terms and Conditions All products are sold subjects to Zetex terms and conditions of sale and this disclaimer save in the event of a conflict between the two when the terms of the contract shall prevail according to region supplied at the time of order acknowledgement For the latest information on technology delivery terms and conditions and prices please contact your nearest Zetex sales office Quality of product Zetex is an ISO 9001 and TS16949 certified semiconductor manufacturer To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our regionally authorized distributors For a complete listing of authorized distributors please visit ww
3. 1362 Device Pin Definition ZXLD1362EV3 User Guide issue 1 2 7 11 01 2008 ZXLD1362EV3 EVALUATION BOARD REFERENCE DESIGN The ZXLD1362EV3 is configured to the reference design in Figure 2 The target application is a driver for one or more series connected LEDs for luminaires in both commercial and automotive applications The maximum operating voltage is 60V and the nominal current is set at 700mA with a 0 15Q sense resistor R1 The device operates in continuous mode at approximately 150 kHz with a 68uH inductor An accurate way of determining the current avoiding the need to insert an ammeter in the current path is to measure the voltage on the sense resistor A 10K resistor and a 1uF capacitor can be used to form a low pass filter and the voltage across the capacitor represents a more stable dc reading of current Using this method 100mV represents 0 7 Amp when using a 0 15Q sense resistor The ADJ pin connects to a low pass filter within the ZXLD1362 chip to provide some decoupling but the external capacitor C2 100nF is used to provide additional decoupling to reduce any high frequency noise as well as enabling the soft start function Both DC and PWM dimming can be achieved by driving the ADJ pin For DC dimming the ADJ pin may be driven between 0 3V and 1 25V Driving the ADJ pin below 0 2V will shut down the output current For PWM dimming an external open collector NPN transistor or open drain N channel MOSFET can be used to dri
4. R1 L1 the LEDs the Schottky diode D1 and back to the supply rail but it decays with the rate of decay determined by the forward voltage drop of the LEDs and the Schottky diode This decaying current produces a falling voltage at R1 which is sensed by the ZXLD1362 A voltage proportional to the sense voltage across R1 is applied at the input of the internal comparator When this voltage falls to the internally set lower threshold the NDMOS switch is turned on again This switch on and off cycle continues to provide an average current set by the sense resistor R1 to the LEDs Please refer to the datasheet 1 for the threshold limits ZXLD1362 internal circuits electrical characteristics and parameters ZXLD1362EV1 Evaluation Board BOM Ref Value Package ____PartNumber__ Manufacturer _ 0 15R 0805 CRL1220 R15TD Tyco 5 200ppm R2 kQ 0805 Generic C2 C4 100nF 100V 0805 NMC0805X7R104K100TRPLPF 100nF 1206 NMC1206X7R104K100TRPLP3KF O 68uH NPIS24H680MTRF 68uH 1 5A rms 100V 3A 30BQ100PBF IR Schottky diode U1 ZXLD1362 TSOT23 5 ZXLD1362E5TA Zetex DC DC converter The aluminium PCB guarantees a good thermal dissipation for the ZXLD1362 device which can produce up to 1 watt of heat under maximum load conditions Other sources of heat are the Schottky diode the inductor and the sense resistor Care must be taken in their placement Warning At 60V operation with 700mA output the board temperature r
5. ZXLD1362EV3 USER GUIDE DESCRIPTION The ZXLD1362EV3 Figure 1 is a PCB constructed using an aluminium base for evaluating the ZXLD1362 LED driver with internal switch 1 The evaluation board can be used to drive an external choice of LEDs the total forward voltage across the LEDs depending on the number and type connected The operating voltage is nominally higher than 30V for the external LEDs and can be raised to 60V maximum which will reduce the supply current Please refer to the Zetex ZXLD1360 and ZXLD1350 products for applications requiring input voltages lower than 30V The nominal current for the evaluation board is set at 700mA with a 0 15Q sense resistor R1 The 68uH inductor used in the circuit is based on a 30V nominal supply which should be connected across VIN and GND pins Note The evaluation board does not have reverse polarity protection It is fitted with a 2 1mm DC power plug with positive to the centre pole Test point ADJ provides a connection point for DC or PWM dimming and shutdown Warning with 700mA output the connected LED will be hot and very bright Z LD1362EV3 Evaluation Board a 43 7 a SEMICONDUCTORS Crowohl Zee PLO AMA ZOBA3JrR1 Figure 1 ZXLD1362EV3 evaluation board ZXLD1362EV3 User Guide issue 1 1 7 11 01 2008 ZXLD1362 DEVICE DESCRIPTION The ZXLD1362 is a continuous mode inductive driver in a TSOT23 5 package for driving one or more series connected LEDs efficiently f
6. ises by around 50C from ambient after 30 minutes of operation Figure 3 Component layout and circuit board view ZXLD1362EV3 User Guide issue 1 4 7 11 01 2008 ZXLD1362EV3 Connection Point Definition Name Description Positive supply voltage Supply Ground OV Internal voltage ref pin 1 25V This pin can be used to achieve dimming and soft start and for switching the output eh off e Leave floating for normal operation e See Circuit Features section to achieve dimming soft start and for switching the output current off LEDA connects to the external LED anode LED K_ connects to the external LED cathode ZXDL1362EV3 Basic operation at full voltage 1 Connect external LEDs across test pins LED A anode and LED K cathode The number of external LEDs that can be connected depends on their operating power and forward voltage drop but typically 16 x 3 4V LEDs can be connected using a 60V rail For an external load other than LEDs the positive terminal of the load should be connected the anode and the negative to the cathode 2 Connect VIN and GND Warning The board does not feature reverse battery supply protection 3 Set the PSU to the desired input voltage usually between 30V and 60V 4 Turn on the PSU The external LEDs will illuminate and the current should be approximately 700mA Warning Do not stare at the LEDs directly Circuit features N B Remove power whilst changing componen
7. itions Product change Zetex Semiconductors reserves the right to alter without notice specifications design price or conditions of supply of any product or service Customers are solely responsible for obtaining the latest relevant information before placing orders Applications disclaimer The circuits in this design application note are offered as design ideas It is the responsibility of the user to ensure that the circuit is fit for the user s application and meets with the user s requirements No representation or warranty is given and no liability whatsoever is assumed by Zetex with respect to the accuracy or use of such information or infringement of patents or other intellectual property rights arising from such use or otherwise Zetex does not assume any legal responsibility or will not be held legally liable whether in contract tort including negligence breach of statutory duty restriction or otherwise for any damages loss of profit business contract opportunity or consequential loss in the use of these circuit applications under any circumstances Life support Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Zetex Semiconductors plc As used herein A Life support devices or systems are devices or systems which 1 are intended to implant into the body or 2 support or sustain life and
8. rom a voltage source higher than the LED voltage The device includes the output switch and a current sense circuit which requires an external sense resistor to set the nominal current up to 1000mA ZXLD1362 DEVICE FEATURES DEVICE APPLICATIONS e Drives one or more series connected LEDs e LED flashlights e LEDs up to 1000mA e High Power LED driving e Internal 60V switch e Low voltage halogen replacement LEDs e Wide input voltage 7V to 60V e Automotive lighting e Inherent open circuit LED protection e Illuminated signs e Brightness control using DC or PWM e Internal PWM filter ZXLD1362 Device Packages Pin and Definitions ZXLD1362 GND 2 43 4O ISENSE TSOT23 5 pack Name Drain of NDMOS switch Ground 0V ADJ 3 Internal voltage ref pin 1 25V Leave floating for normal operation Connect to GND to turn off output current Drive with a DC voltage 0 3V to 1 25V or with a PWM signal to adjust output current Connect a capacitor from this pin to ground to set the soft start time ISENSE 4 Connect a sense resistor Rs from the ADJ pin to VIN to sense the nominal output current Nominal lout 0 1 R1 VIN 5 Input voltage 7V to 60V Decouple to ground with a 100nF and a 10uF or higher ceramic capacitor depending on the input voltage 1 ORDERING INFORMATION EVALBOARD ORDER NUMBER DEVICE ORDER NUMBER ZXLD1362EV3 ZXLD1362E5TA Please note Evaluation boards are subject to availability and qualified leads ZXLD
9. ts Soft start 1 The evaluation board is fitted with capacitor C2 which performs the soft start function by slowing the rise time of the adjust pin at start up The pin output impedance is 50K so CxR is the time constant to reach 66 of output current PWM 1 Remove the soft start capacitor C2 2 Refer to the datasheet for how to perform PWM Switching off the output current 3 Shorting the ADJ pin to GND will cause the LED current to go to zero Releasing this pin will switch on the system creating a soft start power up sequence if the C2 capacitor is used Changing the LED current 1 Remove R1 2 Calculate and fit a new sense resistor R1 the value of which is based on the required LED current without dimming R1 can be calculated using following equation R1 0 1 V lout where lour the LED current R1 the sense resistor value in ohms 0 1V is the nominal sense voltage with ADJ open circuit or set to 1 25V ZXLD1362EV3 User Guide issue 1 5 7 11 01 2008 PERFORMANCE The system efficiency depends on the sense resistor supply voltage switching inductor and the number of LEDs With a 60V supply and 15 LEDs the switching frequency is typically 200 kHz and efficiency levels gt 90 are achievable Visit our website www zetex com to find useful tools for circuit design and simulation REFERENCE 1 ZXLD1362 Datasheet www zetex com ZXLD1362EV3 User Guide issue 1 6 7 11 01 2008 HZEITEX SEMICONDUCTORS Defin
10. ve the ADJ pin The PWM frequency can be low around 100Hz to 1 kHz or high between 10 kHz to 50 kHz For low frequency PWM capacitor C2 should be removed on the evaluation board to give a more accurate duty cycle Shorting R2 will connect the test pin ADJ to device pin ADJ if needed The external capacitor C2 on the ADJ pin sets the soft start time The amount of soft start time achievable is approximately 0 2ms nF For other reference designs or further applications information please refer to the ZXLD1362 datasheet Schematic Diagram Figure 2 shows the schematic for the ZXLD1362EV3 evaluation board Vin LED A R1 C3 Vin V sense Gi CA D1 ADJ L1 W H a ZXLD1362 x a LED K GND Figure 2 Schematic for the evaluation board ZXLD1362EV3 ZXLD1362EV3 User Guide issue 1 3 7 11 01 2008 ZXLD1362 Operation In normal operation when voltage is applied at VIN the ZXLD1362 internal NDMOS switch is turned on Current starts to flow through sense resistor R1 inductor L1 and the LEDs The current ramps up linearly and the ramp rate is determined by the input voltage VIN and the inductor L1 This rising current produces a voltage ramp across R1 The internal circuit of the ZXLD1362 senses the voltage across R1 and applies a proportional voltage to the input of the internal comparator When this voltage reaches an internally set upper threshold the NDMOS switch is turned off The inductor current continues to flow through
11. w zetex com salesnetwork Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels ESD Electrostatic discharge Semiconductor devices are susceptible to damage by ESD Suitable precautions should be taken when handling and transporting devices The possible damage to devices depends on the circumstances of the handling and transporting and the nature of the device The extent of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time Devices suspected of being affected should be replaced Green compliance Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding regulatory requirements with respect to the use of hazardous substances Numerous successful programs have been implemented to reduce the use of hazardous substances and or emissions All Zetex components are compliant with the RoHS directive and through this it is supporting its customers in their compliance with WEEE and ELV directives Product status key Preview Future device intended for production at some point Samples may be available Active Product status recommended for new designs Last time buy LTB Device will be discontinued and last time buy period and delivery is in effect Not recommended for new designs Device is still
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