ZXCT1023EV1 USER GUIDE DESCRIPTION The ZXCT1023EV1 evaluation board is intended for the evaluation of the ZXCT1023 device. The ZXCT1023 is a precision high-side current sense monitor, which eliminates the need to disrupt the ground plane when sensing a load current. The ZXCT1023 provides a fixed gain of 50 for applications where minimal sense voltage is required. The very low offset voltage enables a typical accuracy of 3% for sense voltages of only 10mV, giving better tolerances for small value sense resistors necessary at higher currents. The wide input voltage range of 20V down to as low as 2.5V makes it suitable for a range of applications. It requires no additional components, thus making it a versatile device with minimal component count. The ZXCT1023 in the TDFN1218-4L package is fitted as supplied, but the PCB allows for fitting the TDFN2020-6L packaged version instead. There is also a position for fitting a test socket (TSK1) if desired. R3 consists of two pads with a hole in each pad, or connecting an external RS if required. With the values shown, the board produces an output of 2.5V/A The target applications are battery chargers, power supply units and other applications where high side current measurement is a requirement. The input voltage (voltage on VSUP) range for the ZXCT1023EV1 is from 2.5V to 20V. Figure 1. ZXCT1023 Evaluation Board Issue 1 – March, 2009 www.diodes.com © Diodes Incorporated 2009 1 of 8 FEATURES • High side current sensing • Supply Range 2.5V to 20V. • Fixed gain of 50 • 3% typical accuracy • TDFN1218-4L or TDFN2020-6L package APPLICATIONS • Battery Charging • Power Supplies • Over-current Monitoring • Automotive current measurement ORDERING INFORMATION ORDER NUMBER ZXCT1023EV1 Please note evaluation boards are subject to availability and qualified leads. PAD NAMES AND DEFINITIONS NAME DESCRIPTION VSUP LOAD OUT GND Supply Voltage Connection to Load SL1,SL2 Solder Links Output Voltage 0V / Ground PIN-OUT INFORMATION (top view) TDFN1218-4L OUT 1 4 S+ GND 2 3 S- Issue 1 – March, 2009 www.diodes.com © Diodes Incorporated 2009 2 of 8 Figure 2. ZXCT1023EV1 Schematic S+ RS VSUP VSUPPLY (R1//R2 0.05R//0.5R) S- VSENSE ILOAD LOAD S+ SZXCT1023 VOUT GND OUT GND GND Figure 3. Simplified Schematic Issue 1 – March, 2009 www.diodes.com © Diodes Incorporated 2009 3 of 8 Figure 4. Evaluation board components' layout Components List Ref Value Package Part Number Manufacturer Notes R1 50mΩ 2512 LR2512-R050FI Welwyn R2 500mΩ 2512 LR2512-R500FI Welwyn SMD Sense Resistor 1% SMD Sense Resistor 1% R3 IC1 IC2 TSK1 P1, P4 P2, P3 NOT FITTED ZXCT1023 NOT FITTED NOT FITTED TDFN1218 TDFN2020 ZXCT1023DFGTC ZXCT1023DEETC 03717 017 X218E 1725656 1725672 Diodes Inc Diodes Inc Loranger Phoenix Phoenix Issue 1 – March, 2009 DFN2020 socket Terminal Block, 2 way Terminal Block, 4 way www.diodes.com © Diodes Incorporated 2009 4 of 8 Configuration table for ZXCT1023EV1 LOAD CURRENT (A) 1.0 0.1 1.0 RSENSE (mΩ Ω) VOUT (V) SOLDER LINK CONFIGURATION 50 500 45.4 2.5 2.5 2.273 Short SL1 Short SL2 Short SL1 & SL2 Sense resistor The board has been designed with two selectable values of sense resistor. The value of the sense resistor can be chosen by using the solder links SL1 and SL2. The 50mΩ resistor (R1) is selected by shorting SL1 and opening SL2. This results in an output of 2.5 V/A. The 500mΩ resistor (R2) is selected by shorting SL2 and opening SL1, resulting in an output of 25V/A. If both links are shorted the effective resistance is 45.4mΩ giving an output of 2.273V/A. If both links are open, the optional leaded resistor R3 can be exclusively used as the sense resistor. The maximum power dissipation rating of the resistor must be appropriate to the load current level. Configuration for different LOAD currents. The board can be configured for different load currents by changing the SMD resistors or fitting a suitable wire-ended resistor and opening both solder links. It is important to ensure an appropriate value of RS is selected to obtain the desired accuracy for a given output current. The value of VOUT is the voltage dropped across the sensing resistor, multiplied by 50. Choosing a larger value for RS gives a higher output voltage for a given current, resulting in better resolution, but at the expense of increased voltage drop and higher dissipation in RS. The ZXCT1023 is optimized for values of VSENSE between 10mV and 100mV. Accuracy The ZXCT1023 has a typical 3% accuracy for a VSENSE of between 10mV and 100mV. The accuracy of the output voltage will be influenced by the tolerance of the external sense resistor used. The ZXCT1023EV1 utilizes 1% sense resistors. Issue 1 – March, 2009 www.diodes.com © Diodes Incorporated 2009 5 of 8 P1 ZXCT1023EV1 P2 PSU1 + GND GND VSUP VSUP S+ S- 10R 5W A LOAD LOAD GND GND P3 OUT GND DVM P4 Figure 5. Test diagram for ZXCT1023EV1 SET-UP AND TEST The board is preset to give an output Voltage of 2.5V for a load current of 1A. SL1 is shorted to connect in the 50mΩ (R2) sense resistor. To change the board to give an output Voltage of 2.5V for a current of 100mA, de-solder SL1 and short SL2. This connects the 500mΩ (R2) sense resistor. Required Equipment 1. 2. 3. 1 x 10R 5W resistor (load). 1 x adjustable bench PSU. 2 x DVMs (one for voltage measurement and one for current measurement) 500mA load test 1. Ensure SL1 is shorted. 2. Connect the bench power supply, PSU1, between the VSUP and GND terminals as shown. 3. Connect the resistor in series with an ammeter set to its 1A or 2A range, between the LOAD and GND terminals - 10R 5W suggested. If using a different value, make sure its power rating is P ≥ 2(I2*R). Make sure PSU1 is set to zero volts to start with. 4. Switch on PSU1 and adjust the voltage until the ammeter reads 500 mA ±2 mA, 5. Measure VOUT with a DVM. The output voltage should read 1.25V ± 0.05 V. End of Test. Note: VSENSE can be monitored across connector P1. Issue 1 – March, 2009 www.diodes.com © Diodes Incorporated 2009 6 of 8 Top Silk Top Copper Bottom Copper Figure 6. Board layout Issue 1 – March, 2009 www.diodes.com © Diodes Incorporated 2009 7 of 8 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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