ZXCT1082EV1 USER GUIDE Performance • • • • • Introduction This evaluation circuit simply demonstrates the ZXCT1082 60V High-Side Current Monitor. The circuit is suitable for a wide range of power systems including automotive and industrial applications as well as portable and battery management systems. Current Monitor with wide supply range: 2.7V to 60V Independent chip supply and supply-tobe-monitored Low quiescent current (25µA typ) Total error 3% using 1% external resistors Ambient temperature range -40 to 105°C The sensitivity of the PCB can be selected using solder bridge links to either 1.25V or 2.5V per Ampere of load current. The construction is a double-sided FR4 printed circuit board, 51 x 64 x 1.6 mm with 2oz/sq ft copper (70µm). Ordering Information Order Number ZXCT1082EV1 . Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 1 of 8 ZXCT1082EV1 Schematic R3 DO NOT FIT SL2 R2 0.1R SL1 R1 0.05R TP1 TP4 INPUT IN R4 2.7k GND S+ VCC 5 C1 100nF 100V GND VCC GND GND OUT 1 VCC TP5 U1 ZXCT1082 S- 2 TP2 R5 2.7k 4 C2 DO NOT FIT 3 TP8 GND LOAD LOAD TP6 OUTPUT OUT GND TP3 R6 68k GND GND GND GND TP7 GND GND PCB Layout Top Bottom Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 2 of 8 ZXCT1082EV1 Parts List Count Designator Description 1 C1 Capacitor SMD, 100nF 100V X7R 0 C2 1 R1 1 R2 1 R3 2 R4, R5 1 R6 1 U1 NOT FTTED Resistor, SMD, 0R05 1% 500mW 100ppm/ °C Resistor, SMD, 0R1 1% 500mW 100ppm/ °C NOT FITTED Resistor, SMD, 2.7k 1% 125mW, 250ppm/°C Resistor, SMD, 68k 1% 125mW, 250ppm/°C ZXCT1082 Package Manufacturer Part Number 0805 AVX 08051C104KAZ2A 1206 Welwyn LR1206-R05FI 1206 Welwyn LR1206-R10FI 0805 various 0805 various SOT23-5 Diodes ZXCT1082E5TA I/O and Test points Count Designator Description Function Manufacturer Part Number 1 TP1 Loop Terminal, 2.15mm, green Input Hughes 100-108 1 TP2 Loop Terminal, 2.15mm, green Vcc Hughes 100-108 1 TP3 Loop Terminal, 2.15mm, green Ground Hughes 100-108 1 TP4 Loop Terminal, 2.15mm, green Load Hughes 100-108 1 TP5 Loop Terminal, 2.15mm, green Ground Hughes 100-108 1 TP6 Loop Terminal, 2.15mm, green Output Hughes 100-108 1 TP7 Loop Terminal, 2.15mm, green Ground Hughes 100-108 1 TP8 Loop Terminal, 2.15mm, green Ground Hughes 100-108 Recommended Operating Conditions Symbol Parameter Min Max Units Vin Input Voltage 2.7 60 V Vcc Supply Voltage 2.7 60 V Vout Output Voltage 0 Load voltage -1V V TA Operating Ambient Temperature -40 105 °C Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 3 of 8 ZXCT1082EV1 Detailed Description The voltage gain is set to 25 according to the resistors R4 and R6. Two current sense resistors are provided, which can be selected by solder bridge links. In the initial factory setting, SL1 is connected and SL2 is not, so the sense resistor value is R1=50 milliohms, giving a sensitivity of 1.25V at the Output per Ampere of current in the sense resistor. The second sense resistor provided is 100 milliohms, providing a sensitivity of 2.5V per Ampere. Through-holes are provided for the user to fit an additional resistor R3 if desired. If SL1 only is bridged, the sensitivity of the PCB assembly to load current is set by R1 which is a 1% tolerance thick film resistor of 50 milliohms. The sense voltage is VSENSE = VIN - VLOAD = ILOAD . R1, i.e. 50mV per Amp The voltage gain is VOUT/VSENSE = R6/R4 = 25.185 The sensitivity to current is VOUT/ILOAD = (VOUT/VSENSE) . (VSENSE/ILOAD) = (R6/R4) . R1 = 1.259 V per Amp. If SL2 is bridged instead of SL1, the sense resistance will be 0.1R, so the sensitivity will then be 2.5185 V per Amp. Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 4 of 8 ZXCT1082EV1 Quick Start Guide Suitable test equipment is given in the table below. 5. DMM1 reads between 1.23V and 1.32V. Note that the reading may be slightly higher than the nominal value of 1.25V due to a volt drop of about 1mV in the PCB copper, and that the worst case tolerance is ±3% due to the 1% resistors used. 6. Operation at 60V can be examined easily if the electronic load is available. Set the load to 1.00A and increase the power supply voltage to 60V. 1. Set the power supply to 10.0V but do not switch on. Set the current limit to 1.5A. 2. Check that on the ZXCT1082EV1 board, solder link SL1 is bridged and SL2 is open. 3. Connect up the ZXCT1082EV1 board to the equipment as in the diagram below. Set DMM1 to measure voltage and DMM2 to measure current. 4. Switch on the power supply. DMM2 should now read about 1.0A. Adjust the supply voltage slightly to obtain exactly 1.000A ± 0.005A. Suitable Test Equipment Count Description 1 Adjustable Power Supply, 60V 2A 2 Digital Multimeter 1 Load resistor, 10 ohms ± 5%, 10W, or electronic load, 60V 2A Manufacturer Part Number Thurlby Thandar CPX400A Fluke 179 Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 5 of 8 ZXCT1082EV1 INTENTIONALLY BLANK Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 6 of 8 ZXCT1082EV1 INTENTIONALLY BLANK Issue 1 – September 2009 www.diodes.com © Diodes Incorporated 2009 7 of 8 ZXCT1082EV1 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). 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