ZXCT1086EV1 USER GUIDE Performance • • • • • • Introduction This evaluation circuit simply demonstrates the ZXCT1086 60V High-Side Current Monitor with a fixed gain of 50. 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) Fixed gain of 50 Accuracy 2% Ambient temperature range -40 to 105°C The sensitivity of the PCB can be selected using solder bridge links to either 2.5V or 5.0V 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 ZXCT1086EV1 . Issue 1 – October 2009 www.diodes.com © Diodes Incorporated 2009 1 of 8 ZXCT1086EV1 Schematic R3 DO NOT FIT SL2 R2 0.1R SL1 R1 0.05R TP1 TP4 INPUT IN R4 0R GND S+ VCC 5 C1 100nF 100V GND VCC GND GND OUT 1 VCC TP5 U1 ZXCT1086 S- 2 TP2 R5 0R 4 C2 DO NOT FIT 3 TP8 GND LOAD LOAD TP6 OUTPUT OUT GND TP3 R6 DO NOT FIT GND GND GND GND TP7 GND GND PCB Layout Top Bottom Issue 1 – October 2009 www.diodes.com © Diodes Incorporated 2009 2 of 8 ZXCT1086EV1 Parts List Count Designator Description 1 C1 Capacitor SMD, 100nF 100V X7R 0 C2 1 R1 1 R2 1 R3 2 R4, R5 1 1 R6 U1 NOT FTTED Resistor, SMD, 0R05 1% 500mW 100ppm/ °C Resistor, SMD, 0R1 1% 500mW 100ppm/ °C NOT FITTED Resistor, SMD, 0R 125mW NOT FITTED ZXCT1086 Package Manufacturer Part Number 0805 AVX 08051C104KAZ2A 1206 Welwyn LR1206-R05FI 1206 Welwyn LR1206-R10FI 0805 various SOT23-5 Diodes ZXCT1086E5TA 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 – October 2009 www.diodes.com © Diodes Incorporated 2009 3 of 8 ZXCT1086EV1 Detailed Description The voltage gain from the sense inputs is set to 50 internally to the chip. 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 2.5V at the Output per Ampere of current in the sense resistor. The second sense resistor provided is 100 milliohms, providing a sensitivity of 5.0V 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 = VS+ - VS- = ILOAD . R1, i.e. 50mV per Amp The voltage gain is VOUT/VSENSE = 50 The sensitivity to current is VOUT/ILOAD = (VOUT/VSENSE) . (VSENSE/ILOAD) = 50 . R1 = 2.5 V per Amp. If SL2 is bridged instead of SL1, the sense resistance will be 0.1R, so the sensitivity will then be 5.0 V per Amp. A Note on Tolerance The output voltage tolerance as measured in the Quick Start Guide, below, is approximately +3%, -1%. This consists of the following contributions: 1. The reading is about 2% higher than the nominal value of 2.5V due to the PCB copper resistance, including the solder link, when using the 50 milliohm sense resistor, R1. 2. The tolerance of the sense resistor R1 is ±1%. 3. The ZXCT1086 tolerance is ±1%. 4. The Fluke DMM has an input resistance of about 11Mohm, while the ZXCT1086EV1 output resistance is 125kohm. This means that the reading will be about 1.1% lower than a perfect voltmeter. Issue 1 – October 2009 www.diodes.com © Diodes Incorporated 2009 4 of 8 ZXCT1086EV1 Quick Start Guide Suitable test equipment is given in the table below. the supply voltage slightly to obtain exactly 1.000A ± 0.005A. 5. DMM1 now reads between 2.47V and 2.58V. [This tolerance band includes the effects listed above.] 6. You can examine operation at 60V 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 ZXCT1086EV1 board, solder link SL1 is bridged and SL2 is open. 3. Connect up the ZXCT1086EV1 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 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 – October 2009 www.diodes.com © Diodes Incorporated 2009 5 of 8 ZXCT1086EV1 INTENTIONALLY BLANK Issue 1 – October 2009 www.diodes.com © Diodes Incorporated 2009 6 of 8 ZXCT1086EV1 INTENTIONALLY BLANK Issue 1 – October 2009 www.diodes.com © Diodes Incorporated 2009 7 of 8 ZXCT1086EV1 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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