Two Channel Current Sensor for High Voltage Range

  • Rajkumar Sharma
  • 6 Views
  • moderate
  • Tested
  • SKU: EL154082
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This board is built using a 2 x INA149 precision unity-gain difference amplifier with a very high input common-mode voltage range. The project can be used as a current sensor for high-voltage applications, INA149 provides a common-mode voltage range of +/-275V. The project operates with a wide supply range from +/-5V to +/-15V.  The circuit measures current by sensing the voltage drop across a series of resistors RS, R4, and R12. The application circuit shows the INA149 used to measure the supply currents of a device under test. The sense resistor imbalances the input resistor matching of the INA149, thus degrading its CMR. Also, the input impedance of the INA149 loads RS, causes a gain error in the voltage-to-current conversion. Both of these errors can be easily corrected.

Note: The project can be used to measure current up to 2A, of DC Bus with +/-275V, this project has a few additional optional components R5, R6, C7, C8, C10 + R10, R13, C11, C13, C14, they can be used to overcome of CMR error. Refer to the datasheet of INA149 for more info. All these components are SMD size 0805.

Current Sense Resistors

The board provides dual options for current sense resistors. Users may use THT resistors up to 3W R3, R11, or SMD 2512 R4 and R12 Up to 3W. The default circuit measures current up to 2A. Choose the appropriate current sense resistor for a higher or lower current sense range.

Features

  • Power Supply +/-5V to +/-15V (Wide Supply Range: ±2.0 V to ±18 V)
  • Output 500mV/1A
  • Common-Mode Voltage Range: ±275 V
  • Minimum CMRR: 90 dB from –40°C to +125°C
  • DC Specifications: INA149
    • Maximum Offset Voltage: 1100 µV
    • Maximum Offset Voltage Drift: 15 µV/°C
    • Maximum Gain Error: 0.02%
    • Maximum Gain Error Drift: 10 ppm/°C
    • Maximum Gain Nonlinearity: 0.001% FSR
  • AC Performance: INA149
    • Bandwidth: 500 kHz
  • Input Protection: INA149
    • Common-Mode: ±500 V
    • Differential: ±500 V
  • PCB Dimensions 46.36 x 33.34 mm
  • 4 x 3MM Mounting Holes

The INA149 is a precision unity-gain difference amplifier with a very high input common-mode voltage range. It is a single, monolithic device that consists of a precision op amp and an integrated thin-film resistor network. The INA149 can accurately measure small differential voltages in the presence of common-mode signals up to ±275 V. The INA149 inputs are protected from momentary common-mode or differential overloads of up to 500 V.

Applications

  • High-Voltage Current Sensing
  • Battery Cell Current or Voltage Monitoring
  • Power-Supply Current Monitoring
  • Motor Controls

Connections

  • CN1: Pin 1 = +5V to 15V DC, Pin 2 = GND, Pin 3 = -5V to 15V
  • CN2: Pin1 = Current Sense +I Channel A, Pin 2 Current Sense -I Channel A
  • CN3: Pin 1 REFB=1 CH-A (No Use), Pin 2 GND, Pin 3 = Channel A Output, Pin 4 = REFA-1 CH-A (No Use)
  • CN4: Pin1 = Current Sense +I Channel B, Pin 2 Current Sense -I Channel B
  • CN3: Pin 1 REFB=2 CH-B (No Use), Pin 2 GND, Pin 3 = Channel B Output, Pin 4 = REFA=2 CH-B (No Use)
  • D1: Power LED

Schematic

Parts List

NO.QNTY.REF.DESCMANUFACTURERSUPPLIERSUPPLIER PART NO
11CN13 PIN MALE HEADER PITCH 2.54MMWURTHDIGIKEY732-5316-ND
22CN2,CN42 PIN SCREW TERMINAL PITCH 5.08MMPHOENIXDIGIKEY277-1247-ND
32CN3,CN54 PIN MALE HEADER PITCH 2.54MMWURTHDIGIKEY732-5317-ND
42C1,C310uF/25V CERAM IC SMD SIZE 0805YAGEO/MURATADIGIKEY
54C2,C4,C5,C6100nF/50V CERAMIC SMD SIZE 0805YAGEO/MURATADIGIKEY
610R3,C7,C8,C9,C10,R11,C11,C12,C13,C14DNP
71D1LED SMD SIZE 0805OSRAMDIGIKEY475-1278-1-ND
81R11K 5% SMD SIZE 0805YAGEO/MURATADIGIKEY
910R2,R5,R6,R7,R8,R9,R10,R13,R14,R150E SMD DSIZE 0805YAGEO/MURATADIGIKEY
102R4,R120.5E/2W-3W 1% SMD SIZE 2512VISHAY/DALEDIGIKEY541-10290-1-ND
112U1,U2INA149 SOIC8TIDIGIKEY296-30028-1-ND

Connections

Application Diagram

Gerber View

Photos

INA149 Datahseet

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