0-1A Single-Supply, Low-Side, Current Sensor with Output 0 to 4.9V

This single-supply, low-side, current sensing solution accurately detects load current between 0 and 1A. The current sensor measures 0 to 1A across the shunt resistor, providing 0 to 4.9V output. The OPA320 features wide bandwidth and low offset voltage making it an excellent amplifier for this design. With a single 5V supply, the LM7705 negative bias generator extends the linear output range of the amplifier below 0V. This enables the op-amp to produce a linear output for a zero-input current condition. The wide sensing range of the design allows for precise measurement of small load currents (i.e., low-power or shutdown modes) and higher currents up to 1A. The LM7705 functions as an inverting charge pump and regulates its output to -0.23V when powered by a single supply. By biasing the negative supply (VS-) of the op-amp to -0.23V, the linear output range of the device is extended below 0V. A linear output at 0V allows a calibrated measurement of zero-input current.

Features

• Power Supply 5V DC @ 10mA
• Load Current 0 to 1Amp
• Output 0 to 4.9V
• Full-Scale Error +/-0.1%
• PCB Dimensions 28.58 x 14.13 mm

Connections

• CN1: Pin 1 = VCC 5V DC, Pin 2,3 = GND, Pin 4 = Output
• CN2: Load Pin 1,2 = Load, Pin 3,4 = GND
• D1 Power LED

Schematic

Parts List

Connections

Input-Output Diagram

Gerber View

Photos

Video

LM7705 Datasheet

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