Ultra-Precise, Current-Sense Amplifier

 

The INAx290 is an ultra-precise, current-sense amplifier that can measure voltage drops across shunt resistors over a wide common-mode range from 2.7 V to 120 V. Depending on your application, different gains can be selected.

 – A1 devices: 20 V/V

 – A2 devices: 50 V/V 

– A3 devices: 100 V/V 

– A4 devices: 200 V/V 

– A5 devices: 500 V/V 

Ultra-Precise, Current-Sense Amplifier

 

 

This circuit uses Texas Instruments' ultra-precise current-sense amp, which can measure voltage drops across shunt resistors over a wide common-mode range from 2.7 V to 120 V. The amp is available in a highly space-efficient SC-70 package with a PCB footprint of 2.0 mm x 2.1 mm. It achieves ultra-precise current measurement accuracy due to its ultra-low offset voltage of ±12 µV (maximum), a small gain error of ±0.1% (maximum), and a high DC CMRR of 160 dB.

Designed for DC current measurement and high-speed applications (such as fast overcurrent protection), this amp has a high bandwidth of 1 MHz (at a gain of 20 V/V) and an 85 dB AC CMRR (at 50 kHz). It operates from a single 2.7 V to 20 V supply, drawing a 370 µA supply current (typical). The amp is available with five gain options including 20 V/V, 50 V/V, 100 V/V, 200 V/V, and 500 V/V. Its low offset of the zero-drift architecture enables current-sensing with low ohmic shunts over the extended operating temperature range of -40°C to +125°C.

EEVblog uCurrent - Precision nA Current Measurement Assistant

Here is another useful circuit from EEVblog, that can be used to measure from pico amps to amps current.