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“This is an example of a simple and cheap milliohmmeter that can be made by every maker. The core of the circuit are a current source (LT3092) and a current sense (INA225): a costant current flows through the milliohm resistor …
Content for INA225
The INA225 is a voltage-output, current-sense amplifier that senses drops across current-sensing resistors at common-mode voltages that can vary from 0 V to 36 V, independent of the supply voltage. The device is a bidirectional, current-shunt monitor that allows an external reference to be used to measure current flowing in both directions across a current-sensing resistor. Four discrete gain levels are selectable using the two gain-select terminals (GS0 and GS1) to program gains of 25 V/V, 50 V/V, 100 V/V, and 200 V/V. The low-offset, zero-drift architecture and precision gain values enable current-sensing with maximum drops across the shunt as low as 10 mV of full-scale while maintaining very high accuracy measurements over the entire operating temperature range.