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Select the right current shunt amplifier

Question asked by on Oct 11, 2016

Hi all

for an application I am struggling to identify the shunt amplifier. The Picture below show what I have got so far....

The MCU ist decoding the pulse with coded signal. Therefor it can trigger the ADC conversion / sampling at any given time in the positive or negative halve wave which is min. 50µS wide.

There is always a small load of 20 mA or so. The current measurement must:

- reliably detect an additional load of 10 to 20 mA in the range of 20 mA to 250 mA, e.g a change from 20 to 40 mA or from 200 to 220mA

- detect a current limit of 4 A.

The ADC is not selected yet. On the same board there are 1 MCU, 1 switched power supply (3.3V) but 2 load connections with for each a shunt , an amplifier and an ADC.

The amplifier mus have a bandwith of ate least 100kHz and deliver valid results as close as possible down to 5 mA.

So, what amplifier would fit in and how?

Any input would be be most welcome.

Best regards