How to sense current AC of a sinusoide -100mA to 100mA with 70kHz

Question

Any suggestions about a chip or PCB component that could work?

I tried to use the the current sense transformer PA1005.050NLT https://www.digikey.com/product-detail/en/pulse-electronics-power/PA1005.050NLT/553-1527-1-ND/2362933 to sense a small sinusoidal current (from +100 to -100mA), but it does not seem to produce the expected result for such a small currents:

For 100mA I want to get a 4.4V output, so I set the output resistor to 2k2: VADC=R*Ipeak/50=2k2*100mA/50=4.4V

In the datasheet it says that the expected current for the component is 1/50 the sensed current, but I much smaller current (something like 1/1000) and the signal is very noisy. If I increase the output resistor the signal is amplified but it is too ugly and noisy. Any ideas?

A current transformer sounds like the best solution but the part you have selected is rated for 20A. Pick one with a rating a bit higher than the maximum you expect to see. But, only a bit higher. — Warren Hill, May 20 '20 at 15:21
Using this online tool I get current transformers with a very high maximum current: https://www.coilcraft.com/apps/current_trans/current_trans.cfm, but also there is a parameter which is a maximum voltage of 10V, which I find weird. Should this current transformer work?: https://www.digikey.com/product-detail/en/triad-magnetics/CST25-0050/237-2335-ND/9091774 — algior, May 20 '20 at 19:00

score 0 · Answer 1 · answered Jul 12 '20 at 22:31

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I finally used the PA0368.050NLT (from the company Pulse) and it is working nicely. It is rated for maximum 4A, while the one initially used was rated for 20A. Thanks very much for your help!

answered Jul 12 '20 at 22:31

algior

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You will make your answer to your own post much more valuable, if you add details about your implementation and perhaps conditions and boundaries. – Ariser Jul 13 '20 at 11:15

How to sense current AC of a sinusoide -100mA to 100mA with 70kHz

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