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Part Number: INA225
I am trying to measure small currents with the INA225. (Imax 25mA) High-side 24V. Rshunt = 1Ohm. Gain 100. Vs = +5V.
I have the following measurement C1 is a control step-input. C2 signal measured by INA225 (no load). C4 an external current probe. slowly rising current on C4 is OK (for the moment) there's a PMOSFET controlling the current, which is charging slowly.
What I don't like is INA225 starting to measure only at about 14mA (14mV). Is that behavior intended by TI? How can I know from the datasheet? What can I do better?
Second thing. For larger/faster steps, there is a delay of around 22us from input to output, that I cannot find a reason for.
Thanks for any help/correction/advise!
Sorry, it seems my pictures are not accepted...
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before was measurement nr 2
here comes nr 1
In reply to Simon Steinegger:
Patrick Simmons, TI Sensing Products Applications Support
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In reply to Patrick Simmons:
Thanks for your advice. I just came back form holidays. Vs (+5V), GS0 and GS1 (0V and 3.3V) look fine. Additionally I tried reducing the gain. Didn't help, same curves at different levels.
Your idea with Vref refers to chapter "18.104.22.168 Detailed Design Procedure" on page 22 of the datasheet, right? I'll check that, although my problem is with higher output levels than 10mV...
This will take some more time, as I need to find a safe way to lift pin Nr. 7 from GND plane.
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