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Four Quadrant power supply with current measurement
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sandy.holmarc:
Hello,
I would like to develop a four quadrant power supply with a ammeter and voltmeter for photo voltaic VI measurement. when a current sensing resistor added in the series with the load in this setup  it works fine in the lower voltage .But at voltage above 0.5V the output of LT1970 is oscillates.I need a closed loop circuit to make VI measurement.Is there any other method to develop a Four quadrant power supply with a ammeter and  a source meter ? .Any help would be greatly appreciated.
Best regards,
Sandeep
Rerouter:
It would appear your sense resistor doesnt make sense? are you sure your schematic is correct, as at the moment the current sense doesn't do anything?

Still I thank you for making me aware this IC exists.
Kalvin:
You may want to check your design against the reference design from Analog Design:

"LT1970ACFE | Power Op Amp with Adjustable Current Limit Boosted":
https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/dc453b-b.html#eb-documentation

Schematics:
https://www.analog.com/media/en/technical-documentation/eval-board-schematic/DC453B-SCH.pdf

Note particularly how the feedback capacitor is connected from the LT1970's output to the negative input. You have a capacitor connected from the output to the ground, which is no a good thing as it may cause the op amp circuit oscillate.
sandy.holmarc:
hello ,
Thank you very much for the quick reply. Apologize for not mentioning about the relays.,The relays S1 and S5 are closed for the high current range (10mA to 1A) ,S3 and S4 closed for the range 0.1ma to 10mA and S2 and S6 closed for the 0.1uA to 0.1mA.
sandy.holmarc:
Hello Kalvin ,
Thanks for the assistance,I used this circuit as the reference. The capacitor that you mentioned is 330Pf and 220PF ?
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