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differential amplifier across current sense resistor

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electrophysics

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Hi. how to replace LM358 with LF353 (with jfet input) in switching power supply across current sense resistor as differential amplifier. I have tried the circuit with LM358. but it does not give good wave shape. on the other hand the problem with LF353 is that when I connect single ended supply it does not work. I think it requires dual power supply.
 

Dear Friend!
Hi
Without you schematic , how can i help you? what kind of power supply? AC or DC? did you used compensation network? the open loop gain of op amps are about infinite. so thus the BW is low without feed back . but you can use a compensation network . by the way , if you want to build a current limiter , why you don't use comparators such as lm311?
For more information , it is important to more describe about your circuit.
Best Wishes
Goldsmith
 

When asking for help with a particular design, it's always best to post the schematic. Otherwise, those who can help you are working blind.
 

There's going to ba a lot of common-mode ground garbage on that sense resistor
most likely, and you may need to blank that or sample the current away from any
switching edge. But slow op amps may not come around quick enough if you are
slapping them every cycle. It would probably help you to put scope probes on both
sides of the sense resistor at once and look at the difference as well as the single
ended voltages. You might just get killed by lousy HF CMRR or something like that,
not a datasheet item per se and very design-variable.
 

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