Part Number: LM258A
Pls help to suggestion How to improved current sensing circuit operation range -20C to 80C ?
Test result is below .
@ 25C set current is 3.958A the output opamp is 2.493V the result is PASS
@ 55C set current is 3.625A the output opamp is 2.493V the result is FAIL because the power supply is not operation at max load(3.791A )
@ -20C set current 4.166A the output opamp is 2.493V the result is FAIL because the power supply is not protection by current limit ( 3.958A current limit )
1.The maximum output current of PSU is 3.791A
2.Current limit is 3.958A
Thank you so much&Bestregard
Using your data I see that the change in current from -20C to 55C was 541mA. This is a 5.41mV difference in sense resistor voltage. That is a big change. The 4.7uF direct capacitance on the output far too much. In general, there should be no direct capacitance on the output at all. Does removing this capacitor help? The feedback R and C has a crossover at 1Hz. Do you only want only the average current and can tolerate lag? Last but just as important, make sure that the 1.21k resistor and the non inverting resistor have a kelvin connection to the sense resistor.
Regards,Ronald MichallickLinear Applications
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In reply to Ron Michallick:
Thank you so much for your help .Pls help again
How to adjust R-C network of circuit to meet current limit (3.958A ) in all temperature rang of device ?
In reply to prarinya Maneechompoo:
Start by removing the 4.7uF capacitor. This may be all that is needed.
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