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LM258A: LM258A replaced by LM358B

david sun1
Intellectual 280 points
Part Number: LM258A
Other Parts Discussed in Thread: LM358B, LM358A, LM358, LM258

Hi Amplifier Expert, 

I have a design using LM258A, generally speaking, is LM358A or B a drop-in replacement. is there any trick or concern if I use LM358B? I notice that LM358B Iq = 800uA max, each amp.

LM358A Iq = 1000 uA max, if we use two chips, I can save up to 800uA total in the worst case.

in datasheet P16, the PSRR- is very interesting. If I have a switching regulator output -15V with a 50mV ripple at 100KHz typical per spec, should I expect there will be a ~5mV noise show on the output?

there is no PSRR chart for LM258, do I expect it will be worse than LM358 or similar. 

Thanks,

David.S 

  • 0
    TI__Guru**** 153196 points

    Hello David,

    The PSRR+ and - is similar for all versions of the LM358/2904.

    It is reasonable to expect about 5mV referenced to the input. Then it is multiplied by the op amp forward gain at that frequency. 

    Adding a RC filter to power pin 4 is a practical way to reduced the noise.