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LM1458: Large drift

Part Number: LM1458
Other Parts Discussed in Thread: TLV9302, LM324

Customer are designing in a DC power supply project. They used LM1458 device and power is -15V and +15V by LM7915 and LM7815.

They uses LM1458 to amplify the signal on the sampling resistor, and the signal is amplified 47 times in the same direction. The temperature from 28° to 70°, the output voltage drifts by about 0.0074V.

Customer thinks the drift is large and wants us to recommend the low drift op amp.

I find LM1458 offset drift is 0. So how can I recommend the lower drift device to the customer?   Looking forward to your reply, thanks.

  • Hello Kevin,

    Are they really customers? It is curious that they chose all the parts from the previous century (real old products).  

    The drift isn't really zero. The drift is completely not specified at all. Offset at 25C is not very good and there is no other temperature noted. 

    The (noise) gain of the circuit is 46k/1k +1 = 47. The output DC error will be 47 * Vos (including drift)

    7.4mV drift equates to 157uV drift or 3.7uV/C drift.

    Determine how much (output) error can be accepted. Divide that by 47 then look for an op amp better than that math result.

  • Hi Ron,

    I can understand your curious. Customer really use the LM1458 and I recommend them to test TLV9302. 

    Thank you for help. 

  • Hi Ron,

    there are parts in the world where people are happy to get any OPAmp at all. They cannot switch to the latest OPAmps but must take what they get (LM324, LM1458, etc.).

    And the LM7815 and LM7915 are still used by professionals Relaxed

    Kai

  • Thank Kai,

    Your point of view and experience is always valuable.