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LM4562 topology and return current paths

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Replies: 2

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Hello. I am designing a product that will use the LM4562.


I am analyzing the amplifier with particular concern to decoupling return current paths (see Analog Devices Application Note AN-202), to which the design is particularly sensitive.

The topology of the LM4562 is not made clear. Most opamp architectures refer the integrator that follows the differential to single ended converter to the negative supply terminal. Which must then be decoupled against the load ground. Does the LM4562 follow a similar pattern?


many thanks for any advice or information


Mark

  • Hello Mark-san,

    Thank you for taking LM4562 on your product. Yes, LM4562 is taking most common archtecture as you mentioned. The input stage is PNP diff pare with bias cancellation ckt and NPN turned arround current miller as output of input stage. This output is connected to 2nd stage( integrator) input. And then the output of 2nd stage connect to output stage (Emitter follower) with current limit. 

    I hope this information helps for your concern.

    FYI,

    LM4562 and LME49720 are the same chip and same perfomance. originaly this op-amp released as LM4562 but this device number "4562" was already exsist in competitor device name. Then we assigned new name as "LME49720" but LM4562 was already in mkt. So keep the device name as it is. So you can use LME49720 as well.

    Best regards

    T NAOKAWA

  • In reply to Toyojiro Naokawa:

    Toyojiro,


    Many thanks for your answer, that is exactly the information I am looking for (and a little more, I was not aware there was a bias cancellation circuit, which is somewhat surprising given the near transparent sonic characteristics). The  offset drift and offset specs are also very desirable. Great opamp!


    Thank you also for explaining the reasoning behind the dual product name, that is one less mystery that I do not have to wonder about.


    kind regards

    Mark

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