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OPA541: OPA541 TO-3 Pin Configuration

Eduardo Polonio
Prodigy 10 points

Part Number: OPA541
Other Parts Discussed in Thread: OPA549-HIREL

Hi, 

I would like to evaluate OPA541 with the TO-3 package in one of our existing designs. The pin configuration of the 8-Pin TO-3 package is not clear for me, the datasheet only shows pin configuration of the 11-Pin TO-220.

I need to confirm that the pin configuration before ordering samples to evaluate in our design.

Thanks,

Eduardo

  • 0
    TI__Mastermind 18106 points

    Hey Eduardo, 

    Welcome to the E2E forum,

    The OPA541xM in LMF TO-CAN package is not recommended for new designs. It is still a bit surprising that the pinout was pulled from the datasheet, though this may have been done to actively steer new designs away from this part number. 

    What is the end equipment for this application? 

    Many of these power TO-CAN devices have a somewhat uncertain future due to the packaging.

    Devices like OPA549-HIREL may be a better choice, though I understand if you need this to be a can. 

    Here is the pinout which was removed from the datasheet:

    Let me dig a bit deeper to better understand the plans for this TO-3 device. 

    Thanks,

    Jacob

  • 0 in reply to Jacob Nogaj
    Prodigy 10 points

    Thanks for your replay, this is the opamp circuit we are working with:

    We are evaluating alternatives for the U11 opamp:

    Based on this information, can you confirm that the OPA541 will not work in our application due to a different pin configuration?

    Finally, is there any 8-pin TO-3 package adapter available?

    Thanks,

    Eduardo

  • 0 in reply to Eduardo Polonio
    TI__Mastermind 18106 points

    Hey Eduardo, 

    You are correct, it looks like we are just a little bit off in pinout. 

    The good news is that we are not especially different, though there are a few critical challenges we would need to overcome. The primary issue is the current sense circuitry. Our device at a minimum will need pins 1 and 8 of the OPA541 connected together, though I have never actually shorted these myself without some resistance between them. Our device does not have balance or CC pins, so some of this functionality will not work with OPA541. 

    The minimum to get this working would be to make OPA541 pin 8 to short to OPA541 pin 1 and end up on your ACT1765 pin1. 

    Just for my information, what is currently being populated for ACT1765?

    Eduardo Polonio said:
    Finally, is there any 8-pin TO-3 package adapter available?

    I am not familiar with an adapter  existing, but you could always spin up a PCB or hack together an adapter with a TO-3 socket. These TO-3 packages rely heavily on the mechanical configuration of the package for dissipating power, an adapter board may introduce additional thermal resistance. 

    Thanks,

    Jacob

  • 0 in reply to Jacob Nogaj
    Prodigy 10 points

    Hi Jacob,

    Thanks for your support.

    Would it be possible for TI to implement custom modifications to the OPA541 in terms of pinout and adjusting specs if needed to make it suitable for this application?
    ACT1765 is Apex MPN: PA09-27.
    Kind regards,
    Eduardo
  • +1 in reply to Eduardo Polonio
    TI__Mastermind 18106 points

    Hey Eduardo, 

    I checked with our team, and this type of bond change would be challenging to achieve. Moreover, the PA09 is a high-speed power amp, so there may be performance differences depending on the application. 

    Even if we get this particular OPA541 to work on the PCB, this product is being recommended to not be used for new designs. I would highly recommend we consider using an alternative package if the PCB can be redesigned. Alternatively, it may be possible to design a small adapter PCB to adapt a different pinout/package to fit the existing board. 

    Please let me know if this is a potential option. 

    Thanks,

    Jacob

  • 0 in reply to Jacob Nogaj
    Prodigy 10 points

    Hi Jacob,

    Thank you once again for your support. I'll reach out in case I have further questions.

    Kind regards,

    Eduardo