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OPA2830: About Internal Circuits

Ryu Yamashita
Expert 2690 points
Part Number: OPA2830
Other Parts Discussed in Thread: LM2776

Hi team,

Could you please tell me the internal circuitry of this device?
I would like to use it to study the mounting circuit.

Sincerely,
Ryu.

  • +1
    TI__Expert 6050 points

    Hi Ryu,

    Unfortunately, I am not able to share any design files or internal circuitry details aside from what is disclosed in the datasheet. 

    However, if you have any specific concerns around the design on the amplifier circuit and how it integrates with other parts of your signal chain, I would be happy to help you work through those questions.

    Thanks,

    Nick

  • 0 in reply to Nick Nauman
    Expert 2690 points

    Hi Nick,

    Thanks for the reply.
    Are there parasitic diodes inside?
    I have a -5V power supply connected, but when I start the -5V power supply with multiple OPA2830s connected, it does not start up properly.
    At this time, the -5V power supply outputs 0.8V.
    If I remove the OPA2830, it starts up normally, and if I replace it with another op amp, it starts up normally.

    Sincerely,
    Ryu.

  • 0 in reply to Ryu Yamashita
    Guru 285840 points

    There are diodes (they are not parasitic, but explicitly designed in for ESD protection).

    Going beyond the absolute maximum ratings can damage the device. But the OPA2830 has no GND pin; it is not clear what actually happens in your circuit. Please show a schematic.

  • 0 in reply to Clemens Ladisch
    TI__Expert 6050 points

    Hi Ryu,

    As Clemens suggested, providing a schematic will help with troubleshooting this issue. Can you also provide clarification on how many OPA2830s you have connected and when you say that you remove the OPA2830, is that just one or all OPA2830s? And are you able to share what op amp you dropped in to replace it to get normal start up behavior?

    Thanks,

    Nick

  • 0 in reply to Nick Nauman
    Expert 2690 points

    Hi Nick,

    I use two OPA2830s.
    I am not talking about the op amps inside, but 2ps.
    The -5V power supply supplying these will not start.
    If I remove one of these it will start up.
    Another op amp used UPC4570 and it started up.

    Sincerely,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Expert 6050 points

    Hi Ryu,

    This does not appear to be an OPA2830 issue because when one OPA2830 is connected, the issue is not present. It appears to be a power supply issue.

    If you can share more information about your circuit, I would be happy to help with debugging the issue or forwarding to the appropriate team to cover the issue. Can you share what power supply you are using? Also, is there any other circuitry that is being connected that could be drawing a large amount of current that could be causing abnormal power supply behavior? Is there an input signal present on the amplifiers when you are power sequencing; if there is an input signal present, this could cause a voltage to appear on the power supply pins? This could cause abnormal power supply behavior.

    Thanks,

    Nick

  • 0 in reply to Nick Nauman
    Expert 2690 points

    Hi Nick,

    12V is input to NJM78M05 to create 5V.
    The 5V is input to LM2776 to create -5V.
    These are used as power supplies for the two OPA2830s.

    Sincerely,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Expert 6050 points

    Hi Ryu,

    The power supplies that you are using should have plenty of output current to power two OPA2830s. Have you confirmed that the OPA2830s were not damaged in soldering or that the configuration is not unstable and causing large current draws? Also, can you confirm if there is a input signal present on the amplifiers when power sequencing? If there is an input signal present, this could cause an output voltage to be present on the power supply pins that could effect the results you are seeing.

    Providing a schematic of the OPA2830s would be helpful in debugging further.

    Thanks,

    Nick