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TLV9351: what is the time required to power up the device?

Part Number: TLV9351

How long does it take for the TLV9351 (or any other Amoeba device for that matter) to be up and running after power is applied?

Thank you!

  • Hi Lenio,

    this is mainly determined by the time constants formed by the components of feedback circuitry.

    Kai

  • So there is no way to predict what the timing is going to be? Would a simulation model show this parameter?

  • Hi Lenio,

    We don't have a spec for power up time or turn on time so we can't guarantee anything. But I can reach out to our design team to see if they could give us an estimate for typical behavior. My guess is somewhere in the 10's of microsecond time range.

    Our simulation models to not model power up/down behavior. 

    Kai is correct that sometimes external components will dominate the time it takes for the circuit to "start up". For example, if there is a bias voltage created from the the supply voltage and a voltage divider + filter cap (10kohm + 1uF), the time it takes for the RC circuit to charge (10ms for 10k + 1uF) may be longer than it takes the op amp to turn on.

    Thank you,

    Tim Claycomb

  • Are you only interested in knowing the start up time of the TLV9351? You mentioned "or any other Amoeba device for that matter" in your initial post so this post could be a question on how to determine the start up time more than a asking for a number for the specification. 

    Unless there is a spec named "power up time" or "turn on time" that is not related to the shutdown behavior of a device, there is not a good way to know the start up time of a device.

  • Tim, this is related to the conversation we have been having via email. The main interest is TLV9351, but since the customer is not completely decided on using it, I'd like to understand how the analysis expands to the rest of the family. Obviously the external network of caps and resistors will many times dominate the startup, but it would useful to understand when the OpAmp itself is running within expected parameters. For applications that turn on upon demand, this is critical information. 

  • Hi Lenio,

    There isn't a good way to know the start up time unless there is a specific specification in the datasheet. The start up time is dependent on how fast internal nodes charge and how fast currents are "steered" into different blocks of the op amp or if there is circuitry to help the device start up. Its not always dependent on bandwidth or Iq. 

    Start up time is not a question we get asked very often which is why it probably there is not a specification in our datasheets. I have seen a few devices with a start up time spec but I don't think they are very common.

    Thank you,

    Tim Claycomb

  • And some OPAmps don't even want the supply voltage ramp up all too quickly:

    Kai