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ADA4927-x : Power Down control in cold temperature

Hello ,

I have a question about power down control issue of ADA4927-x.

In page of 22 of  the datasheet, there are following text.

   The power-down feature should not be used in applications in which the ambient temperature falls below 0°C. Contact sales for information regarding applications that require the power-down feature to be used at ambient temperatures below 0°C.

What will happen if PD pin is asserted in cold condition ?

Our customer is asking it to us.

Best regards,

y-suzuki

  • Hello ,

    Could you please reply what will happen by power down in cold condition ?

    Our customer need to know this information to modify his PCB and  circuit.

    Thank you,

    Best regards.

    y-suzuki

  • HI y_suzuki,

    Apologies for late response.

    ADA4927-X PowerDown does not work well in cold temperatures. That means the part will power down but it will take a long time to power up.

    Regards.

  • Can you provide any more information about temperatures and how long it might take to power up?  I'm running into problems with ADA4927-2 where some of them (about 25%) are slow to power up (longer than 1.3mS) even at room temperature (70 F).

  • Hello Andy-san,

    I'm sorry, I have no more information about the ambient temperature of ADA4927-x.
    But I am interested in your information because I introduce ADA4927-x for the customer who needs a highspeed amplifier.
    Is that a quality issue?

    Best regards,

    y_suzuki

  • I do not know if this is a quality problem (bad batch), ESD, or production tolerance specific to this amplifier.  It definitely appears to be temperature-related, because some of the amplifiers will start to work correctly after having been powered on for 5-10 minutes.

    So far, I have only built a single batch of 10 parts, but since I am using 4 amplifiers per board, I only have a 30% yield that is fully functional.  I'm very concerned because I am about to start a second similar design and need to know that I won't have the same problem again.

  • I've been doing some additional testing, and it appears that all of the amplifiers work correctly if they are set to always on.

    After that, I tried testing them with a longer power-up time of 2mS, which was enough to correct 4 out of 7 amplifiers that were not working.

    To fix the remaining bad amplifiers, I ended up cutting the trace to the power down pin and using a 10k pull-up to set it to always on.

    For my design, the reason I'm cycling the amplifiers to power down is to reduce the power draw.  Since I have so many amplifiers on the board, enabling them all at once increases the draw past the capability of the power supply.  I can afford the additional 20mA draw of having one amplifier per board always enabled.

    I should note that I have confirmed that only the ADA4927-2 was having this problem.  I did not have any similar problems when using the ADA4938-2.  I have not done any testing with the ADA4932, but I'm considering using that in the next revision, hoping to avoid the problems.