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Question about INA128

TS Yang
Genius 4800 points
Other Parts Discussed in Thread: INA128, INA128-HT

Hello,

I use INA128 for PAC solution, and there is a phenomenon that INA128 is not working.

The symptom is as below.

- the voltage of pin 5 & pin 6 doesn't change when the voltage of pin 2 & pin 3 is changed.

- this occurs only when just power on, and it starts normal output over time.

My circuit received an input voltage  from the TC sensor and amplified by the INA128, and transfer this signal to AD converter.

I wonder whether certain stress conditions influence when that happens. (e.g. high temperature..)

  • 0
    TI__Mastermind 25815 points

    Hello TS Yang,

    Please note that the pin 5 is considered an input, and should not change as V(-IN) and V(+IN) change.

    It takes some amount of time for the device to start operating linearly upon start up. This is approximately 400-500us, as shown by the "Input Offset Voltage Warm-Up" plot given on page 6 of the data sheet. It is likely that temperature will affect this warm-up time, however this dependence is not characterized.

  • 0 in reply to Pete%20Semig
    Genius 4800 points

    Hello,

    thanks for your kind reply.

    I meant "the voltage of pin 5 & pin 6 doesn't change" as 0V.

    and it start operate normally after 5~30 seconds.

    I guess INA128 damaged from external environment factor like high temperature, because these defective parts were found at a certain customer site.

    I am very causious to predicate that certain stress conditions influence INA128,

    but can you advice about INA128 is vulnerable to certain conditions, and so bring about symptoms below?

  • 0 in reply to TS Yang
    TI__Mastermind 25815 points
    Hello TS Yang,

    I do not know of any high-temperature issues with the INA128. I have also been unable to find any device returns (failure analysis) related to high-temperature operation.

    The specified temperature range of the INA128 is -40C to +85C but it can operate up to +125C. If the device is exposed to temperatures outside of this range, I recommend switching to the INA128-HT. The recommend operating temperature range for the INA128-HT is -55C to +175C.