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About the output trouble of INA199A1

Satoshi
Guru 19615 points

Although INA199A1 is used in the attached circuit, there are a device which about 350 mV of output voltage is outputting to current not flowing, and a device currently outputted about 860 mV.

3566.6886.INA199A1.xlsx
If INA199A1 has broken, a circuit diagram and others have a cause or it may think, please let me know.


Supplementary information is written to below.

- The probability that abnormalities will occur is 5/20 (25%).

-  Turn on and off 16.5V and 3.3V separately.
When 16.5V turns on, there is also the state where 3.3V turns off.


- It becomes below when a power supply is turned on in order of "16.5V ON->3.3V OFF."
     A normal article is set to several 100 mV->0V.
     An unusual article is not set to 0V.

Moreover, it is the same result, even after turning on and setting time also immediately after turning on.


- Since the character of a circuit diagram is small, write the constant of R400 and C337 to below.
     R400=20mohm
     C337=10pF


I'm saved with give advice as soon as possible , sorry.


Thank you for your consideration.

Satoshi

  • 0
    TI__Genius 14825 points

    Satoshi,

    Just to make sure I understand you correctly:

    16.5V is on and 3.3V is on, and then you turn 3.3V off.  Does off mean 3.3V is now open or is it set to 0V?

    When both 16.5V and 3.3V are on, the output is 100+mV, and then when 3.3V is turned off, the output goes to 0V.

    However sometimes when 3.3V is turned off, the output does not go to 0V.  This happens 25% of the time.


    Is this correct?

    A few questions:

    Is this behavior repeatable on 5 of 20 different units; or if you do this 20 times on one unit, it happens 5 times?

    When you say "Moreover, it is the same result, even after turning on and setting time also immediately after turning on," do you mean that the output stays at the incorrect voltage regardless of input when you turn on 3.3V?

    Is the 100+mV on the output a significant problem for the customer?  Does the problem remain if a load is placed on the output?

    A possible explanation:

    Page 12 of the data sheet explains that there are current paths through the resistors between the inputs and output.  However, I speculate that with a 16.5V common mode, the current through the 1Mohm resistor is 16.5uA, which would need at least a 6k resistor to ground on the output to generate 100mV.  What is attached to the output, if anything?

    Please let me know the answers to these questions and I will continue to investigate this issue.

    Thank you,

    Jason Bridgmon