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TPS7A7001: low temp output issue

Dane Zhang
Expert 7915 points
Part Number: TPS7A7001

Hi team,

Our customer's project uses TPS7A7001 for 5.5V to 5V application, and found that when the low temperature is about -40, the LDO output is abnormal.


They used a liquid nitrogen spray device to cool down in the laboratory, and a similar abnormality was also reproduced. The result is that the output voltage suddenly drops, it may drop to 4V, 3V, 2V, and it can slowly recover after a period of time. Through observation, this kind of abnormality will occur during the process of heating up after spraying liquid nitrogen. When the temperature returns to the normal value, the output voltage can be restored to normal.


Could you help me see if similar problems have occurred with this device?


If the device exceeds the temperature range of -40 and the temperature rises to within -40, will the stability of the device vary greatly?

  • 0
    TI__Mastermind 37065 points

    Hi Dane,

    Linear regulators which provide access to the feedback node (whether from TI or another company) can all be susceptible to leakage.  If there is leakage on the board, then the leakage path could form a high impedance across one of the setpoint resistors which would shift the setpoint.  Common ways we see accidental leakage is through: uncleaned flux on the PCB, isopropyl alcohol on the board, freeze spray, etc.  The feedback node is the most sensitive for this leakage in this component.  When the customer applies the liquid nitrogen spray, I believe this is what you are seeing.

    As long as the customer is following the guidance in the datasheet for output capacitance, there should not be any stability concerns (see section 8.1.2 in the datasheet).

    The customer should make sure that the R2 value of the feedback network is set between 27k and 33k ohms.

    Thanks,

    - Stephen