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TPS3895: TPS3895A output can't be released to high level

Part Number: TPS3895


I use the TPS3895ADRYR as a power on reset signal.

The target voltage= (1+511k/110k)x 0.5= 2.82V. 

I know TPS3895A output is push-pull , so I depopulate the R746.

However, I can't see the reset (output) release to high level.

I check the figure 1. of datasheet. It seems that Enable need to be released before Sense. 

I measure my EN and Sense which is shown below (P1)

Enable  is not released before Sense. 

Does the timing of Enable and Sense on P1 cause that output can't be released???



  • Robert,

    Your circuit configuration looks good. And it does not matter if SENSE or ENABLE come up first, SENSE_OUT should come up around 8.84ms after the SENSE and ENABLE are both up. I think it's possible the device is not soldered all the way down and the device may not be connected to the SENSE_OUT trace on the board. The reason I say this is because nothing in the schematic indicates an issue. These are very small SON package devices so my recommendation is to heat up the device while on the board with a heat gun for example and press down with tweezers to make sure the device is soldered completely down. If you are absolutely confident that the device is soldered down correctly, I would recommend using a second device. If that does not work it may be an issue with the board, pad, socket, or layout. A correctly working device with have the SENSE_OUT rise after the delay set by CT after both SENSE is above VIT+ and ENABLE is at least 0.7xVDD.

    Please let me know once you try to re-solder the device if it resolves the issue. Thanks

  • Robert,

    I have not heard back if the issue was a solder or board issue. Please let me know if you still need assistance. Thanks