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TPL5111: Timer is not triggered by the resistor.

fedi makni
Prodigy 90 points
Part Number: TPL5111

Hello,

I am currently using the TPL5111 in the timer mode in my design.

with the resistor i am using a mosfet which is controlled by a sensor so if we detect the sensor it will connect the delay pin to VDD through the mosfet and set DRVn pin to high.
The problem that the TPL5111 couldn't wake up with the attached resistor ( i am using a 47K so it's about one minutes) after waiting for one minute without the trigger from the sensor it should set the DRVn pin to high and wake up the uC but it doesn't.

If I remove the mosfet it will work normally by detecting the resistor.

I couldn't understand the origin of the problem ( i am using the TPL5111 in timer mode. )

Looking forward to your help. thanks 

  • 0
    TI__Genius 16845 points

    Can you share the schematic? It makes sense that it works normally with the mosfet removed; in this case, DELAY/M_DRV is floating, correct?

    Are you issuing a valid DELAY/M_DRV pulse? See figure 11 in the datasheet. If DRVn is already HIGH, DELAY/M_DRV pulse is ignored.

    Kind regards,
    Lane 

  • 0 in reply to Lane Boyd
    Prodigy 90 points

    Hello,

    Here is the schematic used in the design, two ways to trigger the TPL5111, PIR sensor or timer.

    Even if the PIR is not working and the DRVn pin is low, depending on the datasheet it should go to high after the timer pass ( set by the resistor) but it actually doesn't even waiting for a couple of cycle without any trigger and the DRVn stay LOW all the time until a PIR trigger happen so i could get a HIGH output.

    This is weird and i couldn't explain the phenomena.

    Looking forward to your reply.

    Thank you for your cooperation. Best regards.

  • 0 in reply to fedi makni
    Prodigy 90 points

    Hello,

    Is there any helpful information i could get it for this problem?

    Looking forward to your reply.

  • 0 in reply to fedi makni
    TI__Genius 16845 points

    Thanks for sharing the schematic. I see you have TPL5111 configured in timer mode for 1 minute interval. Are you providing a DONE input?

    TPL5111 DRVn output will be driven HIGH after the resistance reading is complete. The output will remain high until either a DONE pulse is received, or 50ms before the time interval expires. The output would remain LOW for the remainder of the 1s interval before returning HIGH.

    If you are observing DRVn is LOW all the time until PIR occurs, it indicates that you may have some issues with the transistor logic (Q1, Q2, Q3, Q4). My current guess is that at power-up, the DELAY/M_DRV pin is tied to VDD. TAfter power-on, TPL5111 will be unable to complete the resistance reading after until VDD is removed from DELAY/M_DRV 

    Kind regards,
    Lane