Hello all,
My customer is having an issue with using the TPL5010. They are using it in a low power application to trigger a reset one time five minutes after the source voltage is turned off.
The setup is very similar to this setup in the datasheet below. The main difference is that RSTn and DONE are tied together since they are not waking a microcontroller but triggering a reset once.
They are using a 43K resistor for Rext in order to set a 5 minute period between Wake signals (this being said, they are only interested in sending 1 wait signal). The SPST switch is normally closed, and when main power is lost, the switch opens and DELAY/M_RST is connected to Rext to read the value and begin the 5 minute wait period.
The issue they are having is that the wait period is not 5 minutes (two to three times greater). Each time they try to reset the timer value by removing power to the device, the timer value is set to a different value, and this value is consistent until power is removed again.
They then tried using a SPDT switch instead of an SPST switch such as the configuration below. This change worked and they are now seeing a 5 minute period each time:
So the primary questions are:
1. Any thoughts on why the SPDT setup is working and the SPST is not? Seems like they should work the same so there is suspicion whether this is the root cause
2. Is it acceptable to tie RSTn and DONE together? We noticed that there is a minimum delay tDdone in the datasheet of DONE to RSTn of 100ns so this could be an issue. If this is not an acceptable setup, is there a way to configure the device such that it will work even if it is not receiving a "Done" signal from an external device?
Thanks so much,
Austin Allen
