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Q: TPS3128 - WDI left floating & WDT is still resetting by 1574398
Our customer is having issues with the TPS3128. The customer has disabled the WDT on the MSP430 they are using. The chip is still being reset at t = 0.8s, and we believe that the WDT on the SVS is triggering the reset.
The customer has left the WDI pin floating according to the app note SLVA145. This seems to be in direct contradiction to the datasheet which says nothing about floating the WDI pin and states "In addition, the TPS3123/4/8 have a watchdog timer that needs to be triggeredperiodically by a positive or negative transition at WDI. When the supervising system fails to retrigger the watchdog circuit within the time-out interval ttout= 0.8 s, RESET output becomes active for the time period (td). This event also reinitializes the watchdog timer.”
A: Re: TPS3128 - WDI left floating & WDT is still resetting by 1090425
Yes, the watchdog on the TPS3128 cannot be disabled. The app note clearly states the parts that it applies to in this sentence:
The watchdog timer in many of TI’s supervisory circuits can be disabled by leaving the WDI pin open.
The datasheet for the parts that have this feature will state the above. The TPS3128 does not support this feature. They must use the WDI on this IC. If they do not want to WDI feature, they can use the pin to pin TPS3125/6. The TPS3820 is an example of a part that does disable the watchdog when WDI is left floating.
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