Hi,
I have an issue with the TPS61305 and the HotDie events.
When I drive the LEDs with a current pulse (4.2A pulse, zero dc current setting) from a supercapacitor (0.6F), I keep getting a “HotDie_Thermal Shutdown” event occurring even though I am pretty sure that the die is not overheating.
Extra info:
- pulse duration for example = 80 ms,
- STIM = 102.2ms,
- Pulse drive from FLASH_SYNC pin.
- Inductor = 2.2uH
- 2 LEDs (one for LED2, the other for LED1 &LED3 outputs together)
If I monitor the HotDie bits during the current pulse they report that the die temperature is <= 55 deg C. However as soon as the pulse finishes the next time I read the HotDie bits I see that the Thermal shutdown has occurred. This behaviour happens regardless of what flash duration I use (I have tried from 50us up to 80ms).
Because I see that at 79ms, during a 80ms pulse, that the die <= 55degC, I do not believe that the die is getting too hot for a 50ms pulse, but I still see the thermal shutdown event occurring at the end of the 50ms pulse (even at the end of a 200us pulse).
I have played with ILIM at initial startup and see it has no effect on this behaviour. I see that ENPSM has not effect on it, also the OV (target voltage) has no effect on the behaviour.
If I program STIM to shorter than the LED pulse duration then I see the Thermal Shutdown event occurring as soon as the STIM times out, I can understand that.
I have re-routed the ground connections and the AVIN connection thinking that ground bounce/supply bounce may be the problem, but it didn’t help.
While I can work around this “false” HotDie Thermal Shutdown event in fw, my feeling is that it should not be occurring.
Any ideas on what may be causing it?
