I have designed a custom board based on Jetson TK1. My design is working fine however in one board I am facing some issue with the power.
Whenever I power up, +VDD_CPU_AP (generated by AS3728) goes down to 0V. The temp signals (between AS3728 and AS3722) also shows 0V. It does not happen all the time. Sometimes the same board boots up properly. In normal scenario, +VDD_CPU_AP provides 1.0V and the TEMP signal also shows 1.2V. CTRL signal of the sub die (AS3728) is always at 5V.
I want to know the exact reason that why is this happening. Usually the problem occurs early in the morning when the board is cold. However by reading the pin description, I feel that this should happen when the temperature of the sub die reached 140 degree celsius.
Hi, if it only happens on one board, then looks like a board issue. That needs to compare to normal board to find out it is component issue or soldering issue. Regarding the temperature consideration, you can use other tools like thermal meter to measure the temperature of chip surface.
Can you please help me in debugging my board. I had seen that sub die0, subdie1, and subdie6 are controlled by AS3722 through TEMP pin and CTRL pin. Upon reading the datasheet, I found that TEMP pin is Analog Input Output pin in both the ICs (AS3722 and AS3728). Can you please tell me in what scenarios does this pin behave as input for AS3728 and output for AS3722 and in what scenario it behave as output for AS3728 and input for AS3722 ?
Also please suggest what are the possible reasons to shutdown only on sub die while other are working fine.
TEMP pin is to indicate temperature of AS3728 is too high. It looks like some short on AS3728 output power rail or it has been broken.