Hi Guys,
We've just completed a custom design, based on the EVM and it is working very well.
We also passed preliminary EMC testing well.
The last issue we are trying to resolve is that the CPU is getting very hot. It seems as if we are driving a wrong voltage level or might have some level of short in the design.
We've done the following tests:
1.) Reduce the clock frequency and disable unused clocks - no effect
2.) Make the boot process stop in u-boot, thus not running Android/Linux - no effect
3.) Reduced clock frequency of LCD driver - no effect
4.) Carefully measure and test all the voltage lines.
We found the we get a voltage of 4.55V on VDDSHV6 - which seems very odd!
We disconnected VDDSHV6 from VAUX2 (on the TPS65910). The VAUX2 then measured 3.3V and the VDDSHV6 rail still measured 4.55V
The only voltage on the board which is above 3.3V is the USB1_VBUS and USB0_VBUS; we disconnected these lines and the VDDSHV6 still measured 4.55V
Why would this be and how is this possible?
VDDSHV6 is now not connected to any external power source and it is still measuring 4.55V and the AM3354 is getting very hot whilst sitting in u-boot.
The temperature measures around 60C
What else can typically cause this high temperature under limited to no load?
Any guidance and suggestions will be appreciated.
Thank you
Louis
