TM4C123AE6PM: Drawing excessive current

Hi Doug,

Doug Broadwell85 said:

I'm bringing up a new board and at power-on the CPU is trying to draw over 200mA

There is definitely some shorts. I would expect at reset, the reset current to be in the single digits. Do you have only one board or multiple boards with the problem? Recently, I came across a customer reporting excessive currents but that was due to using the wrong part number. I don't think you have the same issue but it is worth to double check. 

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1538682/tm4c1290ncpdt-design-review

 If you only have one board then I will suggest you replace the MCU with a new one. Can you repeat the same excessive current? If yes, then you must have a short somewhere. Is this short only detected after you run some program or the short is imminent as soon as the MCU powers up without any code in it? Answering these questions will help isolate the problem. Make sure you are not creating drive conflicts on I/O if other components are the board are driving the opposite values. 

Hello Charles,

I have two boards and they both exhibit the same failure.  There is no short to ground on the supply rails nor on the crystal.  I assume that other than driving the crystal and maybe 1 or 2 JTAG lines that all other I/O is high impedance.  These devices have never been programmed.

Thanks, Doug

I should also mention that the 3.3V supply gets to roughly 2.5V when it starts to over current.