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Associate
February 17, 2025
Question

STM32H735 custom board power draw

Hi,

Ive made a custom board with a STM32H735 micro on it. I have built a board with nothing but a micro and a few of its needed passive components and went to provide it power and test that its working. I supplied power from a benchtop power supply with a current limit of 400ma and it hit this limit at 3v. Dropping to 100ma it hit the limit at 2.2V. Checking the resistance on the power rails it 10.25k and the Vcap rail is 500k. Thermal camera shows a square heat zone expanding from the centre of the IC (LFQP package) towards the outside. Ive now tired 3 different ICs on 3 different boards. The schematic is very similar to the STM32H735G-DK  with changes mostly being things like jumpers. What could be causing this issue and what steps can i take from here?
Thanks in advanced

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15 replies

LCE
Principal III
February 20, 2025

> No matter this config the VFBSMPS is connected correctly

What do you actually mean?

Is VFBSMPS connected or not?

Again, for SMPS I'm pretty sure it must be connected.

pin description:

LCE_0-1740059496097.png

 

Associate
February 21, 2025

Yes, VFBSMPS is connected as is VDDSMPS

AScha.3
Super User
February 21, 2025

Hi,

show your actual circuit, as it is connected (with 0r or not ).

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