STM32H723GT6 bare test failing

[MDeac.1]

I have had a couple of Nucleo 144 test/demo boards for a couple of years and have had no issues with them.

So I decided to try and create the simplest PCB from scratch.

What is happening is the chip itself is resetting when powered with a repeated signal as measured on an oscilliscope.

The devices is powered from a 3.6V LDO regulator that can provide 500mA.

Before I try to program the device I am trying to get the supply to the chip stable.

What I have done on connections all VDD and VSS connected with 100nF caps with the 4.7uF as specified.

I have POR-ON, NRST and BOOT0 pulled high through 10K resistors.

Now the USB (I am not using) VDD33USB I have connected to 3.6V which it says I can in the spec sheet and bypassed with a 100nF capacitor.

I have also connected and bypassed the VDDA pin also.

Am I missing something I need to do or does the empty chip reset itself this way until it is programmed?

Any suggestions would be greatly appreciated.

I have not exceeded the voltage limits.

[TDK]

A fresh chip will not reset itself--something is wrong.

Are VCAP pins connected and bypassed to GND with a 2.2 uF? Perhaps show the schematic.

> STM32H723GT6 

This is missing a letter. STM32H723ZGT6 perhaps?

Design guide here:

https://www.st.com/resource/en/application_note/an5419-getting-started-with-stm32h723733-stm32h725735-and-stm32h730-value-line-hardware-development-stmicroelectronics.pdf

[MDeac.1]

Thank you ... the real answer for me to progress further is the chip should not be visibly resetting.

Yes I do have 2.2uF caps bypass to ground on each VCAP.

Yes I missed the letter off the chip model.

So I am now considering the chip I have used as the 3.6V LDO is a production part I use on another device so well understood. The chip is of uncertain origin as it was obtained from a dubious source when supply was an issue.

I have 2 more though that I got from a reputable outlet so will assemble another for comparison.

So I consider my question answered.