STM32H745 power up issue

[ABora.4]

Hello,

We are using the MCU STM32H745 in our current design.

We have faced the issue of working MCU properly and below are the problem,

Case 1 : At power ON, some time the MCU work properly and sometime does not work properly, when it is not work properly, after pressing the reset switch multiple time, it will start working properly but not every time. In the case of working properly, it takes current of around 300mA but sometime the current will reduce to 100mA, and the interfaces are going to stop.

Case 2 : After then, we remove the SDRAM and disable the other interfaces like I2C, SPI, ADC and keep only UART interface ON and check the log on dock light over UART. In this case, the situation is the same, at power ON, some time it works and some time it is not working and using the reset switch, some time it works. 

So now we have only MCU STM32H745 is mounted on board and we expect that it should be work properly at least at power ON.

Note: This board is working properly with full software and hardware for 30 Days and suddenly, it stops working and behave as mentioned above.

As of now, we are planning to check the voltage level, power on sequence with respect to reset signals.

Kindly provide the steps to debug the issue.

Regards,

Alpesh

[AScha.3]

Hi,

yes, this could work - as a test - maybe need new cpu again, but can try with the actual - if needs much current, take new.

The 1v2 supply has to be clean, good ground connection and no spikes etc. !

+

Why is there D2 on vbat ? If 3v cell there - remove D2 . (useless part)

+

btw

At what speed the core should run ? (or was running, on working board ?)

[ABora.4]

Hello,

As per the Input, I have remove the FB1, L1 to keep the SMPS OFF and apply 1.2V to VDD_SDC at the core voltage and it take 11mA current in core and 64mA in 3.3V. After then I am able to programmed the board and execute the code.

Then I have insert the L1 and apply short link instead of FB1, in this condition the board is also working properly. On Saturday, full day that board is working properly.

On Monday, when I power up the board, it takes 1.5A current so I immediately turn off the board and do the same changes as I do to give 1.2V, core voltage directly. Now, it takes the same current, 11mA for core. But the issue is that after programming the board, the programmed is not execute and I have simple toggle the GPIO and keep LED on it. I can detect the MCU, programmed it successfully but the LED is not blinking.  

Regards,

Alpesh

[AScha.3]

Hi,

so with correct core voltage (about 1.2V ) board ia running. ok.

But i dont understand:

>But the issue is that after programming the board, the programmed is not execute and I have simple toggle the GPIO and keep LED on it. I can detect the MCU, programmed it successfully but the LED is not blinking. 

Programmed ok, but not running at all - or what? Maybe start-problem, reset on core might need power down here for reset - or is this the "1.5A unlucky cpu" -- then maybe very sick cpu...