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STM32G474 discovery kit no voltage at Vin

Associate II

Hi all, I am trying the voltage mode buck converter provided by ST with my STM32 discovery kit. I followed the instructions from an5497-buck-current-mode-with-the-bg474edpow1-discovery-kit-stmicroelectronics.pdf and the program files are directly downloaded from cubeIDE. However, when I compile the function, I found that I cannot measure anything at the Vout pin and the TP1 pin, after investigation, I further found that the Vin pin do not have any voltage either. I have already plugged in both usb-b and usb-c plug, the lights are normally functioning, but there is no voltage at Vin, can anyone tell me why?

ST Employee

Hello @OFN ,

Please make sure that the jumper JP1 is in the USB PD-VIN position.

Thank you.


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ST Employee

Hello @OFN ,

You did not comment @KDJEM.1 's reply, but in case you would still not have found a solution with this advice, I suggest to look at the schematics of the MB1428 Board, and verify few points of measures on MB1428 which may help: 

- Check your USBPD_VBUS is present (5V nominal on C105, bottom side of Board), and if yes, then the issue might come from the Double Switch function of schematics wich is not activated. Then, check that the GPIO PC3 "BUCKBOOST_USBPD_EN" is at high level 3.3V (PC3 is accessible on CN8 pin 31).

If not, it means your software does not manage this PIO correctly.

If yes, check SB12 (top side) is present on board and that R142 / R140 are also populated together with all other main components around : Q12/13/14 (all bottom side). The mid-point between R140 and R142 shall be close to 0 Volt when PC3 is high level.

Keep us aware of any findings.

- Other solution could be to use an external power supply (+5V , GND) and to connect it between VIN and GND pins of JP1 (remove completely the closed jumper and disconnect USB cable from CN12, and please keep on your side the closed jumper for any future use on JP1 with USB cable instead of an external supply, this to protect from unwanted external contact on VIN when VBUS USB is used), and check your Buck current mode application works.


Best Regards,