STM32F769BIT6 Operating current and temperature

[Mr.Developer]

Hi

We have a board with STM32F769BIT6 MCU.

When we drive the board with 3.3V, MCU current consumption is about 400~450 mA and it gets really hot!

When we drive the board with voltages below 3V, for example 2.5V, it takes about 20~30 mA and stays cool and fully functional.

In the datasheet it is stated that the operating voltage range is 1.8 to 3.6. We have designed our board based on 3.3V but this high current consumption and high temperature is not accepted for us.

Our design is completely based on STM32F769I-EVAL. Only the package is different. We are using STM32769BI (LQFP208) whereas the evaluation board is using STM32F769NI (TFBGA216). We have declared all IO pins as analog inputs so as to avoid accidental current draining.

Does anyone have similar experience? Are we missing any point here?

Thanks in advance

[TDK]

That is not typical. There is likely a hardware error or wiring error present.

[Mr.Developer]

We are pretty sure that there is no hardware error. We have checked everything. Our design is completely based on STM32F769I-EVAL. Only the package is different. We are using STM32769BI (LQFP208) whereas the evaluation board is using STM32F769NI (TFBGA216). We have declared all IO pins as analog inputs so as to avoid accidental current draining.

[TDK]

Is this repeatable across multiple boards/chips? If so, I'm going to stick with a hardware/layout issue.

The chip can operate at 3.3V without drawing 400mA as it does on many boards, including the STM32F769I-EVAL.

Share your schematic if you want.

Does it also occur when the flash is erased?

[Mr.Developer]

I have attached the schematic for MCU. I am using external stable power supply for test purpose so I have not included the power section.

[TDK]

VDD12DSI connected to VDD_MCU doesn't look right.

[Mr.Developer]

According to the datasheet page 29, if DSI is not used, then VDD12DSI must be connected to VDD:

[TDK]

> According to the datasheet page 29, if DSI is not used, then VDD12DSI must be connected to VDD:

No, it says VDDDSI must be connected to VDD.

It says VDD12DSI must be connected to VCAPDSI.

VDDDSI (pin 118) and VDD12DSI (pin 125) are different pins.