STM32H747BGT6 MIPI-DSI VDD12DSI

[el659]

Hi, I have a question about supplying power to DSI interface on STM32H747BGT6 (208 LGFP package).

RM0399 says, "The DSI interface is supplied from a dedicated VDD12DSI supply that can be provided either
by the integrated DSI regulator or by an external DSI supply."

The figure also shows the two ways to supply 1.2V to DSI PHY. As far as I read from RM0399, if I want to supply 1.2V to DSI PHY with DSI regulator, I should first deliver 3.3V to VDDDSI, and connect VCAPDSI to VDD12DSI. 

But the pinout diagram of STM32H747BGT6 (208 LGFP package) has no VDDDSI but only two VDD12DSI.

What I would like to ask is:
1. Does this mean STM32H747BGT6 (208 LGFP package) is limited to external 1.2V supply to VDD12DSI only or is one of the VDD12DSI the intended "VDDDSI" for internal DSI regulator?

2. Whats the recommended capacitor value for VDD12DSI pins on STM32H747BGT6 (208 LGFP package)?

Thanks in advance.

[maryjlee]

Hi there,

Thanks for your post about the STM32H747BGT6 and the MIPI‑DSI VDD12_DSI supply issue. Could you please share the following details so we can help further:

1. A schematic or snippet showing how you’ve connected VDD12_DSI (voltage level, power path, decoupling).

2. Which DSI panel/PHY you’re using, and any applicable datasheet reference.

3. Whether you’ve measured the voltage on VDD12_DSI during startup (and if the MCU resets or the DSI link fails).

4. The firmware version (HAL/LL) and any initialization sequence you’re using for the DSI/DSI‑PHY.

Once we have that we can better pinpoint if the issue is hardware‑related or a HAL/driver configuration quirk.

For more info visit - https://www.etei.com/ 

[el659]

1, 2, 3, 4: I am still at design stage. I was about to draw the MIPI-DSI part of the STM32H747BGT6 schematics until I found out that there is no VDDDSI pin on STM32H747BGT6. Datasheet and RM0399 only mentions the presense of VDDDSI pin but diagram of 208 LQFP package, which is STM32H747BGT6, in H747 datasheet, Cube IDE and STM32H747BGT6 on schematics simply has no VDDDSI pin but only VDD12DSI which is for the DSI regulator in the MCU.