STM32H745ZIT6 VCAP Confusion

[andrewliu0116]

Hello, 

I am currently trying to set up the STM32H745ZIT6, and the datasheet wasn’t too clear about how to wire up the 3 VCAP pins. It stated to use 2x 2.2uF caps, but doesn’t state which pins. I found an old forum with many different configurations, typing all VCAP pins together, no VCAP pins tied togehter, and only two VCAP pins tied together. I just wanted some clarification on how I should be typing these pins.

[andrewliu0116]

Here is the old forum I found, which uses a different STM than me, but was the closest thing I found.

[TDK]

The hardware design guide explains this explicitly:

Getting started with STM32H74xI/G and STM32H75xI/G MCU hardware development - Application note

[andrewliu0116]

Hi, Thanks for the clarification.

Is there a pin-to-pin mapping for VCAP1, VCAP2, or VCAP3, as the datasheet just has them as VCAP. If so, is there a reccomended layout placement. For example VCAP1 and VCAP2 should have the 2.2uF caps physically close to them, and VCAP3 doesn’t.

[TDK]

 It should be specified in the datasheet, but it’s not. In practice, these are bulk capacitors so just pick 2 pins and it’ll be fine. Follow the layout of the discovery board:

Pin A7 (pin 140 on LQFP144) is VCAP3.