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STM32U3C5 - SMPS: Is an inductor needed for each VDD11?

AQB
Associate

Hello,
I am working on a design incorporating the STM32U3C5CIU6Q in SMPS mode. This package includes two VDD11 pins. I am having trouble interpreting the datasheet when it comes to the number of inductors I will need. This note under Figure 24 in the datasheet is clear that each pin will need a capacitor to VSSSMPS, but it seems like it could also imply that each VDD11 pin requires its own inductor between VLXSMPS.

AQB_0-1777900009211.png

The power supply scheme (with SMPS) is also not clear to me:

 

AQB_2-1777900236726.png

This section seems more like it is expecting a single inductor:

AQB_3-1777900508633.png

Am I okay to use a single inductor between the VLXSMPS pin and VD11 node, with each VD11 pin having its own capacitors, or should I treat each VD11 as a separate loop with its own inductor as well?

Thanks for any help!

1 ACCEPTED SOLUTION

Accepted Solutions
mƎALLEm
ST Employee

Hello,

I recommend to refer to the AN6011 "Getting started with STM32U3 MCU hardware development" / Section 8 Reference design:

mALLEm_0-1777904800208.png

Hope that helps.

PS: I'll escalate internally to remove this confusion from the datasheet. Internal ticket for follow-up: CDM0062340.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

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1 REPLY 1
mƎALLEm
ST Employee

Hello,

I recommend to refer to the AN6011 "Getting started with STM32U3 MCU hardware development" / Section 8 Reference design:

mALLEm_0-1777904800208.png

Hope that helps.

PS: I'll escalate internally to remove this confusion from the datasheet. Internal ticket for follow-up: CDM0062340.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.
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