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Associate II
Jan 18, 2025 8:27 AM UTC
Solved

Optimizing 12V GPIO Logic Level Conversion: 5V vs. 3.3V on STM32H753ZIT6

I have a 12V GPIO high logic input on my board. Should I convert it to a 5V logic level or a 3.3V logic level? Previously, I have implemented 12V to 5V logic level conversion and already have components for this conversion in my inventory. If feasible, can I proceed with 12V to 5V conversion, or is it generally more advantageous to convert 12V high to 3.3V logic level for better compatibility or performance? Is there any recommended project/schematic/component that I should look into for this application?

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gbm
gbmBest answer
Super User
Jan 18, 2025 9:58 AM UTC

For most use cases, 2 resistor divider is enough (like 27k + 10k). For some, even one serial resistor is enough.

Any details?

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice

3 replies

gbm
gbmBest answer
Super User
Jan 18, 2025 9:58 AM UTC

For most use cases, 2 resistor divider is enough (like 27k + 10k). For some, even one serial resistor is enough.

Any details?

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice
hvs_learnAuthor
Associate II
Jan 19, 2025 12:47 PM UTC

I want to know if the pins are 5V tolerant or just 3V3 tolerant?

AScha.3
Super User
Jan 19, 2025 12:57 PM UTC

See in ds of your cpu. pin list...

 

But anyway: this is a 3v3 cpu, so use 3v3 level for input signals. Not a difficult decision .

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