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AZube.2
Associate III
Apr 28, 2022 11:55 AM UTC
Solved

When using a GPIO pin as output, is the offered voltage stable? Imagine I want to use it to enable (or disable) an LDO, is it okay to connect the GPIO output to the enable pin directly?

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MasterT
MasterTBest answer
Lead II
Apr 28, 2022 10:12 PM UTC

Check data sheet for your LDO, if Logic High within 3.3V.

I wouldn't connect uCPU directly with enable pin, better to set a resistor in series, to stay safe in case of whatever may happened to LDO - power domain is always most vulnerable part of the circuits. 10k - 100k

5 replies

gbm
Super User
Apr 28, 2022 12:26 PM UTC

If the logic level was "unstable", the output would be useless.

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice
TDK
Apr 28, 2022 1:18 PM UTC

Yes, the output will stay high if you set it high, and low if you set it low, until you change it, or the chip loses power or resets.

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AZube.2
AZube.2Author
Associate III
Apr 28, 2022 1:45 PM UTC

Perfect thanks!

MasterT
MasterTBest answer
Lead II
Apr 28, 2022 10:12 PM UTC

Check data sheet for your LDO, if Logic High within 3.3V.

I wouldn't connect uCPU directly with enable pin, better to set a resistor in series, to stay safe in case of whatever may happened to LDO - power domain is always most vulnerable part of the circuits. 10k - 100k

AZube.2
AZube.2Author
Associate III
Apr 29, 2022 7:29 AM UTC

Sounds reasonable now that you said it! Thanks for the tip:)