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AZube.2
Associate III
April 28, 2022
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?

  • April 28, 2022
  • 4 replies
  • 2657 views

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Best answer by MasterT

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

4 replies

gbm
Lead III
April 28, 2022

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
Super User
April 28, 2022

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
April 28, 2022

Perfect thanks!

MasterT
MasterTBest answer
Lead II
April 28, 2022

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
April 29, 2022

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