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7 years, 1 month ago.
How much voltage can open drain mode "pull" an actuator GND?
Hello guys, I have the following issue:
Application: Engage some actuator (e.g. relay) that need a voltage larger than 3.3V
Problem: I hadn't yet been able to find this specification in the Datasheet and User Manual.
What I´ve found so far: At https://developer.mbed.org/teams/TVZ-Mechatronics-Team/wiki/Digital-inputs-and-outputs, says that "The open drain mode is usually used when a voltage needed to engage some actuator (e.g. relay) is larger than 3.3 V (e.g. 5 V, 12 V or 24 V)."
Question: How much voltage can open drain mode "pull" an actuator GND?
Thx in advance!
1 Answer
7 years, 1 month ago.
You have not specified the platform. Most cpu's can only switch 3,3V - some can tolerate 5V. Nearly all ports of a cpu are push pull outputs. If a port is switched to open drain the transistor to VCC is switched to high impedance, but the diode to VCC will draw current if the voltage is higher than VCC. If you want to switch higher voltages use a external transistor or fet.