What is the electrical state of a GPIO in an unpowered Teensy ?

Status
Not open for further replies.

FAlameda

Active member
Greetings,

In my circuit, I am trying to control a channel P MOSFET by means of a Teensy 3.6 pin. The MOSFET is a high side switch that opens or closes a 5V line. Teensy can turn ON the MOSFET putting its gate to GND through the 1K resistance by means of

// Turns ON the MOSFET
pinMode(33, OUTPUT);
digitalWrite(33, LOW);


As the Teensy pins can't reach 5V in high state, the 22K pull-up resistance puts the gate to 5V and turns OFF the MOSFET when Teensy puts pin 33 in high Z by means of

// Turns OFF the MOSFET
pinMode(33, INPUT);


This works more or less, well. The problem is that the circuit fails to keep the MOSFET safely in the OFF state when Teensy goes unpowered. It's as if the Teensy GPIO 33 goes to LOW instead of staying in highZ when Teensy goes unpowered. GPIO 33 is a Digital/Analog pin.


new-2.png
 
Teensy 3.6 is not 5v tolerant, with the pull-up resistor you will damage the pin 33 if not already damaged.
 
Status
Not open for further replies.
Back
Top