« previous next »
Pages: [1]   Go Down

Author Topic: Microcontrollers Resistor  (Read 2761 times)

0 Members and 1 Guest are viewing this topic.

Offline jaRONTopic starter

  • Contributor
  • Posts: 34
Microcontrollers Resistor
« on: September 27, 2011, 01:26:59 am »
do i need a Resistor between the Microcontroller and the Transistor it is irf44
Logged
 

Offline buffalo960

  • Contributor
  • Posts: 22
Re: Microcontrollers Resistor
« Reply #1 on: September 27, 2011, 01:56:28 am »
Logged
 

Offline Psi

  • Super Contributor
  • ***
  • Posts: 10223
  • Country: nz
Re: Microcontrollers Resistor
« Reply #2 on: September 27, 2011, 03:08:38 am »
Assuming 5V drive, you should put a low value resistor, like 200 ohms, between the microcontroller and the gate.
It insures that the current can never get above 25mA  (5V/200) which is safe for the microcontroller i/o port.

It would work fine without the resistor but it's always a good idea to use it anyway.
Resistors are cheap, mosfets and microcontrollers, not so much.

Logged
Greek letter 'Psi' (not Pounds per Square Inch)
 

Offline buffalo960

  • Contributor
  • Posts: 22
Re: Microcontrollers Resistor
« Reply #3 on: September 27, 2011, 07:21:22 pm »
Is there any way (other then switching the mosfet really fast) that the gate current would rise above very low levels?
Logged
 

Offline Psi

  • Super Contributor
  • ***
  • Posts: 10223
  • Country: nz
Re: Microcontrollers Resistor
« Reply #4 on: September 28, 2011, 03:31:45 am »
Yeah, if the mosfet blew up (as they sometimes do) it might short the mosfet supply rail to the micro i/o and damage it. Especially if the mosfet rail is higher than 5V
« Last Edit: September 28, 2011, 03:34:24 am by Psi »
Logged
Greek letter 'Psi' (not Pounds per Square Inch)
 
Pages: [1]   Go Up
« previous next »

Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf

 


EEVblog Main Site EEVblog on Youtube EEVblog on Twitter EEVblog on Facebook EEVblog on Odysee