Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

MOSFET (Si/SiC) Forum Discussions

Harold
Level 1
10 questions asked 10 sign-ins 5 questions asked
Level 1

I want to use a MOSFET as a switch driven by my microcomputer.

aqDwX

 

 

The original circuit using N-channel MOSFET is on the left side. Honestly, I do not understand the choice of the IRLZ44. The circuit is designed for Arduino, which has 5V logic. Which means that for GPIO=True=5V, MOSFET opens and lets the current into the load.

However I have two problems:

I am using Raspberry Pi, which has 3.3V logic. According to available information, 3.3V is not enough to fully open MOSFET.
I want my load to be connected to the ground (I had to do some voltage measurements).
I know enough electronics to assume that using P-channel MOSFET, as shown on the right side, might solve both of my problems at one stroke. For GPIO=False=0V MOSFET will be fully open, while GPIO=True=3.3V puts -1.7V on the MOSFET gate and practically close it down. If that does not suffice, I could also put GPIO into the listening mode and therefore pull the MOSFET gate to 5V.

 

Could you please tell me if the idea will work? And what IRLZ44-equivalent P-channel MOSFET should I use?

 

 

0 Likes
1 Solution
Jingwei
Moderator
Moderator 100 sign-ins 50 replies posted 25 solutions authored
Moderator

Hi, Harold

You have the right idea.

I am pretty sure this PMOS will meet your requirements. You need to pay attention to the design of the drive resistor and the gate resistor to ensure that the MOS can conduct in a reasonable time without overcurrent. Also calculate the theoretical power and operating temperature of the PMOS to ensure that the maximum allowable MOS temperature is not exceeded.

 

 

BR,

Steven

 

View solution in original post

0 Likes
1 Reply
Jingwei
Moderator
Moderator 100 sign-ins 50 replies posted 25 solutions authored
Moderator

Hi, Harold

You have the right idea.

I am pretty sure this PMOS will meet your requirements. You need to pay attention to the design of the drive resistor and the gate resistor to ensure that the MOS can conduct in a reasonable time without overcurrent. Also calculate the theoretical power and operating temperature of the PMOS to ensure that the maximum allowable MOS temperature is not exceeded.

 

 

BR,

Steven

 

0 Likes