H bridge motor driver problems

Thread Starter

zgaunc

Joined Aug 22, 2021
15
Hello, I’m designing a H bridge motor driver. I follow the design in the attached file and made a bread board to test. I use Arduino board to send signal with a 5v power source. A separate power supply connected with the driver bread board. Ground on both board were connected. When I powered up both board, the motor just didn’t run. I don’t know what was the problem. I also attached my bread board picture. The upper mosfet I use is p channel AO3401, lower mosfet is n channel AO3400.
Could any one help me to find out what is wrong with the driver board. Thank you.
 

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bertus

Joined Apr 5, 2008
21,604
Hello,

When de driving transistor is open (not driven) the gate voltages of the mosfets will be about 1/2 Vcc = 6 Volts.
Make the top resistors 1K and the bottom resistors 100 K and try again.

Bertus
 

Thread Starter

zgaunc

Joined Aug 22, 2021
15
Hello,

When de driving transistor is open (not driven) the gate voltages of the mosfets will be about 1/2 Vcc = 6 Volts.
Make the top resistors 1K and the bottom resistors 100 K and try again.

Bertus
Thank you for your answer. I will try later
 

Thread Starter

zgaunc

Joined Aug 22, 2021
15
I found the problem. I wired the two n channel mosfets which located at both sides to receive signals wrong. D should connect with the power, S should connect to ground.
 

click_here

Joined Sep 22, 2020
444
Forget to say that I didn’t add any resistors on both signal wires.
It would probably extend the life of your Arduino output pins if you did.

The ATmega328P has a Max rated output current of 40mA, so you would probably want to make sure that does not happen.

You also want to provide enough current to the NPN to put it in saturation mode

20mA would probably be a good value - 0.6V is the VBE of the NPN

(5V-0.6V)/0.02A = 220R
 
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