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H-bridge Using Power MOSFETs with Enable (MEC125E)

This article was taken from my book Robotics, Mechatronics and Artificial Intelligence (sold out) published in the United States and also from previous articles in other publications, with minor updates. It shows an H-bridge with external Enable using Power MOSFETs, ideal for controlling DC motors and can be used as a shield.

Adding a power MOSFET as shown in Figure 1, the H-bridge using power MOSFET (MEC124E) can be enabled by an external logic signal. Q5 controls all the current across the bridge and is on when the input IN3 is low, and off when the input is high. The control logic is given by the following table:

 

 

 


 

 

Q5 is the same transistor as all others in the bridge, and it is chosen according to the current drained by the motor.

 

Figure 1    Full H-bridge with enable input.
Figure 1 Full H-bridge with enable input.