Combined Bipolar and MOSFET H-bridge (MEC126E)

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 combining bipolar and MOSFETs, ideal for controlling DC motors and can be used as a shield.

The configuration shown by Figure 1 combines bipolar transistors with power MOSFETs. R1 and R2 form a feedback network that determines which bipolar transistor conducts when the power MOSFETs are triggered on. 

The value of these resistors depends on their gain. Using high-gain transistors such as the BD136, BD138, or another, you can use a 1 kΩ resistor. For transistors with less gain, e.g., the TIP32 or TIP42, you’ll need 220 Ω resistors.

All the transistors need heat sinks. The circuit has the same control logic as one shown for MEC125E.



Figure 1    : combined bipolar + power MOSFET.
Figure 1 : combined bipolar + power MOSFET.


See other circuits like this in this section of the site.