Hardware Reference
In-Depth Information
Chapter 7
76 The H-Bridge Driver
One of the challenges of driving DC electric motors is that they sometimes need the
capability to operate in reverse. To do this, the current flow must be reversed. Arranging
for this requires additional hardware.
The H-Bridge driver can be used to drive a reversible DC motor or a bipolar stepper
motor (also LEDs, as covered in Chapter 10 of Raspberry Pi Hardware Reference
[Apress, 2014]). Unlike the unipolar motor, the field windings of a bipolar stepper motor
require reversible current flow to operate. This chapter demonstrates the utility of the
H-Bridge driver, using a bipolar stepper motor.
The L298 Driver
The L298 integrated circuit implements a convenient H-Bridge driver circuit. An H-Bridge
can be built from discrete components, but integrated circuits are more convenient for
lower-current applications. Figure 7-1 shows the block diagram for the L298 driver IC.
You can see the H composed from the driver transistors Q 1 through Q 4 , and the driven
motor in the center (in this case, a DC motor).
Figure 7-1. L298 full-bridge driver
 
Search WWH ::




Custom Search