Contents
What can A H-bridge be used for?
The most common use of an H-bridge is to drive a DC motor, allowing directional control. There are various H-Bridge designs, and some use discrete components consisting of MOSFETs, while other designs utilize a dedicated Integrated Chip (IC) H-bridge.
What happens when a H bridge switch is closed?
The motor spins when the switch closes. The diode becomes reverse biased, and current flows through it. When the switch opens, the induced voltage reverses direction and can flow through the now forward biased diode, as shown in figure 4. Unfortunately, when using an H-bridge circuit, a single flyback diode will not suffice.
How does a H bridge DC motor work?
Figure 1 shows a basic high-level view of an H-bridge circuit controlling a DC motor. When S1 and S4 are closed, the motor is powered and spins in one direction. If S3 and S2 are closed, the motor changes direction and now rotates in the opposite direction.
What kind of circuitry is in a H bridge?
For example, the TC78H620 contains over-current detection, thermal monitoring/shutdown, and undervoltage lockout. At quantities of 2000 parts, they are available for around $0.60 each. Some ICs will contain circuitry to help protect from inductive loads, but the TC78 does not.
Can A H-bridge be turned on and off?
In general all four switching elements can be turned on and off independently, though there are some obvious restrictions. Though the load can in theory be anything you want, by far the most pervasive application if H-bridges is with a brushed DC or bipolar stepper motor (steppers need two H-bridges per motor) load.
How are switches used in a H bridge circuit?
Many H-Bridge circuits have protection to prevent a “shoot-through” condition from occurring, but it is still best to ensure that it will not arise programmatically. The traditional method of constructing an H-bridge is by using discrete components, typically MOSFETs to act as the four switches as shown in figure 2.
What is the operating mode of a H bridge?
The basic operating mode of an H-bridge is fairly simple: if Q1 and Q4 are turned on, the left lead of the motor will be connected to the power supply, while the right lead is connected to ground. Current starts flowing through the motor which energizes the motor in (let’s say) the forward direction and the motor shaft starts spinning.