TC4420 MOSFET Driver Simple H-Bridge Circuit
Fig. 1

Use TC4420 MOSFET Driver for Simple H-Bridge Circuit

by Lewis Loflin

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Here I will illustrate how to build an H-bridge motor control using 4 MOSFETs and 2 TC4420 MOSFET drivers, plus a few capacitors.

If one is unfamiliar with the TC4420 see the following two webpages:

According to the manufacturer:

The TC4420/TC4429 are 6A (peak), single-output MOSFET drivers. The TC4429 is an inverting driver while the TC4420 is a non-inverting driver. These drivers are fabricated in CMOS for lower power and more efficient operation versus bipolar drivers.

Both devices have TTL/CMOS compatible inputs that can be driven as high as VDD + 0.3V or as low as –5V without upset or damage to the device. This eliminates the need for external level-shifting circuitry.

The output swing is rail-to-rail, ensuring better drive voltage margin, especially during power-up/power-down sequencing. Propagational delay time is only 55ns (typical) and the output rise and fall times are only 25ns (typical) into 2500pF across the usable power supply range.

I have used these and they work very well. The circuit is shown in Fig. 1. It has two inputs A and B. Yes one can connect and inverter between A and B for a single input, but to turn the motor off means disconnecting the power. Also tow of the modes will be unavailable.

In most cases the diodes are internal to the MOSFETs. Use MOSFETs with low Rds(on) values such as the IRFZ44N (N-channel) and IRF4905 (p-channel).

the maximum motor voltage is 18 volts.
H-bridge in STOP mode with both p-channels turned on.
Fig. 2

Fig. 2 illustrates the STOP mode with both p-channels turned on. Both A and B are LOW.

H-bridge in BREAK mode with both N-channels on.
Fig. 3

Fig. 3 illustrates the BREAK mode with both N-channels on. Both A and B are HIGH.

H-bridge in FORWARD mode.
Fig. 4

Fig. 4 illustrates the FORWARD mode. A is LOW turning on Q1 while B is HIGH turning on Q4 to complete the current path.

H-bridge in REVERSE mode.
Fig. 5

Fig. 5 illustrates the REVERSE mode. A is HIGH turning on Q3 while B is LOW turning on Q2.

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