This discrete MOSFET H-bridge motor driver enables bidirectional control of one high-power DC brushed motor. The small 1.3″ × 0.8″ board supports a wide 6.5 V to 40 V voltage range and is efficient enough to deliver a continuous 21 A without a heat sink. Additional features of this second-generation (G2) driver include reverse-voltage protection along with basic current sensing and current limiting functionality.

Overview

The Pololu G2 high-power motor driver is a discrete MOSFET H-bridge designed to drive large brushed DC motors. The H-bridge is made up of one N-channel MOSFET per leg; the rest of the board contains the circuitry to take user inputs and control the MOSFETs. The absolute maximum voltage for this motor driver is 40 V, and higher voltages can permanently destroy the motor driver. Under normal operating conditions, ripple voltage on the supply line can raise the maximum voltage to more than the average or intended voltage, so a safe maximum voltage is approximately 34 V.

Note: Battery voltages can be much higher than nominal voltages when they are charged, so the maximum nominal battery voltage we recommend is 28 V unless appropriate measures are taken to limit the peak voltage.

The versatility of this driver makes it suitable for a large range of currents and voltages: it can deliver up to 21 A of continuous current with a board size of only 1.3″ × 0.8″ and no required heat sink. The module offers a simple interface that requires as few as two I/O lines while still allowing for your choice of sign-magnitude or locked-antiphase operation. A current sense output gives an indicator of motor current, and the driver can limit the motor current to a configurable threshold. The power supply inputs feature reverse-voltage protection, while integrated detection of various fault conditions helps protect against other common causes of catastrophic failure; however, please note that the board does not include over-temperature protection.

The G2 High-Power Motor Driver 24v21 is a second-generation successor to our original High-Power Motor Driver 24v20. The G2 driver is much smaller than the original, but its interface and output capabilities make it a near drop-in replacement in typical applications. See “Differences from original high-power motor drivers” below for more details.

This version can be distinguished from the 18v25 by the number 100 on top of the tall silver electrolytic capacitors.

Features

• Operating voltage: 6.5 V to 40 V (absolute maximum)
• Output current: 21 A continuous
• Inputs compatible with 1.8 V, 3.3 V, and 5 V logic
• PWM operation up to 100 kHz
• Current sense output proportional to motor current (approx. 20 mV/A; only active while H-bridge is driving)
• Active current limiting (chopping) with default threshold of 50 A (can be adjusted lower)
• Reverse-voltage protection
• Undervoltage shutdown
• Short circuit protection

Dimensions

General specifications

Identifying markings

Notes:

1

Without included connectors.

2

Absolute maximum; higher voltages can permanently destroy the motor driver. Recommended maximum is approximately 34 V, which leaves a safety margin for ripple voltage on the supply line.

3

Typical results with 100% duty cycle at room temperature.