Pololu G2 High-Power Motor Driver (Discrete MOSFET H-Bridge)
Compact, efficient DC brushed motor driver for demanding robotics and motion builds.
This Pololu high-power motor driver is a discrete MOSFET H-bridge built for driving large DC brushed motors with high efficiency and a small footprint. It uses N-channel MOSFETs (two per leg), with the rest of the circuitry handling user inputs and MOSFET control.
Why you’ll want this driver
- High continuous current: up to 25 A continuous in a compact board (no heatsink required for many builds).
- More with cooling: add a heatsink and good airflow for around 35 A continuous capability.
- Simple control: works with as little as 2 I/O pins (PWM + DIR) while supporting two control modes.
- Fault flags: FF1/FF2 pins help you detect common fault conditions before things get worse.
- Built for real motion projects: ideal for robot drive trains, heavy wheels, winches, actuators, and custom motion rigs.
Important voltage reminder (read this)
The MOSFETs have an absolute maximum rating of 30 V. Higher voltages can permanently destroy the driver. In real systems, supply ripple/spikes can push the voltage above your “average” supply, so a safer working maximum is approximately 24 V.
Note: “24 V” batteries can exceed 24 V when fully charged. This product is not recommended for 24 V batteries unless you add measures to limit peak voltage (good wiring, proper capacitors close to the driver, and spike suppression).
Using the Motor Driver
Connections (power side vs logic side)
The board is laid out with motor power + motor outputs on one side and 5 V logic control on the other. Your motor supply must be capable of high current, and it’s strongly recommended to install a large capacitor close to the driver to handle current surges and reduce voltage spikes.
The included axial capacitors can be installed directly into the pins labeled + and - (as shown below). This is compact, but may limit heatsink options. Depending on your supply quality and motor characteristics, you might need a larger capacitor than what’s included.
For high-power signals (V+, OUTA, OUTB, GND), you get two wiring options: large holes on 0.2" centers (fits the included terminal blocks) or pairs of 0.1" holes for perfboards/headers.
Warning: High-power electronics can be dangerous. During normal operation, this driver can get hot enough to burn you. Use proper wiring, secure connections, and handle with care.
Logic levels
Logic connections are designed for 5 V systems (5.5 V max). The minimum HIGH threshold is 3.5 V, so direct 3.3 V control is not recommended. For 3.3 V MCUs, use a proper level shifter or choose a driver designed for 3.3 V logic.
In typical use, you only need PWM and DIR. Optional pins: FF1/FF2 (fault flags) and RESET (sleep + clears latched faults). The logic-side V+ pin is for monitoring motor supply voltage only (not for high current). There is also a regulated 5V (out) reference output providing only a few milliamps.
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Pinout
Quick reference for wiring and control.
| PIN | Default State | Description |
|---|---|---|
| V+ | — | Main motor supply input (5.5–30 V absolute max; practical safe max ≈ 24 V). Use the larger V+ pad for high current. Smaller V+ pads along the long side are intended for supply capacitors. The small logic-side V+ pad is for monitoring only (not high current). |
| 5V (out) | — | Regulated 5 V output (few mA) for reference or ultra-low-power loads only. Do NOT connect this to other power rails. Do NOT short this to V+—doing so can instantly destroy the board. |
| GND | — | Common ground for logic and motor supply. |
| OUTA | — | Motor output A. |
| OUTB | — | Motor output B. |
| PWM | LOW | PWM input. A PWM signal here modulates the motor outputs. |
| DIR | FLOAT | Direction input. High = current flows OUTA → OUTB, Low = OUTB → OUTA. |
| RESET | HIGH | Pulled up to V+ through 20 kΩ. Pull LOW to enter low-power sleep and clear latched fault flags. |
| FF1 | LOW | Fault flag 1. Goes HIGH for specific fault conditions (see Fault Table below). |
| FF2 | LOW | Fault flag 2. Goes HIGH for specific fault conditions (see Fault Table below). |
Included hardware
Included with each motor driver:
- 16-pin straight breakaway male header
- Two 150 µF capacitors
- Two 2-pin 5 mm terminal blocks
Note: terminal blocks are rated for 15 A. For higher power builds, use thick wires soldered directly to the board. Mounting holes fit #2 screws (not included).
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Motor control options
With PWM = LOW, both motor outputs are held LOW (brake). With PWM = HIGH, the outputs follow the DIR state. This supports:
- Sign-magnitude: PWM duty controls speed; DIR controls direction.
- Locked-antiphase: PWM on DIR while PWM pin is held HIGH; 50% duty turns motor “off”.
Locked-antiphase depends on motor inductance and switching frequency smoothing current. A higher PWM frequency might be required.
| Motor Driver Truth Table | ||||
|---|---|---|---|---|
| PWM | DIR | OUTA | OUTB | Operation |
| H | L | L | H | Forward |
| H | H | H | L | Backward |
| L | X | L | L | Brake |
PWM frequency tips
Supports PWM up to 40 kHz. Higher frequency increases switching losses. There’s also a dead time of about 3 µs per cycle, which limits maximum duty cycle at very high frequencies (e.g., ~88% at 40 kHz, then jumps to 100%).
Real-world power & heat
The driver can tolerate peak currents in excess of 200 A for quick transients, but continuous performance depends heavily on heat. At high current, the board will run extremely hot—use a heatsink, airflow, and proper wiring to keep things safe.
Because there’s no internal over-current/over-temperature shutdown, design your system to keep load current below the 25 A continuous limit. A practical approach is selecting a motor with stall current below that limit, or ensuring your system prevents extended stall conditions.
Warning: No built-in over-current or over-temperature shutoff. Either can cause permanent damage. Consider adding an external current sensor for monitoring.
Fault conditions (FF1 / FF2)
Detectable fault states include output short circuits, under-voltage, and over-temperature indication. Output short faults are latched (requires RESET LOW to clear). Under-voltage disables outputs but is not latched.
| Fault Flag Table | ||||
|---|---|---|---|---|
| FF1 | FF2 | Fault | Disable Outputs | Latched Until Reset |
| L | L | No fault | No | No |
| L | H | Short Circuit | Yes | Yes |
| H | L | Over Temperature (indication) | No | No |
| H | H | Under Voltage | Yes | No |
High-power motor driver versions (comparison)
These G2 driver variants share compatible pinouts; choose based on voltage/current needs.
| Pololu G2 High-Power Motor Drivers | |||
|---|---|---|---|
| Name | Absolute max input voltage |
Max nominal battery voltage |
Max continuous current |
| G2 High-Power Motor Driver 18v25 | 30 V | 18 V | 25 A |
| G2 High-Power Motor Driver 18v17 | 30 V | 18 V | 17 A |
| G2 High-Power Motor Driver 24v21 | 40 V | 28 V | 21 A |
| G2 High-Power Motor Driver 24v13 | 40 V | 28 V | 13 A |
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Pololu G2 High-Power Motor Driver 24v21 and 24v13. |
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File downloads
- IRF8734 datasheet (279k pdf)
- Datasheet for the IRF8734PBF MOSFET.
- High-Power Motor Driver 18v25 drill drawing (96k dxf)
- DXF drawing showing hole locations for mounting and layout planning.
Recommended links
- Active Magnetic Bearing: Tripod Floater v2.0
- Demo build using Pololu high-power motor drivers as PWM amplifiers for magnetic coils in a closed-loop system. (Includes notes and updates from the original author.)
FAQ
Can I use this directly with 3.3V microcontrollers (ESP32, Raspberry Pi Pico, etc.)?
Not recommended directly. The HIGH threshold is around 3.5V, so 3.3V signals can be unreliable. Use a level shifter or choose a driver designed for 3.3V logic.
Do I need a heatsink?
Many builds can run at lower currents without a heatsink, but at high continuous currents the board will get very hot. For sustained high current, add a heatsink and airflow for safer operation.
Does it have over-current or over-temperature shutoff?
No. It has fault detection flags, but it does not provide full over-current/over-temperature shutdown protection. Design your system to avoid extended stall current and consider external current monitoring.
What capacitor should I use on the power input?
Use the included capacitors as a starting point, mounted close to the driver. For noisy supplies, long wires, or high-load motors, a larger capacitor may be required to reduce spikes and ripple.
High-Power Motor Driver 18v25 Pololu
High-Power Motor Driver 18v25 Pololu
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Product Code
SKU:POL758
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