What MOSFETs do I need for a BLDC driver?

Voltage rating: at least 2× the bus voltage to absorb regenerative spikes. 60V parts for 24V/36V systems, 100–150V for 48V, 200V+ for 72V/110V. Current rating: 1.5–2× the motor's rated continuous current. Low RDS(on) (<10 mΩ) reduces conduction loss. Common parts: IRFB-series, IRLR-series for low-voltage; STP-series and IXFH for higher voltage.

What gate driver IC should I use?

Half-bridge gate drivers (IR2104, IR2110, IRS2003, FAN7388) are the typical choice — one IC per half-bridge handles bootstrap supply for the high-side MOSFET. Three-phase integrated drivers (DRV8302, DRV8323, FD6288, IR2136) combine three half-bridges in one package and add features like over-current sense and dead-time programming.

What is dead-time and why does it matter?

Dead-time is a small delay (typically 0.5–2 µs) between turning off the high-side MOSFET and turning on the low-side MOSFET in the same half-bridge. Without dead-time, both MOSFETs would briefly conduct simultaneously — a 'shoot-through' that destroys the bridge in microseconds. Modern integrated gate drivers handle dead-time automatically; discrete designs need an external delay circuit.

Should I build my own BLDC driver or buy a finished controller?

For learning, prototyping or unique research applications — building your own circuit is a reasonable project. For production, hobby builds at >100W, and any commercial product, a finished controller (Shenghe BLD22010 / BLDB6010 / BLD6010) is more cost-effective and less risky. The finished controller has tested gate drive, current sensing, fault protection and PID firmware that takes months to replicate from scratch.

Hardware Design

BLDC Motor Driver Circuit — Three-Phase MOSFET Inverter Walk-Through.

Q: What is a BLDC motor driver circuit?

A BLDC motor driver circuit is the power-electronics circuit that converts a DC bus into a three-phase output for a brushless DC motor's stator windings. Standard topology is a six-MOSFET three-phase inverter (three half-bridges) controlled by an MCU that reads Hall sensors or back-EMF, sequences commutation and runs a PID closed-loop on speed or current.

Q: What gate driver IC should I use?

Half-bridge gate drivers (IR2104, IR2110, IRS2003, FAN7388) are the typical choice — one IC per half-bridge handles bootstrap supply for the high-side MOSFET. Three-phase integrated drivers (DRV8302, DRV8323, FD6288, IR2136) combine three half-bridges in one package and add features like over-current sense and dead-time programming.

Q: What is dead-time and why does it matter?

Dead-time is a small delay (typically 0.5–2 µs) between turning off the high-side MOSFET and turning on the low-side MOSFET in the same half-bridge. Without dead-time, both MOSFETs would briefly conduct simultaneously — a 'shoot-through' that destroys the bridge in microseconds. Modern integrated gate drivers handle dead-time automatically; discrete designs need an external delay circuit.

Q: Should I build my own BLDC driver or buy a finished controller?

For learning, prototyping or unique research applications — building your own circuit is a reasonable project. For production, hobby builds at >100W, and any commercial product, a finished controller (Shenghe BLD22010 / BLDB6010 / BLD6010) is more cost-effective and less risky. The finished controller has tested gate drive, current sensing, fault protection and PID firmware that takes months to replicate from scratch.

A BLDC motor driver circuit converts a DC bus into a three-phase output for a brushless DC motor's stator windings. The standard topology is a six-MOSFET three-phase inverter — three half-bridges, one per phase — controlled by an MCU that reads Hall sensors or back-EMF, sequences commutation and runs PID. This guide walks through the schematic block-by-block, with component selection notes and the trade-offs that matter for production builds.

Reviewed by Shenghe Motor Engineering Team · Updated 2026-04-30

1. Block Diagram

A BLDC motor driver circuit has six functional blocks:

DC bus filter: Bulk electrolytic capacitors stabilize the supply and absorb regenerative spikes.
Three-phase MOSFET inverter: Six MOSFETs in three half-bridges energize motor phases U, V, W.
Gate drivers: Half-bridge or three-phase gate driver ICs translate MCU 3.3V/5V PWM into 10–15V gate drive at the right MOSFET source potential.
MCU: Reads Hall sensors (or back-EMF), runs commutation table and PID, generates PWM.
Current sense: Shunt resistors or Hall-effect current sensors on each phase or on the DC bus, fed back to the MCU for over-current protection and FOC.
Auxiliary supplies: +12V or +15V for gate drivers, +5V or +3.3V for MCU and Hall sensors, derived from the DC bus via a buck converter.

2. The Three-Phase MOSFET Inverter

Six MOSFETs, three half-bridges. Each half-bridge has a high-side MOSFET (drain to V+, source to motor phase) and a low-side MOSFET (drain to motor phase, source to GND). Energizing a phase pair means turning on the high-side of one phase and the low-side of another — current flows from V+ through the high-side, through the motor windings, through the low-side, to GND.

The 6-step commutation cycle for a Hall-sensor BLDC:

Sector	Hall H1 H2 H3	High-side ON	Low-side ON
1	1 0 1	U	V
2	0 0 1	U	W
3	0 1 1	V	W
4	0 1 0	V	U
5	1 1 0	W	U
6	1 0 0	W	V

The MCU reads the 3-bit Hall code and looks up the (high-side, low-side) MOSFET pair in the commutation table. PWM is applied to either the high-side or both sides at 10–25 kHz to control speed.

3. MOSFET Selection

Voltage rating: at least 2× bus voltage to absorb regen spikes. 60V parts for 24V/36V systems, 100–150V for 48V, 200V+ for 72V/110V.
Current rating: 1.5–2× motor rated continuous current. Inrush current at startup can be 3–5× rated.
RDS(on): low (<10 mΩ) reduces conduction loss. Power dissipated = I² × RDS(on) × duty cycle.
Total gate charge (Qg): low (<50 nC) eases gate driver current requirement and improves switching speed.
Common parts: IRFB7430, IRLR7843 (low-voltage); STP140N6F7, IPP100N06S3 (medium); IXFH160N17, STW88N65M5 (high-voltage).

4. Gate Driver IC

The MCU outputs PWM at 3.3V or 5V — too low to drive a power MOSFET's gate (10–15V required for full enhancement). The gate driver IC translates between them and handles two more critical jobs:

High-side level shift: The high-side MOSFET's gate must be ~10V above its source, which floats up to V+ when the MOSFET is on. A bootstrap circuit (a small capacitor + diode) generates the floating supply.
Dead-time: A 0.5–2 µs delay between turning off one MOSFET and turning on the other in the same half-bridge prevents shoot-through (both on simultaneously, which destroys the bridge).

Common ICs:

Half-bridge drivers: IR2104, IR2110, IRS2003, FAN7388 — one chip per half-bridge.
Three-phase integrated: DRV8302, DRV8323, FD6288, IR2136 — full three-phase + over-current sense + dead-time programming in one chip. Preferred for new designs.

5. Hall Sensor Input

Three Hall sensors output open-collector or push-pull 5V signals (one per phase). Standard wiring:

+5V supply to all three sensors
GND common with controller
HU / HV / HW signals through 1–10 kΩ pull-ups (if open-collector) to MCU GPIO
Optional 100 nF + 1 kΩ low-pass filter to reject electrical noise
MCU reads the 3-bit code on commutation interrupts triggered by Hall edge changes

6. Current Sensing

Two common approaches:

Shunt resistor (low-side, on the DC return): a 0.5–10 mΩ shunt with an op-amp differential amplifier. Cheapest, but only sees current when low-side MOSFET is on. Sufficient for over-current protection.
Phase current sense (Hall-effect IC like ACS712 / ACS770 on each motor phase): more accurate, isolated, sees current at all times. Required for FOC. More expensive (1–3 ICs per phase).

7. PWM Commutation Modes

120° trapezoidal: Two phases energized at any time, third floats. Simple, runs from Hall sensors directly. Standard for fans, pumps, low-cost AGV. ~15% torque ripple.
180° sinusoidal: All three phases driven with sinusoidal PWM. Smoother torque (~3% ripple), quieter. Needs higher-resolution rotor angle estimation.
FOC (Field-Oriented Control): Sinusoidal drive with active flux/torque axis decoupling. Best efficiency and lowest torque ripple. Requires good rotor-angle estimation (encoder, high-resolution Hall, or back-EMF observer). Standard for servo applications.

8. Build vs Buy — When to Use a Finished Controller

For learning, prototyping, or unique research applications, building your own BLDC driver is a reasonable project. Reference designs from TI (BOOSTXL-DRV8323), STMicroelectronics (X-NUCLEO-IHM07M1), and Microchip (dsPIC33CK Curiosity) get you to a running motor in a weekend. For everything else — production, hobby builds above 100W, and any commercial product — a finished controller is more cost-effective and less risky.

Shenghe's BLD-series BLDC controllers cover 12V to 110V (BLD22010 / BLDB6010 / BLD6010) with tested gate drive, current sensing, fault protection, FOC firmware and matched motor pairing. Time saved vs starting from a reference design: 3–6 months. Cost: less than the BOM for a comparable in-house build at low volume.

9. Further Reading

BLDC Motor Controller — full BLD22010 / BLDB6010 / BLD6010 spec line
24V BLDC Motor Controller — cabinet PLC integration
72V BLDC Motor Controller — higher voltage class for e-mobility
Sensorless BLDC Motor Control — back-EMF detection theory
What Is a BLDC Motor Controller? — fundamentals