ST4931P 36V Three-Phase BLDC Motor Pre-driver

ST4931P 36V Three-Phase BLDC Motor Pre-driver

ST4931P

The ST4931P is a three-phase brushless DC motor pre-driver IC operating from a wide 4.7V to 36V supply, capable of driving three half-bridges built from six external N-channel power MOSFETs, with commutation logic determined by three Hall inputs with 120° phase difference. The device integrates fixed off-time (25µs) PWM current regulation (200mV VREF limit threshold) and low-power synchronous rectification. Logic inputs include ENABLE (active-low PWM), DIR direction and BRAKEZ brake control, while FG1/FG2 outputs correspond to the Hall signals for speed monitoring. A fixed 1.0µs dead time prevents shoot-through; adjustable lock protection, over-temperature protection (170℃) and VBB under-voltage (4.7V)/over-voltage (29V) protection are built in, and an HBIAS 5V output powers the Hall elements. A power-saving mode is entered when ENABLE stays high for more than 3ms. Housed in a QFN28 (5mm×5mm) package with an exposed thermal pad, the ST4931P operates from -40℃ to 110℃ and suits a wide range of three-phase BLDC motor drive designs.

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Specifications

Power Bus Supply Voltage VMOperating 4.7~36V; Abs. Max 38V
Output Current per PhasePre-driver: gate drive current IGATE 20~30mA (max, drives 6 NMOS)
Rds(on) (HS+LS)- (pre-driver, no built-in FET; depends on external MOSFET)
PWM Carrier Frequency RangeExternal PWM input (ENABLE, fPWM<30kHz)
Current Sensing SchemeSENSE current-monitor pin, external sense resistor (VREF limit 200mV), single-resistor sampling
Motor Control AlgorithmThree-phase 120° trapezoidal commutation (Hall), synchronous rectification
Control InterfaceENABLE (active-low PWM), DIR, BRAKEZ, FG1/FG2 speed outputs, Hall inputs
Dead TimeTdead 1.0µs (0.7~1.3µs) fixed anti-shoot-through
Quiescent/Sleep Current (Iq/Isleep)Operating IBB 4~6mA; power-save 3.3~3.6mA (charge pump on)
Protection FeaturesOTP(170℃), UVLO(4.7V/VCP), OVP(29V), stall lock protection (adjustable)
Fault FeedbackFG1/FG2 speed outputs (Hall-matched), stall indication
Logic SupplyHBIAS 5V Hall supply; logic input 0~7V
Operating Temperature-40~110℃
Modulation Method120° trapezoidal commutation (Hall), synchronous rectification, fixed off-time current regulation
Additional FeaturesSynchronous rectification, fixed off-time PWM, adjustable stall time, FG1/FG2 Hall-matched outputs
PackageQFN28 (5×5, e=0.50)

Product details

Overview

The ST4931P is a three-phase brushless DC motor pre-driver IC operating from a wide 4.7V to 36V supply, capable of driving three half-bridges built from six external N-channel power MOSFETs. Commutation logic is determined by three Hall inputs with 120° phase difference. The device integrates fixed off-time (25µs) pulse-width modulation to regulate current and suppress inrush current, with a 200mV VREF current-limit threshold supporting single-resistor sensing. Built-in synchronous rectification turns on the appropriate low-resistance switch during the decay period in place of the freewheeling diode to minimize power loss, and is automatically disabled when over-voltage is detected to reduce supply voltage fluctuation. Logic inputs include ENABLE (active-low PWM control), DIR direction control and BRAKEZ brake control; FG1/FG2 outputs correspond to the Hall signals for rotation-speed monitoring. A fixed 1.0µs dead time prevents shoot-through, while adjustable lock protection (tlock = Ccld × 20s/µF), over-temperature protection (170℃) and VBB under-/over-voltage protection safeguard the power stage. An HBIAS 5V output powers the Hall elements, and a power-saving mode is entered when ENABLE stays high for more than 3ms. The ST4931P is housed in a QFN28 (5mm×5mm) package with an exposed thermal pad and operates from -40℃ to 110℃.

Features

  • Three-phase 120° trapezoidal commutation (Hall-sensor based), drives three half-bridges (6 NMOS)
  • Wide 4.7~36V supply range (38V absolute maximum), built-in charge pump for high-side NMOS drive
  • 20~30mA gate drive current with fixed 1.0µs anti-shoot-through dead time
  • Fixed off-time (25µs) PWM current regulation, 200mV VREF current-limit threshold
  • Low-power synchronous rectification, disabled on over-voltage detection
  • ENABLE (active-low PWM), DIR direction and BRAKEZ brake control interface
  • FG1/FG2 speed outputs corresponding to Hall signals
  • Lock protection with adjustable timing via CLD capacitor
  • Over-temperature protection (TSD 170℃, 20℃ hysteresis), VBB UVLO (4.7V) and OVP (29V)
  • Power-saving mode (ENABLE high >3ms, IBB 3.3~3.6mA)
  • HBIAS 5V Hall supply output (30mA max)
  • QFN28 (5mm×5mm, exposed thermal pad) package

Typical Applications

  • Three-phase brushless DC (BLDC) motor drive systems
  • Three-half-bridge power stages with six external N-channel MOSFETs
  • Motor speed-control designs on 4.7~36V wide-voltage buses
  • PWM motor-control applications requiring low-loss synchronous rectification

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