Single-phase brushless motor DC pre-driver IC from Allegro MicroSystems

Key features include PWM current control, locked-rotar protection with auto restart, outputs to drive an all N-channel MOSFET H-bridge, a minimal requirement for external components, and programmable commutation delay, soft start and minimum speed.

The motor speed is regulated by either a PWM (pulse width modulated) input or an external analogue voltage – typically from a thermistor. The speed can be monitored via the device’s FG (fan gain) output, and minimum speed is programmed with an external voltage.

Maximum motor current is controlled with the internal PWM fixed off-time current regulator. Synchronous rectification is employed in the PWM ‘off’ cycle to reduce power dissipation. Start-up current can be ramped up for reduced supply current surges, and lock detection with automatic restart functions reduces damage due to motor overheating.
A single resistor is used to program the commutation delay to prevent shoot-through and to reduce fan noise. An internal 5 V regulator is provided for the Hall element.
Protection features include thermal shutdown with hysteresis, undervoltage lockout (UVLO), crossover current and locked-rotor protection with auto restart. Special power-up sequencing is not required.

The new device is targeted at the office automation, telecommunications, consumer and industrial markets.

The A4930 is supplied in a lead (Pb) free 28-pin QFN package (suffix ET) with exposed power tab. It has a 5 x 5 mm footprint and 0.90 mm nominal height.