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Single-phase brushless DC motor pre-drivers blow fans

Posted: 10 Mar 2008 ?? ?Print Version ?Bookmark and Share

Keywords:brushless DC motor pre-drivers? blow fans?

The first device in a series of single-phase brushless DC motor pre-drivers used to control high current fans, blowers or pumps, has been launched by Allegro MicroSytems Inc. Outputs are designed to drive all n-channel MOSFET H-bridges with supply voltages between 8V and 36V. The motor speed is regulated by either a pulse width modulated (PWM) input or external analog voltage, typically a thermistor. Motor speed can be monitored with the fixed gain output and minimum speed can be programmed with an external voltage. This new device is targeted at the office automation, telecommunications, consumer and industrial markets.

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. Startup current can be ramped up for reduced supply current surges and lock detection with auto 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 5V regulator is provided for the Hall element.

Protection features include thermal shutdown with hysteresis, under voltage lockout, crossover current and locked rotor protection with auto restart. Special power up sequencing is not required.

Allegro's A4930 is supplied in a Pb-free 28L QFN package with exposed power tab.

Allegro is one of the exhibitors in the IIC-China 2008.

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