Date: 16/06/2010

New three-phase brushless DC motor pre-driver IC from Allegro

Allegro has unveiled the A4936, a new three-phase brushless DC motor pre-driver with outputs for direct high current gate drive of an all N-channel power MOSFET three phase bridge with a maximum supply voltage of 38 V.

The A4936 has three Hall-element inputs, a sequencer for commutation control, fixed off-time pulse width modulation (PWM) current control, and locked-rotor detection. It is suggested for applications such as laser printer and copier drum drives within the office automation market. The output current is scaled by the capability of the external MOSFETs. Locked rotor detection delay is set by an external capacitor on the CLD terminal. The motor speed, position and torque are controlled using PWM, DIR, BRAKE and STOP inputs. Motor speed can be determined using motor FG coil signal that is amplified and shaped with the internal differential amplifier and comparator to produce a digital FGS output. The external MOSFETS can be Pulse-Width-Modulated (PWM'd) using an external signal on the PWM input, or using the internal PWM current regulator.
The A4936 provides a regulated 7.5 V supply to power the three Hall elements. It also provides internal circuit protection such as thermal shutdown with hysteresis, under voltage lockout and dead time protection.

Package: 5 mm × 5 mm, 32-terminal QFN package with exposed thermal pad.

Operating temperature range: -20°C to 105°C.

For more information: www.allegromicro.com