Three-phase brushless DC motor pre-driver IC for office automation applications

Output current is scaled by the capability of the external MOSFETs, and locked-rotor detection delay is set by an external capacitor on the CLD terminal. The PWM, DIR, BRAKE and STOP inputs can be used to control motor speed, position, and torque. The motor speed can be determined using the motor’s FG (frequency generator) coil signal, which is amplified and shaped with the internal differential amplifier and comparator to produce a digital FG signal output.

The external MOSFETs can be pulse-width-modulated by using an external signal on the PWM input or the internal PWM current regulator. In either case, the synchronous rectification capability of the A4936 reduces power dissipation by turning on the appropriate MOSFETs during current decay.

The Hall elements can be inexpensive types, and are used in conjunction with internal noise filtering to prevent false commutation signals. The A4936 provides a regulated 7.5 V supply to power the three Hall elements. Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout and dead-time protection. Special power-up sequencing is not required. The operating temperature range is -20°C to +105°C.

The A4936 is supplied in a 5 x 5 mm, 32-terminal QFN package with exposed thermal pad. This small footprint package is lead (Pb) free with 100% matt tin leadframe plating.