ICs Control Three- or Four-Phase Motors

Sept. 1, 1999

Designed to control three- or four-phase brushless dc motors in open- or closed-loop configurations, the LS7560 and LS7561 brushless dc motor controller ICs are implemented in CMOS silicon gate technology. Operational features include open- or closed-loop speed control, electrical sensor separation selection, dynamic or PWM dynamic braking, fault detection and indication, overcurrent protection, direction controls, enable input PWM select for both top and bottom drivers only, and top driver polarity select. The ICs' ratiometric design provides precision operation over a 10V to 18V range. Major function blocks include a sensor decoder for commutation sequencing, a frequency-to-pulse width converter and error amplifier for closed-loop motor control, a comparator and sawtooth oscillator for generating PWM, a voltage reference generator to power the motor sensors, and level detectors for overcurrent sense, enable input, low power supply and low voltage reference.

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