A3974

• ±1.5 A, 50 V Continuous Output Rating
• Low rDS(on) DMOS Output Drivers
• Programmable Slow, Fast, and Mixed Current-Decay Modes
• Serial-Interface Controls Chip Functions
• Synchronous Rectification for Low Power Dissipation
• Internal UVLO and Thermal Shutdown Circuitry
• Crossover-Current Protection
• Sleep and Idle Modes

Description

Designed for pulse width modulated (PWM) current control of two DC motors, the A3974 is capable of output currents to ±1.5 A and operating voltages to 50 V. Internal fixed off-time PWM current-control timing circuitry can be programmed via a serial interface to operate in slow, fast, and mixed currentdecay modes.

Independant ENABLE input terminals are provided for use in controlling the speed and torque of each dc motor with externally applied PWM control signals.

Synchronous rectification circuitry allows the load current to flow through the low rDS(on) of the DMOS output driver during the current decay. This feature will eliminate the need for external clamp diodes in most applications, saving cost and external component count, while minimizing power dissipation. Internal circuit protection includes thermal shutdown with hysteresis, undervoltage monitoring of VDD and the charge pump, and crossover-current protection. Special power-up sequencing is not required.

The A3974 is supplied in a 44-pin plastic PLCC with 3 internally fused pins on each side, for maximum heat dissipation. The fused pins are at ground potential and need no electrical isolation.