3974

3974 LOAD 43 SUPPLY1 SENSE1 OUT1A ENABLE1 GND GND GND NC OUT1B NC NC DMOS DUAL FULL-BRIDGE PWM MOTOR DRIVER Designed for pulse-width modulated (PWM) current control of two dc motors, the A3974SED 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 current-decay 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 A3974SED is supplied in a 44-lead plastic PLCC with four copper batwing tabs for maximum heat dissipation. The power tabs are at ground potential and need no electrical isolation. 41 44 42 40 2 4 6 5 3 1 Data Sheet 29319.35 VBB1 NC STROBE CLOCK 7 39 NC CP2 CP1 CP GND GND GND OSC SLEEP VREG NC 8 9 CHARGE PUMP SERIAL PORT 38 37 36 35 34 33 PROGRAM PWM TIMER LOGIC DATA 10 GND 11 GND 12 GND 13 REF...