A3968SLB

3968 ADVANCE INFORMATION (subject to change without notice) September 3, 1999 DUAL FULL-BRIDGE PWM MOTOR DRIVER WITH BRAKE The A3968SA and A3968SLB are designed to bidirectionally control two dc motors. Each device includes two H-bridges capable of continuous output currents of ±650 mA and operating voltages to 30 V. Motor winding current can be controlled by the internal fixed-frequency, pulse-width modulated (PWM), current-control circuitry. The peak load current limit is set by the user’s selection of a reference voltage and current-sensing resistors. Except for package style and pinout, the two devices are identical. The fixed-frequency pulse duration is set by a user-selected external RC timing network. The capacitor in the RC timing network also determines a user-selectable blanking window that prevents false triggering of the PWM current-control circuitry during switching transitions. To reduce on-chip power dissipation, the H-bridge power outputs have been optimized for low saturation voltages. The sink drivers feature Allegro’s patented Satlington™ output structure. The Satlington outputs combine the low voltage drop of a saturated transistor and the high peak current capability of a Darlington. For each bridge, the INPUTA and INPUTB terminals determine the load current polarity by enabling the appropriate source and sink driver pair. When a logic low is applied to both INPUTs of a bridge, the braking function is enabled. In brake mode, both source drivers are turned OFF and both sink drivers are turned ON, thereby dynamically braking the motor. When a logic high is applied to both INPUTs of a bridge, all output drivers are disabled. Special power-up sequencing is not required. Internal circuit protection includes thermal shutdown with hysteresis, ground-clamp and flyback diodes, and crossover-current protection. The A3968SA is supplied in a 16-pin dual in-line plastic package. The A3968SLB is supplied in a 16-lead plastic SOIC with copper heat sink tabs. The power tab is at ground potential and needs no electrical isolation. Data Sheet 29319.29 A3968SLB OUT1A INPUT1A INPUT1B GROUND SENSE 1 OUT 1B LOAD SUPPLY REFERENCE 1 V 2 3 4 5 6 7 8 V VBB V CC RC LOGIC LOGIC BB 16 15 14 13 12 11 10 9 OUT 2A INPUT2A INPUT2B GROUND SENSE 2 OUT 2B LOGIC SUPPLY RC REF Dwg. PP-066 ABSOLUTE MAXIMUM RATINGS Load Supply Voltage, VBB ................... 30 V Output Current, IOUT (peak) .......... ±750 mA (continuous) .............................. ±650 mA Logic Supply Voltage, VCC ................. 7.0 V Input Voltage, Vin ..... -0.3 V to VCC + 0.3 V Sense Voltage, VS ................................ 1.0 V Package Power Dissipation (TA = 25°C), PD A3968SA ................................... 2.08 W* A3968SLB ................................. 1.87 W* Operating Temperature Range, TA ................................... -20°C to +85°C Junction Temperature, TJ ................................................. +150°C Storage Temperature Range, TS ................................. -55°C to +150°C Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current rating or a junction temperature of 150°C. * Per SEMI G42-88 Specification, Thermal Test Board Standardization for Measuring Junctionto-Ambient Thermal Resistance of Semiconductor Packages. FEATURES s s s s s s s s s ±650 mA Continuous Output Current 30 V Output Voltage Rating Internal Fixed-Frequency PWM Current Control Satlington™ Sink Drivers Brake Mode User-Selectable Blanking Window Internal Ground-Clamp & Flyback Diodes Internal Thermal-Shutdown Circuitry Crossover-Current Protection and UVLO Protection Always order by complete part number: Part Number A3968SA A3968SLB Package 16-pin DIP 16-lead batwing SOIC RθJA 60°C/W 67°C/W RθJC 38°C/W — RθJT — 6°C/W 3968 DUAL FULL-BRIDGE PWM MOTOR DRIVER WITH BRAKE FUNCTIONAL BLOCK DIAGRAM (one-half of circuit shown) LOGIC SUPPLY LOAD SUPPLY OUTA OUTB INPUTA V CC + V BB UVLO & TSD INPUTB CONTROL LOGIC SOURCE ENABLE PWM LATCH R Q S BLANKING GATE CURRENT-SENSE COMPARATOR SENSE TO OTHER BRIDGE ÷4 + – TO OTHER BRIDGE GROUND RC OSC TO OTHER BRIDGE RS RT CT REFERENCE Dwg. FP-036-4 A3968SA SENSE 1 OUT 1B LOAD SUPPLY REFERENCE RC LOGIC SUPPLY OUT 2B SENSE 2 1 16 INPUT1B INPUT1A OUT 1A GROUND GROUND OUT 2A INPUT 2A INPUT 2B TRUTH TABLE INPUTA L L H H INPUTB L H L H OUTA L L H Z OUTB L H L Z Description Brake mode “Forward” “Reverse” Disable 2 3 4 5 6 7 8 V REF RC V LOGIC 15 14 V BB 13 12 11 Z = High impedance CC LOGIC 10 9 Dwg. PP-066-3 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 1998, Allegro MicroSystems, Inc. 3968 DUAL FULL-BRIDGE PWM MOTOR DRIVER WITH BRAKE ELECTRICAL CHARACTERISTICS at TA = +25°C, VBB = 30 V, VCC = 4.75 V to 5.5 V, VREF = 2 V, VS = 0 V, 56 kΩ & 680 pF RC to Ground (unless noted otherwise) Limits Characteristic Output Drivers Load Supply Voltage Range Output Leakage Current VBB ICEX Operating, IOUT = ±650 mA, L = 3 mH VOUT = 30 V VOUT = 0 V Output Saturation Voltage VCE(SAT) Source Driver, IOUT = -400 mA Source Driver, IOUT = -650 mA Sink Driver, IOUT = +400 mA, VS = 0.5 V Sink Driver, IOUT = +650 mA, VS = 0.5 V Clamp Diode Forward Voltage VF IF = 400 mA IF = 650 mA Motor Supply Current (No Load) IBB(ON) IBB(OFF) Both bridges ON (forward or reverse) All INPUTs = 2.4 V VCC — — — — — — — — — — —