A3955

3955 FULL-BRIDGE PWM MICROSTEPPING MOTOR DRIVER PFD REF RC GROUND GROUND LOGIC SUPPLY PHASE D2 1 2 3 4 LOGIC 5 6 7 8 VCC 12 11 10 9 GROUND SENSE OUTA D1 VBB 16 15 14 13 LOAD SUPPLY OUTB D0 GROUND Data Sheet 29319.41 The A3955SB and A3955SLB are designed for driving one winding of a bipolar stepper motor in a microstepping mode. The outputs are rated for continuous output currents to ±1.5 A and operating voltages to 50 V. Internal pulse-width modulated (PWM) current control combined with an internal three-bit nonlinear digital-to-analog converter allows the motor current to be controlled in full-, half-, quarter-, or eighth-step (microstepping) modes. Nonlinear increments minimize the number of control lines necessary for microstepping. Microstepping provides for increased step resolution, and reduces torque variations and resonance problems at low speed. Internal circuitry determines whether the PWM current-control circuitry operates in a slow (recirculating) current-decay mode, fast (regenerative) current-decay mode, or in a mixed current-decay mode in which the off time is divided into a period of fast current decay with the remainder of the fixed off time spent in slow current decay. The combination of user-selectable current-sensing resistor and reference voltage, digitally selected output current ratio; and slow, fast, or mixed current-decay modes provides users with a broad, variable range of motor control. Internal circuit protection includes thermal shutdown with hysteresis, transient-suppression diodes, and crossover current protection. Special power-up sequencing is not required. The A3955S— is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs (suffix ‘B’), and a 16-lead plastic SOIC with copper heat-sink tabs (suffix ‘LB’). For both package styles, the power tab is at ground potential and needs no electrical isolation. Dwg. PP-056-2 Note the A3955SB (DIP) and the A3955SLB (SOIC) are electrically identical and share a common terminal number assignment. ABSOLUTE MAXIMUM RATINGS Load Supply Voltage, VBB . . . . . . . . . . 50 V Output Current, IOUT (Continuous) . . . . . . . . . . . . . . ±1.5 A* Logic Supply Voltage, VCC . . . . . . . . . 7.0 V Logic/Reference Input Voltage Range, VIN . . . . . . . . . . . -0.3 V to VCC + 0.3 V Sense Voltage, VS . . . . . . . . . . . . . . . . 1.0 V Package Power Dissipation, PD . . . . . . . . . . . . . . . . . . . . See Graph 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. † Fault conditions that produce excessive junction temperature will activate the device’s thermal shutdown circuitry. These conditions can be tolerated but should be avoided. FEATURES s s s s s s s s ±1.5 A Continuous Output Current 50 V Output Voltage Rating Internal PWM Current Control 3-Bit Non-Linear DAC Fast, Mixed Fast/Slow, and Slow Current-Decay Modes Internal Transient-Suppression Diodes Internal Thermal-Shutdown Circuitry Crossover-Current and UVLO Protection Always order by complete part number: Part Number A3955SB A3955SLB Package 16-Pin DIP 16-Lead SOIC 3955 FULL-BRIDGE PWM MICROSTEPPING MOTOR DRIVER FUNCTIONAL BLOCK DIAGRAM LOGIC SUPPLY PHASE 7 6 VCC 10 15 VBB GROUND 4 5 12 13 UVLO & TSD MIXED-DECAY COMPARATOR PWM LATCH BLANKING GATE CURRENT-SENSE COMPARATOR LOAD SUPPLY OUTA OUTB 16 SENSE 11 PFD 1 + – BLANKING R Q S +– RC 3 V TH 2 REF + – ÷3 D/A DISABLE VCC RS 8 D2 9 D1 14 D0 RT CT Dwg. FP-042 Table 1 — PHASE Truth Table PHASE H L OUTA H L OUTB L H V PFD Table 2 — PFD Truth Table Description Slow Current-Decay Mode Mixed Current-Decay Mode Fast Current-Decay Mode ≥3.5 V 1.1 V to 3.1 V ≤0.8 V 115 Northeast Cutoff, Box 15036 W Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 1997 Allegro MicroSystems, Inc. 3955 FULL-BRIDGE PWM MICROSTEPPING MOTOR DRIVER ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS 5 RθJT = 6.0°C/W Table 3 — DAC Truth Table D2 H H SUFFIX 'B', R θJA = 43°C/W 4 DAC DATA D1 D0 H H L L H H L L H L H L H L H L Current Ratio, % 100 92.4 83.1 70.7 55.5 38.2 19.5 VREF /VS 3.00 3.25 3.61 4.24 5.41 7.85 15.38 3 H H L L 2 1 SUFFIX 'LB', R θJA = 63°C/W L 125 150 0 25 50 75 100 TEMPERATURE IN °C L All Outputs Disabled where VS = ITRIP•RS. See Applications section. Dwg. GP-049-2A ELECTRICAL CHARACTERISTICS at TA = 25˚C, VBB = 5 V to 50 V, V CC = 4.5 V to 5.5 V (unless otherwise noted.) Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units Power Outputs Load Supply Voltage Range Output Leakage Current V BB ICEX Operating, IOUT = ±1.5 A, L = 3 mH VOUT = VBB VOUT = 0 V Output Saturation Voltage (Forward or Reverse Mode) VCE(SAT) VS = 1.0 V: Source Driver, IOUT = -0.85 A Source Driver, IOUT = -1.5 A Sink Driver, IOUT = 0.85 A Sink Driver, IOUT = 1.5 A Sense Current Offset Clamp Diode Forward Voltage (Sink or Source) Motor Supply Current (No Load) ISO VF IS - IOUT, IOUT = 850 mA, VS = 0 V, VCC = 5 V IF = 0.85 A IF = 1.5 A IBB(ON) IBB(OFF) D0 = D1 = D 2 = 0.8 V — — — — 20 — — — — 1.0 1.3 0.5 1.3 33 1.2 1.4 2.0 1.0 1.2 1.5 0.6 1.5 40 1.4 1.7 4.0 50 V V V V mA V V mA µA VCC — — —