A3955SLB

A3955 Full-Bridge PWM Microstepping Motor Driver Discontinued Product This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available. Date of status change: January 30, 2012 Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the A4975. NOTE: For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. Allegro MicroSystems, Inc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. A3955 Full-Bridge PWM Microstepping Motor Driver Features and Benefits Description ▪ ±1.5 A continuous output current ▪ 50 V output voltage rating ▪ Internal PWM current control ▪ 3-bit nonlinear DAC ▪ Fast, mixed fast/slow, and slow current-decay modes ▪ Internal transient-suppression diodes ▪ Internal thermal shutdown circuitry ▪ Crossover-current and UVLO protection The A3955 is designed to drive 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 digitalto-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 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 and 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. Packages: Package B, 16-pin DIP with exposed tabs Package LB, 16-pin SOIC with internally fused pins Not to scale Continued on the next page… 10 6 VCC PHASE 15 LOAD SUPPLY OUTB OUTA LOGIC SUPPLY Functional Block Diagram 16 7 VBB GROUND 4 5 UVLO & TSD 12 13 MIXED-DECAY COMPARATOR CURRENT-SENSE COMPARATOR R + – Q S ÷3 BLANKING 11 D/A DISABLE RS RC 3 RT V TH CT 2 8 9 14 D1 + – D0 VCC SENSE + – D2 1 BLANKING GATE REF PFD PWM LATCH Dwg. FP-042 29319.41G A3955 Full-Bridge PWM Microstepping Motor Driver Description (continued) Internal circuit protection includes thermal shutdown with hysteresis, transient-suppression diodes, and crossover-current protection. Special power-up sequencing is not required. The A3955 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 internally fused pins (suffix ‘LB’). For both package styles, the thermally enhanced pins are at ground potential and need no electrical isolation. Both packages are lead (Pb) free, with leadframe plating 100% matte tin. Selection Guide Part Number A3955SB-T A3955SLBTR-T Packing 16-pin DIP with exposed thermal tabs 16-pin SOICW with internally fused pins Package 25 per tube 1000 per reel Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Load Supply Voltage VBB 50 V Logic Supply Voltage VCC 7.0 V Logic/Reference Input Voltage Range VIN –0.3 to VCC + 0.3 V Sense Voltage VS 1.0 V ±1.5 A Output Current, Continuous IOUT Package Power Dissipation PD Operating Ambient Temperature TA Maximum Junction Temperature TJ(max) Storage Temperature 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. Range S See graph W –20 to 85 ºC 150 ºC –55 to 150 ºC Value Units 43 ºC/W 67 ºC/W 6 ºC/W Fault conditions that produce excessive junction temperature will activate the device’s thermal shutdown circuitry. These conditions can be tolerated but should be avoided. Tstg Thermal Characteristics Characteristic Symbol Test Conditions* B Package, single-layer PCB, 1 in.2 2-oz. exposed copper Package Thermal Resistance, Junction to Ambient RθJA Package Thermal Resistance, Junction to Tab RθJT LB Package, 2-layer PCB, 0.3 side in.2 2-oz. exposed copper each ALLOWABLE PACKAGE POWER DISSIPATION (W) *Additional thermal information available on Allegro website. 4 R θJT = 6.0°C/W 3 SUFFIX 'B', R θJA = 43°C/W 2 1 SUFFIX 'LB', R θJA = 67°C/W 0 25 50 75 100 TEMPERATURE IN °C 125 150 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 A3955 Full-Bridge PWM Microstepping Motor Driver ELECTRICAL CHARACTERISTICS at TA = 25°C, VBB = 5 V to 50 V, VCC = 4.5 V to 5.5 V (unless otherwise noted.) Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units VCC — 50 V Power Outputs Load Supply Voltage Range VBB Operating, IOUT = ±1.5 A, L = 3 mH Output Leakage Current ICEX VOUT = VBB —