A3979 Microstepping DMOS Driver with Translator Features and Benefits Description 2.5 A, 35 V output rating The A3979 is a complete microstepping motor driver with Low R outputs: 0.28 source, 0.22 sink, typical built-in translator, designed as a pin-compatible replacement for DS(On) 1 Automatic current decay mode detection/selection the successful A3977, with enhanced microstepping ( /16 step) 3.0 to 5.5 V logic supply voltage range precision. It is designed to operate bipolar stepper motors in Slow, Fast or Mixed current decay modes full-, half-, quarter-, and sixteenth-step modes, with an output Home output drive capacity of up to 35 V and 2.5 A. The A3979 includes a Synchronous rectification for low power dissipation fixed off-time current regulator that has the ability to operate in Internal UVLO and thermal shutdown circuitry Slow, Fast, or Mixed decay modes. This current-decay control Crossover-current protection scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation. The translator is the key to the easy implementation of the A3979. It allows the simple input of one pulse on the STEP pin to drive the motor one microstep, which can be either a full step, half, quarter, or sixteenth, depending on the setting of the MS1 and MS2 logic inputs. There are no phase-sequence tables, Package: 28 lead TSSOP (suffix LP) with high-frequency control lines, or complex interfaces to program. exposed thermal pad The A3979 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened. Internal synchronous-rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, UVLO (undervoltage lockout), and crossover-current protection. Special power-on sequencing is not required. The A3979 is supplied in a low-profile (height 1.20 mm), Not to scale 28-pin TSSOP with exposed thermal pad. The package is lead (Pb) free, with 100% matte tin leadframe plating. Pin-out Diagram SENSE1 1 28 VBB1 HOME 2 27 SLEEP DIR 3 26 ENABLE OUT1A 4 25 OUT1B PFD 5 24 CP2 PWM Timer Charge RC1 6 23 CP1 Pump Translator AGND 7 22 VCP and Control REF 8 8 21 PGND Logic RC2 9 20 Reg VREG VDD 10 19 STEP OUT2A 11 18 OUT2B 12 MS2 17 RESET 13 MS1 16 SR 15 SENSE2 14 VBB2 AGND and PGND must be connected together externally 26184.23FA3979 DMOS Microstepping Driver with Translator Selection Guide Part Number Packing A3979SLPTR-T 4000 pieces per reel Absolute Maximum Ratings Load Supply Voltage V 35 V BB Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of Output Current I 2.5 A OUT conditions, do not exceed the specified current rating or a junction temperature of 150C. Logic Supply Voltage V 7.0 V DD t > 30 ns 0.3 to V + 0.3 V W DD Logic Input Voltage Range V IN t < 30 ns 1 to V + 1 V W DD Sense Voltage V 0.5 V SENSE Reference Voltage V V V REF DD Operating Ambient Temperature T Range S 20 to 85 C A Junction Temperature T (max) 150 C J Storage Temperature T 55 to 150 C stg Allegro MicroSystems, LLC 2 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com