A3983 DMOS Microstepping Driver with Translator Features and Benefits Description Low R outputs The A3983 is a complete microstepping motor driver with DS(ON) Automatic current decay mode detection/selection built-in translator for easy operation. It is designed to operate Mixed and Slow current decay modes bipolar stepper motors in full-, half-, quarter-, and eighth-step Synchronous rectification for low power dissipation modes, with an output drive capacity of up to 35 V and 2 A. Internal UVLO and thermal shutdown circuitry The A3983 includes a fixed off-time current regulator which Crossover-current protection has the ability to operate in Slow or Mixed decay modes. The translator is the key to the easy implementation of the A3983. Simply inputting one pulse on the STEP input drives the motor one microstep. There are no phase sequence tables, high frequency control lines, or complex interfaces to program. The A3983 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened. Package: 24-pin TSSOP with exposed thermal pad (suffix LP) The chopping control in the A3983 automatically selects the current decay mode (Slow or Mixed). When a signal occurs at the STEP input pin, the A3983 determines if that step results in a higher or lower current in each of the motor phases. If the change is to a higher current, then the decay mode is set to Slow decay. If the change is to a lower current, then the current decay is set to Mixed (set initially to a fast decay for a period amounting to 31.25% of the fixed off-time, then to a slow decay for the remainder of the off-time). This current decay Not to scale Continued on the next page Functional Block Diagram 0.1 F 0.22 F VREG ROSC CP1 CP2 VDD Current Charge OSC Regulator Pump VCP 0.1 F DMOS Full Bridge VBB1 REF DAC OUT1A OUT1B PWM Latch Blanking SENSE1 Mixed Decay STEP Gate R S1 Drive DMOS Full Bridge DIR VBB2 RESET Control Translator Logic MS1 OUT2A MS2 OUT2B PWM Latch ENABLE Blanking SENSE2 Mixed Decay SLEEP R S2 DAC V REF 26184.29D(R = 28 C/W) JA A3983 DMOS Microstepping Driver with Translator Description (continued) control scheme results in reduced audible motor noise, increased lockout (UVLO), and crossover-current protection. Special power- step accuracy, and reduced power dissipation. on sequencing is not required. Internal synchronous rectification control circuitry is provided to The A3983 is supplied in a low-profile (1.2 mm maximum height), improve power dissipation during PWM operation. Internal circuit 24-pin TSSOP with exposed thermal pad (suffix LP). It is lead (Pb) free, with 100% matte tin leadframe plating. protection includes: thermal shutdown with hysteresis, undervoltage Selection Guide Part Number Package Packing A3983SLPTR-T 24-pin TSSOP with exposed thermal pad 4000 pieces per 13-in. reel Absolute Maximum Ratings Characteristic Symbol Notes Rating Units 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 conditions, Output Current I 2 A OUT do not exceed the specified current rating or a junction tem- perature of 150C. Logic Input Voltage V 0.3 to 7 V IN Sense Voltage V 0.5 V SENSE Reference Voltage V 4V REF Operating Ambient Temperature T Range S 20 to 85 C A Maximum Junction T (max) 150 C J Storage Temperature T 55 to 150 C stg THERMAL CHARACTERISTICS Characteristic Symbol Test Conditions* Value Units Package Thermal Resistance R 4-layer PCB, based on JEDEC standard) 28 C/W JA *In still air. Additional thermal information available on Allegro Web site. Maximum Power Dissipation, P (max) D 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 20 40 60 80 100 120 140 160 180 Temperature (C) Allegro MicroSystems, LLC 2 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Power Dissipation, PD (W)