A3984 DMOS Microstepping Driver with Translator Features and Benefits Description Low RDS(ON) outputs The A3984 is a complete microstepping motor driver with Automatic current decay mode detection/selection built-in translator for easy operation. It is designed to Mixed and Slow current decay modes operate bipolar stepper motors in full-, half-, quarter-, and Synchronous rectification for low power dissipation sixteenth-step modes, with an output drive capacity of up to Internal UVLO and thermal shutdown circuitry 35 V and 2 A. The A3984 includes a fixed off-time current Crossover-current protection regulator which has the ability to operate in Slow or Mixed decay modes. The translator is the key to the easy implementation of the A3984. 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 A3984 interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened. Package: 24-pin TSSOP with exposed The chopping control in the A3984 automatically selects thermal pad (suffix LP) the current decay mode (Slow or Mixed). When a signal occurs at the STEP input pin, the A3984 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 Not to scale Continued on the next page Pin-out Diagram GND CP1 1 24 CP2 ENABLE 2 23 VCP OUT2B 3 22 VBB2 VREG 4 21 MS1 SENSE2 5 20 MS2 OUT2A 6 19 RESET OUT1A 7 18 ROSC SENSE1 8 17 SLEEP 9 16 VBB1 VDD OUT1B 10 15 STEP DIR 11 14 REF 12 13 GND 26184.30E Charge OSC Reg Pump Translator & Control Logic (R = 28 C/W) JA A3984 DMOS Microstepping Driver with Translator Description (continued) initially to a fast decay for a period amounting to 31.25% of Internal circuit protection includes: thermal shutdown with the fixed off-time, then to a slow decay for the remainder of the hysteresis, undervoltage lockout (UVLO), and crossover-current off-time). This current decay control scheme results in reduced protection. Special power-on sequencing is not required. audible motor noise, increased step accuracy, and reduced power The A3984 is supplied in a low-profile (1.2 mm maximum), dissipation. 24-pin TSSOP with exposed thermal pad (package LP). It is lead Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. (Pb) free, with 100% matte tin leadframe plating. Selection Guide Part Number Packing A3984SLPTR-T 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 *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 Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com Power Dissipation, PD (W)