A3987 DMOS Microstepping Driver with Translator Features and Benefits Description Low R outputs The A3987 is a complete microstepping motor driver with DS(on) Short-to-ground protection built-in translator for easy operation. It is designed to operate Shorted load protection bipolar stepper motors in full, half, quarter, and sixteenth step Automatic current decay mode detection/selection modes, with output drive capability of 50 V and 1.5 A. The Mixed and slow current decay modes A3987 includes a fixed off-time current regulator, which has Synchronous rectification for low power dissipation the ability to operate in slow or mixed decay modes. Internal UVLO and thermal shutdown circuitry The translator is the key to the easy implementation of the Crossover-current protection A3987. Simply inputting one pulse on the step input drives the motor to take one microstep. There are no phase sequence tables, high frequency control lines, or complex interfaces to program. The A3987 interface is an ideal fit for applications where a complex microprocessor is unavailable or over-burdened. The A3987 chopping control automatically selects the current decay mode (slow or mixed). When a STEP signal occurs, Package: 24 pin TSSOP with exposed the translator determines if that step results in a higher or thermal pad (suffix LP) 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 decay mode is set to 30.1% fast decay. This current decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation. Approximate scale Continued on the next page Typical Application Diagram 0.1 F 0.22 F X7R VREG CP1 CP2 0.1 F X7R VCP VDD 10 F 5 k VBB1 ROSC Microcontroller or A3987 VBB2 100 F Controller Logic STEP OUT1A DIR OUT1B SLEEP/RESET SENSE1 ENABLE MS1 OUT2A MS2 OUT2B REF SENSE2 3987DS, Rev. 7(R = 28 C/W) JA (R = 32 C/W) JA A3987 DMOS Microstepping Driver with Translator Description (continued) Internal synchronous rectification control circuitry is provided to protection. Special power-up sequencing is not required. improve power dissipation during PWM operation. The A3987 is supplied in a thin profile (1.2 mm maximum height) Internal circuit protection includes: thermal shutdown with 24-lead TSSOP (suffix LP) with exposed thermal tab. The package hysteresis, undervoltage lockout (UVLO), and crossover current is lead (Pb) free with 100% matte tin leadframe plating. Selection Guide Part Number Package Packing A3987SLPTR-T 24-pin TSSOP with exposed thermal pad 4000 pieces / reel Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Load Supply Voltage V 50 V BB Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, Output Current I 1.5 A OUT do not exceed the specified current rating or a junction tem- perature of 150C. Logic Supply Voltage V 7.0 V DD Logic Input Voltage Range V 0.3 to V + 0.3 V IN DD VBBx to OUTx 50 V Sense Voltage V 0.5 V SENSE Reference Voltage V 0 to 4 V REF Nominal Operating Temperature T Range S 20 to 85 C A Maximum Junction Temperature T (max) 150 C J Storage Temperature T 55 to 150 C stg Thermal Characteristics* Characteristic Symbol Notes Rating Units 4-layer PCB based on JEDEC standard 28 C/W Package Thermal Resistance R JA 2 2-layer PCB with 3.8 in. 2 oz. copper each side 32 C/W *Additional thermal data available on the Allegro website. 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, P (W) D