A4985 DMOS Microstepping Driver with Translator And Overcurrent Protection Features and Benefits Description Low R outputs The A4985 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. Step modes are selectable by MSx logic inputs. It has Internal UVLO an output drive capacity of up to 35 V and 1 A. The A4985 Crossover-current protection includes a fixed off-time current regulator which has the ability 3.3 and 5 V compatible logic supply to operate in Slow or Mixed decay modes. Thin profile QFN and TSSOP packages The ET package meets customer requirements for no smoke Thermal shutdown circuitry no fire (NSNF) designs by adding no-connect pins between Short-to-ground protection critical output, sense, and supply pins. So, in the case of a Shorted load protection pin-to-adjacent-pin short, the device does not cause smoke Low current Sleep mode, < 10 A or fire. Additionally, the device does not cause smoke or fire No smoke no fire (NSNF) compliance (ET package) when any pin is shorted to ground or left open. Packages: The translator is the key to the easy implementation of the A4985. Simply inputting one pulse on the STEP input drives 24-contact QFN the motor one microstep. There are no phase sequence tables, with exposed thermal pad high frequency control lines, or complex interfaces to program. 4 mm 4 mm 0.75 mm The A4985 interface is an ideal fit for applications where a (ES package) complex microprocessor is unavailable or is overburdened. During stepping operation, the chopping control in the A4985 32-contact QFN automatically selects the current decay mode, Slow or Mixed. with exposed thermal pad In Mixed decay mode, the device is set initially to a fast decay 5 mm 5 mm 0.90 mm for a proportion of the fixed off-time, then to a slow decay for (ET package) the remainder of the off-time. Mixed decay current control results in reduced audible motor noise, increased step accuracy, and reduced power dissipation. 24-pin TSSOP with exposed thermal pad Continued on the next page (LP Package) Typical Application Diagram V 0.1 F0.1 F DD 0.22 F VREG ROSC CP1 CP2 VCP VBB1 0.22 F VDD 100 F VBB2 5 k Microcontroller or SLEEP OUT1A Controller Logic A4985 OUT1B STEP SENSE1 MS1 MS2 DIR OUT2A ENABLE OUT2B RESET SENSE2 VREF GND GND 4985-DS, Rev. 1DMOS Microstepping Driver with Translator A4985 And Overcurrent Protection Description (continued) Internal synchronous rectification control circuitry is provided The A4985 is supplied in three surface mount packages: two QFN to improve power dissipation during PWM operation. Internal packages, the 4 mm 4 mm, 0.75 mm nominal overall height ES circuit protection includes: thermal shutdown with hysteresis, package, and the 5 mm 5 mm 0.90 mm ET package. The LP undervoltage lockout (UVLO), and crossover-current protection. package is a 24-pin TSSOP. All three packages have exposed pads Special power-on sequencing is not required. for enhanced thermal dissipation, and are lead (Pb) free (suffix T), with 100% matte tin plated leadframes. Selection Guide Part Number Package Packing A4985SESTR-T 24-contact QFN with exposed thermal pad 1500 pieces per 7-in. reel A4985SETTR-T 32-contact QFN with exposed thermal pad 1500 pieces per 7-in. reel A4985SLPTR-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 I 1 A OUT Logic Input Voltage V 0.3 to 5.5 V IN Logic Supply Voltage V 0.3 to 5.5 V DD VBBx to OUTx 35 V Sense Voltage V 0.5 V SENSE Reference Voltage V 5.5 V 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 Allegro MicroSystems, Inc. 2 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com