原标题：Allegromicro A4986全桥步进马达驱动方案

　　Allegromicro公司的A4986是双DMOS全桥步进马达驱动器,具有并行输入通信和过流保护,每个全桥输出额定电压高达35V,电流±2 A. A4986兼容3.3V和5V逻辑电平,睡眠电流小于10uA.本文介绍了A4986主要特性和优势, 功能方框图, 典型应用框图以及PCB应用布局图.

　　The A4986 is a dual DMOS full-bridge stepper motor driver with parallel input communication and overcurrent protection. Each full-bridge output is rated up to 35 V and ±2 A.

　　The A4986 includes fixed off-time pulse width modulation (PWM) current regulators, along with 2- bit nonlinear DACs (digital-to-analog converters) that allow stepper motors to be controlled in full, half, and quarter steps. The PWM current regulator uses the Allegro® patented mixed decay mode for reduced audible motor noise, increased step accuracy, and reduced power dissipation.

　　Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. The outputs are protected from shorted load and short-toground events, which protect the driver and associated circuitry from thermal damage or flare-ups. Other protection features include thermal shutdown with hysteresis, undervoltage lockout (UVLO) and crossover current protection. Special power-up sequencing is not required.

　　The A4986 is supplied in a 24-pin TSSOP (LP) with exposed thermal pad for enhanced thermal performance. It has a 0.65 pitch and an overall package height of ≤1.2 mm. It is lead (Pb) free, with 100% matte tin leadframe plating.

　　A4986主要特性和优势:

　　▪ Low RDS(ON) outputs

　　▪ Internal mixed current decay mode

　　▪ Synchronous rectification for low power dissipation

　　▪ Internal UVLO

　　▪ Crossover-current protection

　　▪ 3.3 and 5 V compatible logic supply

　　▪ Thin profile QFN and TSSOP packages

　　▪ Thermal shutdown circuitry

　　▪ Short-to-ground protection

　　▪ Shorted load protection

　　▪ Low current Sleep mode, < 10 μA

　　图1.A4986功能方框图

　　图2.A4986典型应用框图