型号	输出电压范围	输出电流	桥数	接口	逻辑输入电压范围	驱动电机类型	封装
A3955	Vcc~30v	650mA	双全桥	并行	4.75V~5.5V	步进	DIP16，SOIC-16

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A3966
双路全桥式 PWM 电动机驱动器

特点

• ±650 毫安连续输出电流
• 30 伏特输出电压额定值
• 内部固定频率 PWM 电流控制
• Satlington? 灌电流驱动器
• 用户可选择空白窗口
• 内部接地钳位和反激二极管
• 内部过热关机电路
• 交叉电流和欠压锁定 (UVLO) 保护

描述

A3966 可驱动两相双极步进电动机的两个绕组。该器件包括两个能够连续输出电流为 ±650 mA 以及操作电压达至 30 V 的全电桥。可通过内部固定频率、脉宽调制 (PWM) 及电流控制电路来控制电动机绕组电流。用户可通过选择参考电压和电流感测电阻设置峰值载荷电流限制。

用户可通过选择外部 RC 计时网络设置固定频率脉冲持续时间。RC 计时网络中的电容器也可以确定用户可选择空白窗口，该窗口在开关转换过程中可防止对 PWM 电流控制电路的误触发。

为减少芯片功率耗散，已优化全桥功率输出，以适应低饱和电压。灌电驱动器具有 Allegro? 已取得专利的 Satlington? 输出结构。Satlington 输出将饱和晶体管的低电压降落与达林顿高峰值电流容量相结合。

每个电桥的“相位”输入可通过选择适当的源极与汲入型驱动器件控制负载电流的极性。每个电桥的“启用”输入持高时，禁用输出驱动器。不需要特别的加电排序。内部电路保护包括因滞后引起的过热关机、接地钳位反激二极管及交叉电流保护。

A3966 采用 16 引脚塑料 SOIC 封装，具有两个通过内部熔断器连接至下垫板的引脚，增强散热效果。这些引脚处于接地电位，且不需要电绝缘。该器件为无铅产品，引脚框采用 100% 雾锡电镀。

典型应用

功能方框图

Features

• ±650 mA continuous output current
• 30 V output voltage rating
• Internal fixed-frequency PWM current control
• Satlington? sink drivers
• User-selectable blanking window
• Internal ground-clamp and flyback diodes
• Internal thermal-shutdown circuitry
• Crossover-current protection and UVLO protection

Description

The A3966 is designed to drive both windings of a two-phase bipolar stepper motor. The device includes two full-bridges capable of continuous output currents of ±650 mA and operating voltages to 30 V. Motor winding current can be controlled by the internal fixed-frequency, pulse-width modulated (PWM), current-control circuitry. The peak load current limit is set by user selection of a reference voltage and current-sensing resistors.

The fixed-frequency pulse duration is set by a user-selected external RC timing network. The capacitor in the RC timing network also determines a user-selectable blanking window that prevents false triggering of the PWM current-control circuitry during switching transitions.

To reduce on-chip power dissipation, the full-bridge power outputs have been optimized for low saturation voltages. The sink drivers feature the Allegro? patented Satlington? output structure. The Satlington outputs combine the low voltage drop of a saturated transistor and the high peak current capability of a Darlington.

For each bridge, a PHASE input controls load-current polarity by selecting the appropriate source and sink driver pair. For each bridge, an ENABLE input, when held high, disables the output drivers. Special power-up sequencing is not required. Internal circuit protection includes thermal shutdown with hysteresis, ground-clamp and flyback diodes, and crossover-current protection.

The A3966 is supplied in a 16-lead plastic wide SOIC with two pins internally fused to the die pad for enhanced thermal dissipation. These pins are at ground potential and need no electrical isolation. The device is lead (Pb) free, with 100% matte tin leadframe plating.

Typical Application

Functional Block Diagram