图1.A4982功能方框图
图2.A4982典型应用框图
图3.A4982 LP封装应用电路和PCB布局框图
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图4.A4982 ET封装应用电路和PCB布局框图
A4982 是一款完全的微步电动机驱动器，带有内置转换器，易于操作。该产品可在完整、1/2、1/4 及 1/16 步进模式时操作双极步进电动机，输出驱动性能为 35 V 及 ±2 A。A4982 包括一个固定停机时间电流稳压器，该稳压器可在慢或混合衰减模式下操作。
ET 封装在关键输出、感应及电源管脚间添加无连接管脚，满足客户对无烟无火 (NSNF) 设计的要求。因此，即使管脚与邻近管脚间发生短路，该器件也不会冒烟或着火。此外，即使任何管脚与接地短路或开路，该器件也不会冒烟或着火。
转换器是 A4982 易于实施的关键。只要在―步进‖输入中输入一个脉冲，即可驱动电动机产生微步。无须进行相位顺序表、高频率控制行或复杂的界面编程。A4982 界面非常适合复杂的微处理器不可用或过载的应用。
在微步运行时，A4982 内的斩波控制可自动选择电流衰减模式（慢或混合）。在混合衰减模式下，该器件初始设置为在部分固定停机时间内快速衰减，然后在余下的停机时间慢速衰减。混合衰减电流控制方案能减少可听到的电动机噪音、增加步进精确度并减少功耗。
提供内部同步整流控制电路，以改善脉宽调制 (PWM) 操作时的功率消耗。内部电路保护包括：带滞后的过热关机、欠压锁定 (UVLO) 及交叉电流保护。不需要特别的通电排序。
A4982 采用两款表面安装封装： ET — 5 mm × 5 mm, 0.90 mm 标称整体封装高度 QFN 封装，以及 LP 封装— 24 针 TSSOP。两种封装具有外露焊盘，以提高散热功能，且均是无铅产品（后缀：–T），引脚框采用 100% 雾锡电镀。
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? ? ? ? ? ? ? ? ? ? ? ? ? 低 RDS(开) 输出
自动电流衰减模式检测/选择 混合与慢电流衰减模式 对低功率耗散同步整流 内部 UVLO 交叉电流保护
3.3 及 5 V 兼容逻辑电源 超薄 QFN 和 TSSOP 封装 过热关机电路 接地短路保护 加载短路保护
低电流休眠模式， <10 μA
符合无烟无火(NSNF) 规范 （ET 封装）
基于A4982设计的DMOS微型步进马达驱动技术
Allegro公司的A4982是集成了电平转换和过流保护的微型步进马达驱动器,适用于双极步进马达驱动,工作在全步进,半步进,1/4步进和1/6步进模式,输出驱动能力高达35V和±2 A. A4982包括固定的离线电流调节器,兼容3.3V和5V逻辑,睡眠模式电流小于10 μA.本文介绍了A4982主要特性和优势, 功能方框图, 典型应用框图以及LP和ET封装的应用电路和PCB布局框图.
DMOS Microstepping Driver with Translator and Overcurrent Protection
The A4982 is a complete microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and sixteenth-step modes, with an output drive capacity of up to 35 V and ±2 A.
The A4982 includes a fixed off-time current regulator which has the ability to operate in Slow or Mixed decay modes. The ET package meets customer
requirements for no smoke no fire (NSNF) designs by adding no-connect pins between critical output, sense, and supply pins. So, in the case of a pin-to-adjacent-pin short, the device does not cause smoke or fire. Additionally, the device does not cause smoke or fire when any pin is shorted to ground or left open.
The translator is the key to the easy implementation of the A4982. 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 A4982 interface is an ideal fit for applications where a complex
microprocessor is unavailable or is overburdened. During stepping operation, the chopping control in the A4982 automatically selects the current decay mode, Slow or Mixed. In Mixed decay mode, the device is set initially to a fast decay for a proportion of the fixed off-time, then to a slow decay for the remainder of the off-time. Mixed decay current control results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.
Internal synchronous rectification control circuitry is provided to improve
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power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), and crossover-current protection.
Special power-on sequencing is not required. The A4982 is supplied in two
surface mount package, the ET, a 5 mm × 5 mm, 0.90 mm nominal overall package height QFN package, and the LP package, a 24-pin TSSOP. Both packages have exposed pads for enhanced thermal dissipation, and are lead (Pb) free (suffix –T), with 100% matte tin plated leadframes.
A4982主要特性和优势:
? Low RDS(ON) outputs
? Automatic current decay mode detection/selection
? Mixed and Slow current decay modes
? 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
? No smoke no fire (NSNF) compliance (ET package)
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图1.A4982功能方框图
图2.A4982典型应用框图
图3.A4982 LP封装应用电路和PCB布局框图
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a4982中文资料
