Allegro A144x全桥马达驱动方案

Allegro公司的A144x(A1444和A1445)全桥马达驱动器集成了霍尔元件,全桥输出驱动器以及PWM速度控制逻辑, 用来驱动低压无刷DC马达(BLDC). A1444和A1445采用软开关算法以降低马达开关时的噪音和EMI干扰.本文介绍了A1444和A1445的主要特性和优势, 方框图以及典型应用电路.

The A1444 and A1445 are full-bridge motor drivers designed to drive low-voltage brushless DC (BLDC) motors in applications that require rotor speed control and fast rotor start-stop cycles.

A high density CMOS semiconductor process allows the integration of a Hall element, a full-bridge output driver, and PWM speed control logic into one monolithic IC. Commutation of the motor is achieved by use of a single Hall element sensor to detect the rotational position of an alternating-pole ring magnet. Low-voltage design techniques have been employed to achieve full device functionality down to a VDD of 1.8 V.

The voltage applied to the PDC pin is used to externally control the maximum speed of the motor by adjusting the PWM duty cycle of the output driver.

The A1444 and A1445 employ a soft switching algorithm to reduce audible switching noise and EMI interference. The externally controlled speed regulation and braking functions can be used to create motor designs requiring faster start-stop cycles. The A1444 and A1445 have different selectable internal PWM duty cycle options to accommodate a wide range of motor designs. Each device has a braking function enable pin that also includes a micropower sleep mode for battery management in portable electronic devices. This feature eliminates the requirement for a FET transistor to switch the device on and off.

The devices are optimized for vibration motor applications that require fast start-stop cycles, such as in cellular phones, pagers, and hand-held video game controllers. The devices can also be used for low-power fan motors rated at 5 V. This fully integrated single-chip solution provides enhanced reliability, including reverse battery protection and output short circuit protection.
The small package outline and low profile make this device ideally suited for use in applications where printed circuit board area and component headroom are at a premium. It is available in a lead (Pb) free (leadframe plating nickel palladium) 6-contact MLP/DFN microleadframe package for surface mount assembly. The underside of the package also features an exposed pad for enhanced thermal dissipation.




主要特性和优势:
Low voltage operation: 1.8 to 4.2 V
Externally controlled motor speed regulation
Fast motor startup and braking function allows faster start-stop cycles
Reverse voltage protection on the VDD and S¯ ¯  E¯ E¯ Ppins
Output short circuit and thermal shutdown protection
Soft switching algorithm for reduced audible switching noise and EMI interference
Unidirectional operating mode results in motor rotation in only one direction
Chopper stabilization reduces Hall signal offset drifts and results in increased signal accuracy over full operating temperature range
Sleep mode pin allows device enable/disable for reducing average power consumption
Antistall feature guarantees continuous rotation
Single-chip solution for high reliability
Miniature MLP/DFN package



图1. A1444/45方框图



图2. A1444/45应用电路(用户控制睡眠/使能模式,A1444/45则在全功率状态)



图3. A1444/45应用电路(用户同时控制功率和睡眠模式