Diodes one-to-many one-phase 12V fan motor driver

     Diodes Incorporated introduces the AH5772 and AH5773 one-in-one single-phase 12V fan motor drivers for low to medium voltage brushless DC fan control for consumer products, home appliances, industrial and office equipment. Two highly integrated fan drivers offer micro-package options and heat treatment capabilities to save space by reducing the number of components and the size of the printed board.

     The new device integrates a highly sensitive Hall sensor and a pair of input amplifiers, which can be used with a fan motor magnet with weak magnetic field strength, which is more efficient and cost-effective. Sensors provide ideal voltage and thermal coefficients over a very wide operating range, coupled with minimal tolerances, which help stabilize motor performance and simplify manufacturing and test processes.

     Two compact motor drivers feature low on-resistance H-bridge output stages that support up to 500mA of continuous pump and fill current at 1A peak to match the performance of larger, more complex drivers and front-facing drivers. The device is available in ultra-thin package options with a small number of pins, including MSOP8-EP and U-DFN2020-6 packages for the AH5773, and TO-94 packages for the AH5772.

     The new fan driver offers a wide operating voltage range from 2.4V to 18V, and the low starting voltage allows the fan to operate at 20% lower than the 12V rating, making it suitable for a variety of brushless DC cooling fan applications. The operating temperature range of the device is -40oC to 105oC, so it can meet the strict temperature requirements of the application.

     Both drivers regulate the fan speed through voltage input control, and the AH5773 also provides more precise speed control by varying the duty cycle of a series of PWM signals applied to a dedicated pulse width modulation (PWM) input. When the PWM pin of the AH5773 is pulled down to more than 65ms, the device enters standby mode, typically consuming only 100μA of current. If the PWM pin is pulled high, the drive output will restart. This quick start function can be used when the rotor is locked and protected to restart the fan motor before the end of the lockout time.

     To prevent the fan motor coils from overheating or damaging, both fan drivers include rotor lock protection, which turns off the driver output when a rotor lock is detected, and the driver restarts automatically when the rotor is unlocked. The device handles the time of lock detection, shutdown and automatic restart internally, without the need for external timing capacitors.

     AH5772 and AH5773 also integrate comprehensive protection features such as overvoltage protection, which turns off the device when overvoltage is detected and then enters standby mode to prevent pressure on the motor coil. The overtemperature shutdown function effectively protects the temperature of the device.