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MA7151F/R

Major Power Technology Co., Ltd.

Rev.1.0 Sep.18, 2017

1. Voltage mode PWM :

Applying a DC voltage to the PWM pin and the MA7151 will generate PWM pulses internally

with the “ON” duty cycle ratio according to the diagram below(Figure.1), which can be utilized

by the user to control the speed of the motor. The rotation speed will be higher if the voltage

applied to the PWM pin is higher.

0%

0.14VDD

PWM ON rate

100%

0.5VDD

Figure.1

2. Pulse mode PWM :

User can also apply PWM pulses directly to the PWM pin. The MA7151 will pass this pulse to the

coil driver with the original duty-cycle ratio.

Note:

(1) While using pulse mode PWM, the “High” Value of the input pulse should be higher than

0.5*VDD and the“Low” value should be lower than 0.14*VDD

(2) The lower-limit for the PWM pulse frequency is 200Hz, and the recommended frequency range

is higher than 30KHz where the PWM input pulses will not generate acoustic noise.

Note. The “PWM” pin contains an internal pull-up resistor so the MA7151 will rotate at full-speed

(100% ON) when this pin is left un-connected(floating).

PWM signal and Standby Mode

This IC would enter standby mode when the PWM input keeps low level for then 30ms(typ.). In

standby mode, it will shutdown amplifier and FG. In standby mode, the lock protection function

doesn’t work, therefore, starting fan is unobstructed when releasing standby mode.

PWM

Lock protect enable

disable

enable

30ms

Soft Switching

MA7151 uses soft switching of the motor coil current during commutation for to minimize audible

switching noise and electromagnetic interference (EMI) to provide a low noise solution.

Soft

Switching

GND

VDD

200us