UF2768

Preliminary

CMOS IC

UNISONIC TECHNOLOGIES CO., LTD

5 of 8

www.unisonic.com.tw

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FU N CT I ON AL

DESCRI PT I ON

PWM Speed Control (Fixed-Frequency Output)

It is possible to change rotation speed of the motor by switching output transistor. The on-duty of switching

de-pends on the signal from input to PWM terminal. The output PWM frequency is fixed frequency.(30KHZ) (See

Figure 1 PWM Input Waveform).

Quick Start

This IC disables the lock protection function when the PWM input keeps low level for more than 16ms. (See Figure

2 Quick Start Waveform)

FG Output

The FG pin is an open-drain output, connecting a pull up resistor to a high level voltage for the speed detection

function. When WO pin voltage switches to high, the FG is high (switch off) and the WO pin voltage switches to low

then FG is low (switch on). The FG output only works in sensor- less mode. (See Figure 3 FG Output Waveform)