Application Note

Page 4 of 8

V.

Forward PWM control mode

a)

VREF is connected to VCC and RIN is a low input (<0.8V), selected through SW1. R5 is disconnected by opening

the jumper connection, SW2 is set to H position and a PWM signal with a frequency range between 20-100kHz with

an amplitude range same as that of VCC is given to FIN.

b)

The speed of the motor can be controlled by varying the duty cycle of the input PWM signal. OUT1 pin is high and

OUT2 pin toggles between low and high impedance states. The motor which is connected between OUT1 and

OUT2 rotates in the forward (clockwise) direction. A path for the recovery current from the motor is established by

the 10µF bypass capacitor connected between VCC and GND as shown in Figure 1.

VI.

Reverse PWM control mode

a)

VREF is connected to VCC and FIN is a low input (<0.8V), selected through SW2. R4 is disconnected by opening

the jumper connection, SW1 is set to H position and a PWM signal with a frequency range between 20-100kHz with

an amplitude range same as that of VCC is given to RIN.

b)

The speed of the motor can be controlled by varying the duty cycle of the input PWM signal. OUT2 pin is high and

OUT1 pin toggles between low and high impedance states. The motor which is connected between OUT1 and

OUT2 rotates in the reverse (anti-clockwise) direction. A path for the recovery current from the motor is established

by the 10µF bypass capacitor connected between VCC and GND as shown in Figure 1.

VII.

Forward VREF control mode

a)

FIN is a high input (>2V) and RIN is a low input (<0.8V) and are selected through SW2 and SW1 respectively. The

speed of the motor can be controlled by the VREF voltage given through a potentiometer connection varying

between VCC and ground as shown in the schematic.

b)

OUT1 pin is high and OUT2 pin toggles between the low and high and the motor which is connected between

OUT1 and OUT2 rotates in the forward (clockwise) direction. The duty conversion circuit provides the switching

duty corresponding to the voltage levels of the VREF and VCC pins.

c)

The on duty is represented by the following equation in this mode,

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d)

The switching on duty is limited by the range of VREF pin voltage. The PWM output carrier frequency in this mode

is 25kHz (nominal). A path for the recovery current from the motor is established by the 10µF bypass capacitor

connected between VCC and ground as shown in Figure 1.

VIII.

Reverse VREF control mode

a)

RIN is a high input (>2V) and FIN is a low input (<0.8V) and are selected through SW1 and SW2 respectively. The

speed of the motor can be controlled by the VREF voltage given through a potentiometer connection varying

between VCC and ground as shown in the schematic.

b)

OUT2 pin is high and OUT1 pin toggles between the low and high and the motor which is connected between

OUT1 and OUT2 rotates in the reverse (anti-clockwise) direction. The duty conversion circuit provides the switching

duty corresponding to the voltage levels of the VREF and VCC pins.

c)

The on duty is represented by the following equation in this mode,

������������������������=����������������(����)

������������(����)

d)

The switching on duty is limited by the range of VREF pin voltage. The PWM output carrier frequency in this mode

is 25kHz (nominal). A path for the recovery current from the motor is established by the 10µF bypass capacitor

connected between VCC and ground as shown in Figure 1.