FD036KT

FD036UT

Rev1.3 Sep. 24, 2008

P.4

FEELING

TECHNOLOGY

Functional Descriptions

PWM

PWM(pulse-width modulation) is used for the speed control for FD036. 2 types of PWM input signals can be

used :

1. Voltage mode PWM :

Applying a constant(DC) voltage to the PWM pin and the FD036 will generate PWM pulses internally with the

“ON” H/(L+H) duty cycle ratio according to the diagram below(Fig.4), 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.

Fig.4

2. Pulse mode PWM :

User can also apply PWM pulses directly to the PWM pin. The FD036 will pass this pulse to the coil driver with

the original duty-cycle ratio. The rotation speed will be higher with a higher H/(L+H) ratio.

Note:

(1) While using pulse mode PWM, the “High” Value of the input pulse should be higher than VDD/2 and the

“Low” value should be lower than VDD/7

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

range of 25KHz~30KHz where the PWM input pulse does not generate additional acoustic noise.

(3) The “PWM” pin contains an internal pull-up resistor so the FD036 will rotate in full-speed(100% ON) when

this pin is left un-connected(floating).

Soft-switching

FD036 uses the “soft-switching” technique to reduce the vibration and acoustic noise during rotation.

Direction of rotation

The direction of rotation can be selected by the setting the input voltage of “FR” to VDD(Forward) or

VSS(Reverse). The “FR” pin contains an internal pull-up resistor so the FD036 will rotate in the “Forward”

direction when this pin is left un-connected(floating).

Protection strategies for the coil driver

1. Thermal Shutdown

FD036 will shutdown the driver when the IC temperature rises beyond 165

°C. It would release the shutdown

condition when the temperature drops below 140

°C.

2. Lock protection and auto-restart function

FD036 will shutdown the driver when the rotor is blocked for a short period of time, which keeps the coil from

over-heated. It will try to restart the motor after the shutdown interval.

VDD/2

VDD/7

Vpwm

ON duty

100%

0%