MV1001SC

27

5.3 Dimming circuit

5.3.1

Example of dimming circuit smoothing PWM signal

Figure 24 shows an example of a dimming circuit that smooths a PWM dimming signal and applies it to the REF pin.

transistor is turned off in Figure 24, obtain the approximate values of those voltages using the formulas given below.

dimming accuracy.

To ensure that the IC operates in the minimum dimming region when Q101 is turned on, set the value of resistors R103

μA (typical).

is applied to the REF pin. Adjust the capacitance levels of C101 and C102 to 1 uF or less while checking dimming

characteristics.

Figure 24 Example of PWM dimming signal smoothing circuit





102

R

101

R

R102

V

H

_

V

DD

REF











104

R

103

R

ref

_

I

L

_











L

_

V

Don

H

_

V

Don

1

V

REF

REF

REF











CAT.No.1A0102-1E