MV1012SC

26

5.3 Dimming circuit

5.3.1

Example of dimming circuit smoothing PWM signal

Figure 23 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 23, obtain the approximate values of those voltages using the formulas given below.

dimming accuracy.

To ensure that the IC operates in the oscillation off 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 23 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.1A0602-1E