MB39C604 datasheet(12/36 Pages) CYPRESS

12 / 36 page

Document Number: 002-08441 Rev.*A

Page 12 of 36

MB39C604

8.2

PFC (Power Factor Correction) Function

Switching on time (TON) is generated by comparing VCOMP with an internal sawtooth waveform (refer to Figure 2). Since VCOMP is

slow varying with connecting an external capacitor (CCOMP) from the COMP pin to the GND pin, TON is nearly constant within an AC

line cycle. In this state, IP_PEAK is nearly proportional to the AC Line voltage (VBULK). It can bring the phase differences between the

input voltage and the input current close to zero, so that high Power Factor can be achieved.

8.3

Dimming Function

MB39C604 has the built-in dimmable circuit to control ILED by changing a reference of Err Amp based on the input voltage level on

the DIM pin (VDIM), and realizes dimming. Figure 6 shows ILED dimming ratio based on VDIM.

Figure 7 shows the input circuit to the DIM pin for PWM dimming. PWM signal is divided and filtered into an analog voltage with RC

network. It is possible to configurate PWM dimmable system by inputting the voltage to the DIM pin.

Figure 6. Dimming Curve

Figure 7. DIM Pin Input Circuit

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

110%

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

DIM [V]

MB39C604 Datasheet(PDF) 12 Page - Cypress Semiconductor