AN628 Datasheet, PDF (16/35 Pages) STMicroelectronics – DESIGNING A HIGH POWER FACTOR SWITCHING

AN628 APPLICATION NOTE
where: R_fm is the programming current resistor.
K is a constant value = 0.1157 for R value in KΩ and f_SW in KHz.
A typical 20%
∆_----f_--s---w--
f_sw
can be a good compromise.
Figure 18.
a)
16/35
1.28V
+
-
I
Ifm
1
1/V_MRS
8.5V
10I
200I
-
+
b)
ROSC
R_OSC
17
VRMS
7
FREQ-MOD
2 POLES
FILTER
16
COSC
Rfm
18
C_OSC
D94IN065A
Modulation Frequency Normalzed in an Half Cycle of the Mains Voltage
Vl
1
fsw
1
0.8
0.8
c)
0.4
0.4
0.2
0.2
0
0
0
45
90
135
180
Electrical degrees