HA16158P Datasheet, PDF (17/23 Pages) Renesas Technology Corp – PFC & PWM Control IC

HA16158P/FP
7. Operating Frequency
The operating frequency is adjusted by timing resinstance RT.
Adjustment examples are shown in the graph below. The operating frequency fpwm in the PWM section is
determined by the RT. The operating frequency fpfc in the PFC section is half the value of fpwm.
The operating frequency in the PWM section can be estimated using the approximate equation shown
below.
RT = 200 kΩ:
fpwm ≈ ^{2.60 × 1010} = 130 [kHz]
RT
fpfc = ^fpwm = 65 [kHz]
2
This is only an approximate equation, and the higher the frequency, the greater will be the degree of error
of the approximate equation due to the effects of the delay time in the internal circuit, etc.
When the operating frequency is adjusted, it is essential to confirm operation using the actual system.
1000
100
10
10
100
RT (kΩ)
Figure 7
fpwm
fpfc
1000
Rev.0, Aug. 2002, page 17 of 23