HA16150T Datasheet, PDF (15/25 Pages) Renesas Technology Corp – High-Speed Current Mode Push-Pull PWM Control IC

HA16150T/P
5. Operating Frequency
The operating frequency is adjusted by means of CT and RT.
Adjustment examples are shown in the graph below. This graph shows driver output operating frequencies. The
reference operating frequency generated at the CT pin is twice the driver output frequency.
The driver output operating frequency can be estimated using the approximate equation shown below.
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 CT pin voltage overshoot, undershoot and so forth.
When the operating frequency is adjusted, it is essential to confirm operation using the actual system.
fosc =
8
3 × CT × RT
=
8
3 × C6 × R7
=
8
3 × 470 [pF] × 27 [kΩ]
= 210 [kHz]
10000
fosc (RT = 5.1kΩ)
fosc (RT = 10kΩ)
fosc (RT = 27kΩ)
fosc (RT = 75kΩ)
1000
100
0
100
1000
CT (pF)
Figure 6
10000
Rev.3.00 Jan 30, 2007 page 15 of 24