STCMB1 datasheet(20/59 Pages) STMICROELECTRONICS

部件名	STCMB1

功能描述	TM PFC with X-cap discharge and LLC resonant combo controller

PDF	59 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

标志

20 / 59 page

Application information

STCMB1

20/59

DocID028958 Rev 4

Figure 8. Conventional COT controlled TM PFC waveforms

The enhanced constant on-time (ECOT) control integrated in the STCMB1 is a proprietary

solution that outperforms the typical THD performance of the conventional COT control. The

idea is to cancel out the constant term “(x)” in Equation 3 with a corresponding positive term.

This can be done by delaying the instant start of the timer that sets the on-time until the

inductor current reaches a preset value ILth. In this way it is no longer the ON-time TON of

the power switch that is controlled (and kept constant) but the time TON_C defined as:

Equation 4

(y)

Of course, the on-time TON will no longer be constant as in the conventional COT:

Equation 5

Lth

Lpk

sin







sin

Lvy

Lth









STCMB1 数据表(PDF) 20 Page - STMicroelectronics