CM6900G Datasheet, PDF (7/12 Pages) Champion Microelectronic Corp. – Resonant Controller

Timing Diagram
Dead Time
PRIDRVB
PRIDRV
Delay Time
CM6900G
Resonant Controller
SRDRVB
Delay Time
SRDRV
Oscillator
The oscillator frequency is determined by the values of RT and CT.
fosc = 1 / (tRAMP + t DEADTIME)
tRAMP = RT * CT * ln((VREF + ICHG*RT -1.25)/(VREF + ICHG*RT -3)) where ICHG = 4*(FEAO-VBE)/RSET
tDEADTIME = 2.125V/2.5mA * CT = 850 * CT
Resonant Section
FM Modulator
Frequency modulation of the resonant controller section is accomplished by controlling the charging current of the
oscillator through resonant error amplifier. The frequency of the resonant section is ½ of the oscillator frequency.
Compensation is accomplished by connecting R and C in series to the FEAO pin.
ICHG = 4*(FEAO-VBE)/RSET
ICHG(max) = 20V/RSET
2007/11/22 Rev1.0
Champion Microelectronic Corporation
Page 7