CM6900G
Resonant Controller
Timing Diagram
Dead Time
PRIDRVB
PRIDRV
Delay Time
Delay Time
SRDRVB
SRDRV
Oscillator
The oscillator frequency is determined by the values of RT and CT.
f
osc
= 1 / (t
RAMP
+ t
DEADTIME
)
t
RAMP
= RT * CT * ln((V
REF + ICHG*RT
-1.25)/(V
REF + ICHG*RT
-3)) where I
CHG
= 4*(F
EAO
-V
BE
)/R
SET
t
DEADTIME
= 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.
I
CHG
= 4*(F
EAO
-V
BE
)/R
SET
I
CHG(max)
= 20V/R
SET
2007/11/22 Rev1.0
Champion Microelectronic Corporation
Page 7
CHAMP [ CHAMPION MICROELECTRONIC CORP. ]
