Datasheet

fsw
QR Mode
Switching
Frequency
Feedback
Voltage
Power Supply
Output Voltage
t
t
t
(40 kHz)
This mode applies bursts of
40kHz soft−start pulses to the
power MOSFET gate. The
average fsw is shown in this
operating mode.
DCM
(maximum fs)
IC Off
Softstart
Regular Operation
Green Mode
Peak MOSFET
Current
t
Fixed Frequency
Status, pulled up
to VDD
t
Green Mode,
PFC bias OFF
Load Power
t
f
MAX
=
Oscillator Frequency
(130 kHz)
SS Mode
(Fixed f
SW
)
f
SS
V
FB
V
OUT
V
STATUS
Load shown is slightly
less than overcurrent
threshold
P
OUT, (max)
P
OUT
f
GRMODE_MX
(40 kHz)
f
QR_MIN
Internally Limit-
ed to 40 kHz
Hysteretic
Transition into
Green Mode
Frequency
Foldback
(Valley Switching, VS)
(VS)
FFM, (VS)
Green Mode
Burst Hysteresis
UCC28600
www.ti.com SLUS646J –NOVEMBER 2005– REVISED JULY 2011
Figure 4. Operation Mode Switching Frequencies
Copyright © 2005–2011, Texas Instruments Incorporated 13