NCP4355
http://onsemi.com
14
ON
ON
SKIP
SKIP
OFF
OFF
2
4
Start−up and regulation
6
Light load −> skip mode
8
Very light load −> off mode
10a
10b
10c
12
14
15
16
Very light load −> off mode
Status
VMIN Threshold
1 kHz 12% wide
pulses
1 kHz
12%
wide
pulses
1
3
5
7
9
11
13
COMPRESSED TIME
Figure 28. Typical Application States and Waveforms in OFF Mode with Active On Primary Controller
Start up, I
OUT
nominal or low
Very low I
OUT
activates OFF mode with rarely C
OUT
charging
V
REF
V
CC_Prim
V
CCON
V
AUX
V
FB_Prim
I
FBC
I
LED
V
OUT
I
OUT
I
ONOFF
V
SNS
V
MIN
V
OFFDET
10% V
CC
V
REM_prim
I
BIASV
switched on
I
BIASV
switched off
Max I
FBC
at
off mode
FBC sink current disappears −>
lower current consumption
Application powered from C
OUT
Very light load −> skip mode
C
OUT
charging
V
OUT
< V
MIN
−> I
ONOFF
starts flow, primary V
CC
is rising
V
OUT
is close to minimum set voltage
Long time of C
OUT
discharging
Primary V
CC
cap is charged by DSS
FBC sink current disappears −>
lower current consumption
Application powered from C
OUT
