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Circuit Description
NEC-FA150ATUA
The loading of lamp before lighting up=œ, the loading after lighting
up=
Iout
Vout
Before lighting up:
Vout=Vopen,
Vc=0
After lighting up:
Vout=lamp voltage
Vc=Vopen-Vout
l
The output current was decide by Co capacitor and CCFL equivalent impedance.
(6) Feedback loop:
For sensor output current, we change the ac voltage to dc voltage and connector to error amplifier of control IC, to
stable the output current.
Note:
OVP – Over Voltage Protection
SCP – Short-Circuit Protection
UVL – Under Voltage Lockout
Functional Block Diagram
SCP
NDRV
ZVS
CONTROLLER
PDRV
SST
NDR
PDR
Vdd
ENA
OPS
CT
RT
REF
IBIAS
&
REFERENCE
2.50V
HCLMP
LCLMP
ADJ
FB
CMP
GND
PULSE GEN
ACTIVE
"HIGH"
-
EA
+
-
+
LAMP
ON/OFF
Vmax
Vmin
(fix value)
V
V>Vmax -- -> Vmax
Vmin<V<Vmax ->V
V<Vmin -- ->Vmin
UNDER VOLTAGE
LOCKOUT
t1+t2
(slow start)
PROTECTION
+
-
COMP
COMP
COMP
COMP
t1
(slow start)
RAMP
COMP.
Vmax=2.6V-Vset
COMP
Vset
3
4
2
5
6
7
1
10
16
15
14
13
12
11
9
8
POFF
POFF
2.5V
0.5V
CLK
0.6V
RA
M
P
CO
M
P
. P
ULS
E
SS2
UVLO
OLPROT
PO
F
F
ENABLE
Pgate
2.5V
Ngate
RESET
SS1
Vdd
1.5V
SS1
V_SS2
MN1
R2
4K
I=2.5uA
I=12uA
R4
70k
R5
630k
-
+
-
+
-
+
-
+
-
+
R1
300k