KSI-8019-000
1
S6520
LCD Back Light Inverter with Analog Dimming
F
Description
The S6520 contains all of the necessary control circuitry to implement a highly efficient
cold cathode fluorescent back-light driver and provides a near sinusoidal output voltage
and current waveforms for a CCFL. A specially designed integrated circuit provides all
control functions for a current fed push-pull converter and contains two PWM(Pulse Width
Modulation) control circuits to drive 4 CCFLs for LCD monitor. The S6520 operates at
constant frequency in a PWM mode and it has feed forward control method, this function
preventing lamp flickering against input voltage step changing. Therefore, even though
input voltage is changed suddenly, the lamp current remains constant because of the feed
back and feed forward control. Typical operating frequency ranges between 30kHz to
200kHz, dependent upon the CCFL and transformer characteristics. It provides protection
functions such as OLP(Open Lamp Protection), SCP(Short Circuit Protection).
Features
Complete Dual PWM Power Control Circuitry
Internal Soft Start for Soft Lamp lgnition
Enable Function to lock the output off until Out Signal is Operational
Analog Dimming Function
Internal Stable 5V Reference Supply
Open Lamp Protection
Internal Short Circuit Protection
Ordering
Information
Type NO. Marking Package Code
S6520 S6520 SOP-16
Outline Dimensions unit :
mm
S
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m
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KSI-8019-000
2
S6520
Internal Block Diagram
Pin Number
Symbol
I/O
Pin Function Description
1 CT1
I
Frequency
Trimming
Capacitor for Main Frequency Setting 1
2
SS
I
Initial Soft Start
3
OLR1
I
Open Lamp Regulation 1
4
FB1
I
Feedback 1 (Error Amplifier Negative Input)
5
CMP1
-
Error Amplifier Output 1
6
ENA
I
ON/OFF Control Pin. TTL Signal is Applicable.
7 OUT1
O
Output
Drive1
8 GND
-
Ground
9 VCC
I
Supply
Voltage
10 OUT2 O
Output
Drive
2
11
ADIM
-
Analog Dimming Input
12
CMP2
-
Error Amplifier Output 2
13
FB2
I
Feedback 2 (Error Amplifier Negative Input)
14
OLR2
I
Open Lamp Regulation 2
15 CT2 I
Frequency
Trimming
Capacitor for Main Frequency Setting 2
16
REF
O
Reference Voltage (VREF) = 5V
OUT1
7
Output 1
5V Vref
Internal
bias
ENA
+
-
1.4V
ena
6
Enable Switch
Vcc
9
Ct1
1
Ct2
15
-
+
Vref
Oscillator1
FB1
4
ADIM
11
CMP1
5
+
-
+
Comparator 1
7V Vz
+
-
+
Vref
Amplifier 1
+
OUT2
Short Circuit Protection
10
GND
8
Shut Down Signal to Output
Output 2
-
n*Vref
OLR1
3
OLR2
14
+
+
FB2
13
Amplifier 2
CMP2
12
+
+
-
SS
2
Comparator 2
+
+
+
Vref
-
reset signal from bias
S
Q
R
iss
-
+
Vref
Oscillator2
from FB1
from FB2
-
Vref
+
+
regulation signal
to COMP1, COMP2
Open Lamp Regulation
REF
16
delay timer
10us
PIN Collection
KSI-8019-000
3
S6520
ABSOLUTE MAXIMUM RATINGS
CHARACTERISTICS SYMBOL
VALUE
UNITS
Supply Voltage
V
CC
22 V
Power Dissipation
P
D
1
W
Operating Temperature
T
OPR
-25~+85
Storage Temperature
T
STG
-40~+125
Electrical Characteristics
Ta=25, V
CC
= 10V, unless otherwise specified.
Characteristic Symbol
Test
Condition
Min.
Typ.
Max.
Unit
REFERENCE SECTION
Reference Voltage
V
ref
-
4.925
5.0
5.075
V
Line Regulation
V
ref. LINE
8Vcc20
- 2.0 25 mV
Load Regulation
V
ref. LOAD
0mAIref5mA
- 1.0 15 mV
Temperature Coefficient (note 1)
V
ref
/T -25Ta85
- 0.01 - %/
ERROR AMPLIFIER SECTION (EA1, EA2)
Inverting Reference Voltage
V
ref(EA)
-
2.4
2.5
2.6
V
Input Bias Current
I
B(EA)
V
CMP
=2.5V -
-0.1
-1.0
uA
Output Sink Current
I
SINK
V
CMP
=2.5V 0.3
2 - mA
Output Source Current
I
SOURCE
V
CMP
=2.5V -0.3
-2 - mA
Dimming Input Voltage Range
V
DIM
-
0
-
2.5
V
SOFT START SECTION
Initial Soft Start Current
I
SS
-
7.5
12.5
17
uA
Soft Start Limit Voltage
V
SSL
-
4.1
4.7
5.3
V
PROTECTION SECTION (SCP1, SCP2 & OLR1, OLR2)
SCP Threshold Voltage
V
SCP
-
2.55
2.7
2.85
V
OLR Threshold Voltage
V
OLR
-
2.35
2.5
2.65
V
On/Off Threshold Voltage
V
ENA
-
1.1
1.4
1.7
V
OSCILLATOR SECTION (OSC1, OSC2)
Oscillator Frequency
F
O
R
t
=50k, C
t
=680pF 45 50 55 kHz
KSI-8019-000
4
S6520
Electrical Characteristics(Continued)
Ta=25, V
CC
= 10V, unless otherwise specified.
Characteristic Symbol
Test
Condition
Min.
Typ.
Max.
Unit
OUTPUT SECTION (OUT1, OUT2)
P-CH Output High Voltage
V
POH
I
SINK
=10mA
Vcc-
0.9
Vcc-
0.7
Vcc-
0.4
V
P-CH Output Low Voltage
V
POL
I
SOURCE
=10mA
Vcc-
7.5
Vcc-
6.0
Vcc-
4.5
V
Output Rising Time (Note1)
t
R
C
OUT
=0.5nF -
200
300
nsec
Output Falling Time (Note1)
t
F
C
OUT
=0.5nF -
100
200
nsec
START SECTION
Stand by Current 8V
I
SB8
- -
10
30
uA
Stand by Current 20V
I
SB20
- -
20
60
uA
Operating Current
I
CC
- -
4
6
mA
* Note 1. These parameters, although guaranteed, are not 100% tested in production
KSI-8019-000
5
S6520
Electrical Characteristic Curves
Fig. 1 V
CC
- I
SB
Fig. 3 V
CC
- V
ref
Fig. 4 V
ref(EA)
- V
CMP
Fig. 2 V
CC
- I
CC
Fig. 7 V
SCP
- V
OUT
Fig. 8 V
ENA
- I
CC
Fig. 2 V
CC
- I
CC
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