LT1184F_15 Datasheet, PDF (20/24 Pages) Linear Technology – CCFL/LCD Contrast Switching Regulators

LT1182/LT1183/LT1184/LT1184F
TYPICAL APPLICATIONS N
90% Efficient Grounded CCFL Configuration with Negative Polarity LCD Contrast
C1 MUST BE A LOW LOSS CAPACITOR,
C1 = WIMA MKP-20
Q1, Q2 = ZETEX ZTX849 OR ROHM 2SC5001
L1 = COILTRONICS CTX210605
L2 = COILTRONICS CTX100-4
L3 = COILTRONICS CTX02-12403
*DO NOT SUBSTITUTE COMPONENTS
COILTRONICS [phone]
THE I_CCFL CURRENT REQUIRED FOR AN
RMS BULB CURRENT IS:
I_CCFL (9 × 10^–3) (I_BULB).
0% TO 90% DUTY CYCLE FOR THE PWM
SIGNAL CORRESPONDS TO 0 TO 6mA.
D5
BAT85
R4
38.3k
V (PWM) 1%
0V TO 5V
1kHz PWM
C6 ⁺
2.2µF
SHUTDOWN
1
R5,38.3k, 1% ₂
3
C7, 1µF
4
5
6
C8,0.68µF
7
R7, 10k ₈
UP TO 6mA
LAMP
C2
27pF
10
6 ^3kV
L1
3
2 14
5
+ C3B
C5
R2
1000pF _220k
2.2µF
35V
C1*
0.068µF
R3
100k
Q2*
Q1*
CCFL
PGND
I_CCFL
16
CCFL V_SW
15
BULB
14
DIO
BAT
LT1183
13
CCFL V_C
ROYER
AGND
12
V_IN
SHDN
11
REF
LCD V_C
LCD
PGND
10
FB
9
LCD V_SW
L2
D1
100µH _1N5818
V (CONTRAST) ^{R10, 10k, 1%}
0V TO 5V
R1
750Ω
+ _C3A
2.2µF
35V
+ _C12
2.2µF
35V
D3
1N5934A ⁴
24V
D2
1N914 ²
V_IN
+
≥ 3V
C4
2.2µF
R9, 4.99k, 1%
C9
0.01µF
D5
1N4148
BAT
8V TO 28V
VARYING THE V(CONTRAST)
VOLTAGE FROM 0V TO 5V GIVES
VARIABLE NEGATIVE CONTRAST
FROM –10V TO –30V
L3
6
+
9
N = 1:2
D4
1N914
C11
22µF
35V
NEGCON
C10
0.1µF
R11
40.2k
1%
1182 TA02
20