LT1786FCS Linear Technology, LT1786FCS Datasheet - Page 18
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LT1786FCS
Manufacturer Part Number
LT1786FCS
Description
IC SW REG CCFL SMBUS PROG 16SOIC
Manufacturer
Linear Technology
Datasheet
1.LT1786FCS.pdf
(20 pages)
Specifications of LT1786FCS
Applications
Converter, CCFL
Voltage - Input
4.5 ~ 30 V
Number Of Outputs
1
Operating Temperature
0°C ~ 70°C
Mounting Type
Surface Mount
Package / Case
16-SOIC (3.9mm Width)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Voltage - Output
-
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LT1786FCS
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Company:
Part Number:
LT1786FCS#PBF
Manufacturer:
LT
Quantity:
88
Part Number:
LT1786FCS#PBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
Part Number:
LT1786FCS#TRPBF
Manufacturer:
LINEAR/凌特
Quantity:
20 000
LT1786F
TYPICAL
Dual Transformer CCFL Power Supply
Space constraints may dictate utilization of two small
transformers instead of a single, larger unit. Although this
approach is somewhat more expensive, it can solve space
problems and offers other attractive advantages. Figure
2’s approach is essentially a “grounded lamp” LT1786F-
based circuit. The transistors drive two transformer pri-
maries in parallel. The transformer secondaries, stacked
in series, provide the output. The relatively small trans-
formers, each supplying half the load power, may be
located directly at the lamp terminals. Aside from the
obvious space advantage (particularly height), this
arrangement minimizes parasitic wiring losses by elimi-
18
SHUTDOWN
APPLICATION
1 F
Figure 2. Dual Transformers Save Space and Minimize parasitic Losses While Maintaining
Current Accuracy and Line Regulation. Trade-Off Is Increased Cost
1000pF
1
2
3
4
5
6
7
8
PGND
I
DIO
V
AGND
SHDN
SMBSUS
ADR
CCFL
C
100k
220k
LT1786F
U
BAT54
ROYER
BULB
V
I
SDA
BAT
SCL
OUT
V
SW
IN
16
15
14
13
12
11
10
9
3
10
ZDT1048
0.1 F*
Q1-Q2
+
TO
SMBus
HOST
+
2
L2
2.2 F
6
2.2 F
16V
nating high voltage lead length. Additionally, although the
lamp receives differential drive, with its attendant low
parasitic losses, the feedback signal is ground referred.
Thus, the stacked secondaries afford floating lamp oper-
ating efficiency with grounded mode current certainty and
line regulation.
L1 is directly driven, with winding 4-5 furnishing feedback
in the normal fashion. L3, “slaved” to L1’s and L3’s
interconnects must be laid out for low inductance to
maintain waveform purity. The traces should be as wide as
possible (e.g., 1/8") and overlaid to cancel inductive
effects.
1
4
27pF
L1, L3 = COILTRONICS CTX110605
COILTRONICS (561) 241-7876
MBRS130L
L2 = COILTRONICS CTX100-4
* = WIMA MKI OR MKP-20
5
L1
= PANASONIC ECH-U
SEE TEXT AND NOTES
OVERLAY INDICATED TRACES BETWEEN L1 AND L3
LAMP
750
WIDE TRACE
WIDE TRACE
+V
V
5V
IN
BAT
3
0.1 F*
6
+
2
10
2.2 F
1
1786 F02
NC
4
5
NC
L3