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LT1947EMS#TRPBF

P1-P3P4-P6P7-P9P10-P12
LT1947
1
1947fa
■
TFT-LCD Notebook Display Panels
■
TFT-LCD Desktop Monitor Display Panels
■
Digital Cameras
■
Handheld Computers
■
Complete Solution Under 1.2mm
■
Develops Three Outputs from a 3.3V or 5V Supply
■
Externally Programmable V
ON
Delay
■
Fixed Frequency Low Noise Outputs
■
All Ceramic Capacitors
■
3MHz Switching Frequency
■
Fast Transient Response
■
Few External Components Required
■
2.7V to 8V Input Range
■
Adjustable AV
DD
and V
ON
Voltages
■
Tiny 10-Lead MSOP and Thermally Enhanced
10-Lead MSOP Packages
Adjustable Output TFT-LCD
Triple Switching Regulator
Figure 1. 3.3V Powered TFT-LCD Bias Generator
The LT
®
1947 is a highly integrated multiple output DC/DC
converter designed for use in TFT-LCD panels. The device
contains two independent switching regulators. The main
regulator has an adjustable output voltage with an internal
1.1A switch that can generate a boosted voltage as high as
30V. The second regulator’s output is also adjustable up
to 30V and can deliver 10mA for positive bias. A simple
level-shift charge pump off the main switch node gener-
ates the negative bias voltage. An external capacitor sets
the delay time from AV
DD
’s final value to the rising edge at
the V
ON
pin. The 3MHz switching frequency allows the use
of tiny low profile chip inductors and capacitors through-
out, providing a low noise, low cost total solution with all
components under 1.2mm in height. The device operates
from an input range of 2.7V to 8V and is available in
10-lead MSOP and thermally enhanced 10-lead MSOP
packages.
SW2
D2
V
IN
SW1
L1
3.3µH
L2
4.7µH
D1
D3 D4
SHDN
C
T
LT1947
GND
V
O2
R3
182k
R1
53.6k
C2
3.3µF
CERAMIC
×2
C1: TAIYO YUDEN LMK316BJ225MD
C2: TAIYO YUDEN LMK325BJ335MD × 2
C3: AVX 0.22µF 25V X7R
C4, C6: TAIYO YUDEN LMK107BJ684MA
C4
0.68µF
CERAMIC
C6
0.68µF
AV
DD
8V
200mA
V
ON
24V
10mA
V
OFF
–8V
10mA
R2
10k
1947 F01
R4
10k
FB1
V
ON
C5
10nF
C3
220nF
C1
2.2µF
CERAMIC
V
IN
SHUTDOWN
FB2
D1: MBRM120LT3
D2: CMDSH-3
D3, D4: BAT54S DUAL DIODE
L1: SUMIDA CLQ4D103R3
L2: TAIYO YUDEN LB2012B4R7M
2ms/DIV 1947 TA01.tif
V
SHDN
5V/DIV
V
ON
20V/DIV
AV
DD
10V/DIV
V
OFF
10V/DIV
Start-Up Waveforms
APPLICATIO S
U
FEATURES
TYPICAL APPLICATIO
U
DESCRIPTIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LT1947
2
1947fa
V
IN
Voltage ................................................................ 8V
C
T
Voltage.................................................................. 6V
SW1, SW2 Voltage .................................................. 36V
V
ON
, V
O2
Voltage ..................................................... 30V
ORDER PART
NUMBER
MSE PART MARKING
LTBQW
LT1947EMSE
(Note 1)
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Order Options Tape and Reel: Add #TR, Lead Free: Add #PBF, Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
FB1, FB2 .................................................................... 3V
SHDN......................................................................... 8V
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Lead Temperature (Soldering, 10 sec).................. 300°C
1
2
3
4
5
FB1
FB2
C
T
SW1
GND
10
9
8
7
6
V
ON
V
O2
SHDN
SW2
V
IN
TOP VIEW
MS PACKAGE
10-LEAD PLASTIC MSOP
ORDER PART
NUMBER
MS PART MARKING
LTUE
LT1947EMS
T
JMAX
= 125°C, θ
JA
= 120°C/W
T
JMAX
= 125°C, θ
JA
= 40°C/W
1
2
3
4
5
FB1
FB2
C
T
SW1
GND
10
9
8
7
6
V
ON
V
02
SHDN
SW2
V
IN
TOP VIEW
11
MSE PACKAGE
10-LEAD PLASTIC MSOP
EXPOSED PAD (PIN 11) IS GND
MUST BE SOLDERED TO PCB
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.3V, V
SHDN
= 3.3V unless otherwise specified.
ELECTRICAL CHARACTERISTICS
SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage Range 2.7 8 V
Supply Current SHDN = 2.4V 9.5 12.5 mA
SHDN = 0V 1 µA
FB1 Voltage 1.240 1.26 1.280 V
● 1.225 1.295 V
FB2 Voltage 1.225 1.26 1.295 V
● 1.210 1.310 V
Reference Line Regulation V
IN
= 2.7V to 8V 0.01 0.05 %/V
LT1947
3
1947fa
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT1947 is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3.3V, V
SHDN
= 3.3V unless otherwise specified.
SYMBOL CONDITIONS MIN TYP MAX UNITS
Error Amplifier Voltage Gain EA1 and EA2 100 V/V
C
T
Current Source V
FB1
= 1.3V 4 5.5 6.5 µA
C
T
Threshold to Turn On Q3 1.25 1.28 1.30 V
FB1 Voltage to Begin C
T
Charge 1.17 1.2 1.23 V
SW1 Current Limit (Note 3) 1.1 1.4 2 A
SW2 Current Limit (Note 3) 0.35 0.6 1 A
SW1 Saturation Voltage I
SW1
= 800mA 0.230 0.280 V
SW2 Saturation Voltage I
SW2
= 300mA 0.3 0.36 V
SW1 Maximum Duty Cycle 82 %
SW2 Maximum Duty Cycle 85 %
Oscillator Frequency ● 2.3 3 3.5 MHz
V
ON
Switch Drop I
Q3
= 7mA 160 200 mV
SW1 Leakage Current Switch Off, SW1 = 3.3V 0.01 5 µA
SW2 Leakage Current Switch Off, SW2 = 3.3V 0.01 5 µA
SHDN Pin Bias Current V
SHDN
= 2.4V 10 25 µA
SHDN Pin High Active Mode 2.4 V
SHDN Pin Low Shutdown Mode 0.4 V
ELECTRICAL CHARACTERISTICS
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Switch current limit guaranteed by design and/or correlation to
static tests.
3.3V TFT-LCD Converter Efficiency
AV
DD
LOAD CURRENT (mA)
0
35
EFFICIENCY (%)
40
50
55
60
85
70
50
100
125
1947 G01
45
75
80
65
25 75
150
175
200
V
IN
= 2.7V
V
IN
= 3.3V
V
IN
= 3V
Supply Current C
T
Current Source
–50 –25 0 25 50 75 100
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
12
10
8
6
4
1947 G02
SHDN = 2.4V
–50 –25 0 25 50 75 100
TEMPERATURE (°C)
C
T
CURRENT (µA)
–2
–4
–6
–8
–10
1947 G03
TYPICAL PERFOR A CE CHARACTERISTICS
UW
P1-P3P4-P6P7-P9P10-P12

LT1947EMS#TRPBF

Mfr. #:
Buy LT1947EMS#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators DC/DC Converter for TFT-LCD Panels
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
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