QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 697
HIGH CURRENT QUAD OUTPUT SWITCHING REGULATOR FOR 5V INPUT TFT-LCD PANELS
1
LT1943
DESCRIPTION
Demonstration Circuit 697 is a quad output power
supply intended for use in large TFT-LCD panels. The
circuit features the LT1943 high current quad-output
switching regulator and generates a 3.3V logic supply
along with the triple output supply required for the
TFT-LCD panels. With an input voltage range of 4.5V
to 8V, a step down regulator provides 3.3V VLOGIC with
up to 1.5A current; a high power boost converter, a
lower power boost converter and an inverting con-
verter provide three independent output voltages
AVDD, VON and VOFF required by the LCD panels. An in-
ternal high side PNP provides delayed turn on of the
VON signal.
All four switchers are synchronized to the internal
1.2MHz clock, allowing the use of low profile induc-
tors and ceramic capacitors. They all have soft-start
to limit inrush current.
Long wires run from input sources (such as wall
adaptors) can cause large voltage spikes during initial
plug-in. C17 is installed on DC697 to damp the pos-
sible voltage spikes. C17 is not required for applica-
tions where input source is close to the regulator.
Please refer to Application Note 88 for details.
Design files for this circuit board are available. Call
the LTC factory.
LT is a trademark of Linear Technology Corporation
Table 1.
Performance Summary (TA = 25°C unless otherwise noted)
PARAMETER CONDITION VALUE
Minimum Input Voltage -40°C to 85°C 4.5V
Maximum Input Voltage -40°C to 85°C 8V
Output Voltage VLOGIC V
IN = 4.5V to 8V, IOUT = 0A to 1.5A 3.3V ±3%
Maximum Output Current at VLOGIC V
IN = 4.5V to 8V 1.5A
Typical Output Ripple VLOGIC V
IN = 5V, load at VLOGIC = 1.5A (20MHz BW) 19mVP–P
Typical Output Ripple AVDD V
IN = 5V, load at AVDD = 500mA (20MHz BW) 33mVP–P
Typical Switching Frequency 1.2MHz
Logic Low Voltage-Off, -40°C to 85°C 0.4V MAX
On/Off Control
Logic High Voltage-On 2.4V MIN
QUICK START PROCEDURE
Demonstration circuit 697 is easy to set up to evalu-
ate the performance of the LT1943. Refer to Figure 1
for proper measurement equipment setup and follow
the procedure below:
NOTE:
When measuring the input or output voltage
ripple, care must be taken to avoid a long ground lead
on the oscilloscope probe. Measure the input or out-
put voltage ripple by touching the probe tip directly
across the input or one of the outputs and GND ter-
minals. See Figure 2 for proper scope probe tech-
nique.
1.
With power off, connect the input power supply to
Vin and GND.
2.
Set the input between 4.5V to 8V. Turn on the
power at the input.
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 697
HIGH CURRENT QUAD OUTPUT SWITCHING REGULATOR FOR 5V INPUT TFT-LCD PANELS
2
3.
Check for the proper output voltages. If there is no
output, temporarily disconnect the load to make
sure that the load is not set too high.
4.
Once the proper output voltages are established,
adjust the loads within the operating range and ob-
serve the output voltage regulation, ripple voltage,
efficiency and other parameters.
NOTE: If more than 20mA is needed at VON, connect
L3 to a higher input, such as AVDD.
Figure 1.
Proper Measurement Equipment Setup
Figure 2.
Measuring Input or Output Ripple
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
Vin
4.5V-8V
Voff
-10V@50mA
RUN-SS
Vlogic
3.3V@1.5A
Von
30V@20mA
PGOOD
AVdd
13V@500mA
GND
GND
GND
GND
A
DC697A
Tuesday, November 18, 2003
11
June Wu 7/23/03
Dongyan Zhou 7/23/03
Switching Regulator For 5V Input TFT-LCD Panels
LT1943EFE, High Current Quad Output
SIZE
SCALE:
CAGE CODE DWG NO REV
SHEET OF
FILENAME:
TITLE
CONTRACT NO.
APPROVALS DATE
DRAWN
CHECKED
APPROVED
ENGINEER
DESIGNER
TECHNOLOGY
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
CUSTOMER NOTICE
D6
ZHCS400
U1
LT1943EFE
8
19
18
22
12
17
7
15 16 21
13
14
4
27
28
5
23
25
26
24
6
20
11
1
10932
FB4
SW4
RUN-SS
BIAS
BOOST
SS-234
NFB4
VIN VIN SW3
SW1
SW1
FB1
SW2
SW2
FB2
PGOOD
CT
VON
E3
FB3
GND
SGND
GND
VC4VC3VC2VC1
R3
80.6K
E3
C26
1uF
10V
C10
2.2uF
35V
C20
100pF
R4
10.0K
C1
10uF
10V
E8
D2
CMDSH-3
C12
4700pF
+
C17
68uF
16V
C13
1500pF
E1
R15
100K
L4
10uH
C22
100pF
L2
4.7uH
C14
2200pF
C6
2.2uF
10V
C5
0.015uF
R9
232K
E6
C3
0.22uF
10V
E7
D5
B240A
C23
100pF
C7
0.47uF
16V
L1
4.7uH
R10
7.5K
C25
1uF
16V
R6
95.3K
L3
6.8uH
E5
E10
R8
10.0K
C8
10uF
16V
C21
100pF
E11
E4
E9
Q1
Si2343DS
1
2 3
D1
B230A
R5
10.0K
R11
4.7K
R2
16.5K
R12
30K
E2
R13
13K
C15
0.47uF
35V
C9
0.047uF
C24
10pF
C4
0.015uF
R1
10.0K
C11
2700pF
D3
ZHCS400
C2
22uF
Linear Technology Corporation
LT1943EFE
Bill Of Material
Demo Bd. #697A
6/20/2005
Item Qty Reference Part Description Manufacture / Part #
1 1 C1 CAP., X7R, 10uF, 10V, 20% 1210 Taiyo Yuden, LMK325BJ106MN
2 1 C8 CAP., X5R, 10uF, 16V, 20% 1210 Taiyo Yuden, EMK325BJ106MN
3 1 C2 CAP., X5R, 22uF, 6.3V, 20% 1206 Taiyo Yuden, JMK316BJ226ML
4 1 C3 CAP., X7R, 0.22uF, 10V, 20% 0603 AVX, 0603ZC224MAT2A
5 2 C5,C4 CAP., X7R, 0.015uF, 16V, 20% 0402 AVX, 0402YC153MAT2A
6 1 C6 CAP., X7R, 2.2uF, 10V, 10% 0805 MuRata, GRM21BR71A225KA01L
7 1 C7 CAP., X5R, 0.47uF, 16V, 20% 0603 AVX, 0603YD474MAT2A
8 1 C9 CAP., X5R, 0.047uF, 16V, 10% 0402 AVX, 0402YD473KAT2A
9 1 C10 CAP., X5R, 2.2uF, 35V, 20% 1210 Taiyo Yuden, GMK325BJ225MN
10 1 C11 CAP., X7R, 2700pF, 50V, 20%, 0402 AVX, 04025C272MAT2A
11 1 C14 CAP., X7R, 2200pF, 50V, 20% 0402 AVX, 04025C222MAT2A
12 1 C12 CAP., X7R, 4700pF, 50V, 20% 0402 AVX, 04025C472MAT2A
13 1 C13 CAP., X7R, 1500pF, 50V, 20% 0402 AVX, 04025C152MAT2A
14 1 C15 CAP., X5R, 0.47uF, 35V, 20% 0805 Taiyo Yuden, GMK212BJ474MG
15 1 C17 CAP., TANT, 68uF, 16V, 20% 6032 AVX, TAJC686M016R
16 4 C20-C23 CAP., X7R, 100pF, 50V, 20% 0402 AVX, 04025C101MAT2A
17 1 C24 CAP., NPO, 10pF, 50V, 10% 0402 AVX, 04025A100KAT2A
18 1 C25 CAP., X5R, 1.0uF 16V, 20% 0805 TAIYO YUDEN, EMK212BJ105MG
19 1 C26 CAP., X7R, 1.0uF 10V, 20% 0805 TAIYO YUDEN, LMK212BJ105MG
20 1 D1 Schottky Barrier REC., B230A SMA Diodes Inc., B230A-13
21 1 D2 Schottky Diode, CMDSH-3 SOD-323 CENTRAL SEMI., CMDSH-3-LTC
22 2 D3,D6 Schottky Barries Dio., ZHCS400, SOD-323 ZETEX, ZHCS400TA
23 1 D5 Schottky Barrier REC., B240A SMA Diodes Inc., B240A-13
24 1 Q1 P-Mosfet, Si2343DS, SOT-23 VISHAY, SI2343DS
25 11 E1-E11 TURRET, MILL-MAX, 2501-2
26 1 L1 INDUCTOR, 4.7uH RLF7030 TDK, RLF7030T-4R7M3R4
27 1 L2 INDUCTOR, 4.7uH SLF6028 TDK, SLF6028T-4R7M1R6
28 1 L4 INDUCTOR, 10uH RLF5018 TDK, RLF5018T-100MR94
29 1 L3 INDUCTOR, 6.8uH RLF5018 TDK, RLF5018T-6R8M1R1
30 1 R10 RES., CHIP, 7.5K, 1/16W, 5% 0402 AAC, CR05-752JM
31 1 R11 RES., CHIP, 4.7K, 1/16W, 5% 0402 AAC, CR05-472JM
32 4 R1,R5,R8,R4 RES., CHIP, 10K, 1/16W, 1% 0402 AAC, CR05-1002FM
33 1 R12 RES., CHIP, 30K, 1/16W, 5% 0402 AAC, CR05-303JM
34 1 R13 RES., CHIP, 13K, 1/16W, 5% 0402 AAC, CR05-133JM
Page 1 - of - 2
Linear Technology Corporation
LT1943EFE
Bill Of Material
Demo Bd. #697A
6/20/2005
Item Qty Reference Part Description Manufacture / Part #
35 1 R2 RES., CHIP, 16.5K, 1/16W, 1% 0402 AAC, CR05-1652FM
36 1 R3 RES., CHIP, 80.6K, 1/16W, 1% 0402 AAC, CR05-8062FM
37 1 R6 RES., CHIP, 95.3K, 1/16W, 1% 0402 AAC, CR05-9532FM
38 1 R9 RES., CHIP, 232K, 1/16W, 1% 0402 AAC, CR05-2323FM
39 1 R15 RES., CHIP, 100K, 1/16W, 5% 0402 AAC, CR05-104JM
40 1 U1 I.C.LT1943EFE, TSSOP28FE LINEAR., LT1943EFE
41 1 PRINTED CIRCUIT BOARD FAB., DEMO CIRCUIT 697A
42 1 STENCIL STENCIL 697A
Page 2 - of - 2
