DEMO MANUAL DC1980A
LT3514
Triple Step-Down Switching Regulator
with 100% Duty Cycle Operation
Description
Demonstration circuit 1980A is a triple current mode PWM
step-down DC/DC converter featuring the
LT
®
3514.
The
demo circuit is designed for 5V, 3.3V and 1.8V outputs
from a 5.4V to 36V input. The current capability of 5V
and 1.8V outputs is 1A and the 3.3V output is capable of
2A output. Individual soft-start and current limit for each
output as well as frequency synchronous function simplify
the complex design of triple-output power converters.
Each converter is synchronized to either a common ex-
ternal clock input or a resistor programmable 250kHz to
2.2MHz internal oscillator. Programmable frequency allows
optimization between efficiency and external component
size. Each output can be independently disabled using its
own RUN/SS pin.
The LT3514 data sheet gives complete description of the
device, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for the demo circuit 1980A.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
5
10
15
20
25
V
IN
(V)
30
35
40
DC1980a F01
Figure 1. System Efficiency at f = 1MHz with I
OUT1
= I
OUT4
= 1A
and I
OUT3
= 2A
DC1980a F02
Figure 2. Thermal Image at V
IN
= 12V, f = 1MHz with
I
OUT1
= I
OUT4
= 1A and I
OUT3
= 2A
performance summary
SYMBOL
V
IN
V
OUT1
V
OUT3
V
OUT4
Frequency
I
OUT1
PARAMETER
Input Supply Range
Output Voltage 1
Output Voltage 3
Output Voltage 4
Switching Frequency
V
OUT1
Maximum Output Current
Specifications are at T
A
= 25°C
CONDITIONS
MIN
5.4
4.85
3.2
1.746
V
IN
= 12V
V
IN
= 5.4V ~ 36V
0.9
1
5
3.3
1.8
1
TYP
MAX
36
5.15
3.4
1.854
1.1
UNITS
V
V
V
V
MHz
A
dc1980af
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DEMO MANUAL DC1980A
performance summary
SYMBOL
I
OUT3
I
OUT4
PARAMETER
V
OUT3
Maximum Output Current
V
OUT4
Maximum Output Current
Specifications are at T
A
= 25°C
CONDITIONS
V
IN
= 5.4V ~ 36V
V
IN
= 5.4V ~ 36V
VIN = 5.4V ~ 36V, I
OUT1
= 1A
VIN = 5.4V ~ 36V, I
OUT3
= 2A
VIN = 5.4V ~ 36V, I
OUT4
= 1A
MIN
2
1
25
25
25
TYP
MAX
UNITS
A
A
mV
mV
mV
VOUT1(AC) VOUT1 Output Ripple
VOUT3(AC) VOUT3 Output Ripple
VOUT4(AC) VOUT4 Output Ripple
Quick start proceDure
Demonstration circuit 1980A is easy to set up to evalu-
ate the performance of the LT3514. Refer to Figure 3 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 output
voltage ripple by touching the probe tip directly across
the VIN or VOUT and GND terminals. See Figure 4 for
proper scope probe technique.
1. Place JP1 to JP4 on ON position.
2. With power off, connect the input power supply to VIN
and GND.
3. Turn on the power at the input.
NOTE. Make sure that the input voltage does not exceed
36V
4. Check for the proper output voltages.
NOTE. If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
5. Once the proper output voltages are established, adjust
the load within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
dc1980af
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DEMO MANUAL DC1980A
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
1
2
3
4
5
6
7
8
1
2
3
QTY
1
1
1
1
4
3
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
0
0
3
0
0
0
0
15
4
4
REFERENCE
C1
C3
C4
C5
C6, C19, C26, C27
C7, C17, C18
C21
C23
D1, D4
D3
L1
L3
L4
L5
R1
R3
R4
R5
R6
R7
R8
R9, R11, R12
U1
C8
C10 (OPT)
C11 (OPT)
C12 TO C14
C20, C25, C28 (OPT)
C24 (OPT)
FB1 (OPT)
L6 (OPT)
E1 TO E15
JP1 TO JP4
xJP1 TO xJP4
PART DESCRIPTION
CAP, X5R, 22µF, 6.3V, 10% 0805
CAP, X5R, 47µF, 6.3V, 10% 1206
CAP, X5R, 22µF, 10V, 10% 0805
CAP, X5R, 2.2µF, 6.3V, 10% 0603
CAP, X5R, 1µF, 50V, 10% 0603
CAP, X7R, 47nF, 10V, 10% 0603
CAP, NP0, 330pF, 50V, 5% 0603
CAP, NP0, 100pF, 50V, 5% 0603
DIODE, SCHOTTKY BARRIER RECTIFIER
SCHOTTKY RECTIFIER, SMA
IND, 8.2µH
IND, 4.7µH
IND, 4.2µH
IND, 10µH
RES, CHIP, 12.7k, 1% 1/16W, 0603
RES, CHIP, 31.6k, 1% 1/16W, 0603
RES, CHIP, 53.6k, 1%, 1/16W, 0603
RES, CHIP, 18.2k, 1% 1/16W, 0603
RES, CHIP, 200k, 5% 1/16W, 0603
RES, CHIP, 475k, 1% 1/16W, 0603
RES, CHIP, 100k, 1% 1/16W, 0603
RES, CHIP, 10k, 1% 1/16W, 0603
IC, 36V TRIPLE BUCK REGULATOR
CAP, ALUM, 22µF, 50V, 20%
CAP, X7R, 0.01µF, 50V,10% 0603
CAP, X7R, 2.2µF, 50V, 10% 1206
CAP, X7R, 0.1µF, 50V, 10% 0603
CAP, X7R, 0.1µF, 50V, 10% 0603
CAP, 0603
FERRITE BEAD, OPTION
IND, 8.2µH OPTION
TURRET
HEADER, 3PIN, 2mm
SHUNT, 2mm
OPTION
VISHAY, IHLP-2525CZ-01 OPTION
MILL MAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM-103-02-L-S
SAMTEC, 2SN-BK-G
MANUFACTURER/PART NUMBER
TDK, C2012X5R0J226K
MURATA, GRM31CR60J476KE19L
TDK, C2012X5R1A226K
TDK, C1608X5R0J225K
TDK, C1608X5R1H105K
AVX, 0603ZC473KAT2A
AVX 06035A331JAT2A
AVX 06035A101JAT
ON SEMI, MBRM140T3G
VISHAY, B240A-M3
SUMIDA, CDRH5D28NP-8R2NC
NIC, NPIM73P4R7MTRF
SUMIDA, CDRH5D28NP-4R2NC
COILCRAFT, XPL2010-103MLB
VISHAY, CRCW060312K7FKED
VISHAY, CRCW060331K6FKED
VISHAY, CRCW060353K6FKED
VISHAY, CRCW060318K2FKED
VISHAY, CRCW0603200KJNED
VISHAY, CRCW0603475KFKED
VISHAY, CRCW0603100KFKED
VISHAY, CRCW060310K0FKED
LINEAR TECHNOLOGY, LT3514EUFD#PBF
SUN ELECT, 50CE22BS
TDK, C1608X7R1H103K OPTION
MURATA, GCM31CR71H225KA55L
MURATA, GRM188R71H104KA93D
MURATA, GRM188R71H104KA93D
Required Circuit Components
Additional Demo Board Circuit Components
Hardware: For Demo Board Only
dc1980af
4
PCB Design
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