DEMO MANUAL DC1829A
LTC3866EUF
High Efficiency Step-Down Converter
with Very Low DCR Inductor
DESCRIPTION
Demonstration circuit 1829A is a high efficiency, high
density, synchronous buck converter with 4.5V to 14V
input voltage range. It can supply a 30A maximum load
current with a 1.5V output. This demo board utilizes the
,
LTC
®
3866EUF a feature-rich single phase synchronous
buck controller with very low DCR current sensing capabil-
ity, on-chip drivers and remote output voltage sensing. This
board is setup with 0.32mΩ DCR inductor. The temperature
compensation function guarantees accurate current limit
over a wide temperature range with DCR sensing.
The LTC3866 is suitable for operation from an input voltage
of 4.5V to 38V and output voltages up to 3.5V. It can provide
high efficiency, high power density and versatile power
solutions for telecom and datacom systems, industrial and
medical instruments, along with DC power distribution
systems and computer systems. The LTC3866 is available
in 24-pin 4mm
×
4mm QFN and 24-lead FE packages.
To shut down the converter, set the RUN pin voltage below
1.2V (JP2: OFF). Use JP1 jumper to select Burst Mode
®
operation, pulse skipping mode or forced continuous mode
operation at light load. Switching frequency is preset at
about 400kHz, and it can be easily modified from 250kHz
to 770kHz. Onboard dynamic circuit is also available for
transient test. Please see LTC3866 data sheet for more
detailed information.
Design files for this circuit board are available at
http://www.linear.com/demo
L,
LT, LTC, LTM, μModule, Linear Technology, the Linear logo and Burst Mode are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
PERFORMANCE SUMMARY
PARAMETER
Input Voltage Range
Output Voltage, V
OUT
Maximum Output Current, I
OUT
Typical Efficiency
Typical Switching Frequency
(T
A
= 25°C)
VALUE
4.5V to 14V
1.5V ±2%
30A
90.3%
400kHz
CONDITION
V
IN
= 4.5V to 14V, I
OUT
= 0A to 30A
V
IN
= 4.5V to 14V, V
OUT
= 1.5V
V
IN
= 12V, V
OUT
= 1.5V, I
OUT
= 30A
dc1829af
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DEMO MANUAL DC1829A
QUICK START PROCEDURE
Demonstration circuit 1829A is easy to set up to evaluate
the performance of the LTC3866EUF Refer to Figure 1 for
.
the proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the input power supply to V
IN
(4.5V to 14V) and GND (input return).
2. Connect the 1.5V output load between V
OUT
and GND
(Initial load: no load).
3. Connect the DVMs to the input and outputs. Set default
jumper position: JP1: CCM; JP2: ON.
4. Turn on the input power supply and check for the proper
output voltages. V
OUT
should be 1.5V ±2%.
5. Once the proper output voltages are established, ad-
just the loads within the operating range and observe
the output voltage regulation, ripple voltage and other
parameters.
Note: When measuring the output or input voltage ripple,
do not use the long ground lead on the oscilloscope probe.
See Figure 2 for the proper scope probe technique. Short,
stiff leads need to be soldered to the (+) and (–) terminals
of an output capacitor. The probe’s ground ring needs to
touch the (–) lead and the probe tip needs to touch the
(+) lead.
Figure 1. Proper Measurement Equipment Setup
dc1829af
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DEMO MANUAL DC1829A
QUICK START PROCEDURE
Figure 2. Measuring Output Voltage Ripple
Efficiency Test at CCM
96
94
92
EFFICIENCY (%)
90
88
86
84
82
80
78
76
0
5
10
20
15
LOAD CURRENT (A)
V
IN
= 4.5V
V
IN
= 12V
V
IN
= 14V
25
30
dc1829a F03
Figure 3. Efficiency vs Load Current
Load Regulation at V
IN
= 12V
1.7
1.5
OUTPUT VOLTAGE (V)
1.3
1.1
0.9
0.7
0.5
0
10
20
30
LOAD CURRENT (A)
40
dc1829a F04
Figure 4. Output Voltage vs Load Current
dc1829af
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DEMO MANUAL DC1829A
QUICK START PROCEDURE
Top View
Bottom View
L
Q
B
Q
T
3866
dc1829a F05a
dc1829a F05b
Figure 5. Thermal Performance at V
IN
= 14V, V
O
= 1.5V, I
O
= 30A, No Forced Air, T
A
= 25°C
V
SW
(200mV/DIV)
V
P-P
= 331mV
I
O
(20A/DIV)
I
O
= 0A TO 25A
t (50μs/DIV)
dc1829a F06
Figure 6. Transient Performance at V
IN
= 12V, V
O
= 1.5V, I
O
= 0A ~ 25A
dc1829af
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DEMO MANUAL DC1829A
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
24
25
26
27
28
29
30
1
2
3
4
5
6
QTY
2
2
2
4
2
2
2
1
1
1
1
1
1
1
1
5
1
1
1
1
1
1
2
1
1
1
1
1
1
1
0
0
0
0
0
0
REFERENCE
CIN1, CIN2
CIN3, CIN4
COUT1, COUT2
COUT3, COUT6, C15, C16
C19, C21
C22, C27
C24, C25
C26
C28
C31
D2
L1
Q1
Q3
Q5
R9, R32, R34, R36, R44
R10
R11
R12
R27
R28
R30
R31, R45
R37
R38
R39
R40
R42
R43
U1
COUT4, COUT5
C23, C29, C32, C33, C34
Q2, Q4
RN1
R1-R6, R35, R41, R47, R48
R18
PART DESCRIPTION
CAP 180μF 20% 16V
,
CAP 1210 10μF 20% 25V X5R
,
CAP 7343 330μF 20% 2.5V POSCAP
,
CAP 1210 100μF 20% 6.3V X5R
,
CAP 0603 1μF 10% 25V X5R
,
CAP 0603 220nF 10% 25V X7R
,
CAP 0603 0.1μF 10% 10V X5R
,
CAP 0603 1.5nF 5% 50V C0G
,
CAP 0603 220pF 10% 25V NPO
,
CAP 0805 4.7μF 20% 10V X5R
,
DOIDE, CMDSH-3
IND, 0.33μH
XSTR, POWER MOSFET
XSTR, POWER MOSFET
XSTR, SUD50N03-09P MOSFET
RES, 0603 0Ω JUMPER 1/10W
RES, 0603 100k 5% 1/10W
RES, 0603 10k 5% 1/10W
RES, 2512 0.010Ω 5% 1W
RES, 0603 100k 1% 1/10W
RES, 0603 1k 1% 1/10W
RES, 0603 931Ω 1% 1/10W
RES, 0603 10Ω 5% 1/10W
RES, 0603 2.2Ω 5% 1/10W
RES, 0603 20k 1% 1/10W
RES, 0603 30.1k 1% 1/10W
RES, 0603 10k 1% 1/10W
RES, 0603 3.01k 1% 1/10W
RES, 0603 4.64k 1% 1/10W
IC, STEP-DOWN CONVERTER
CAP 7343 330μF 20% 2.5V POSCAP OPTION
,
CAP 0603 OPTION
,
XSTR, OPTION
THERMISTOR, OPTION
RES, 0603 OPTION
RES, 2512 OPTION
MANUFACTURER/PART NUMBER
SANYO 16SVP180MX
TAIYO YUDEN TMK325BJ106MM-T
SANYO 2R5TPE330M9
TDK C3225X5R0J107M
TAIYO YUDEN TMK107BJ105MA-T
TDK C1608X7R1E224K
AVX 0603ZD104KAT
MURATA GRM1885C1H152JA01D
AVX 06033A221KAT2A
TDK C2012X5R1A475M
CENTRAL SEMI CMDSH-3
WURTH ELEKTRONIK M744301033
INFINEON BSC050NE2LS
INFINEON BSC010NE2LS
SILICONIX SUD50N03-09P
VISHAY CRC06030000Z0EA
VISHAY CRCW0603100KJNEA
VISHAY CRCE060310K0JNEA
VISHAY WSL2512R0100FEA
VISHAY CRCW0603100KFKEA
VISHAY CRCW06031K00FKEA
YAGEO RC0603FR-07931RL
VISHAY CRCW060310R0JNEA
VISHAY CRCW06032R20JNEA
VISHAY CRCW060320K0FKEA
VISHAY CRCW060330K1FKEA
VISHAY CRCW060310K0FKEA
VISHAY CRCW06033K01FKEA
VISHAY CRCW06034K64FKEA
LINEAR TECH LTC3866EUF
SANYO 2R5TPE330M9 OPTION
OPTION
OPTION
OPTION
OPTION
OPTION
Required Circuit Components
Additional Demo Board Circuit Components
dc1829af
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