DEMO MANUAL DC2012A
LT8610AB
42V, 3.5A Micropower Synchronous
Step-Down Regulator
Description
Demonstration circuit 2012A is a 42V, 3.5A micro-
power synchronous step-down regulator featuring the
LT
®
8610AB.
The LT8610AB is a compact, high efficiency,
high speed synchronous monolithic step-down switching
regulator that consumes only 2.5µA of quiescent current
when output is regulated at 5V. The efficiency of the circuit
is greater than 90% at light load up to 1.5A. This is a 10%
improvement over competing parts. Top and bottom power
switches, compensation components and other necessary
circuits are inside of the LT8610AB to minimize external
components and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple burst mode operation. To synchronous to an
external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Once JP1 is on SYNC position,
a DC voltage of higher than 2V or INTV
CC
can be applied
to the SYNC turret for pulse-skipping operation. Figure 1
shows the efficiency of the circuit at 12V input.
Figure 2 shows the thermal performance of the circuit.
When running at input voltage greater than 30V, 3.5A
output current and 2MHz switching frequency, the tem-
perature rise will be significant. Either reducing the input
voltage, the output current or the switching frequency will
bring the temperature down to acceptable level without
external cooling.
The demo board has an EMI filter installed. The board
and the IC are designed to minimize conducted and radi-
ated EMI. The conducted EMI performance of the board
is shown on Figure 3. The limit in Figure 3 is EN55022
class B, average. It shows the circuit passes the test with
a wide margin.
The LT8610AB data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for DC2012A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2012A
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.
performance summary
SYMBOL
V
IN
*
V
OUT
I
OUT
f
SW
EFE
PARAMETER
Input Supply Range
Output Voltage
Maximum Output Current
Switching Frequency
Efficiency at DC
Specifications are at T
A
= 25°C
CONDITIONS
MIN
5.5
4.8
3.5
1.85
I
OUT
= 1A
2
91
2.15
5
TYP
MAX
42
5.2
UNITS
V
V
A
MHz
%
* Refer to Figure 2 to determine the maximum input voltage. If IC temperature exceeds target, reduce input voltage, output current or switching
frequency.
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DEMO MANUAL DC2012A
Quick start proceDure
DC2012A is easy to set up to evaluate the performance of
the LT8610AB. Refer to Figure 4 and Figure 5 for proper
measurement equipment setup and follow the procedure
below:
1. With power off, connect the input power supply to V
IN
and GND.
2. With power off, connect the load V
OUT
and GND.
3. Check JP1 setting
4. Turn on the power at the input.
5. Carefully evaluate other design parameters as needed.
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
0
0.01
0.1
1
LOAD CURRENT (A)
10
DC2012A F01
140
CASE TEMPERATURE RISE (°C)
120
100
80
60
40
20
0
6
2MHz, 2.5A
11
16
21
V
IN
(V)
26
31
36
700kHz, 3.5A
2MHz, 3.5A
DC2012A F02
Figure 1. LT8610AB 12V
IN
to 5V
OUT
Efficiency at
2MHz Switching Frequency
Figure 2. LT8610AB Case Temperature Rise.
V
OUT
= 5V, T
A
= 25°C
70
60
50
40
30
dBµV
20
10
0
–10
–20
–30
START 150kHz
RES BW 9kHz
V
BW
62kHz
STOP 30MHz
DC2012A F03
EN55022 CLASS B
Figure 3. LT8610AB Demo Circuit Conducted EMI Performance
2
dc2012af
DEMO MANUAL DC2012A
Quick start proceDure
Figure 4. Proper Measurement Equipment Setup
Figure 5. Measure Output Ripple
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DEMO MANUAL DC2012A
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
1
2
3
4
QTY
1
1
1
2
1
1
1
1
1
2
1
1
1
2
1
1
2
1
1
0
9
1
1
4
REFERENCE
C2
C4
C5
C6, C14
C7
C8
L1
R2
R3
R1, R4
R5
U1
C1
C3, C10
C9
C11, C12
C13
FB1
L2
R6
E1-E9
JP1
XJP1
MH1-MH4
PART DESCRIPTION
CAP., X7R, 2.2µF, 50V, 10%, 1206
CAP., X7R, 0.22µF, 16V, 10%, 0603
CAP., C0G, 10pF, 25V, 10%, 0402
CAP., X7R, 47µF, 10V, 10%, 1210
CAP., X7R, 1.0µF, 25V, 10%, 0603
CAP., X7R, 0.1µF, 16V, 10%, 0402
IND., 2.2µH
RES., CHIP, 18.2k, 1/10W, 1% 0603
RES., CHIP, 49.9k, 1/16W, 1% 0402
RES., CHIP, 1M, 1/16W, 1% 0402
RES., CHIP, 243k, 1/16W, 1% 0402
IC, LT8610ABEMSE#PBF MSE16
CAP., ALUM, 22µF, 63V
CAP., X7R, 4.7µF, 50V, 10%, 1206
CAP., X7R, 1.0µF, 16V, 10%, 0805
CAP., X7R, 0.1µF, 50V, 10%, 0402
CAP., X7R, 0.1µF, 50V, 10%, 0603
FERRITE BEAD 0805
IND., 4.7µH
RES., OPT, 0402
TESTPOINT, TURRET, .094"
HEADER 1X3 079
SHUNT, .079" CENTER
STAND-OFF, NYLON 0.50" TALL
MANUFACTURER/PART NUMBER
MURATA, GCJ31CR71H225KA12L
AVX, 0603YC224KAT2A
AVX, 04023A100KAT2A
MURATA, GRM32ER71A476KE15L
MURATA, GRM188R71E105KA12D
MURATA, GRM155R71C104KA88D
COILCRAFT, XAL5030-222MEC
VISHAY, CRCW060318K2FKEA
VISHAY, CRCW040249K9FKED
VISHAY, CRCW04021M00FKED
VISHAY, CRCW0402243KFKED
LINEAR TECH, LT8610ABEMSE#PBF
SUN ELECT, 63CE22BS
MURATA, GRM31CR71H475KA12L
AVX, 0805YC105KAT2A
TDK, C1005X7R1H104K
MURATA, GCJ188R71H104KA12D
TDK, MPZ2012S101AT
VISHAY, IHLP2020BZ-ER4R7M01
OPT
MILL-MAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM-103-02-L-S
SAMTEC, 2SN-BK-G
KEYSTONE, 8833(SNAP ON)
Required Circuit Components
Additional Demo Board Circuit Components
Hardware: For Demo Board Only
4
dc2012af
5
4
3
2
1
D
D
schematic Diagram
VIN
5.5V - 42V
+
C1
*
FB1
R1
1M
C3
4.7uF
50V
1206
22uF
63V
SUNCON
63CE22BS
C10
4.7uF
50V
1206
C2
2.2uF
50V
1206
C13
0.1uF
50V
0603
L2
4.7uH
E1
GND
E2
C11
0.1uF
50V
C12
0.1uF
50V
U1
LT8610ABEMSE
5
VIN
VIN
EN/UV
SYNC
INTVCC
TR/SS
RT
PGND
GND
GND
17
FB
16
R5
243k
C4
0.22uF
16V
0603
L1
2.2uH
XAL5030-222MEC
C14
47uF
10V
1210
C6
47uF
10V
1210
C9
1uF
16V
0805
E4
R3
R4
1Meg
C5
10pF
E8
PG
B
BST
12
R6
OPT
6
4
SW
SW
SW
BIAS
PG
15
14
11
10
1
9
EN/UV
VOUT
E3
E6
SYNC
GND
JP1
VOUT
5V / 3.5A
C
C
SYNC
E5
3
2
1
13
2
C7
1uF
0603
25V
GND
3
7
8
GND
49.9k
E9
R2
18.2k
(2MHz)
0603
C8
0.1uF
TR/SS
E7
B
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
4
3
2
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE 0402.
ALL CAPACITORS ARE 0402.
A
A
*
REFER TO THE DEMO MANUAL FOR VIN RANGE.
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1
DEMO MANUAL DC2012A
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