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DEMO MANUAL DC2012A
Description
LT8610AB
42V, 3.5A Micropower Synchronous
Step-Down Regulator
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 INTVCC can be applied
to the SYNC turret for pulse-skipping operation. Figure 1
shows the efficiency of the circuit at 12V input.
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
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
Specifications are at TA = 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN* Input Supply Range 5.5 42 V
VOUT Output Voltage 4.8 5 5.2 V
IOUT Maximum Output Current 3.5 A
fSW Switching Frequency 1.85 2 2.15 MHz
EFE Efficiency at DC IOUT = 1A 91 %
* 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 VIN
and GND.
2. With power off, connect the load VOUT and GND.
3. Check JP1 setting
4. Turn on the power at the input.
5. Carefully evaluate other design parameters as needed.
Figure 1. LT8610AB 12VIN to 5VOUT Efficiency at
2MHz Switching Frequency
Figure 2. LT8610AB Case Temperature Rise.
VOUT = 5V, TA = 25°C
Figure 3. LT8610AB Demo Circuit Conducted EMI Performance
LOAD CURRENT (A)
EFFICIENCY (%)
DC2012A F01
100
95
90
85
80
75
70
65
60 0 0.01 1 100.1
VIN (V)
CASE TEMPERATURE RISE (°C)
DC2012A F02
140
120
100
80
60
40
20
06 11 21 3616 3126
2MHz, 3.5A
700kHz, 3.5A
2MHz, 2.5A
START 150kHz
RES BW 9kHz
VBW 62kHz STOP 30MHz
dBµV
DC2012A F03
70
60
30
20
50
40
10
0
–10
–20
–30
EN55022 CLASS B
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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 QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C2 CAP., X7R, 2.2µF, 50V, 10%, 1206 MURATA, GCJ31CR71H225KA12L
2 1 C4 CAP., X7R, 0.22µF, 16V, 10%, 0603 AVX, 0603YC224KAT2A
3 1 C5 CAP., C0G, 10pF, 25V, 10%, 0402 AVX, 04023A100KAT2A
4 2 C6, C14 CAP., X7R, 47µF, 10V, 10%, 1210 MURATA, GRM32ER71A476KE15L
5 1 C7 CAP., X7R, 1.0µF, 25V, 10%, 0603 MURATA, GRM188R71E105KA12D
6 1 C8 CAP., X7R, 0.1µF, 16V, 10%, 0402 MURATA, GRM155R71C104KA88D
7 1 L1 IND., 2.2µH COILCRAFT, XAL5030-222MEC
8 1 R2 RES., CHIP, 18.2k, 1/10W, 1% 0603 VISHAY, CRCW060318K2FKEA
9 1 R3 RES., CHIP, 49.9k, 1/16W, 1% 0402 VISHAY, CRCW040249K9FKED
10 2 R1, R4 RES., CHIP, 1M, 1/16W, 1% 0402 VISHAY, CRCW04021M00FKED
11 1 R5 RES., CHIP, 243k, 1/16W, 1% 0402 VISHAY, CRCW0402243KFKED
12 1 U1 IC, LT8610ABEMSE#PBF MSE16 LINEAR TECH, LT8610ABEMSE#PBF
Additional Demo Board Circuit Components
1 1 C1 CAP., ALUM, 22µF, 63V SUN ELECT, 63CE22BS
2 2 C3, C10 CAP., X7R, 4.7µF, 50V, 10%, 1206 MURATA, GRM31CR71H475KA12L
3 1 C9 CAP., X7R, 1.0µF, 16V, 10%, 0805 AVX, 0805YC105KAT2A
4 1 C11, C12 CAP., X7R, 0.1µF, 50V, 10%, 0402 TDK, C1005X7R1H104K
5 2 C13 CAP., X7R, 0.1µF, 50V, 10%, 0603 MURATA, GCJ188R71H104KA12D
6 1 FB1 FERRITE BEAD 0805 TDK, MPZ2012S101AT
7 1 L2 IND., 4.7µH VISHAY, IHLP2020BZ-ER4R7M01
8 0 R6 RES., OPT, 0402 OPT
Hardware: For Demo Board Only
1 9 E1-E9 TESTPOINT, TURRET, .094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 HEADER 1X3 079 SAMTEC, TMM-103-02-L-S
3 1 XJP1 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G
4 4 MH1-MH4 STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8833(SNAP ON)
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DEMO MANUAL DC2012A
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.
schematic Diagram
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
ALL CAPACITORS ARE 0402.
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE 0402.
SUNCON
63CE22BS
(2MHz)
*
*
REFER TO THE DEMO MANUAL FOR VIN RANGE.
VOUT
R6
OPT
R6
OPT
R5
243k
R5
243k
E2
GND E2
GND
E9
GND
E9
GND
E6
EN/UV
E6
EN/UV
C14
47uF
10V
1210
C14
47uF
10V
1210
R1
1M
R1
1M
C2
2.2uF
50V
1206
C2
2.2uF
50V
1206
U1
LT8610ABEMSE
U1
LT8610ABEMSE
VIN
5
VIN
6
EN/UV
4
SYNC
1
INTVCC
13
TR/SS
2
RT
3
PGND
7
GND
8
FB 16
PG 15
BIAS 14
SW 11
SW 10
SW 9
BST 12
GND
17
C12
0.1uF
50V
C12
0.1uF
50V
JP1
GND
SYNC
JP1
GND
SYNC
1
3
2
C7
1uF
0603
25V
C7
1uF
0603
25V
E5
SYNC
E5
SYNC
C11
0.1uF
50V
C11
0.1uF
50V
L1
2.2uH
XAL5030-222MEC
L1
2.2uH
XAL5030-222MEC
C13
0.1uF
0603
50V
C13
0.1uF
0603
50V
R2
18.2k
0603
R2
18.2k
0603
FB1FB1
E7
TR/SS
E7
TR/SS
C9
1uF
0805
16V
C9
1uF
0805
16V
R4
1Meg
R4
1Meg
C8
0.1uF
C8
0.1uF
L2
4.7uH
L2
4.7uH
C5
10pF
C5
10pF
C6
47uF
10V
1210
C6
47uF
10V
1210
C3
4.7uF
50V
1206
C3
4.7uF
50V
1206
E8 PG
E8 PG
+
C1
22uF
63V
+
C1
22uF
63V
R3
49.9k
R3
49.9k
E4 GND
E4 GND
C10
4.7uF
50V
1206
C10
4.7uF
50V
1206
C4
0.22uF
0603
16V
C4
0.22uF
0603
16V
E3
VOUT
5V / 3.5A
E3
VOUT
5V / 3.5A
E1
VIN
5.5V - 42V E1
VIN
5.5V - 42V
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DEMO MANUAL DC2012A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2013
LT 1113 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LT C for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
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arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
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agency certified (FCC, UL, CE, etc.).
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observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LT C applica-
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Copyright © 2004, Linear Technology Corporation
