Linear Technology DC1992A Quick setup guide

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DEMO MANUAL DC1992A
Description
LT8620
65V, 2A Micropower Synchronous
Monolithic Step-Down Regulator
Demonstration circuit 1992A is a 65V, 2A micropower
synchronous monolithic step-down regulator featuring
the LT
®
8620. The LT8620 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. Top and bottom power
switches,compensationcomponentsandother necessary
circuits are inside of the LT8620 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 pulse skipping operation.
Figure 1 shows the efficiency of the circuit at 12V input.
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
performance summary
The demo board has an EMI filter installed. The board and
the IC are designed to minimize conducted and radiated
EMI.TheradiatedEMIperformances of the boardare shown
on Figure 2 to Figure 4. The limits on those figures are
CISPR25, Class 5 peak limits. It shows the circuit passes
the test with a wide margin.
The LT8620 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 demo circuit 1992A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1992A
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 5.5 65 V
VOUT Output Voltage 4.8 5 5.2 V
IOUT Maximum Output Current 2 A
fSW Switching Frequency 1.85 2 2.15 MHz
EFE Efficiency at DC IOUT = 1A 92 %
Figure 1. LT8620 12VIN to 5VOUT Efficiency at 2MHz Switching Frequency
LOAD CURRENT (A)
0
EFFICIECNY (%)
100
95
85
90
80
70
75
65
60 1.00.5 1.5
dc1992a F01
2.0

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DEMO MANUAL DC1992A
Figure 3. 30MHz to 1GHz Radiated EMI Performance. VIN = 12V, VOUT = 5V, IOUT = 2A
Antenna Polarization: Vertical; Switching Frequency: 2MHz
Figure 2. 30MHz to 1GHz Radiated EMI Performance. VIN = 12V, VOUT = 5V, IOUT = 2A
Antenna Polarization: Horizontal; Switching Frequency: 2MHz
Description
Figure 4. 150kHz to 30MHz Radiated EMI Performance. VIN = 12V, VOUT = 5V, IOUT = 2A
Antenna Polarization: Vertical; Switching Frequency: 2MHz
(In the Frequency Range Between 150kHz and 30MHz, Only Vertical Polarization Is Required)

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DEMO MANUAL DC1992A
Demonstration circuit 1992A is easy to set up to evalu-
ate the performance of the LT8620. Refer to Figure 5 and
Figure 6 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.
Quick start proceDure
Figure 5. Proper Measurement Equipment Setup
Figure 6. Measure Output Ripple

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DEMO MANUAL DC1992A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C2 CAP., X7R, 2.2µF, 100V, 10%, 1206 MURATA, GRM31CR72A225K
2 1 C4 CAP., X7R, 0.1µF, 16V, 10%, 0402 MURATA, GRM155R71C104KA88D
3 1 C5 CAP., C0G, 10pF, 25V, 10%, 0603 AVX, 06033A100KAT2A
4 1 C6 CAP., X7R, 47µF, 10V, 10%, 1210 MURATA, GRM32ER71A476KE2015L
5 1 C7 CAP., X5R, 1.0µF, 10V, 10%, 0402 MURATA, GRM155R61A105K
6 1 C8 CAP., X7R, 0.1µF, 16V, 10%, 0603 MURATA, GRM188R71C104K
7 1 L1 IND, 2.2µH XFL4020 COILCRAFT, XFL4020-222MEC
8 1 R2 RES., CHIP, 18.2k, 1/10W, 1%, 0603 VISHAY, CRCW060318K2FKED
9 1 R3 RES., CHIP, 49.9k, 1/16W, 1%, 0603 VISHAY, CRCW060349K9FKED
10 2 R1, R4 RES., CHIP, 1M, 1/16W, 1%, 0603 VISHAY, CRCW06031M00FKED
11 1 R5 RES., CHIP, 243k, 1/16W, 1%, 0603 VISHAY, CRCW0603243KFKED
12 1 U1 IC, LT8620EMSE, MSE16 LINEAR TECH. CORP., LT8620EMSE#PBF
Additional Demo Board Circuit Components
1 1 C1 CAP., ALUM, 10µF, 100V SUN ELECT, 100CE10BS
2 2 C3, C10 CAP., X7S, 4.7µF, 100V, 10%, 1210 TDK, C3225X7S2A475K
3 1 C9 CAP., X7R, 1.0µF, 16V, 10%, 0805 AVX, 0805YC105KAT2A
4 2 C11, C12 CAP., X7R, 0.1µF, 100V, 10%, 0603 MURATA, GRM188R72A104K
5 1 C13 CAP., X5R, 0.1µF, 100V, 10%, 0402 MURATA, GRM155R62A104K
6 1 FB1 FERRITE BEAD 0805 TDK, MPZ2012S221A
7 1 L2 IND, 4.7µH IHLP2020BZ-01 VISHAY, IHLP2020BZ-ER4R7M01
8 0 R6 (OPT) RES., 0603
Hardware: For Demo Board Only
1 9 E1-E9 TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 3 PIN 0.079" SINGLE ROW HEADER SULLIN, NRPN031PAEN-RC
3 1 XJP1 SHUNT, 0.079" 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 DC1992A
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 0603.
NOTES: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE 0603.
SUNCON 100CE10BS
(2MHz)
VOUT
R6 OPT R6 OPT
R5 243k R5 243k
E2
GND E2 GND
E9
GND
E9
GND
E6
EN/UV
E6
EN/UV
R1
1M
R1
1M
C2
2.2uF
100V
1206
C2
2.2uF
100V
1206
U1
LT8620EMSE
U1
LT8620EMSE
VIN
5
VIN
6
EN/UV
4
SYNC
1
INTVCC
13
TR/SS
2
RT
3
NC
7
GND
8
FB 16
PG 15
BIAS 14
SW 11 SW 10 SW 9
BST 12
GND
17
C12 0.1uF
100V
C12 0.1uF
100V
JP1
GND SYNC
JP1
GND SYNC
1 3 2
C7 1uF 0402 6.3V C7 1uF 0402 6.3V
E5
SYNC
E5
SYNC
C11 0.1uF
100V
C11 0.1uF
100V
L1
2.2uH
XFL4020-222MEC
L1
2.2uH
XFL4020-222MEC
C13
0.1uF 0402
100V
C13
0.1uF 0402
100V
R2
18.2k
R2
18.2k
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
100V
1210 C3 4.7uF
100V
1210
E8 PG E8 PG
+
C1 10uF 100V
+
C1 10uF 100V
R3 49.9k R3 49.9k
E4 GND E4 GND
C10 4.7uF
100V
1210 C10 4.7uF
100V
1210
C4 0.1uF 16V 0402 C4 0.1uF 16V 0402
E3
VOUT
5V / 2A
E3
VOUT
5V / 2A
E1
VIN
5.5V - 65V E1
VIN
5.5V - 65V

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DEMO MANUAL DC1992A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
LT 0614 • 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
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
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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
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
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customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
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Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
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-
tion engineer.
Mailing Address:
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1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation

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