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dc2205afa
DEMO MANUAL DC2205A
DESCRIPTION
LT8495 SEPIC/Boost Converter
with 2A, 70V Switch, 9µA Quiescent
Current, POR and Watchdog Timer
Demonstration circuit 2205A is a monolithic SEPIC con-
verter featuring LT
®
8495. The demo board is designed for
5V output from a 3V to 60V input at 450kHz switching
frequency. The max output current is 1A when the input
voltage is above 12V, and is reduced with lower input volt-
age. The LT8495 is a monolithic switching regulator with
a power-on reset and watchdog timer. Quiescent current
can be less than 9μA when operating. Dual supply pins
(VIN and BIAS) allow the part to automatically operate
from the most efficient supply.
The switching regulation, watchdog timer and reset detec-
tion functions are controlled by the SWEN, WDE and RSTIN
respectively. The reset and watchdog timeout periods are
independently adjustable using external capacitors C5 and
C6. The watchdog timer is enabled by default on the demo
board, and it can be disabled by moving the JP1 to GND. L, LT, LTC, LTM, 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
Low Ripple Burst Mode
®
operation increases the efficiency
at the light load while keeping the output ripple below
10mV. Figure 1 shows the demo board efficiency at 12V
input voltage. Figure 2 shows the max load current with
different input voltages of the demo board.
The LT8495 data sheet gives a complete description of the
part, operation and application information. The data sheet
must be read in conjunction with this demo manual for
demo circuit 2205A. The LT8495 is assembled in a 20-lead
plastic TSSOP package. Proper board layout is essential
for maximum thermal and electrical performance. See the
data sheet sections for details.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2205A
Specifications are at TA = 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 3 60 V
VOUT Output Voltage 4.86 5.04 5.24 V
fSW Switching Frequency RT = 169kΩ 414 450 477 kHz
IOUT Max Output Current VIN = 12V 1 A
EFE Efficiency at DC VIN = 12V, IOUT = 1A 80.2 %
V
IN
= 12V
V
OUT
= 5V
f
SW
= 450kHz
LOAD CURRENT (A)
0
0.2
0.4
0.6
0.8
1
40
50
60
70
80
90
EFFICIENCY (%)
DC2205A F01
INPUT VOLTAGE (V)
0
0.5
1.0
1.5
2.0
2.5
MAX LOAD CURRENT (A)
DC2205A F02
0
20
10
30
40
50
60
Figure1. LT8495 Efficiency
Figure2. LT8495 Max Load Current (Typical) vs Input Voltage
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DEMO MANUAL DC2205A
QUICK START PROCEDURE
Demonstration circuit 2205A is easy to set up to evalu-
ate the performance of the LT8495. 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 the proper
scope technique.
1. Place JP1 on the RST position to enable the watchdog
timer. It can be disabled by placing JP1 on the GND
position.
2. With power off, connect the input power supply to VIN
and GND. Make sure that the input voltage does not
exceed 60V.
3. With power off, connect loads from VOUT to GND.
4. Turn on the power at the input.
5. Check for the proper output voltages (VOUT = 5V).
Note. If there is no output, temporarily disconnect the load
to make sure that the load is not set too high or is shorted.
6. Once the proper output voltages are established, adjust
the load within the operating ranges and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
Figure3. Proper Measurement Equipment Setup
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DEMO MANUAL DC2205A
Figure4. Measuring Input or Output Ripple
V
OUT
GND
QUICK START PROCEDURE
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DEMO MANUAL DC2205A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Demo Board Circuit Components
1 1 C2 CAP., 2.2μF, X7R, 100V, 10%,1206 AVX, 12061C225KAT2A
2 2 C3, C4 CAP., 47μF, X5R, 10V, 1210 MURATA, GRM32ER61A476KE20L
3 1 C5 CAP., 4.7nF, X7R, 50V, 10%, 0603 AVX, 06035C472KAT2A
4 1 C6 CAP., 1nF, X7R, 25V, 10%, 0603 AVX, 06033C102KAT2A
5 2 C7, C9 CAP., 1μF 20% 25V X5R 0603 AVX, 06033D105MAT2A
6 1 C8 CAP., 2.2μF, X7R, 100V, 10%, 1210 AVX,12101C225KAT2A
7 1 C11 CAP., 4.7pF, C0G, 50V, ±.25pF, 0603 MURATA, GRM1885C1H4R7CA01D
8 1 D1 DIODE, SCHOTTKY, 2A, 100V, SMA ON SEMI., MBRA2H100T3G
9 1 L1 IND, 15μH, 20% VISHAY, IHCL4040DZER150M5A
10 2 R1, R10 RES., 1M, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA
11 1 R2 RES., 316k,1/10W, 1%, 0603 VISHAY, CRCW0603316KFKEA
12 2 R3, R4 RES., 100k, 1/10W, 1%, 0603 VISHAY, CRCW0603100KFKEA
13 1 R5 RES., 8.87k,1/10W, 1%, 0603 VISHAY, CRCW06038K87FKEA
14 1 R6 RES., 169k,1/10W, 1%, 0603 VISHAY, CRCW0603169KFKEA
15 1 R9 RES., 0Ω, 1/10W, 0603 VISHAY, CRCW06030000Z0EA
16 1 U1 I.C., LT8495EFE, TSSOP20FE LINEAR TECH., LT8495EFE#PBF
Additional Demo Board Circuit Components
1 1 C1 CAP., ALUM., ELECT., 10μF, 63V SUN ELECTRONIC INDUSTRIES CORP., 63CE10BS
2 0 C10 CAP., OPTION, 0603 OPT
3 0 R11 RES., OPTION, 0603 OPT
Hardware/Components (for Demo Board Only)
1 9 E1-E9 TP, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 CONN., HEADER, 1X3, 2mm WÜRTH, 62000311121
3 1 XJP1 SHUNT, 2mm WÜRTH, 60800213421
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DEMO MANUAL DC2205A
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
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS AND CAPACITORS ARE IN OHMS, 0603.
(450kHz)
100V
IHCL-4040DZ-5A
* THE MAX LOAD CURRENT IS REDUCED WHEN THE
INPUT VOLTAGE IS LESS THAN 12V. PLEASE SEE
DEMO MANUAL FOR DETAILS.
RST
GND
WDE
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
LT8495EFE
Wednesday, February 25, 2015 1 1
LT
MOLLY Z.
N/A
DEMO CIRCUIT 2205A
POR AND WATCHDOG TIMER
SEPIC CONVERTER WITH LOW IQ,
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
LT8495EFE
Wednesday, February 25, 2015 1 1
LT
MOLLY Z.
N/A
DEMO CIRCUIT 2205A
POR AND WATCHDOG TIMER
SEPIC CONVERTER WITH LOW IQ,
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
LT8495EFE
Wednesday, February 25, 2015 1 1
LT
MOLLY Z.
N/A
DEMO CIRCUIT 2205A
POR AND WATCHDOG TIMER
SEPIC CONVERTER WITH LOW IQ,
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
MOLLY Z.
PRODUCTION
202-25-15
_
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
MOLLY Z.
PRODUCTION
202-25-15
_
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
MOLLY Z.
PRODUCTION
202-25-15
_
C4
47uF
10V
1210
C4
47uF
10V
1210
R5
8.87K
1%
R5
8.87K
1%
R11
OPT
R11
OPT
JP1JP1
1
3
2
E1
VIN
3V - 60V *
E1
VIN
3V - 60V *
LT8495EFE
U1
LT8495EFE
U1
SS
8
RT
10
RSTIN 11
SWEN
12
WDE 13
WDO 15
VIN
18
WDI 16
GND
14
SW 20
BIAS 1
FB 3
CPOR
5
CWDT
6
RST 7
NC
17
FB 2
NC
4
NC
9
NC
19
GND
21
C2
2.2uF
100V
1206
C2
2.2uF
100V
1206
L1
15uH
L1
15uH
4
3
1
2
R2
316K
1%
R2
316K
1%
E9
SWEN
E9
SWEN
C5
4.7nF
C5
4.7nF
R4
100K
1%
R4
100K
1%
R6
169k
R6
169k
E7 WDI
E7 WDI
E4 GND
E4 GND
R1
1 Meg
1%
R1
1 Meg
1%
C8
2.2uF
1210
C8
2.2uF
1210
4.7pF
C11
4.7pF
C11
E8 WDE
E8 WDE
E2
GND
E2
GND
E6 RST
E6 RST
R9
0
R9
0
D1
MBRA2H100T3G
D1
MBRA2H100T3G
C10
OPT
C10
OPT
R3
100K
1%
R3
100K
1%
C7
1uF
C7
1uF E5 WDO
E5 WDO
C3
47uF
10V
1210
C3
47uF
10V
1210 1uF
C9
1uF
C9
C6
1nF
C6
1nF
R10
1 Meg
R10
1 Meg
E3 VOUT
5V / 1A *
E3 VOUT
5V / 1A *
+
C1
10uF
63V
+
C1
10uF
63V
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dc2205afa
DEMO MANUAL DC2205A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2015
LT 0515 REV A • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) 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 LTC 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.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
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.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
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 LTC application
engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
