Linear Technology DC1825A Guide de configuration rapide
1
dc1825af
DEMO MANUAL DC1825A
Description
LT8300
100VIN Micropower Isolated Flyback
Converter with 150V/260mA Switch
Demonstration circuit 1825A is an isolated flyback con-
verter featuring the LT
®
8300. This demo circuit outputs
5.0V, and maintains tight regulation with a load current
from ~1mA to 250mA and over an input from 22V to 75V,
withanominal48V.Theoutputcurrentcapabilityincreases
with the input voltage.
TheDC1825Aneedsaverysmallminimumload(~1mA)to
regulate the output voltage, thanks to the accurate current
limit capability and ultra low switching frequency of the
LT8300 at very light load. The standby input current of
the demo circuit is less than 400µA(typical) because of
the low quiescent current design of the IC and very small
minimum load requirement.
The Performance Summary table summarizes the perfor-
mance of the demo board at room temperature. The demo
circuitcanbeeasilymodifiedfordifferentapplicationswith
some pre-designed transformers.
performance summary
TheLT8300isasimple-to-usehighvoltagemonolithiciso-
lated flyback converter. No third winding or opto-isolator
is required for regulation. The part sets the isolated out-
put voltage with a single external resistor and integrates
compensation and soft start circuitry inside. Boundary
mode operation provides a small magnetic solution with
improved load regulation. Low ripple Burst Mode
®
opera-
tionmaintainshighefficiencyatlightloadswhileminimizing
the output voltage ripple. A 260mA, 150V DMOS power
switch is integrated along with all high voltage circuitry
and control logic into a 5-lead ThinSOT™ package.
The LT8300 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 DC1825A.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Voltage 22 48 75 V
VIN Quiescent Current IOUT = 0mA, VIN = 75V 400 µA
Output Voltage VIN = 22V – 75V
IOUT = 1mA – 250mA 4.75 5 5.25 V
Maximum Output Current VIN = 22V 250 mA
Output Voltage Ripple (Peak to Peak) VIN = 22V – 75V, IOUT = 250mA 50 mV
Typical Switching Frequency VIN = 48V, IOUT = 250mA 330 kHz
Minimum Switching Frequency IOUT = 0mA 8 kHz
Efficiency VIN = 48V, IOUT = 250mA 80 %
Specifications are at TA= 25°C
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2
dc1825af
DEMO MANUAL DC1825A
Quick start proceDure
TheDC1825Aiseasytosetupto evaluatethe performance
of the LT8300. Refer to Figure 1 for proper equipment
setup and follow the procedure below.
1. With power off, connect the input power supply to the
boardthroughVIN(E1)andGND(E3)terminals.Connect
the load to the terminals VOUT+ (E4) and VOUT– (E2)
on the board.
2. Turn on the power at the input. Increase VIN slowly to
22V.
NOTE: Make sure that the input voltage is always within
spec. To operate the board with higher input/output
voltage, input capacitor, output capacitor and output
diode with higher voltage ratings are needed.
NOTE: To run overload tests on the demo board with
VIN higher than 40V, a RC snubber (200Ω, 150pF) or
Schottky plus Zener clamp circuit is recommended to
make sure the voltage spike at the switching node is
always less than 150V.
3. Checkfortheproperoutputvoltages.Theoutputshould
be regulated at 5.0V (±5%).
NOTE: The LT8300 requires very small minimum load
to maintain good output voltage regulation. A Zener
diode is placed on the output to clamp the voltage to
~5.0V. This Zener is optional, and can be replaced with
a 5.1k resistor.
4. Once the proper output voltage is established, adjust
the input voltage and load current within the operating
range and observe the output voltage regulation, ripple
voltage, efficiency and other parameters.
NOTE: When measuring the input or output voltage
ripples, 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 (E1) and GND (E3), or VOUT+ (E4) and
VOUT– (E2) terminals. See Figure 2 for proper scope
probe technique.
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dc1825af
DEMO MANUAL DC1825A
Figure 1. Proper Measurement Equipment Setup
Quick start proceDure
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
INPUT OR OUTPUT CAPACITOR
Figure 3. Typical Efficiency and Regulation Curves
LOAD CURRENT (mA)
50
EFFICIENCY (%)
60
70
85
55
65
75
80
100 200
DC1825A F03a
250500 150
VIN = 22V
VIN = 48V
LOAD CURRENT (mA)
4.50
VOUT (V)
4.60
4.70
5.00
4.55
4.65
4.75
4.90
4.85
4.95
4.80
100 200
DC1825A F03b
250500 150
VIN = 48V
VIN = 22V
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4
dc1825af
DEMO MANUAL DC1825A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C2 CAP., X7R, 2.2µF 100V, 10% 1210 MURATA, GRM32ER72A225KA35L
2 1 C3 CAP., X5R, 100µF 6.3V, 20% 1210 AVX, 12106D107MAT2A
3 1 C4 CAP., X7R, 4700pF 1000V, 10% 1210 VISHAY/VITRAMON, VJ1210Y472KXGAT5Z
4 1 D1 DIODE, SCHOTTKY, 30V 1A PWRDI123 DIODES INC., DFLS130-7
5 1 D2 SMT ZENER DIODE, 5.6V SOD-523 DIODES INC., BZT52C5V6T-7
6 1 R1 RES., CHIP, 806k, 1%, 0805 VISHAY, CRCW0805806KFKEA
7 1 R2 RES., CHIP, 53.6k, 1%, 0603 VISHAY, CRCW060353K6FKEA
8 1 R3 RES., CHIP, 365k, 1%, 0603 VISHAY, CRCW0603365KFKEA
9 1 T1 TRANSFORMER 7:1 WÜRTH ELECTONIK, 750312366
10 1 U1 I.C., LT8300ES5, TSOT-23 LINEAR TECH., LT8300ES5#PBF
Additional Demo Board Circuit Components
1 0 C1 CAP., 0805 OPT
2 0 R4 RES., 0805 OPT
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5
dc1825af
DEMO MANUAL DC1825A
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
VIN
GND
+5V
22V - 75V
100V MICROPOWER ISOLATED FLYBACK CONVERTER
750312366
NOTE: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS AND CAPACITORS ARE 0603.
SEE QSG
*
5.6V
+5V / 0.25A
VIN
SW
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
Monday, July 02, 2012
11
HZ
ZHONGMING Y.
N/A
LT8300ES5
DEMO CIRCUIT 1825A
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
Monday, July 02, 2012
11
HZ
ZHONGMING Y.
N/A
LT8300ES5
DEMO CIRCUIT 1825A
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
Monday, July 02, 2012
11
HZ
ZHONGMING Y.
N/A
LT8300ES5
DEMO CIRCUIT 1825A
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
ZHONGMING Y.
PRODUCTION21-9-12
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
ZHONGMING Y.
PRODUCTION21-9-12
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
ZHONGMING Y.
PRODUCTION21-9-12
__
D2
BZT52C5V6T-7
D2
BZT52C5V6T-7
1 2
OPT
C1
0805
OPT
C1
0805
T1T1
4
6
1
2
3E2
VOUT-
E2
VOUT-
R2
53.6K
1%
R2
53.6K
1%
E1E1
D1
DFLS130L
D1
DFLS130L
12
R3 365KR3 365K
R1
806K
1%
R1
806K
1%
E4 VOUT+
E4 VOUT+
E3E3
3.3nF
250C4
1210
3.3nF
250C4
1210
R4
OPT
R4
OPT
2.2uF
100V
C2
1210
2.2uF
100V
C2
1210
100uF
C3
6.3V
1210
100uF
C3
6.3V
1210
U1
LT8300ES5
U1
LT8300ES5
VIN 5
EN/UV
1
RFB
3
GND
2
SW 4
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6
dc1825af
DEMO MANUAL DC1825A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ●FAX: (408) 434-0507 ●www.linear.com
LINEAR TECHNOLOGY CORPORATION 2012
LT 0912 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC ) provides the enclosed product(s) under the following AS IS conditions:
Thisdemonstration board (DEMO BOARD) kitbeingsold or provided by LinearTechnologyisintendedfor 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. LT C 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 applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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