DC1825A - Demo Manual

DEMO MANUAL DC1825A
LT8300
100VIN Micropower Isolated Flyback
Converter with 150V/260mA Switch
Description
Demonstration circuit 1825A is an isolated flyback converter 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,
with a nominal 48V. The output current capability increases
with the input voltage.
The DC1825A needs a very small minimum load (~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 performance of the demo board at room temperature. The demo
circuit can be easily modified for different applications with
some pre-designed transformers.
The LT8300 is a simple-to-use high voltage monolithic isolated flyback converter. No third winding or opto-isolator
is required for regulation. The part sets the isolated output 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® operation maintains high efficiency at light loads while minimizing
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.
Performance Summary
PARAMETER
Specifications are at TA = 25°C
CONDITIONS
Input Voltage
MIN
22
VIN Quiescent Current
IOUT = 0mA, VIN = 75V
Output Voltage
VIN = 22V – 75V
IOUT = 1mA – 250mA
4.75
250
TYP
MAX
48
75
400
5
UNITS
V
µA
5.25
V
Maximum Output Current
VIN = 22V
Output Voltage Ripple (Peak to Peak)
VIN = 22V – 75V, IOUT = 250mA
50
mA
mV
Typical Switching Frequency
VIN = 48V, IOUT = 250mA
330
kHz
Minimum Switching Frequency
IOUT = 0mA
8
kHz
Efficiency
VIN = 48V, IOUT = 250mA
80
%
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DEMO MANUAL DC1825A
Quick Start Procedure
The DC1825A is easy to set up to evaluate the 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
board through VIN (E1) and GND (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.Check for the proper output voltages. The output should
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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DEMO MANUAL DC1825A
Quick Start Procedure
Figure 1. Proper Measurement Equipment Setup
INPUT OR OUTPUT CAPACITOR
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
85
5.00
VIN = 22V
4.90
VIN = 48V
70
VIN = 22V
4.85
VOUT (V)
EFFICIENCY (%)
75
65
4.80
4.75
4.70
4.65
60
4.60
55
50
VIN = 48V
4.95
80
4.55
0
50
150
100
200
LOAD CURRENT (mA)
250
4.50
0
50
150
100
200
LOAD CURRENT (mA)
DC1825A F03a
250
DC1825A F03b
Figure 3. Typical Efficiency and Regulation Curves
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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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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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
A
B
C
5
E1
E3
C2
2.2uF
100V
1210
VIN
R2
53.6K
1%
R1
806K
1%
3
2
1
4
5
SW
3
C4
1
2
3
T1
6
4
750312366
3.3nF
250
1210
APPROVALS
R4
OPT
C1
OPT
0805
__
ECO
C3
100uF
6.3V
1210
4
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
APPROVED
1
DATE
VOUT+
+5V / 0.25A
DATE:
N/A
SIZE
DEMO CIRCUIT 1825A
LT8300ES5
2
Monday, July 02, 2012
IC NO.
1
SHEET 1
OF 1
2
REV.
100V MICROPOWER ISOLATED FLYBACK CONVERTER
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
E4
*
VOUT-
+5V
SEE QSG
E2
ZHONGMING Y. 1-9-12
D2
5.6V
BZT52C5V6T-7
DESCRIPTION
REVISION HISTORY
PRODUCTION
D1
DFLS130L
2
1
2
REV
2
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
TECHNOLOGY
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
HZ
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
TITLE:
SCHEMATIC
APP
ENG.
ZHONGMING
Y.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
CUSTOMER NOTICE
1. ALL RESISTORS AND CAPACITORS ARE 0603.
SW
VIN
R3 365K
RFB
GND
EN/UV
U1
LT8300ES5
NOTE: UNLESS OTHERWISE SPECIFIED
GND
VIN
22V - 75V
4
2
1
D
5
A
B
C
D
DEMO MANUAL DC1825A
Schematic Diagram
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DEMO MANUAL DC1825A
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
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Linear Technology Corporation
LT 0912 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2012
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