DC2014A - Demo Manual

DEMO MANUAL DC2014A
LT8302
Micropower No-Opto
Isolated Flyback Converter
Description
Demonstration circuit 2014A is a micropower No-Opto
isolated flyback converter featuring the LT®8302. This demo
circuit outputs 5V, and maintains tight regulation with a
load current from 10mA to 2.2A over an input voltage
from 10V to 30V. The output current capability increases
with the input voltage.
The LT8302 typically needs less than 0.5% of its full output
power as a minimum load to maintain good output voltage
regulation. On the DC2014A, in order to avoid pre-loading,
a 5.6V Zener diode is placed between its VOUT+ and VOUT–
to serve as a minimum load.
Transformer leakage inductance causes a voltage spike
on the primary side after the power switch turns off. To
limit this leakage inductance spike within MOSFET voltage rating of 65V, an RC snubber and a TVS clamp are
installed to damp the ringing and clamp the MOSFET drain
voltage to a safe level.
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 LT®8302 is a simple to use monolithic micropower
isolated flyback converter. By sampling the isolated output
voltage directly from the primary-side flyback waveform,
the part requires no third winding or opto-isolator for
regulation. The output voltage is programmed with two
external resistors and a third optional temperature compensation resistor. By integrating the loop compensation and
soft-start inside, the part reduces the number of external
components. Boundary mode operation provides a small
magnetic solution with excellent load regulation. Low ripple
Burst Mode® operation maintains high efficiency at light
load while minimizing the output voltage ripple. A 3.6A,
65V DMOS power switch is integrated along with all the
high voltage circuitry and control logic into a thermally
enhanced 8-lead SO package.
The LT8302 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 2014A.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Burst Mode, 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
PARAMETER
Specifications are at TA = 25°C
CONDITIONS
Input Voltage
MIN
TYP
MAX
10
24
30
V
5
5.25
V
Output Voltage
VIN = 10V to 30V, IOUT = 10mA to 2.2A
4.75
Maximum Output Current
VIN > 15V
2.2
Output Voltage Ripple (Peak to Peak)
VIN = 10V to 30V, IOUT = 2.2A
UNITS
A
100
mV
Typical Switching Frequency
VIN = 24V, IOUT = 2.2A
345
kHz
Minimum Switching Frequency
IOUT = 0mA
12
kHz
Efficiency
VIN = 10V, IOUT = 2.2A
VIN = 24V, IOUT = 2.2A
VIN = 30V, IOUT = 2.2A
80
84
84
%
%
%
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DEMO MANUAL DC2014A
Quick Start Procedure
Demonstration circuit 2014A is easy to set up to evaluate
the performance of the LT8302. Refer to Figure 1 for proper
measurement equipment setup and follow the procedure:
1. With power off, connect the input power supply to the
board through VIN (E1) and GND (E2) terminals. Connect the load to the terminals VOUT+ (E3) and VOUT– (E4)
on the board.
2. Turn on the power at the input. Increase VIN slowly to 10V.
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.
3. Check for the proper output voltages. The output should
be regulated at 5.0V (±5%).
+
IIN
–
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 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 (E1)
and GND (E2), or VOUT+ (E3) and VOUT– (E4) terminals.
See Figure 2 for proper scope probe technique.
–
IOUT
+
+
POWER
SUPPLY
NOTE: The LT8302 requires very small minimum load to
maintain good output voltage regulation. A Zener diode
is placed on the output to clamp the voltage to 5.6V. This
Zener can be replaced with a 560Ω resistor at the tradeoff
of lower efficiency.
+
VIN
+
+
–
–
–
VOUT
LOAD
–
Figure 1. Proper Measurement Equipment Setup
INPUT OR OUTPUT CAPACITOR
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
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DEMO MANUAL DC2014A
Quick Start Procedure
5VOUT Load and Line Regulation
95
5.10
90
5.05
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
5VOUT Efficiency vs Load Current
85
80
75
VIN = 10V
VIN = 24V
VIN = 30V
70
65
400
0
1600
800 1200
LOAD CURRENT (mA)
5.00
4.95
4.90
VIN = 10V
VIN = 24V
VIN = 30V
4.85
4.80
2000
0
400
1600
800 1200
LOAD CURRENT (mA)
dc2014 F03
2000
dc2014 F04
Figure 3. Typical Efficiency and Regulation Curves
VOUT
50mV/DIV
VOUT
50mV/DIV
VOUT
20mV/DIV
VSW
20V/DIV
VSW
20V/DIV
VSW
20V/DIV
1µs/DIV
dc2014a F04a
1µs/DIV
VIN = 24V, IOUT = 2.2A, Quasi-Resonant
dc2014a F04b
VIN = 24V, IOUT = 0.5A, Discontinuous Mode
Boundary Mode
20µs/DIV
dc2014a F04c
VIN = 24V, IOUT = 0, Low Ripple Burst Mode
Figure 4. VOUT Ripple and Switch Node Voltage Waveforms at Different Load Conditions
VOUT
100mV/DIV
IOUT
1A/DIV
1ms/DIV
dc2014a F05
Figure 5. Load Transient Responses (VIN = 24V, Load transient between 1A and 2A)
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DEMO MANUAL DC2014A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C1
CAP.,ALUM. ELEC. 22µF, 50V,
NIPPON CHEMI-COM, EMZA500ADA220MF61G
2
1
C2
CAP., CHIP, X5R, 10µF, 50V, 10% 1210
Taiyo Yuden, UMK325BJ106K
3
1
C3
CAP., CHIP, X5R, 1µF, 25V, 10% 0603
AVX, 06033D105KAT2A
4
1
C4
CAP., CHIP, C0G, 220pF, 50V, 5% 0805
AVX, 08055A221JAT2A
5
3
C5, C6, C7
CAP., CHIP, X5R, 100µF, 6.3V, 10% 1210
AVX, 12106D107KAT2A
6
1
C8
CAP., CHIP, X7R, 4.7nF, 250V, 10% 1812
MURATR, GA343DRGD472KW01L
7
1
D1
DIODE, PDS1040L, PowerDI-5
Diodes Inc., PDS1040L-13
8
1
D2
DIODE, CMHZ5232B, SOD-123
Central Semi., CMHZ5232B
9
1
D3
DIODE, SMAJ18A, SMA
Diodes Inc., SMAJ18A-13-F
10
1
D4
DIODE, CMMSH1-100, SOD-123F
Central Semi., CMMSH1-100G TR
11
1
R1
RES., CHIP, 1M, 1/10W, 1% 0603
VISHAY, CRCW06031M0FKEA
12
1
R2
RES., CHIP, 200k, 1/10W, 1% 0603
VISHAY, CRCW0603200KFKEA
13
1
R3
RES., CHIP, 100, 1/4W, 5% 1206
VISHAY, CRCW1206100RJNEA
14
1
R4
RES., CHIP, 150k, 1/10W, 1% 0603
VISHAY, CRCW0603150KFKEA
15
1
R5
RES., CHIP, 113k, 1/10W, 1% 0603
VISHAY, CRCW0603113KFKEA
16
1
R6
RES., CHIP, 10k, 1/10W, 1% 0603
VISHAY, CRCW060310K0FKEA
17
1
T1
TRANFORMER, 750311564
WURTH ELEC., 750311564
18
1
U1
I.C. LT8302 SO8E
LINEAR TECH., LT8302ES8E#PBF
TESTPOINT, TURRET, .094" PBF
MILL-MAX, 2501-2-00-80-00-00-07-0
Hardware: For Demo Board Only
1
4
4
E1-E4
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DEMO MANUAL DC2014A
Schematic Diagram
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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.
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DEMO MANUAL DC2014A
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 1013 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
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