DC2393A - Demo Manual

DEMO MANUAL DC2393A
LT8304
Micropower No-Opto Isolated
Flyback Converter with 150V/2A Switch
DESCRIPTION
Demonstration circuit 2393A is a micropower no-opto
isolated flyback converter featuring the LT®8304. This
demo circuit outputs 5.0V, and maintains tight regulation with a load current from 20mA up to 4.2A and over
an input voltage from 18V to 72V. The output current
capability increases with the input voltage, as shown in
the Performance Summary table.
The DC2393A needs less than 0.5% of its full output power
as a minimum load to maintain good output voltage regulation. On the DC2393A, 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 150V, 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.
PERFORMANCE SUMMARY
PARAMETER
The LT8304 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
2A, 150V DMOS power switch is integrated along with all
the high voltage circuitry and control logic into a thermally
enhanced 8-lead SO package.
The LT8304 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 2393A
Design files for this circuit board are available at
http://www.linear.com/demo/DC2393A
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.
Specifications are at TA = 25°C
CONDITIONS
MIN
TYP
18
48
72
V
Output Voltage
VIN = 18V – 72V
IOUT = 20mA – 2A
4.75
5
5.25
V
Maximum Output Current
VIN = 18V
2
A
VIN = 24V
2.4
A
VIN = 48V
3.5
A
VIN = 72V
4.2
A
Input Voltage
MAX
100
UNITS
Output Voltage Ripple (Peak–to–Peak)
VIN = 48V, IOUT = 3.5A
Minimum Switching Frequency
IOUT = 0mA
11
kHz
mV
Efficiency
VIN = 24V, IOUT = 2.4A
83
%
VIN = 48V, IOUT = 3.5A
84
%
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DEMO MANUAL DC2393A
QUICK START PROCEDURE
Demonstration circuit 2393A is easy to set up to evaluate the performance of the LT8304. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below:
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 18V.
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%).
Note: The LT8304 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 249Ω resistor
at the trade off of lower efficiency.
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 (E2), or VOUT+ (E3) and VOUT– (E4) terminals.
See Figure 2 for proper scope probe technique.
Figure 1. Proper Measurement Equipment Setup
2
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DEMO MANUAL DC2393A
QUICK START PROCEDURE
INPUT OR OUTPUT CAPACITOR
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
5VOUT Load and Line Regulation
5.30
85
5.20
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
5VOUT Efficiency vs Load Current
95
75
VIN = 18V
VIN = 24V
VIN = 48V
VIN = 72V
65
55
0
1
2
3
LOAD CURRENT (A)
4
5.10
5.00
4.90
5
VIN = 18V
VIN = 24V
VIN = 48V
VIN = 72V
0
1
2
3
LOAD CURRENT (A)
4
5
dc2393a F03b
dc2393a F03a
Figure 3. Typical Efficiency and Regulation Curves
IOUT
2A/DIV
VOUT
200mV/DIV
4ms/DIV
dc2393a F04
Figure 4. Load Transient Responses (VIN = 48V, Load Transient Between 1A and 3.5A)
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DEMO MANUAL DC2393A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
CIN
CAP., ALUM 18µF 80V
SUN ELECTRONIC INDUSTRIES CORPORATION, 80HVH18M
2
2
C1, C2
CAP., 4.7µF, X7S, 100V, 10% 1210
TDK, C3225X7S2A475K200AB
3
1
C3
CAP., 1µF, X7R, 25V, 10% 1206
MURATA, GRM31MR71E105KA01L
4
1
C4
CAP., 270pF, C0G, 50V, 5% 0805
MURATA, GRM2165C1H271JA01D
5
4
C5, C6, C7, C8
CAP., 100µF, X5R, 6.3V, 20% 1210
MURATA, GRM32ER60J107ME20L
6
1
C9
CAP., 4.7nF, X7R, 250V, 10% 1812
MURATA, GA343DR7GD472KW01L
7
1
D1
DIODE, SBR1045D1, DPAK
DIODES INC., SBR1045D1-13
8
1
Z2
DIODE, CMHZ5232B, SOD-123
CENTRAL SEMI., CMHZ5232B
9
1
Z1
DIODE, SMBJ51A, SMB
DIODES INC., SMBJ51A-13-F
10
1
D2
DIODE, CMMR1U-02, SOD-123F
CENTRAL SEMI., CMMR1U-02
11
1
R1
RES., 402k, 1/10W, 1% 0603
VISHAY, CRCW0603402KFKEA
12
1
R2
RES., 32.4k, 1/10W, 1% 0603
VISHAY, CRCW060332K4FKEA
13
1
R3
RES., 100Ω, 1W, 1% 2515
VISHAY, WSC2515100R0FEA
14
1
R4
RES., 309k, 1/8W, 1% 0805
VISHAY, CRCW0805309KFKEA
15
1
R5
RES., 100k, 1/10W, 1% 0603
VISHAY, CRCW0603100KFKEA
16
1
R6
RES., 10k, 1/10W, 1% 0603
VISHAY, CRCW060310K0FKEA
17
1
T1
TRANSFORMER, 750315125
WURTH ELEKTRONIK, 750315125
18
1
U1
IC LT8304 SO8E
LINEAR TECH., LT8304ES8E#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
dc2393af
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
VIN
GND
18V - 72V
E2
E1
5
C1
4.7uF
100V
1210
C2
4.7uF
100V
1210
R2
32.4k
C3
1uF
25V
1206
2
4
1
U1
LT8304ES8E
INTVcc
GND
EN/UVLO
4
1. ALL RESISTORS AND CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
80HVH18M
18uF
80V
+ CIN
R1
402k
4
3
Z1
SMBJ51A
TC
RREF
RFB
SW
8
7
6
5
D2
CMMR1U-02
VIN
GND
9
D
5
R5
100k
R4
309k
0805
3
3
R6
10K
R3
100
2515
C4
270pF
0805
3
5
4.7nF
250V
1812
C9
T1
750315125
9
10
6
7
3
1
4
D1
SBR1045D1
2
2
C5
100uF
6.3V
1210
C6
100uF
6.3V
1210
C7
100uF
6.3V
1210
Z2
CMHZ5232B
1
E4
C8
100uF
6.3V
1210
E3
VOUT-
*
VOUT+
5V
* SEE DEMO MANUAL
1
A
B
C
D
DEMO MANUAL DC2393A
SCHEMATIC DIAGRAM
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5
DEMO MANUAL DC2393A
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
6
dc2393af
Linear Technology Corporation
LT 0516 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
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