DC1961A - Demo Manual

DEMO MANUAL DC1961A
LT8309
No-Opto Flyback Converter
with Synchronous Rectifier
Description
Demonstration circuit 1961A features the LT®8309, a
secondary synchronous driver in an isolated, no optocoupler, flyback converter. It regulates a 12V, 5A output
from a 36V to 72V input source.
configuration allows the synchronous MOSFET to remain
conducting at all times, even when output is shorted
to ground, so as to provide a very robust short circuit
performance.
Output regulation is handled on the primary side by the
LT3748, a boundary conduction mode flyback controller
which senses output voltage directly from the primary, resulting in a simple flyback schematic with no opto-coupler.
The Performance Summary table summarizes the performance of the demo board at room temperature. For
thermally critical applications, proper amount of air flow
can help to reduce power components’ temperature rise,
therefore greatly improving circuit reliability.
The LT8309 synchronous rectifier driver replicates the
behavior of a diode by sensing the synchronous MOSFET
drain-to-source voltage to determine its turn on period.
By replacing the diode with a N-channel MOSFET, applications are no longer restricted by the heat constraints of
the rectifier diode.
On the DC1961A, the LT8309 is biased from the rectified drain voltage node of secondary side synchronous
MOSFET, not directly connecting to output voltage. This
The LT8309 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 1961A.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, 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
Specifications are at TA = 25°C
PARAMETER
CONDITIONS
Input Voltage
Output Voltage
VIN = 36V to 72V, IOUT = 0.15A to 5A
Maximum Output Current
MIN
TYP
MAX
36
48
72
V
11.4
12
12.6
V
5
UNITS
A
Output Voltage Ripple (Peak to Peak)
VIN = 36V to 72V, IOUT = 5A (20MHz BW)
150
mV
Boundary Mode Switching Frequency
VIN = 48V, IOUT = 5A
133
kHz
Minimum Switching Frequency
IOUT = 0mA
42
kHz
Efficiency
VIN = 36V, IOUT = 5A
91
%
VIN = 48V, IOUT = 5A
91.5
%
VIN = 72V, IOUT = 5A
91.5
%
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1
DEMO MANUAL DC1961A
Quick Start Procedure
Demonstration circuit 1961A is easy to set up to evaluate the performance of the LT8309. 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 and GND terminals. Connect the
load to the terminals VOUT+ and VOUT– on the board.
2. Turn on the power at the input.
NOTE: Make sure that the input voltage does not exceed
72V. To operate the board with higher input/output voltage, input capacitor, output capacitor and MOSFETs with
higher voltage ratings are needed.
POWER SUPPLY
+
–
–
VIN
+
3. Check for the proper output voltages. The output should
be regulated at 12V (±5%).
NOTE: The LT3748 requires a minimum load to maintain
good output voltage regulation. On the DC1961A, in order
to avoid pre-loading, a Zener diode is placed between its
VOUT+ and VOUT– to serve as a minimum load.
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
and GND, or VOUT+ and VOUT– terminals. See Figure 2 for
proper scope probe technique.
+
–
IIN
+
IOUT
+
–
+
VOUT
–
LOAD
–
Figure 1. Proper Measurement Equipment Setup
INPUT OR OUTPUT CAPACITOR
Figure 2. Proper Scope Probe Placement for Measuring Input/Output Ripple
2
dc1961af
DEMO MANUAL DC1961A
performance
Efficiency Curve
100
95
EFFICIENCY (%)
90
85
80
75
70
36VIN
48VIN
72VIN
65
60
0.15
0.5
1
1.5
2
2.5
3
3.5
4
4.5
DC1961A F03
5
OUTPUT CURRENT (A)
Figure 3. Typical Efficiency Curve
Output Load and Line Regulation
12.60
OUTPUT VOLTAGE (V)
12.40
12.20
12.00
11.80
36VIN
48VIN
72VIN
11.60
11.40
0.15
0.5
1
1.5
2
2.5
3
3.5
4
4.5
DC1961A F04
5
OUTPUT CURRENT (A)
Figure 4. Typical Regulation Curve
dc1961af
3
DEMO MANUAL DC1961A
performance
DRAIN VOLTAGE OF
SYNCHRONOUS MOSFET
200mV/DIV
GATE OF SYNCHRONOUS
MOSFET, 5V/DIV
1µS/DIV
DC1961A F05
Figure 5. Synchronous MOSFET Drain and Gate Voltage (VIN = 48V, IOUT = 5A)
INTVCC VOLTAGE OF
LT8309, 10V/DIV
SWITCH NODE VOLTAGE
OF PRIMARY MOSFET,
50V/DIV
1mS/DIV
DC1961A F06
Figure 6. Output Short Circuit Waveforms (VIN = 48V)
Figure 7. Thermal Picture, 48VIN and 5AOUT (TA = 25°C, Air Flow 200LFM)
Synchronous MOSFET, 52.5°C; Primary MOSFET, 46.7°C; Transformer, 74.1°C
4
dc1961af
DEMO MANUAL DC1961A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C1
CAP., ALUM, 47µF, 80V, 20%, SMD
Nippon Chemi-Con, EMZA800ADA470MJA0G
2
3
C2, C3, C4
Cap., X7S, 4.7µF, 100V, 20%, 1210
TDK, C3225X7S2A475MT
3
1
C5
Cap., U2J, 120pF, 250V, 5%, 0805
Murata, GRM21A7U2E121JW31D
4
1
C6
Cap., X7S, 1µF, 100V, 10%, 0805
TDK, C2012X7S2A105K
5
6
C7-C12
Cap., X5R, 47µF, 16V, 10%, 1210
Murata, GRM32ER61C476KE15L
6
1
C13
Cap., X5R, 4.7µF, 16V, 20%, 0805
TDK, C2012X5R1C475M
7
1
C14
Cap., X7R, 0.22µF, 25V, 10%, 0603
TDK, C1608X7R1E224K
8
1
C15
Cap., NPO, 470pF, 25V, 5%, 0603
AVX, 06033A471JAT2A
9
1
C16
Cap., X7R, 1µF, 100V, 20%, 1206
TDK, C3216X7R2A105M
10
1
C17
Cap., X5R, 4.7µF, 25V, 10%, 0805
TDK, C2012X5R1E475K
11
1
C18
Cap., NPO, 47pF, 25V, 5%, 0603
AVX, 06033A470JAT2A
12
1
C19
Cap., X7R, 0.033µF, 25V, 10%, 0603
AVX, 06033C333KAT2A
13
1
C20
Cap., X7R, 4700pF, 250V, 10%, 1812
Murata, GA343DR7GD472KW01L
14
1
D1
Diode, TVS UNI-DIR 85V, 600W, SMB
Diodes Inc., SMBJ85A-13-F
15
1
D2
Diode, 1A/200V, SOD-123
Central Semi., CMMR1U-02 TR
16
1
D3
Diode Zener, 13V SMA
Central Semi., CMZ5928B TR
17
2
D4, D5
DIODE, SWITCHING 150V, 0.2A, SOD123
Diodes Inc., BAV20W-7-F
18
1
D6
Zener Diode, 36V, SOD-123
Central Semi., CMHZ5258B TR
19
1
L1
Inductor, 22µH, XAL6060
Coilcraft, XAL6060-223MEC
20
1
L2
Inductor, 1µH, XAL6030
Coilcraft, XAL6030-102MEB
21
1
Q1
MOSFET, N-CH, 80V, 100A, TDSON-8
Infineon, BSC047N08NS3 G
22
1
Q2
MOSFET, N-CH, 200V, 36A, TDSON-8
Infineon, BSC320N20NS3 G
23
1
R1
Res., Chip 100, 0.50W, 5%, 1210
Vishay, CRCW1210100RJNEA
24
1
R3
Res., Chip 1.2M, 0.1W, 5%, 0603
Vishay, CRCW06031M20JNEA
25
1
R4
Res., Chip 51k 0.1W 5% 0603
Vishay, CRCW060351K0JNEA
26
1
R5
Res., Chip 68, 1/8W, 5%, 0805
Vishay, CRCW080568R0JNEA
27
2
R6, R8
Res/Jumper, Chip 0Ω, 0.25W, 5A, 0603
Vishay, CRCW06030000Z0EA
28
1
R7
Res., Chip 160k, 1/8W, 1%, 0805
Vishay, CRCW0805160KFKEA
29
1
R9
Res., Chip 3Ω, 1/8W, 5%, 0805
Vishay, CRCW08053R00JNEA
30
1
R10
Res., Chip 60.4k, 0.1W, 1%, 0603
Vishay, CRCW060360K4FKEA
31
1
R11
Res., Chip 3, 1/10W, 5%, 0603
Vishay, CRCW06033R00JNEA
32
1
R12
Res., Chip 7.50k, 0.1W, 1%, 0603
Vishay, CRCW06037K50FKEA
33
1
R13
Sense Res., RL Vert. 0.010, 1W, 1%, 0815
SUSUMU, RL3720WT-R010-F
34
1
R14
Res., Chip 6.04k, 0.1W, 1%, 0603
Vishay, CRCW06036K04FKEA
35
1
R15
Res., Chip 2.37k, 0.25W, 1%, 1206
Vishay, CRCW12062K37FKEA
36
1
T1
Transformer, ±5%, 20.5µH, EFD20 Platform
Pulse Engrng., PA1736NLT
37
1
U1
I.C., Rectifier Driver, TSOT23-S5
Linear Tech. Corp. LT8309ES5#PBF
38
1
U2
I.C., No-Opto Flyback Converter
Linear Tech. Corp. LT3748EMS#PBF
39
1
FAB, PRINTED CIRCUIT BOARD Rev 2
DEMO CIRCUIT #1961A
dc1961af
5
DEMO MANUAL DC1961A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Additional Demo Board Circuit Components
1
0
C21
Cap., 0805
2
0
R2
Res., 1206
Hardware: For Demo Board Only
1
6
4
E1, E2, E3, E4
Turret, Testpoint
Mill Max, 2501-2-00-80-00-00-07-0
dc1961af
GND
E2
E1
VIN
36V to 72V
VIN
R10
60.4k
1%
C2
4.7µF
100V
1210
C15
470pF
C3
4.7µF
100V
1210
C19
33nF
R12
7.50k
1%
R4
51k
R3
1.2M
C4
4.7µF
100V
1210
RREF
VC
TC
SS
8
1
VIN
GND
EN/UVLO
R14
6.04k
1%
14
11
12
10
3
U2
LT3748EMS
1. ALL RESISTORS 0603.
2. ALL CAPACITORS 0603.
C6
1µF
100V
0805
9
SENSE
GND
GATE
RFB
INTVCC
NOTE: UNLESS OTHERWISE SPECIFIED.
C14
0.22uF
47µF
80V
+ C1
Coilcraft
L1
22µH
XAL6060-223MEC
7
6
16
5
R5
C18
47pF
0 Ohm
R8
D4
R7
BAV20W-7-F
3 Ohm
R11
160k
1%
0805
68
0805
C13
4.7µF
16V
0805
INTVCC
D2
CMMR1U-02
D1
SMBJ85A-13-F
6
1
5
2
4
3
R13
0.010
1%
0815
C20
4700pF
250V
1812
T1
PA1736NL
Q2
BSC320N20NS3G
C5
120pF
250V
0805
R1
100
1210
7
8
9
10
11
12
R9
C8
47µF
16V
1210
R15
2.37k
1%
1206
C9
47µF
16V
1210
R6
C21
(Opt)
0805
C16
1uF
100V
1206
5
4
C10
47µF
16V
1210
C11
47µF
16V
1210
DRAIN
VIN
GATE
GND
INTVCC
U1
LT8309ES5
0 Ohm
Q1
BSC047N08NS3
BAV20W-7-F 3 Ohm
0805 D6
36V
D5
C7
47µF
16V
1210
Coilcraft
L2
1µH
XAL6030-102MEC
1
2
3
C12
47µF
16V
1210
C17
4.7uF
25V
0805
D3
CMZ5928B
R2
(Opt)
1206
VOUT
E4
E3
VOUT-
VOUT+
12V / 5A
DEMO MANUAL DC1961A
Schematic Diagram
dc1961af
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.
7
DEMO MANUAL DC1961A
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
8
dc1961af
Linear Technology Corporation
LT 0114 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
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