DC1739B-C - Demo Manual

DEMO MANUAL DC1739B-C
LTC3765/LTC3766
120W Isolated Forward Converter
with Synchronous Rectification
DESCRIPTION
Demonstration circuit 1739B-C is a 120W isolated forward
converter with synchronous rectification featuring the
LTC®3765/LTC3766 chip set.
This circuit was designed to demonstrate the high level of
performance, efficiency, and small solution size attainable
using this chip set in an active-clamp-reset forward converter power supply. It operates at 240kHz and produces
a regulated 12V, 10A output from an input voltage range
of 9V to 36V: suitable for telecom, industrial, and other
applications. It has an eighth-brick footprint area. Synchro-
PERFORMANCE SUMMARY
nous rectification helps to attain efficiency exceeding 94%.
Secondary-side control eliminates complex opto-coupler
feedback, providing fast transient response with minimum
output capacitance. For other output requirements, see the
LTC3766 data sheet or contact the LTC factory.
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.
Specifications are at TA = 25°C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
VIN
Input Supply Range
VOUT
Output Voltage
IOUT
Output Current Range, Continuous
fSW
Switching (Clock) Frequency
VOUT(P-P)
Output Ripple
VIN = 24V, IOUT = 10A (20MHz BW)
IREG
Output Regulation
Line and Load (9VIN to 36VIN, 0AOUT to 10AOUT)
±0.27
%
POUT/PIN
Efficiency (See Figure 3)
VIN = 24V, IOUT = 10A
92.7
%
Isolation
Basic
Approximate Size
Component Area × Top Component Height
9
MAX
36
12.0
200LFM
0
UNITS
V
V
10
A
240
kHz
40
mVP–P
1500
VDC
2.3 × 0.9 × 0.47
Inches
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1
DEMO MANUAL DC1739B-C
OPERATING PRINCIPLES
The LTC3765 active clamp forward controller and gate
driver is used on the primary and provides start-up, gate
drive, and protection functions. Once start-up is accomplished, the LTC3766 high efficiency, secondary-side
synchronous forward controller takes over, and provides
the LTC3765 with timing information and bias power
through a small pulse transformer.
When input voltage is applied, the LTC3765 commences
soft-start of the output voltage. When the secondary bias
source reaches the undervoltage threshold, the LTC3766
comes alive and takes control by sending encoded PWM
gate pulses to the LTC3765 through T3. These pulses
also provide primary bias power efficiently over a wide
input voltage range.
The transition from primary to secondary control occurs
at some fraction of the nominal output voltage. From then
on, operation and design is simplified to that of a simple
buck converter. Secondary control eliminates delays, tames
large-signal overshoot, and reduces output capacitance
needed to meet transient response requirements.
An optional LC filter stage on the input lowers rms input
current. The filter must have output impedance that is
less than the converter input impedance to assure stability. This may require a damping impedance. (See Linear
Technology Application Note 19 for a discussion of input
filter stability.) A source with a 170mΩ or higher ESR
at the filter resonant frequency (~35kHz) is one way of
providing damping for the filter elements provided on the
DC1739B-C. For bench testing, an electrolytic capacitor
has been added at the input terminals to provide suitable
damping and ripple current capability. The values selected
have a filter resonant frequency that is below the converter
switching frequency, thus avoiding high circulating currents in the filter.
QUICK START PROCEDURE
Demonstration circuit 1739B-C is easy to set up to evaluate the performance of the LTC3765/LTC3766. Refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below:
b.If efficiency measurements are desired, an ammeter
capable of measuring 10ADC or a resistor shunt can
be put in series with the input supply in order to
measure the DC1739B-C’s input current.
Note: When measuring the output voltage ripple, care must
be taken to avoid a long ground lead on the oscilloscope
probe. Measure the output voltage ripple by touching the
probe tip and ground ring directly across the last output
capacitor as shown in Figure 1.
c. A voltmeter with a capability of measuring at least
36V can be placed across the input terminals in order
to get an accurate input voltage measurement.
1.Set an input power supply that is capable of 9V to 36V
to 9V. Then turn off the supply.
2.Direct an airflow of 200lfm across the unit for sustained
operation at full load.
3.With power off, connect the supply to the input terminals
+VIN and –VIN.
a. Input voltages lower than 9V can keep the converter
from turning on due to the undervoltage lockout
feature of the LTC3765 / LTC3766.
4.Turn on the power at the input.
Note: Make sure that the input voltage never exceeds 36V.
5.Check for the proper output voltage of 12V. Turn off
the power at the input.
6.Once the proper output voltages are established, connect a variable load capable of sinking 10A at 12V to
the output terminals +VOUT and –VOUT. Set the current
for 0A.
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2
DEMO MANUAL DC1739B-C
QUICK START PROCEDURE
a. If efficiency measurements are desired, an ammeter
or a resistor shunt that is capable of handling 10ADC
can be put in series with the output load in order to
measure the DC1739B-C’s output current.
7.Turn on the power at the input.
Note: If there is no output, temporarily disconnect the load
to make sure that the load is not set too high.
8.Once the proper output voltage is again established,
adjust the load within the operating range and observe
the output voltage regulation, ripple voltage, efficiency
and other desired parameters.
b.A voltmeter with a capability of measuring at least 12V
can be placed across the output terminals in order
to get an accurate output voltage measurement.
Figure 1. Proper Measurement Equipment Setup
96
10
12VIN
EFFICIENCY (%)
8
24VIN
92
6
PD 24VIN
90
88
86
4
PD 12VIN
2
0
2
6
8
4
OUTPUT CURRENT (A)
10
POWER DISSIPATION (W)
94
0
Figure 2. Efficiency and Power Dissipation
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DEMO MANUAL DC1739B-C
QUICK START PROCEDURE
Figure 3. Output Ripple at 24VIN and 10AOUT (50mV, 5A, 2µs/Div, 20MHz)
Figure 4. Transient Response Waveform at 24VIN and 5A – 7.5A – 5AOUT (5A, 100mV, 100µs/Div)
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4
DEMO MANUAL DC1739B-C
QUICK START PROCEDURE
Figure 5. Thermal Map, Front Side at 24VIN and 10AOUT (TA = 25°C, 200LFM)
Figure 6. Thermal Map, Back Side at 24VIN and 10AOUT (TA = 25°C, 200LFM)
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DEMO MANUAL DC1739B-C
PARTS LIST
ITEM QTY REFERENCE
Required Circuit Components
1
1
C1
2
4
C2, C3, C4, C5
3
1
C6
4
1
C7
5
2
C8, C9
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
1
2
1
1
1
3
1
1
2
2
1
1
1
1
1
2
1
1
1
2
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
4
1
1
1
C10
C12, C27
C13
C14
C16
C17, C20, C35
C18, C33
C19
C21, C23
C22
C24
C25
C28
C29
C32
C37, C44
C36
C39
D1
D3, D5
L1
L4
Q1
Q3
Q4
Q5
Q6
R1
R4
R7, R37
R10
R11
R14
R17
R18
R19, R20, R23, R24
R22
R25
R26
PART DESCRIPTION
MANUFACTURER/PART NUMBER
CAP., AL., TH,100uF, 50V, ME-PX SERIES
CAP., X7R, 10µF, 50V, 10%, 1210
CAP., C0G, 47pF, 200V, 5%, 1206
CAP., C0G, 15pF, 200V, 5%, 0805
CAP., POSCAP, 68µF, 16V, 20%, 7343
SUNCON, 50ME100PX
MURATA, GRM32ER71H106KA12
AVX, 12062A470JAT2A
AVX, 08052A150JAT2A
SANYO, 16TQC68M
CAP., X7R, 2.2nF, 630V, 5%, 1206
CAP., X7R, 10µF, 16V, 20%, 1206
CAP., X7R, 1.0µF, 100V, 10%, 1206
CAP., X7R, 0.1µF, 250V, 10%, 1206
CAP., C0G, 1000pF, 25V, 5%, 0402
CAP., X7R, 0.1µF, 25V, 10%, 0603
CAP., C0G, 2200pF, 50V, 5%, 0603
CAP., X7R, 12nF, 50V,10%, 0805
CAP., X7R, 1.0µF, 16V 10%, 0805
CAP., C0G, 220pF, 25V, 5%, 0603
CAP., X7R, 2200pF, 250V, 10%, 1812
CAP., COG, 0.033uF, 25V, 5%, 0805
CAP., X7R, 0.010µF, 50V, 10%, 0603
CAP., X7R, 0.033µF, 25V, 10%, 0603
CAP., C0G, 47pF, 25V, 5%, 0603
CAP., C0G, 1000pF, 25V, 5%, 0603
CAP., X7R, 1500pF, 50V,10%, 0402
CAP., X7R, 1.0uF, 50V, 10%, 0805
DIODE ULTRA FAST 1A 200V SMP
DIODE SCHOTTKY 40V 0.4A SOD323
INDUCTOR, 0.56µH 20%
INDUCTOR, 16µH
MOSFET N-CH 60V POWERPAK-SO-8
MOSFET N-CH POWERPAK-SO-8
MOSFET N-CH 150V POWERPAK-SO-8
MOSFET, P-CH, IRF6217, SO-8
MOSFET, N-CH, SUPER SOT23
RES., CHIP, 12.4Ω, 1/4W, 1%, 1206
RES., CHIP, 15k, 1W 2512
RES., CHIP, 909Ω, 1/8W, 1%, 0805
RES., CHIP, 0.005Ω, 1W, 1%, 2512
RES., CHIP, 51.1Ω, 1/8W, 1%, 0805
RES., CHIP, 0.004Ω, 3W, 5%, 1225
RES., CHIP, 28.7k, 1/8W, 1%, 0805
RES., CHIP, 100k, 1/8W, 5%, 0805
RES., CHIP, 100Ω, 1/16W, 1%, 0402
RES., CHIP, 1.82k, 1/4W, 1%, 1206
RES., CHIP, 10k, 1/10W, 1%, 0603
RES., CHIP, 2.21k, 1/10W, 1%, 0603
MURATA, GRM31A7U2J222JW31
MURATA, GRM31CR71C106MA12
MURATA, GRM31CR72A105KA01
MURATA, GRM31CR72E104KW03
TDK, C1005C0G1E102J
AVX, 06033C104KAT2A
MURATA, GRM1885C1H222JA01D
AVX, 08055C123KAT2A
MURATA, GRM21BR71C105KA01L
AVX, 06033A221JAT2A
MURATA, GA343QR7GD222KW01L
TDK, C2012C0G1E333J
AVX, 06035C103KAT2A
AVX, 06033C333KAT2A
AVX, 06033A470JAT2A
AVX, 06033A102JAT2A
AVX, 04025C152KAT2A
MURATA, GRM21BR71H105KA12
VISHAY, ES1PD-M3 / 84A
DIODES INC., ZHCS400TA
VISHAY, IHLP2525EZERR56M01
CHAMPS PQA2050-16-LTC
INFINEON, BSC028N06NS
INFINEON, BSC057N08NS3G
INFINEON, BSC190N15NS3
IR, IRF6217TR
FAIRCHILD, 2N7002
VISHAY, CRCW120612R4FKEA
VISHAY, CRCW251215KJNEG
VISHAY, CRCW0805909RFKEA
PANASONIC, ERJ-M1WTF5M0U
VISHAY, CRCW080551R1FKEA
SUSUMU, KRL6432D-C-R004-F-T5
VISHAY, CRCW080528K7FKEA
VISHAY, CRCW0805100KJNEA
VISHAY, CRCW0402100RFKEA
VISHAY, CRCW12061K82FKEA
VISHAY, CRCW060310K0FKEA
VISHAY, CRCW06032K21FKEA
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6
DEMO MANUAL DC1739B-C
PARTS LIST
ITEM QTY REFERENCE
44
1
R27
45
1
R29
46
1
R35
47
1
R36
48
1
R38, R39, R56
48
1
R40
49
1
R41
49
1
R42
50
1
R44
51
1
R46
52
1
R47
53
1
R48
54
1
R49
55
1
R50
56
1
R51
57
1
R52
58
1
R53
49
1
T1
50
1
T3
51
1
U1
52
1
U2
Additional Demo Board Circuit Components
53
0
C42, C43
54
0
C15, C30, C31, C41
55
0
C38, C40
56
1
C26
57
0
C11, C34
58
1
D2
59
0
D4
60
0
D7, D8, D9, D10
61
0
D11
62
0
L5
0
Q2
63
64
0
Q7,Q9
65
0
Q8
66
12 R8, R9, R21, R28, R30-R34, R45,
R54, R59
67
1
R6
68
0
R2, R3, R12, R43, R58
69
0
R55, R57, R60
70
0
T4
Hardware For Demo Board Only
5
E1, E2, E3, E4, E5
71
72
4
J1, J2, J3, J4
73
4
MTGS AT 4 CORNERS
PART DESCRIPTION
RES., CHIP, 0.750Ω, 1/3W, 1%, 0805
RES., CHIP, 20.0k, 1/10W, 1%, 0603
RES., CHIP, 1.82k, 1/10W, 1%, 0603
RES., CHIP, 11.5k, 1/10W, 1%, 0603
RES., CHIP, 100Ω, 1/10W, 1%, 0603
RES., CHIP, 464k, 1/10W, 1%, 0603
RES., CHIP, 14.7k, 1/10W, 1%, 0603
RES., CHIP, 78.7k, 1/10W, 1%, 0603
RES., CHIP, 102k, 1/10W, 1%, 0603
RES., CHIP, 60.4k, 1/10W, 1%, 0603
RES., CHIP, 15.0k, 1/10W, 1%, 0603
RES., CHIP, 4.99k, 1/10W, 1%, 0603
RES., CHIP, 1.87k, 1/10W, 1%, 0603
RES., CHIP, 604Ω, 1/10W, 1%, 0603
RES., CHIP, 16.2k, 1/10W, 1%, 0603
RES., CHIP, 21.5k, 1/10W,1%, 0603
RES., CHIP, 8.25k, 1/10W, 1%, 0603
TRANSFORMER, 3T:6T
TRANSFORMER, 1.25T:1T
I.C. LTC3765EMSE, MSOP-16PIN
I.C. LTC3766EGN28, SSOP-GN28
MANUFACTURER/PART NUMBER
SUSUMU, RL1220S-R75-F
VISHAY, CRCW060320K0FKEA
VISHAY, CRCW06031K82FKEA
VISHAY, CRCW060311K5FKEA
VISHAY, CRCW0603100RFKEA
VISHAY, CRCW0603464KFKEA
VISHAY, CRCW060314K7FKEA
VISHAY, CRCW060378K7FKEA
VISHAY, CRCW0603102KFKEA
VISHAY, CRCW060360K4FKEA
VISHAY, CRCW060315K0FKEA
VISHAY, CRCW06034K99FKEA
VISHAY, CRCW06031K87FKEA
VISHAY, CRCW0603604RFKEA
VISHAY, CRCW060316K2FKEA
VISHAY, CRCW060321K5FNEA
VISHAY, CRCW06038K25FKEA
CHAMPS, G45R2-0603-xx
COILCRAFT, CT8281-BL
LINEAR TECH., LTC3765EMSE
LINEAR TECH., LTC3766EGN
CAP., OPT, 0402
CAP., OPT, 0603
CAP., OPT, 0805
0Ω JUMPER 0603
CAP., OPT, 1206
DIODE 4148 SOD323
DIODE OPT 220AA
DIODE OPT SOD323
DIODE OPT SOT23
INDUCTOR, OPT 1608
MOSFET OPT POWERPAK-SO-8
TRANSISTOR, NPN, OPT SOT23
TRANSISTOR, NPN/PNP, OPT SOT23-6
0Ω JUMBER 0402
OPT
OPT
OPT
VISHAY, CRCW06030000Z0EA
OPT
DIODES INC., 1N4148WS
OPT
OPT
OPT
OPT
OPT
OPT
OPT
VISHAY, CRCW04020000Z0ED
0Ω JUMBER 0603
RES., OPT, 0402
RES., OPT, 0805
TRANSFORMER, OPT
VISHAY, CRCW06030000Z0ED
OPT
OPT
OPT
TESTPOINT, TURRET, 0.090" PBF
CONNECTOR, BANANA JACK
STANDOFF, NYLON 0.5 1/2"
MILL-MAX, 2501-2-00-80-00-00-07-0
Keystone, 575-4
KEYSTONE, 8833(SNAP-ON)
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7
DEMO MANUAL DC1739B-C
SCHEMATIC DIAGRAM
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8
DEMO MANUAL DC1739B-C
SCHEMATIC DIAGRAM-COMPLETE PCB
dc1739bcf
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.
9
DEMO MANUAL DC1739B-C
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
dc1739bcf
10 Linear Technology Corporation
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●
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