Linear Technology DC2050A User manual

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DEMO MANUAL DC2050A
DESCRIPTION
LT3753
Active Clamp
Forward Converter with
Synchronous Rectification
Demonstration circuit 2050A is an active clamp forward
converter with synchronous rectification featuring the
LT
®
3753.
This circuit was designed to demonstrate the high level
of performance, efficiency, and small solution size attain-
able using this part. It operates at 250kHz and produces
a regulated 5V, 20A output from an input voltage range
of 36V to 72V: suitable for telecom, industrial, and other
applications.Ithas an eighth-brick footprint area. Synchro-
nous rectificationhelps to attain efficiency exceeding 94%.
The DC2050 circuit features soft-start which prevents out-
put voltage overshoot during start-up or when recovering
from an overload condition.
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
The DC2050 has a precise overcurrent protection circuit
that allows for continuous operation and low power dis-
sipation during short-circuit conditions which ensures
high reliability.
Please refer to the LT3753 data sheet for design details
and applications information.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 36 72 V
VOUT Output Voltage 4.9 5.0 5.1 V
IOUT Output Current Range, Continuous 20 A
fSW Switching (Clock) Frequency 250 kHz
VOUT(P-P) Output Ripple VIN = 48V, IOUT = 20A (20MHz BW) 50 mVP-P
VREG Output Regulation Line and Load (36V to 72VIN, 0A to 20AOUT) ±0.1 %
POUT/PIN Efficiency (See Figure 2) VIN = 48V, IOUT = 20A 94 %

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DEMO MANUAL DC2050A
QUICK START PROCEDURE
Note:When measuring the outputvoltage 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.
1. Set an input power supply that is capable of 36V to
72V to 36V. Then turn off the supply.
2. Withpower off, connect the supplyto the input terminals
+VIN and –VIN.
a. Input voltages lower than 36V can keep the converter
from turning on due to the undervoltage lockout
feature of the LT3753.
b. If efficiency measurements are desired, an ammeter
capable of measuring 5A DC can be put in series with
the input supply in order to measure the DC2050A’s
input current.
c. A voltmeter with a capability of measuring at least
72V can be placed across the input terminals in order
to get an accurate input voltage measurement.
3. Turn on the power at the input.
Note: Make sure that the input voltage does not exceed
100V.
4. Check for the proper output voltage of 5V. Turn off the
power at the input.
5. Once the proper output voltages are established, con-
nect a variable load capable of sinking 20A at 5V to the
output terminals +VOUT and –VOUT. Set the current
for 0A.
a. If efficiency measurements are desired, an ammeter
or a resistor shunt that is capable of handling 20A
DC can be put in series with the output load in order
to measure the DC2050A’s output current.
b. Avoltmetercan be placed across theoutput terminals
in order to get an accurate output voltage measure-
ment.
6. 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.
7. 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.

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DEMO MANUAL DC2050A
QUICK START PROCEDURE
LOAD CURRENT (A)
3753 F21a
201210 16 18140
EFFICIENCY (%)
96
94
92
86
90
88
42 86
36VIN
48VIN
72VIN
Figure 1. Proper Measurement Equipment Setup
Figure 2. Efficiency vs Load Current

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DEMO MANUAL DC2050A
QUICK START PROCEDURE
Figure 3. Output Ripple at 48VIN and 20AOUT (20MHz BW)
Figure 5. Thermal Map, Front Side at 48VIN and 20AOUT
(TA= 25°C)
Figure 6. Thermal Map, Back Side at 48VIN and 20AOUT
(TA= 25°C)
Figure 4. Transient Response Waveform at 48VIN and
10A to 20AOUT
2µs/DIV
50mV/DIV
100µs/DIV
500mV/DIV
10A/DIV

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DEMO MANUAL DC2050A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 3 CIN1, CIN2, CIN3 CAP., X7S, 4.7µF, 100V, 10% 1210 TDK, CGA6M3X7S2A475K
2 1 CO1 CAP., X7R, 47µF, 10V, 10% 1210 MURATA, GRM32ER71A476KE15L
3 1 CSYS CAP., ALUM., 560µF, 10V, PANASONIC., 10SEP560M
4 1 CY1 CAP., X7R, 2200pF, 250V, 10% 1812 MURATA, GA343QR7GD222KW01L
5 1 C2 CAP., X7R, 4.7µF, 25V, 10% 0805 MURATA, GRM21BR61E475KA12L
6 1 C3 CAP., X7R, 22nF, 25V, 10% 0603 MURATA, GRM188R71E223KA01D
7 1 C4 CAP., X7S, 1µF, 100V, 10% 0805 TDK, C2012X7S2A105K
8 1 C5 CAP., C0G, 22pF, 50V, 5% 0603 MURATA, GRM1885C1H220JA01D
9 1 C12 CAP., X7R, 0.1µF, 50V, 10% 0603 MURATA, GRM188R71H104KA93D
10 3 C1, C13, C20 CAP., X7R, 1µF, 25V, 10% 0603 MURATA, GRM188R71E105KA12D
11 1 C14 CAP., X7R, 68nF, 250V, 10% 1206 MURATA, GRM31BR72E683KW03L
12 1 C15 CAP., X7R, 0.22µF, 250V, 10% 1210 MURATA, GRM32DR72E224KW01L
13 1 C18 CAP., C0G, 4.7nF, 50V, 5% 0603 MURATA, GRM1885C1H472JA01D
14 1 C21 CAP., C0G, 3.3nF, 50V, 5% 0603 MURATA, GRM1885C1H332JA01D
15 1 C22 CAP., X5R, 22µF, 10V, 10% 0805 TDK, C2012X5R1A226K
16 1 D4 ZENER DIODE, 4.3V, SOD-123 DIODES., BZT52C4V3-7-F
17 1 D5 DIODE, HIGH SPEED DIODE, SOD-523 NXP/PHILLIPS SEMI., BAS516
18 1 L1 INDUCTOR, 3.3µH CHAMPS, PQI2050-3R3
19 1 Q1 N-MOSFET POWER-56 INFINEON, BSC190N15NS3 G
20 1 Q2 SMPS MOSFET SO8 IR, IRF6217
21 2 Q3, Q4 POWER MOSFET, PG-TDSON-8 INFINEON, BSC0902NSI
22 1 RCS1 RES., CHIP, 0.012Ω, 1W, 1%, 0815 SUSUMU, RL3720WT-R12-F
23 1 R1 RES., Chip, 30.1k, 0.1W, 1% 0603 VISHAY, CRCW060330K1FKEA
24 1 R2 RES., Chip, 14.7k, 0.1W, 1% 0603 VISHAY, CRCW060314K7FKEA
25 1 R5 RES., Chip, 44.2k, 0.1W, 1% 0603 VISHAY, CRCW060344K2FKEA
26 1 R6 RES., Chip, 57.6k, 0.1W, 1% 0603 VISHAY, CRCW060357K6FKEA
27 1 R7 RES., Chip, 1.87k, 0.1W, 1% 0603 VISHAY, CRCW06031K87FKEA
28 1 R8 RES., Chip, 1.96k, 0.1W, 1% 0603 VISHAY, CRCW06031K96FKEA
29 1 R9 RES., Chip, 105k, 0.125W, 1% 0805 YAGEO, RC0805FR-07105KL
30 3 R15, R21, R24 RES., Chip, 1.0k, 0.1W, 5% 0603 VISHAY, CRCW06031K00JNEA

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DEMO MANUAL DC2050A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
31 1 R16 RES., Chip, 34.8k, 0.1W, 1% 0603 VISHAY, CRCW060334K8FKEA
32 1 R17 RES., Chip, 15Ω, 0.1W, 5% 0603 VISHAY, CRCW060315R0JNEA
33 2 R18, R19 RES., Chip, 100k, 0.1W, 5% 0603 VISHAY, CRCW0603100KJNEA
34 2 R20, R28 RES., Chip, 137k, 0.25W, 1% 0603 VISHAY, CRCW0603137KFKEA
35 1 R23 RES., Chip, 100Ω, 0.1W, 5% 0603 VISHAY, CRCW0603100RJNEA
36 1 R25 RES., Chip, 10k, 0.1W, 5% 0603 VISHAY, CRCW060310K0JNEA
37 1 R26 RES., Chip, 200Ω, 0.125W, 1% 0805 YAGEO, RC0805FR-07200R
38 1 R29 RES., Chip, 100Ω, 0.125W, 1% 0805 VISHAY, CRCW0805100RFKEA
39 1 R32 RES., Chip, 5.1Ω, 0.125W, 5% 1206 VISHAY, CRCW12065R10JNEA
40 1 R33 RES., Chip, 5.1Ω, 0.125W, 5% 0805 VISHAY, CRCW08055R10JNEA
41 1 T1 TRANSFORMER, CHAMPS, G45R2-0209
42 1 U1 I.C., LT3753EFE#TRPBF, TSSOP-38(31) LINEAR TECH., LT3753EFE#TRPBF
43 1 U2 I.C., PS2801C-1-P-A NEC, PS2801C-1-P-A
44 1 U3 I.C., LT1431CS8 SO8 LINEAR TECH., LT1431CS8#TRPBF
Additional Demo Board Circuit Components
1 0 CO2 (OPT) CAP., 1210
2 0 C31 (OPT) CAP.,
3 0 R10 (OPT) RES., 0603
Hardware-For Demo Board Only
1 2 E1, E2 TESTPOINT, TURRET, 0.061" PBF MILL-MAX, 2308-2-00-80-00-00-07-0
2 4 E3, E4, E5, E6 TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0
3 4 J1-J4 BANANA JACK KEYSTONE, 575-4
4 4 MH1-MH4 STAND-OFF, NYLON 0.25" KEYSTONE, 8831(SNAP ON)
5 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 2050A

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DEMO MANUAL DC2050A
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
SCHEMATIC DIAGRAM
SW1 +VO1
INTVCC
INTVCC
T1-2 T1-5
T1-2
T1-5
SW1
SW2
SW2
SGND
+VO1
+VO1
+VO1
+VOUT 5V / 20A
-VIN
36V - 72V
+VIN
NOTE: UNLESS OTHERWISE SPECIFIED: ALL RESISTORS & CAPACITORS ARE 0603 . ALL RESISTORS ARE 1% MULTILAYER RESISTORS. ALL CERAMIC CAPACITORS ARE X7R EVAL1: EFE PACKAGE (FE38 (31) ) BOARD SIZE: 2.30 BY 1.45
-VOUT
SYNC
GND
L1
3.3uH
PQI2050-3R3
L1
3.3uH
PQI2050-3R3
CIN3CIN3
PA2720NL
T1(OPT 2)
PA2720NL
T1(OPT 2)
10
2 47 18
6
59
T1
G45R2-0209
T1
G45R2-0209
5 28
11
R20 137K R20 137K
J3J3
C5
22pF
C5
22pF
R19
100K
R19
100K
C22
22uF
0805
10V
C22
22uF
0805
10V
Q4 BSC0902NSI Q4 BSC0902NSI
CY1
2200pF
250V 1812
CY1
2200pF
250V 1812
CO2 1210
OPT
CO2 1210
OPT
R21 1KR21 1K
E6E6
R23
100
R23
100
R28 137K R28 137K
RCS1
0.012
0815 RCS1
0.012
0815
R25 10K R25 10K
J2J2
U1
LT3753EFE
U1
LT3753EFE
COMP
5
FB
4
RT
3
SYNC
6
TBLNK
14
SS1
7
TOS
13
GND
18
NC
2
SS2
17
OUT
24
AOUT
32
OC
22
ISENSEN
20
ISENSEP
21
VIN
28
NC
34
TEST2
36
TEST1
1
TAS
12
TAO
11
IVSEC
8
UVLO_VSEC
9
OVLO
10
INTVCC
26
SOUT
30
PGND
19
PGND
38
PGND
39
NC
15
NC
16
NC
37
R7 1.87K R7 1.87K
U2
PS2801-1
U2
PS2801-1
1
3 4
2
C20
1uF
C20
1uF
R5 44.2K R5 44.2K
C13 1uF C13 1uF
R9 105K
0805
R9 105K
0805
R1
30.1K
R1
30.1K
C12
0.1uF
C12
0.1uF
E3E3
U3
LT1431CS8
U3
LT1431CS8
COLLECTOR
1
GND-F
6
GND-S
5
RMID
7
RTOP
4
COMP
2
REF
8
V+
3
C15 0.22uF 250V
1210
C15 0.22uF 250V
1210
J1J1
R24
1K
R24
1K
CIN2
100V CIN2 100V R17
15
R17
15
CIN1
4.7uF
1210 CIN1
4.7uF
1210
J4J4
R6 57.6K R6 57.6K
R16
34.8K
R16
34.8K
C14
1206 250V 68nF
C14
1206 250V 68nF
C1
1uF
C1
1uF
D5 BAS516 D5 BAS516
R33
5.1
0805
R33
5.1
0805
47uF
10V
CO1
1210
47uF
10V
CO1
1210
R18
100K
R18
100K
E5E5
R8 1.96K R8 1.96K
D4
BZT52C4V3
D4
BZT52C4V3
R15 1K R15 1K
E2E2
E4E4
C3
22nF
C3
22nF
+
CSYS
560uF
10V
+
CSYS
560uF
10V
Q3
BSC0902NSI
Q3
BSC0902NSI
Q1
BSC190N15NS3 G
Q1
BSC190N15NS3 G
R29 100 0805 R29 100 0805
C4
1uF
100V
0805
C4
1uF
100V
0805
C2
4.7uF
25V
0805
C2
4.7uF
25V
0805
+
C31
33uF 100V
(OPT)
+
C31
33uF 100V
(OPT)
C18 4.7nF C18 4.7nF
Q2
IRF6217
Q2
IRF6217
R32
5.1
1206
R32
5.1
1206
R2 14.7KR2 14.7K
C21
3.3nF
C21
3.3nF
R10 OPT R10 OPT
R26
200
0805
R26
200
0805
E1E1

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DEMO MANUAL DC2050A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
LT 0414 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) 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 LT C 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 LT C 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. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LT C 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 LT C applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation

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