Linear Technology DC2061A Quick setup guide
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dc2061af
DEMO MANUAL DC2061A
DESCRIPTION
LTC3784
High Efficiency PolyPhase
®
Synchronous Boost Converter
Demonstration circuit DC2061 is a DC/DC synchro-
nous boost converter featuring the LT C
®
3784 con-
stant frequency current mode synchronous boost
controller. The DC2061A operates over a 6V to 60V
input, develops a 48V output and provides 3A to 12A
of output current as shown in Figure 3. The 150kHz
(2 • 150kHz at the output) constant frequency operation
results in a small and efficient circuit. The converter pro-
vides high output voltage accuracy (typically ±3%) over
wide load range with no minimum load requirement. The
L, LT, LTC, LTM, Linear Technology, the Linear logo and PolyPhase are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
PERFORMANCE SUMMARY
demonstration circuit can be easily modified to generate
different output voltages.
The DC2061 has a small circuit footprint. It is a high per-
formance and cost effective solution for telecom, auto-
motive and Power over Ethernet applications.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at TA= 25°C
PARAMETER CONDITION VALUE
Minimum Input Voltage IOUT = 0A to 3A 6V
Maximum Input Voltage IOUT = 0A to 12A 60V
VOUT VIN = 6V to 47V, IOUT = 0A to 3A 48V ±3%
Typical Output Ripple VOUT VIN = 6V to 47V, IOUT = 3A 200mVP-P
Nominal Switching Frequency 150kHz
QUICK START PROCEDURE
Demonstration circuit DC2061 is easy to set up to evaluate
the performance of the LTC3784. For proper measure-
ment equipment setup refer to Figure 1 and follow the
procedure below:
Note: When measuring the input or output voltage ripple,
care must be taken to minimize the length of oscilloscope
probe ground lead. Measure the input or output voltage
ripple by connecting the probe tip directly across the VIN
or VOUT and GND terminals as shown in Figure 2.
1. With power off, connect the input power supply to VIN
and GND.
2. Keep the load set to 0A or disconnected.
3. Turn the input power source on and slowly increase
the input voltage. Be careful not to exceed 60V.
Note: Make sure that the input voltage, VIN, does not ex-
ceed 60V. If higher operating voltage is required, power
components with higher voltage ratings should be used.
When the input voltage is set higher than 48V the output
voltage will follow the input voltage.
4. Set the input voltage to 6V and check for the proper
output voltage of 48V. Set the output load to 2A. If there
is no output, temporarily disconnect the load to make
sure that the load is not set too high.
5. Once the proper output voltage is established, adjust
the load and observe the output voltage regulation,
ripple voltage, efficiency and other parameters.
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DEMO MANUAL DC2061A
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Input or Output Ripple
QUICK START PROCEDURE
+ –
VOUT GND
COUT
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DEMO MANUAL DC2061A
QUICK START PROCEDURE
Changing The Output Voltage
To set the output voltage lower than 48V, change the
bottom voltage divider resistors connected to LTC3784
FB pin (see the Schematic Diagram). To get higher than a
48V output voltage, MOSFETs and capacitors with higher
voltage ratings may be required.
Note that the output voltage will start following the input
voltage when input voltage is greater than the voltage
set by the voltage divider. In this mode (wire mode) the
synchronous output rectifier MOSFET is turned continu-
ously ON. The only losses in this mode are due to the
current sense resistors, inductors and output MOSFETs
DC resistance.
Converter Efficiency And Output Current
The DC2061 output current capability depends on the
input voltage and proper cooling. Typical performance of
DC2061A is shown in Figure 3. As can be seen from Fig-
ure3, the output current capability depends on the input
voltage. Also, when input voltage is equal to, or higher
than the output voltage setting (wire mode) the efficiency
is very high (99%) since the converter is not really running
and the output MOSFET is shorting VIN to VOUT.
Figure 3. High Efficiency of DC2061 Allows the Board to Be Used
in Thermally Critical Applications with Outputs Over 3A
Figure 4. Fast Transient Response of DC2061 is Achieved with a
Small Amount of Output Capacitance
IOUT (A)
0
EFFICIENCY (%)
90
86
82 4 8
26 10
94
98
88
84
92
96
12
6VIN
9VIN
12VIN
24VIN
Output Load Step Response
The load step response of DC2061A is very good even
though relatively small amount of output capacitance
is present at the output. If higher load steps need to be
handled more output capacitance can be added in order to
keep the voltage transients at the desired level. The load
step transients are shown in Figure 4. Also, note that the
load step response even from 0% load is excellent thanks
to synchronous rectification.
Soft-Start Function
The DC2061 features soft-start circuit that controls the
inrush current and output voltage ramp at start-up. The
capacitor C15 (Figure 6) controls the start-up period. The
start-up waveforms are shown in Figure 5. Please note the
small output voltage step at about –2ms mark. The step
is resulting from synchronous MOSFET being turned on.
When the synchronous MOSFET is turned on the voltage
drop across the synchronous MOSFET (body diode) is
reduced from about 0.7V to IOUT • RDS(ON). While the syn-
chronous MOSFET is in off state (prior to –2ms mark) the
synchronous MOSFET body diodes are dissipating about
0.7V • IOUT or about 2.1W with 3A load. Please refer to
the LTC3784 data sheet for details about proper handling
of synchronous MOSFETs in your application.
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DEMO MANUAL DC2061A
PARTS LIST
QUICK START PROCEDURE
Figure 5. The DC2061 Ramps the Output Slowly at Start-Up
without Generating an Input Current Surge
Bias Circuit
The LTC3784 can operate with input voltages up to 65V.
However, depending oninput voltage, operating frequency
and MOSFETs that are used the power dissipation in the
part may become too high. In order to provide bias power
at high input voltage the DC2061 circuit is equipped with
high efficiency bias circuit LTC3630A.
If the circuit is to be used with limited input voltage the bias
power can be derived directly from input power source.
Options to power the LTC3784 from VIN or VOUT are
provided on DC2061. Please remove the LTC3630A circuit
in order to use these options. Also, refer to the data sheet
for more information about bias power.
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 5 CIN1, COUT5, COUT10, COUT11, COUT12 CAP., 33µF, 63V, EP-CAP SUN ELECTRONICS, 63HVH33M
2 12 COUT1, COUT2, CIN2, COUT3, CIN3, COUT4,
CIN4, CIN5, COUT6, COUT7, COUT8, COUT9
CAP., X7S, 4.7µF 100V,20% 3225/1210 TDK, C3225X7S2A475M
3 1 C2 CAP., NPO, 100pF, 25V,10%, 0603 AVX, 06033A101KAT
4 1 C3 CAP., X7R, 15nF, 25V, 10%, 0603 AVX, 06033C153KAT
5 5 C4, C9, C16, C17 CAP., X5R, 0.1µF, 25V, 10%, 0603 AVX, 06033D104KAT2A
6 2 C5, C10 CAP., NPO, 1000pF, 25V,10%, 0603 AVX, 06033A102KAT
7 1 C8 CAP., X5R, 4.7µF, 25V, 10%, 0805 TAIYO YUDEN, TMK212BJ475KG-T
8 1 C12 CAP., X7R, 0.1µF, 100V, 10%, 1206 AVX, 12061C104KAT
9 1 C13 CAP., X7R, 47nF, 25V, 10%, 0603 AVX, 06033C473KAT
10 1 C14 CAP., X5R, 22µF, 16V, 10%, 1206 AVX, 1206YD226KAT2A
11 1 C15 CAP., X5R, 1µF, 10V, 10%, 0603 AVX, 06033D104KAT2A
12 3 D1, D2 DIODE, BAS170W SOD323 INFINEON, BAS170W
13 1 D5 DIODE, PDZ6.8B SOD323 NXP, PDZ6.8B
14 2 L1, L2 IND, 10µH COILCRAFT, SER2918H-103KL
15 1 L3 IND, 220µH IND-744775222 WURTH ELEC., 744775222
16 4 Q2, Q4, Q6, Q8 MOSFET, N-Channel, LFPAK INFINEON, BSC028N06LS3
17 4 RSNS1, RSNS2, RSNS3, RSNS4 RES., Chip, 0.006Ω, 1%, 2010 VISHAY, WSL20106L000FEA
18 7 R2, R3, R7, R13, R15, R18, R21 RES., Chip, 0Ω, 1%, 0603 VISHAY, CRCW06030000Z0EA
19 1 R5 RES., Chip, 30.1k, 1%, 0603 VISHAY, CRCW060330K1FKEA
20 1 R6 RES., Chip, 475k, 1%, 0603 VISHAY, CRCW0603475KFKEA
21 2 R8 RES., Chip, 12.1k, 1%, 0603 VISHAY, CRCW060312K1FKEA
22 1 R9 RES., Chip, 15k, 1%, 0603 VISHAY, CRCW060315K0FKEA
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DEMO MANUAL DC2061A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
23 2 R17, R23 RES., Chip, 10Ω, 1%, 0603 VISHAY, CRCW060310R0FKEA
24 2 R26, R35 RES., Chip, 100k, 1%, 0603 VISHAY, CRCW0603100KFKEA
25 1 R29 RES., Chip, 47k, 1%, 0603 VISHAY, CRCW060347K0FKEA
26 1 R30 RES., Chip, 523k, 1%, 0603 VISHAY, CRCW0603523KFKEA
27 1 R33 RES., Chip, 150k ,1%, 0603 VISHAY, CRCW0603150KFKEA
28 1 R34 RES., Chip, 38.3k ,1%, 0603 VISHAY, CRCW060338K3FKEA
29 1 R36 RES., Chip, 80.6k, 1%, 0603 VISHAY, CRCW060380K6FKEA
30 1 U1 I.C. LTC3784IUFD QFN28–4 x 5 LINEAR TECH., LTC3784IUFD#PBF
31 1 U2 I.C. LTC3630AEMSE LINEAR TECH., LTC3630AEMSE
Additional Demo Board Circuit Components
1 0 C1, C19, C20 OPT, 0603 OPT
2 0 D3, D4 DIODE, OPT PDS760 POWERID5-2P OPT
3 0 D6 DIODE, OPT SOD123 OPT
4 0 Q1, Q3, Q5, Q7 OPT, LFPAK OPT
5 0 R1, R4, R10, R11, R12, R14, R16, R27, R28,
R31, R32, R37, R38
OPT, 0603 OPT
Hardware-For Demo Board Only
1 11 E1, E5-E8, E11-E15, E21 TURRET, TESTPOINT , 091" MILL-MAX, 2501-2-00-80-00-00-07-0
2 2 E2, E4 JACK BANANA KEYSTONE, 575-4
3 2 E9, E10 STUD, TEST PIN PEM, KFH-032-10
4 4 (E9, E10) x 2 NUT, BRASS NUTS # 10-32 ANY, #10-32
5 2 E9, E10 RING, LUG RING # 10 KEYSTONE, 8205
6 2 E9, E10 WASHER, #10, TIN PLATED BRASS ANY, #10 EXT BZ TN
7 1 JP1 HEADER, 6 PINS 2 x 3 100 Ctrs. SAMTEC, TSW-106-07-L-D
8 2 JP2, JP4 HEADER, 3 Pins 2mm CTRS. SULLINS, NRPN031PAEN-RC
9 1 JP3 HEADER, 4 Pins 2mm CTRS. SULLINS, NRPN041PAEN-RC
10 3 XJP2, XJP3, XJP4 SHUNT, 2mm CTRS. SAMTEC, 2SN-BK-G
11 1 XJP1 SHUNT, 100 CTRS. SAMTEC SNT-100-BK-G
12 4 MTGS HEX STANDOFF 6-32 NYLON 3/4" KEYSTONE, 1903D
13 4 MTGS SCREW, PAN PHILLIPS 6-32 B & F, PMSSS 632 0038 PH
14 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 2061A
15 2 STENCILS TOP AND BOTTOM STENCIL DC2061A
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DEMO MANUAL DC2061A
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D
D
C
C
B
B
A
A
NOTES:
- SEE QSG
*
*
1. ALL RESISTORS ARE IN OHMS, 0603.
ALL CAPACITORS ARE IN MICROFARADS, 0603.
2. INSTALL SHUNTS AS SHOWN.
SENSE1+
SENSE1-
TECHNOLOGY
TECHNOLOGY
TECHNOLOGY
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DEMO MANUAL DC2061A
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
5
5
4
4
3
3
2
2
1
1
D
D
C
C
B
B
A
A
TECHNOLOGY
TECHNOLOGY
TECHNOLOGY
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DEMO MANUAL DC2061A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ●FAX: (408) 434-0507 ●www.linear.com
LINEAR TECHNOLOGY CORPORATION 2014
LT 0314 REV A • 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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