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DEMO MANUAL DC2002A
Description
LTC3774EUHE
High Efficiency Dual Output Step-Down
Converter with Very Low DCR Inductor
Demonstration circuit DC2002A is a dual output synchro-
nous buck converter featuring the LTC3774EUHE. The
demo board supplies two rails of 1.5V / 30A and 1.2V / 30A.
The power stage for each rail consists of a 0.33µH 0.32mΩ
DCR inductor with a 11mm × 11mm footprint and a
6mm × 6mm DrMOS driven by the PWM outputs of the
LTC3774EUHE at a switching frequency of 400kHz. The
inductor, DrMOS and the local ceramic input and output
capacitors forms the core converter which occupies a
1.1˝ × 1.1˝ area on the top layer. The control circuit is
directly underneath on the bottom layer and occupies an
area of 0.9˝ × 1.1˝. The result is a two sided core converter
with a current density of 50A per square inch and a full
load efficiency of 91.1% for the 1.5V rail and 90.0% for
the 1.2V rail.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot Swap
is a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
performance summary
Additional features of this demo board include:
• Remote Sensing for Each Output
• PLLIN and CLKOUT Pins
• PGOOD, RUN and TRK/SS Pins for Each Output
• Optional Resistors to Tie the Tw o Outputs Together
• Optional Footprint for Hot Swap™ FET on the Input of
Each Phase for MOSFET Failure Protection
• Optional Footprint for an LTC4449 Gate Driver and
Discrete MOSFETs
• Optional Footprint for a Dual Phase Delta Power Block
Design files for this circuit board are available at
http://www.linear.com/demo/DC2002A
PARAMETER CONDITIONS VALUE
Minimum Input Voltage 7V
Maximum Input Voltage 14V
Output Voltage VOUT1 IOUT1 = 0A TO 30A, VIN = 7V to 14V 1.5V ±2%
Output Voltage VOUT2 IOUT2 = 0A TO 30A, VIN = 7V to 14V 1.2V ±2%
VOUT1 Maximum Output Current, IOUT1 VIN = 7V to 14V, VOUT1 = 1.5V 30A
VOUT2 Maximum Output Current, IOUT2 VIN = 7V to 14V, VOUT2 = 1.2V 30A
Nominal Switching Frequency 400kHz
Efficiency
See Figures 2 and 3
VOUT1 = 1.5V, IOUT1 = 30A, VIN = 12V 91.1% Typical
VOUT2 = 1.2V, IOUT2 = 30A, VIN = 12V 90.0% Typical
Specifications are at TA = 25°C, No Airflow
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DEMO MANUAL DC2002A
Quick start proceDure
Demonstration circuit 2002A is easy to set up to evaluate
the performance of the LTC3774EUHE. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below.
1. With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A
and VIN supply to be 0V. For both assemblies, place
the jumpers in the following positions:
JP1 RUN1 ON
JP2 RUN2 ON
JP5 MODE CCM
2. Adjust the input voltage to be between 7V and 14V.
VOUT1 should be 1.5V ±2%.
VOUT2 should be 1.2V ±2%.
3. Next, apply 30A load to each output and re-measure
VOUT.
4. Once the DC regulation is confirmed, observe the output
voltage ripple, load step response, efficiency and other
parameters.
Note 1. Use the BNC connectors labeled VOUT1 or VOUT2
to measure the output voltage ripple.
Note 2. Do not connect load from the VOS1+ turret to the
VOS1– turret or from the VOS2+ turret to the VOS2– tur-
ret. This could damage the converter. Only apply load
across the stud connectors on the edge of the board.
Dynamic Load Circuit (Optional)
Demonstration circuit 2002A provides a simple load step
circuit consisting of a MOSFET and sense resistor for each
rail. To apply a load step, follow the steps below.
1. Pre-set the amplitude of a pulse generator to 0.0V and
the duty cycle to 5% or less.
2. Connect the scope to the VOUT1/VOUT2 BNC connectors
for the rail under test with a coax cable. To monitor the
load step current, connect the scope probe across the
ISTEP± turrets for that rail.
3. Connect the output of the pulse generator to the PULSE
GEN turret for the rail under test and connect the return
to the adjacent GND turret.
4. With the converter running, slowly increase the am-
plitude of the pulse generator output to provide the
desired load step pulse height. The scaling for the load
step signal is 5mV/Amp.
Single Output/Dual Phase Operation
A single output/dual phase converter may be preferred for
higher output current applications. The optional compo-
nents required to tie the phases together are found on the
lower left of the 1st sheet. To tie the two outputs together,
make the following modifications:
1. Tie the two VOUT shapes together with a piece of copper
or a 0mΩ jumper at R47 and R36. One part to consider
is Tepro RN5326.
2. Tie VOSNS1 to VOSNS2 by stuffing a 0Ω resistor at R53
and tie VOS1– to VOS2– by stuffing a 0Ω resistor at R92.
3. Tie ITH1 to ITH2 by stuffing a 0Ω resistor at R68.
4. Tie RUN1 to RUN2 by stuffing a 0Ω resistor at R54.
5. Tie TK/SS1 to TK/SS2 by stuffing a 0Ω resistor at R48.
Paralleling Boards
Up to 6 DC2002A demo boards can be paralleled to
produce a single output, 12 phase converter. To connect
two or more DC2002A boards together, first tie the two
phases together as described in the Single Output/Dual
Phase Operation section. Next, place the boards side by
side such that header J8 of one board mates with socket
J9 of the other. This will connect the common control
signals together which are the VOSNS, VOS–, ITH, RUN
and TK/SS signals. It will also tie the CLKOUT signal of
one phase to the PLLIN input of the other phase. Next,
tie the VOUT, VIN and GND of the boards together using
the exposed copper on the edges of the board. Figure 6
shows how to tie 2 boards together for a single output,
4 phase converter.
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DEMO MANUAL DC2002A
Quick start proceDure
+
–
+
–
VOUT *A
VOUT2 *A
VIN1 *B
+
–
VIN2 *B
+
–
IIN IOUT1
VOUT1
LOAD
VIN
SUPPLY
+
–
+
–
IOUT2
VOUT2
LOAD
–
+
*A MONITOR THE OUTPUT VOLTAGE ACROSS EITHER COUT4 OR COUT9 FOR ACCURATE EFFICIENCY MEASUREMENTS.
*B MONITOR THE VOLTAGE AT VIN1 WHEN MEASURING THE EFFICIENCY OF PHASE 1 AND VIN2 WHEN MEASURING THE
EFFICIENCY OF PHASE 2.
Figure 1. Proper Measurement Equipment Setup
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DEMO MANUAL DC2002A
60
70
80
90
100
0 10 20 30 40
Load Current (Amps)
Efficiency (%)
VIN = 7V
VIN = 14V
VIN = 12V
L = Würth 744301033
0.33µH, DCR = 0.32mΩ TYP
FDMF6820A DrMOS
Quick start proceDure
Figure 2. Efficiency Curves for the 1.5V Rail at VIN = 12V, 14V and 7V in CCM.
Figure 3. Efficiency Curves for the 1.2V Rail at VIN = 12V, 14V and 7V in CCM.
1.5V/30A Rail, CCM, fSW = 400kHz
1.2V/30A Rail, CCM, fSW = 400kHz
Load Current (Amps)
Efficiency (%)
VIN = 7V
VIN = 14V
VIN = 12V
60
70
80
90
100
0 10 20 30 40
L = Würth 744301033
0.33µH, DCR = 0.32mΩ TYP
FDMF6820A DrMOS
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DEMO MANUAL DC2002A
Quick start proceDure
Figure 4. 50% to 100% to 50% Load Step Response of the 1.5V Rail.
COUT = 3× Sanyo 2R5TPE330M9 || 2× 100µF X5R 1206, L = Würth 744301033 (0.33µH), fSW = 400kHz.
Figure 5. 50% to 100% to 50% Load Step Response of the 1.2V Rail.
COUT = 3× Sanyo 2R5TPE330M9 || 2× 100µF X5R 1206, L = Würth 744301033 (0.33µH), fSW = 400kHz.
1.5V(AC)
50mV/DIV
15A
DC2002A F04
30A
144mV
50µs/DIV
LOAD STEP
5A/DIV
1.2V(AC)
50mV/DIV
15A
30A
136mV
50µs/DIV
LOAD STEP
5A/DIV
DC2002A F05
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DEMO MANUAL DC2002A
Quick start proceDure
BOARD #1 BOARD #2
VOUT
VIN
TOP LAYER
BOARD #2 BOARD #1
BOTTOM LAYER
GND
GND
= COPPER FOIL
Figure 6. How to Parallel Tw o Boards for a Single Output, 4 Phase Converter
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DEMO MANUAL DC2002A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 2 CIN1, CIN2 CAP, 180µF, 20%, 16V, OSCON SANYO, 16SVP180MX
2 4 CIN3, CIN4, CIN5, CIN6 CAP, 22µF, 20%, 16V, X5R 1210 MURATA, GRM32ER61C226KE20L
3 6 COUT1-COUT3, COUT6-COUT8 CAP, 330µF, 20%, 2.5V, 7343 SANYO, 2R5TPE330M9
4 4 COUT4, COUT5, COUT9, COUT10 CAP, 100µF, 20%, 6.3V, X5R 1206 MURATA, GRM31CR60J107ME39L
5 6 C1, C9, C36, C37, C38, C40 CAP, 0.22µF, 10%, 25V, X7R 0603 AVX, 06033C224KAT2A
6 2 C2, C13 CAP, 0.1µF, 10%, 25V, X7R 0603 AVX, 06033C104KAT2A
7 4 C3, C11, C34, C35 CAP, 2.2µF, 10%, 16V, X7R 0603 MURATA, GRM188R61C225KE15D
8 2 C5, C10 CAP, 0.01µF, 10%, 25V, X7R 0603 AVX, 06033C103KAT2A
9 2 C6, C14 CAP, 2200pF, 5%, 25V, X7R 0603 AVX 06033C222JAT2A
10 2 C7, C41 CAP, 330pF, 10%, 50V, NPO 0603 AVX 06035A331KAT
11 1 C8 CAP, 4.7µF, 10%, 16V, X7R 0805 AVX, 0805YC475KAT2A
12 1 C12 CAP, 1µF, 20%, 25V, X5R 0603 AVX, 06033D105MAT2A
13 2 C46, C47 CAP, 22pF, 10%, 25V, NPO 0603 AVX, 06033A220KAT2A
14 2 C28, C29 CAP, 10µF, 20%, 6.3V, X5R 0805 AVX, 08056D106MAT2A
15 2 L1, L2 IND., 0.33µH, 0.325mΩ, DCR 20% WÜRTH, 744301033
16 2 R1, R45 RES, 40.2k, 1%, 1/10W, 0603 VISHAY, CRCW060340K2FKEA
17 3 R2, R25, R35 RES, 2.2Ω, 1%, 1/10W, 0603 VISHAY, CRCW06032R20FKEA
18 2 R3, R26 RES, 1Ω, 1%, 1/10W, 0603 VISHAY, CRCW06031R00FKEA
19 12 R4-R7, R9, R29, R30, R40, R41,
R46, R85, R89 RES, 10k, 1%, 1/10W, 0603 VISHAY, CRCW060310K0FKEA
20 1 R8 RES, 15k, 1%, 1/10W, 0603 VISHAY, CRCW060315K0FKEA
21 4 R11, R18, R39, R43 RES, 10Ω, 1%, 1/10W, 0603 VISHAY, CRCW060310R0FKEA
22 3 R12, R21, R22 RES, 0Ω, JUMPER 0603 VISHAY, CRCW06030000Z0EA
23 2 R20, R42 RES, 4.64k, 1%, 1/10W, 0603 VISHAY, CRCW06034K64FKEA
24 1 R23 RES, 37.4k, 1%, 1/10W, 0603 VISHAY, CRCW060337K4FKEA
25 2 R38, R51 RES, 931Ω, 1%, 1/10W, 0603 VISHAY, CRCW0603931RFKEA
26 2 R49, R50 RES, 0.001Ω, 2512, 5% PANASONIC ERJM1WTJMOU
27 2 R73, R88 RES, 100K 1% 1/10W 0603 VISHAY, CRCW0603100KFKEA
28 1 U1 LTC3774EUHE LINEAR TECH., LTC3774EUHE#PBF
29 2 U2, U3 MOSFET, DrMOS DC/DC 3.3V PWM FAIRCHILD, FDMF6820A
30 2 R19, R37 RES, 8.06k, 1%, 1/16W, 0603 VISHAY, CRCW06038K06FKEA
5V BIAS (for DrMOS)
1 1 R59 RES, 0Ω, JUMPER 1206 VISHAY, CRCW12060000Z0EA
2 1 U4 I.C., BUCK REGULATOR LT3470ETS8 LINEAR TECH., LT3470ETS8#PBF
3 1 C17 CAP, 0.22µF, 10%, 25V, X7R 0603 AVX, 06033C224KAT2A
4 2 C18, C26 CAP, 1µF, 20%, 25V, X5R 0603 AVX, 06033D105MAT2A
5 1 L3 IND., 33µH, -53DLC TOKO, A914BYW-330M=P3
6 1 C19 CAP, 22µF, 20%, 16V, X5R 1210 MURATA, GRM32ER61C226KE20L
7 1 C21 CAP, 22pF, 10%, 25V, NPO 0603 AVX, 06033A220KAT2A
8 1 R61 RES, 604k, 1%, 1/10W, 0603 VISHAY, CRCW0603604KFKEA
9 1 R63 RES, 200k, 1%, 1/10W, 0603 VISHAY, CRCW0603200KFKEA
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DEMO MANUAL DC2002A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Dynamic Load Circuits
1 2 R56, R58 RES, 10k, 1%, 1/10W, 0603 VISHAY, CRCW060310K0FKEA
2 2 Q1, Q2 MOSFET, N-Channel 30-V VISHAY, SUD50N03-12P-E3
3 2 R57, R60 RES 0.005Ω, 1%, 0.5W, 2010 VISHAY, WSL20105L000FEA
Additional Components
1 0 CIN7-CIN12, CIN13, CIN14, C25 CAP, 1210 OPT
2 0 COUT15-COUT20 (OPT) CAP, 7343 OPT
3 0 COUT11-COUT14 CAP, 1206 OPT
4 0 C16 CAP, 0805 OPT
5 0 C15, C20, C22-C24, C27, C30-C33,
C39, C42, C43, C44-C48 CAP, 0603 OPT
6 0 D1 DIODE SOT23 OPT
7 0 D2, D3 DIODE SOD-323 OPT
8 0 L4 IND, -53DLC OPT
9 0 PB1 POWER BLOCK, D12S1R845A OPT
10 0 Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10 MOSFET, PG-TDSON-8 OPT
11 0 RN1, RN2 RES, NTC, 0805 OPT
12 0 R10, R14, R15, R24, R27, R28,
R31, R33, R44, R48, R52-R55,
R62, R65-R72, R74-R84, R86, R87,
R90, R91, R92
RES, 0603 OPT
13 0 R16, R32, R17, R34 RES, 0603 OPT
14 0 R36, R47 RES, 2512 OPT
15 0 R64 RES, 1206 OPT
16 0 U5 OPT, BUCK REGULATOR LT3470ETS8 OPT
17 0 U8, U9 GATE DRIVER, LTC4449EDCB OPT
18 0 E28 OPT, TESTPOINT, TURRET, .095" OPT
19 0 JP4 HEADER, 3 PIN, 0.079 SINGLE ROW OPT
Hardware
1 25 E1-E13, E16-E25, E29, E30 TESTPOINT, TURRET, .095" MILL MAX, 2501-2-00-80-00-00-07-0
24 JP1, JP2, JP3, JP5 HEADER, 3 PIN 0.079 SINGLE ROW SULLINS, NRPN031PAEN-RC
3 4 XJP1, XJP2, XJP3, XJP5 SHUNT, .079" CENTER SAMTEC, 2SN-BK-G
4 6 J1, J2, J3, J4, J5, J6 STUD, TEST PIN PEM, KFH-032-10
5 12 (J1, J2, J3, J4, J5, J6)x2 NUT, BRASS PL #10-32 ANY, 10-32M/S BR PL
6 6 J1, J2, J3, J4, J5, J6 RING, LUG #10 KEYSTONE, 8205
7 6 J1, J2, J3, J4, J5, J6 WASHER, TIN PLATED BRASS ANY, #10EXT BZ TN
8 2 J7, J10 CON, BNC, 5 PINS CONNEX, 112404, 7 Trays
9 1 J8 Header, Dbl Row, RT Angle, 2 × 4, 8 Pin MILL-MAX, 802-10-008-20-001000
10 1 J9 Socket, Dbl Row, RT Angle, 2 × 4, 8 Pin MILL-MAX, 803-43-008-20-001000
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DEMO MANUAL DC2002A
schematic Diagram
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DEMO MANUAL DC2002A
schematic Diagram
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DEMO MANUAL DC2002A
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
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DEMO MANUAL DC2002A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2013
LT 0713 • PRINTED IN USA
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.
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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.
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 LT C applica-
tion engineer.
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Copyright © 2004, Linear Technology Corporation
