DC1807A - Demo Manual

DEMO MANUAL DC1807A
LTC3869EUFD
Dual, 2-Phase Synchronous
Step-Down DC/DC Controllers
DESCRIPTION
Demonstration circuit 1807A is a dual output, dual phase
synchronous buck converter featuring the LTC3869EUFD.
The demo board uses a high density, two sided drop-in
layout. The power components, excluding the bulk output and input capacitors, fit within a 1.35” × 0.75” area
on the top layer. The control circuit resides in a 0.60” ×
0.75” area on the bottom layer. The package style for the
LTC3869EUFD is a 4mm × 5mm 28-lead QFN with an
exposed ground pad.
The main features of the board include an internal 5V linear
regulator for bias, RUN pins for each output, an EXTVCC
pin and a PGOOD signal. The board can be configured
for either CCM (original setting), Burst Mode operation,
or pulse-skipping operation with the mode jumper. The
board also has optional resistors for single output/dual
phase operation, rail tracking and synchronization to an
external clock.
PERFORMANCE SUMMARY
PARAMETER
Two versions of the board are available. DC1807A-A has
an on-board sense resistor for current feedback, while
the DC1807A-B is configured with a DCR sense circuit
that allows the converter to use the inductors DCR as the
sense element instead of the on-board sense resistors to
save cost and board space and improves efficiency.
The input voltage range is 4.5V to 14V, output voltages
and currents are 1.5V/15A and 1.2V/15A. The LTC3869
datasheet gives a complete description of the part, operation and application information. The datasheet must be
read in conjunction with this demo manual for DC1807A.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, μModule, Burst Mode, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
(TA = 25°C)
CONDITIONS
VALUE
Minimum Input Voltage
4.5V
Maximum Input Voltage
14V
Output Voltage VOUT1
VIN = 4.5V to 14V, IOUT1 = 0A to 15A
Output Voltage VOUT2
VIN = 4.5V to 14V, IOUT2 = 0A to 15A
1.2V±2%
Typical Output Ripple VOUT
VIN = 12V, IOUT1 = 15A (20MHz BW)
<30mVP-P*
VIN = 12V, IOUT2 = 15A (20MHz BW)
Nominal Switching Frequency
Efficiency
1.5V±2%
<30mVP-P*
400kHz
DC1807A-A
DC1807A-B
VOUT1 = 1.5V, IOUT1 = 15A; VIN = 12V
88.7%** Typical
86.7%** Typical
VOUT2 = 1.2V, IOUT2 = 15A; VIN = 12V
89.1%** Typical
87.4%** Typical
*Measured at bulk output capacitor
**See Figures 3 and 4 for efficiency curves
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DEMO MANUAL DC1807A
QUICK START PROCEDURE
Demonstration circuit 1807A is easy to set up to evaluate
the performance of the LTC3869EUFD. Refer to Figure 1
for proper measurement equipment setup and follow the
procedure below:
NOTE. When measuring the input or output voltage ripple,
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 or
VOUT and GND terminals. See Figure 2 for proper scope
probe technique.
1. Make sure jumpers are in the following positions:
JUMPER
POSITION
JP1
ON
JP2
ON
JP3
CCM
2. With power off, connect the input power supply to VIN
and GND. Connect active loads to outputs.
3. Turn on the power at the input.
NOTE. Make sure that the input voltage does not exceed
28V.
4. Check for the proper output voltages.
VOUT1 = 1.470V to 1.530V,
VOUT2 = 1.176V to 1.224V,
NOTE. 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 voltages are established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage, efficiency and
other parameters.
6. Different operating modes can be evaluated by changing position of jumper JP3.
V
A
VOUT1
Load
A
V
POWER
SUPPLY
A
VOUT2
Load
V
Figure 1. Proper Measurement Equipment Setup
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2
DEMO MANUAL DC1807A
QUICK START PROCEDURE
Figure 2. Measuring Output Voltage Ripple
Rail Tracking
Demonstration circuit 1807A is setup for independent turn-on
of VOUT1 and VOUT2. The ramp-rate for VOUT1 is determined
by the TRK/SS1 cap at C2 and the ramp-rate for VOUT2 is
determined by the TRK/SS2 cap at C47. The turn-on of one
rail will not affect the other for the original demo board.
This board can be modified on the bench to allow VOUT1
to track an external signal. It can also be modified to allow
VOUT2 to track VOUT1 or to allow VOUT2 to track an external
signal. Tables 2 and 3 cover the rail tracking options for
each rail, with the –B version used as an example.
Table.1 VOUT1 Tracking Options for a 1.5V Output.
TRACK 1 DIVIDER
CONFIGURATION
TRK/SS1 CAPACITOR
R3
R2
C2
Soft Start Without Tracking
0Ω
OPEN
0.1μF
External Coincident Tracking
17.8kΩ
20.0kΩ
OPEN
Table.2 VOUT2 Tracking Options for a 1.2V Output.
TRACK 2 DIVIDER
CONFIGURATION
R36
TRK/SS2 CAPACITOR
R34
R37
C47
Soft Start Without Tracking
0Ω
OPEN
OPEN
0.1μF
Coincident Tracking to VOUT1 (1.5V)
0Ω
10.0kΩ
20.0kΩ
OPEN
External Coincident Tracking
17.8kΩ
OPEN
20.0kΩ
OPEN
Single Output/Dual Phase Operation
A single output/dual phase converter may be preferred
for high output current applications. The benefits of single output/dual phase operation is lower ripple current
through the input and output capacitors, improved load
step response and simplified thermal design. To implement
single output / dual phase operation, make the following
modifications:
2. Tie ITH1 to ITH2 by stuffing 0 at R49. Turn on the power
at the input.
3. Tie VFB1 to VFB2 by stuffing 0 at R50.
4. Tie TRK/SS1 to TRK/SS2 by stuffing 0 at R52.
5. Tie RUN1 to RUN2 by stuffing 0 at R55.
6. Remove the redundant ITH compensation network and
VFB divider.
1. Tie VOUT1 to VOUT2 by tying together the exposed copper pads near J3 and J5 at the edge of the board. Use
a piece of heavy copper foil.
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DEMO MANUAL DC1807A
QUICK START PROCEDURE
95
90
85
EFFICIENCY (%)
80
75
70
65
6.5VIN,1.5VOUT, RSENSE, 400kHz
12VIN,1.5VOUT, RSENSE, 400kHz
60
14VIN,1.5VOUT, RSENSE, 400kHz
55
50
0
3
6
9
12
15
LOAD CURRENT (A)
95
90
85
EFFICIENCY (%)
80
75
70
65
6.5VIN,1.2VOUT, RSENSE, 400kHz
60
12VIN,1.2VOUT, RSENSE, 400kHz
14VIN,1.2VOUT, RSENSE, 400kHz
55
50
0
3
6
9
12
15
LOAD CURRENT (A)
Figure 3. Typical Efficiency Curves vs Load Current with A-A (RSENSE) Board for: (A) 1.5V Rail and (B) 1.2V Rail
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DEMO MANUAL DC1807A
QUICK START PROCEDURE
95
90
EFFICIENCY (%)
85
80
75
70
65
6.5VIN,1.5VOUT, DCR SENSE, 400kHz
60
12VIN,1.5VOUT, DCR SENSE, 400kHz
55
14VIN,1.5VOUT, DCR SENSE, 400kHz
50
0
3
6
9
12
15
LOAD CURRENT (A)
95
90
EFFICIENCY (%)
85
80
75
70
65
6.5VIN,1.2VOUT, DCR SENSE, 400kHz
60
12VIN,1.2VOUT, DCR SENSE, 400kHz
55
14VIN,1.2VOUT, DCR SENSE, 400kHz
50
0
3
6
9
12
15
LOAD CURRENT (A)
Figure 4. Typical Efficiency Curves vs Load Current with A-B (DCR Sense) Board for: (A) 1.5V Rail and (B) 1.2V Rail
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DEMO MANUAL DC1807A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
CAP, 180μF 20% 16V OSCON
CAP, 1210 10μF 10% 16V X5R
CAP, 1210 100μF 20% 6.3V X5R
CAP, 7343 330μF 20% 2.5V POSCAP
CAP, 0603 0.1μF 10% 25V X7R
CAP, 0805 4.7μF 10% 6.3V X5R
CAP, 0603 100pF 5% 25V X7R
CAP, 0603 220pF 5% 25V X7R
CAP, 0603 1μF 20% 16V X7R
CAP, 0603 1nF 10% 50V X7R
DIODE,CMDSH-3 SOD323
XSTR, N-CHANNEL MOSFET
XSTR, N-CHANNEL MOSFET
RES, 2010 0.002Ω 5% 1/2W
RES, 0603 0Ω JUMPER
RES, 0603 100Ω 5% 1/10W
RES, 0603 10kΩ 1% 1/16W
RES, 0603 2.2Ω 5% 1/10W
RES, 0603 30.1kΩ 1% 1/10W
RES, 0603 5.9kΩ 1% 1/10W
RES, 0603 20kΩ 1% 1/10W
RES, 0603 102kΩ 5% 1/10W
RES, 0603 100kΩ 5% 1/10W
IC, Dual, 2-Phase Synchronous StepDown DC/DC Controllers
IND, 0.47μH
SANYO OSCON 16SVP180MX
TAIYO YUDEN EMK325BJ106KN-T
TDK C3225X5R0J107MT
SANYO 2R5TPE330M9
TDK C1608X7R1E104K
AVX 08056D475KAT
AVX 06033C101JAT
AVX 06033C221JAT2A
AVX 0603YC105MAT2A
AVX 06035C102KAT
CENTRAL CMDSH-3-LTC
INFINEON BC050NE2LS
INFINEON BSC010NE2LS
VISHAY WSL20102L000FEA
PANASONIC ERJ3GEY0R00V
VISHAY CRCW0603100RJNEA
VISHAY CRCW060310K0FKEB
YAYEO RC0603JR-072R2
YAYEO RC0603FR-0730K1
VISHAY CRCW06035K9FKEA
YAYEO RC0603FR-0720K
VISHAY CRCW0603102KJNEA
VISHAY CRCW0603100KJNEB
LINEAR TECH.LTC3869EUFD
Required Circuit Components
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
1
2
2
4
5
3
1
1
1
2
2
2
2
2
7
4
1
1
1
2
3
1
1
1
CIN1
CIN2, CIN3
COUT1, COUT4
COUT2, COUT3, COUT5, COUT6
C2, C17, C20, C21, C47
C11, C32, C36
C42
C43
C50
C14, C15, C41, C44
D1, D2
Q1, Q3
Q2, Q4
RS1, RS2
R1, R3, R9, R25, R36, R48, R54
R29, R30, R39, R40
R4
R18
R27
R31, R35
R32, R33, R43
R10
R46
U1
25
2
L1, L2
VITEC 59PR9875, 0.4μH
Additional Circuit Components
1
0
CIN4, CIN5
CAP, 1210 OPTION
OPTION
2
0
C1,C37,C38,C48,C49
CAP, 0603 OPTION
OPTION
3
0
R2, R26, R28, R34, R37, R38,
R41, R42, R44, R45, R47, R49,
R50, R51, R52, R53, R55, R60,
R61, R62
RES, 0603 OPTION
OPTION
4
0
Q5, Q6, Q7, Q8
DO NOT STUFF
OPTION
12
E1-E6, E9-E14
TURRET
MILL-MAX 2501-2-00-80-00-00-07-0
Hardware
1
2
2
JP1, JP2
HEADER, 3 PIN, 2mm
SAMTEC TMM-103-02-L-S
3
1
JP3
HEADER, 4 PIN
SAMTEC TMM-104-02--L-S
4
6
J1, J2, J3, J4, J5, J6
JACK, BANANA
KEYSTONE 575-4
5
3
JP1-JP3
SHUNT, 2mm
SAMTEC 2SN-BK-G
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DEMO MANUAL DC1807A
SCHEMATIC DIAGRAM
dc1807af
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 DC1807A
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
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Linear Technology Corporation
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