DC2045A - Demo Manual

DEMO MANUAL DC2045A
LTC3118EUFD
18V, 2A Buck-Boost DC/DC Converter
with Low-Loss Dual Power Path
Description
Demonstration Circuit 2045A featuring the LTC3118 is a
dual input fixed frequency synchronous buck-boost converter with an intelligent integrated low-loss Power-Path™.
The unique all N-Channel architecture provides efficient
operation from either input source to a programmable
output voltage above, below or equal to the input. Voltage capability of up to 18V provides flexibility and voltage
margin for a variety of applications and power sources.
The LTC3118 uses a low noise, current mode architecture
with a fixed 1.2MHz PWM mode frequency that minimizes
the solution footprint. For high efficiency at light loads,
automatic Burst Mode™ operation can be selected consuming only 50μA of quiescent current in sleep.
Typical efficiencies for both Burst Mode and fixed frequency
are shown in Figure 1. JP2 in the FIXED FREQ position
results in low output ripple but also lower efficiency at
light loads. Moving the JP2 position to AUTOBURST
enables Burst Mode operation which improves efficiency
at light load.
System level features include selectable IDEAL DIODE
Mode (shown in Figure 2) or PRIORITY mode operation
(shown in Figure 3)
The system can be monitored through V1GD, V2GD and
PGD (power good) indicators There are accurate RUN
comparators to program independent UVLO thresholds,
and output disconnect in shutdown. Other features include
2μA shutdown current, short-circuit protection, soft-start,
inductor current limit and thermal overload protection.
The DC2045A circuit has excellent transient load response
in both fixed frequency and automatic Burst Mode operation as shown in Figures 4 and 5.
The LTC3118 data sheet has detailed information about
the operation, specifications, and applications of the part.
The data sheet should be read in conjunction with this
Quick Start Guide.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2045A
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Performance Summary
Specifications are at TA = 25°C
Input Voltage Range:
2.5V to 18.0V
VOUT
5.0V
IOUT
2.0A for VIN > 5.0V
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DEMO MANUAL DC2045A
Quick Start Procedure
100
90
80
EFFICIENCY (%)
70
60
50
VIN=3.3V, BURST MODE
40
VIN=5V, BURST MODE
30
VIN=12V, BURST MODE
20
VIN=3.3V, FIXED FREQ
VIN=5V, FIXED FREQ
10
VIN=12V, FIXED FREQ
0
1
10
100
1000
10000
LOAD (mA)
Figure 1. Typical Efficiency as a Function of Input Voltage and Load Current
VOUT = 100mV/DIV
VOUT DC = 5V
VIN1 = 2V/DIV
VIN1 PEAK = 10V
VIN1 VALLEY = 4V
VIN2 = 2V/DIV
VIN2 DC = 8V
Figure 2. Ideal Diode Mode Operation
VIN1 = 2V/DIV
VOLTAGE PEAK = 10V
VOLTAGE VALLEY = 1V
VOUT = 500mV/DIV
VOUT DC = 5V
IIN1 = 500mA/DIV
VIN2 = 14V and is Not Shown on Screen
Figure 3. Transitioning from VIN1 to VIN2 and Back in PRIORITY Mode Operation with VIN2 at 14V
2
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DEMO MANUAL DC2045A
Quick Start Procedure
OUTPUT VOLTAGE
OUTPUT CURRENT
Figure 4. 100mA to 600mA Load Transient with VIN1 = 3.5V in Fixed Frequency Mode
OUTPUT VOLTAGE
OUTPUT CURRENT
Figure 5. 50mA to 600mA Load Transient with VIN1 = 3.5V in Burst Mode
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DEMO MANUAL DC2045A
Quick Start Procedure
Using short twisted pair leads for any power connections
and with all loads and power supplies off, refer to Figure 6
for the proper measurement and equipment setup. The
Power Supplies should not be connected to the circuit
until told to do so in the procedure below.
When measuring the input or output voltage ripple, care
must be taken to avoid a long ground lead on the oscilloscope probe.
The indicators for PGD, V1GD and V2GD are negative
logic. PGD indicates the output voltage is good if it is
pulled to ground and V1GD and V2GD indicate that the
input voltage on the respective sources are good if the
pins are pulled to ground.
1. JP1 and JP2 settings to start:
JP1 SELECT = IDEAL DIODE (VCC)
JP2 MODE
= FIXED FREQ (VCC)
2. With power OFF connect the power supplies (PS1,
PS2) as shown in Figure 6. If accurate current measurements are desired (for efficiency calculations for
example) then connect the ammeters in series with
the supplies as shown. The ammeters however, are
not required.
3. Connect the load, set at 50Ω, to VOUT as shown in
Figure 6. Again, connect an ammeter if accurate current
measurement or monitoring is desired.
7. Turn off PS1 and repeat steps 3 to 6 with PS2. The part
will turn on with PS2 at approximately 4.5V. Once on,
PS2 can be varied between 3.8V and 18V. The voltage
measurements of step 5 will change where V1GD will
be at VCC and V2GD will be pulled low. Set the load to
50Ω.
8. Set PS2 to 7V and turn on PS1 slowly increasing the
voltage from 0V to 8V. Note that PS1 starts to supply
the power as the voltage of PS1 exceeds the voltage
on PS2 by at least 400mV.
9. Now decrease the voltage on PS1 and observe that
when the voltage on VIN1 falls below the voltage on
PS2, PS1 stops supplying the power and PS2 takes
over. See Figure 2 for typical performance for steps
8 and 9.
10. Turn off PS1 and PS2. Change the SELECT jumper
(JP1) to VCC (the PRIORITY position). Turn on PS2
and adjust it to 14V.
11. By cycling the voltage on PS1 from 1V to 10V you can
observe the transition of power from PS2 to PS1 and
back as the voltage on VIN1 goes through its startup
(approximately 2.9V) and shutdown (approximately
2.5V) thresholds. Typical response is shown in Figure 3.
Turn off PS1 and PS2.
Steps 12 and 13 are optional for looking at load step
response if desired.
4. Turn on the Power Supply, PS1, and slowly increase
the voltage. The converter will start at approximately
2.9V.
12. With JP2 in the FIXED FREQ position and PS1 at 3.5V
switch the load from 100mA to 600mA and back. Note
the output voltage response. (Figure 4).
5. Verify VOUT is ~5.0V, and that V2GD is pulled high by
VCC and PGD and V1GD are pulled low.
13. With JP2 in AUTOBURST and PS1 at 12V switch the
load from 50 mA to 600 mA and back. Note the output
voltage ripple. (Figure 5). See the data sheet for more
information.
6. PS1 can now be varied between 2.5V and 18.0V. VOUT
will remain in regulation for load currents up to 2 amps
with VIN greater than VOUT. As VIN1 falls below VOUT the
input current may increase to the maximum average
inductor current, depending on the load, which will
then limit the load current and the output voltage.
4
Note: Remove D1 for VOUT > 5V to prevent damage to
the converter.
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DEMO MANUAL DC2045A
Quick Start Procedure
PGD
AM2
10k
PS2
AM3
VM2
VM3
LOAD
AM1
10k
PS1
VM1
V2GD
V1GD
Figure 6. Measurement Setup
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DEMO MANUAL DC2045A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
CAP., 22µF, X7R, 25V, 20%, 1812
TDK, C4532X7R1E226M250KC
Required Circuit Components
1
2
C1, C4
2
3
C2, C5, C9
3
0
C3, C6
4
2
5
6
7
CAP., 1µF, X7R, 25V, 10%, 0603
TDK, C1608X7R1E105K080AB
CAP., ALUM., RADIAL, 150µF, 50V, 20%
PANASONIC, EEU-FM1H151
C7, C8
CAP., 47µF, X5R, 10V, 20%, 1812
TDK, C4532X5R1A476M280KA
1
C10
CAP., 1800pF, C0G, 50V, 5%, 0603
TDK, CGJ3E2C0G1H182J080AA
1
C11
CAP., 22PF, NPO, 25V, 10%, 0603
KEMET, C0603C220K3GACTU
2
C12, C13
CAP., CER 0.1µF, 25V, 10%, X7R, 0603
TDK, C1608X7R1E104K
(OPT)
8
2
C14, C17
CAP., CER 0.047µF, 50V, 10%, X7R, 0603
TDK, C1608X7R1H473K080AA
9
2
C15, C16
CAP., 0.01µF, X7R, 25V, 10%, 0603
TDK, C1608X7R1E103K080AA
TDK, C1608X5R0J475M080AB
10
1
C18
CAP., 4.7µF, X5R, 6.3V, 20%, 0603
11
0
C19, C20, C21 (OPT)
CAP., OPTION, 0603
12
1
D1
DIODE, SCHOTTKY, 30V, 0.2A, SOD-523F
FAIRCHILD SEMI., BAT54XV2
13
1
L1
INDUCTOR, PWR., SHIELED, 3.3µH. XAL 40xx Series
COILCRAFT, XAL4030-332MEC
14
1
R1
RES., 402k, 1/16W, 1%, 0402
VISHAY, CRCW0402402KFKED
15
1
R2
RES., 100k, 1/16W, 1%, 0402
VISHAY, CRCW0402100KFKED
16
1
R3
RES., 40.2k, 1/16W, 1%, 0402
VISHAY, CRCW040240K2FKED
17
5
R4, R6, R8, R9, R10
RES., 1M, 1/16W, 1%, 0402
VISHAY, CRCW04021M00FKED
18
1
R5
RES., 715k, 1/16W, 1%, 0402
VISHAY, CRCW0402715KFKED
19
1
R7
RES., 374k, 1/16W, 1%, 0402
VISHAY, CRCW0402374KFKED
20
1
R11
RES., 49.9Ω, 1/16W, 1%, 0402
VISHAY, CRCW040249R9FKED
21
0
R12
RES., OPTION, 0402
22
1
U1
I.C.,18V, 2A BUCK-BOOST DC/DC CONVERTER WITH
LOW-LOSS DUAL INPUT POWERPATH
LINEAR TECHNOLOGY, LTC3118EUFD*PBF
23
12
E1-E12
TP, TURRET, 0.094", MTG. HOLE
MILL-MAX, 2501-2-00-80-00-00-07-0
24
2
JP1, JP2
CONN., HEADER, 1×3, 2mm
SAMTEC, TMM-103-02-L-S
25
2
XJP1-XJP2
SHUNT, 2mm
SAMTEC, 2SN-BK-G
26
4
STAND OFF
STANDOFF, NYLON, SNAP-ON, 0.625"
KEYSTONE, 8834 (SNAP ON)
27
1
PCB, DC2045A
DEMO CIRCUIT 2045A-2
28
2
STENCILS, DC2045A (TOP & BOTTOM)
STENCILS, DC2045A-2 - TOP & BOTTOM
6
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DEMO MANUAL DC2045A
Schematic Diagram
dc2045af
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.
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DEMO MANUAL DC2045A
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
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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
LT 0315 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
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