1
dc2220afb
DEMO MANUAL DC2220A
DESCRIPTION
LTC3643
Bidirectional Charger/Regulator for
System Power Backup
Demonstration circuit 2220A is a 2A, bidirectional charger/
regulator featuring the LT C
®
3643, a bidirectional synchro-
nous step-up charger and step-down converter. DC2220A
implements backup by charging a storage capacitor up to
40V in boost mode, when the input voltage is present. It
discharges the storage capacitor in buck mode, providing
a regulated load voltage of 3V to 17V (set to 5V), when
the input is interrupted. Its wide voltage range, both in
capacitor charger mode and in system backup mode,
makes it well suited to a wide variety of applications. The
ability of the LTC3643 to boost an input rail to a relatively
high voltage of 40V, combined with the DC2220 option of
adding external capacitor banks, makes this regulator an
excellent choice for energy storage applications.
The DC2220A features automatic switching from charge
to backup mode, 2A input current limit during charging,
the ability to set maximum current in the backup mode of
operation, Burst Mode
®
operation, fast 1MHz switching
frequency, and open-collector outputs to indicate charge
status and input power fail.
The 1MHz constant-frequency operation results in a small
and efficient circuit. In backup mode, the LTC3643 provides
high output voltage accuracy over a wide load range with
no minimum load requirement.
PERFORMANCE SUMMARY
Demo circuit 2220A is set up for automatic mode opera-
tion. In this mode, the DC2220 automatically charges the
energy storage capacitor when a system voltage is present.
It automatically switches to work as a step-down DC/DC
converter providing system backup power to the load when
system power is removed. An on board MOSFET isolates
the backup circuit from the input line if the system voltage
is not present, implementing PowerPath™ functionality.
The DC2220A supports three levels of load current limits:
2A, 3A and 4A when working as step-down converter
discharging the energy storage capacitor.
The DC2220A has a small circuit footprint. It is a high
performance and cost effective solution for high voltage
capacitor backup converters, servers, solid-state drives,
RAID and RF systems.
The LTC3643's input disconnect circuitry protects the
DC2220A from short circuit and overcurrent conditions
in the boost mode of operation, in case a short circuit oc-
curs on a high voltage rail. A similar circuit protects the
DC2220A against a short circuit in step-down mode, when
the load is supplied from an energy storage capacitor.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2220A
L, LT, LTC, LTM, Linear Technology, Burst Mode 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.
Specifications are at TA = 25°C
PARAMETER CONDITIONS UNITS
Minimum Input Supply Voltage 3.0 V
Maximum Input Supply Voltage 17.0 V
System Voltage Range Backup (Step-Down) Mode 3.0 to 17.0 V
Energy Storage Capacitor Voltage Range 3.0V to 40V V
Typical Switching Frequency 1.0 MHz
Efficiency Typical, Backup Mode VCAP = 12V, VLOAD = 5.0V, ILOAD = 0.5A 93 %
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dc2220afb
DEMO MANUAL DC2220A
QUICK START PROCEDURE
Demonstration circuit 2220A is easy to set up to evaluate
the performance of the LTC3643 bidirectional regulator.
Refer to Figure 1 for the 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.
To verify the capability of the DC2220A for charging energy
storage capacitors, proceed with the following steps:
1. Place jumper RUN (JP1) to OFF position.
2. Place jumper ILIM_BUCK (JP2) to 2.0A position.
3. With power off, connect the input power supply to
terminals VIN (E1) and GND, voltmeter to VCAP (E8)
and GND, load to LOAD (E3) and GND as shown on
Figure1.
Figure1. Proper Measurement Equipment Setup
20V
POWER
SUPPLY
LOAD
–
+
+
–
+–
GND
VIN
Figure2. Measuring Input or Output Ripple
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dc2220afb
DEMO MANUAL DC2220A
QUICK START PROCEDURE
4. Turn the input power source on and slowly increase
the input voltage to 5.5V. Set the load to 0.1A. You
have to see voltage around 4.8V on terminal LOAD,
a diode forward voltage drop lower compared to VIN.
If there is no output, temporarily disconnect the load
to make sure that the load is not set too high.
5. Place jumper RUN (JP1) in the ON position. Voltage
on VCAP terminal should rise to 39V level. Voltage on
terminal LOAD should be equal to input voltage.
To verify the ability of DC2220 to work in backup mode,
proceed with the following:
6. Disconnect input power from VIN terminal; energy
storage capacitor C5 starts discharging from 39V level,
however LTC3643 will maintain a voltage of 5.0V on
terminal LOAD.
7. To increase holdup time, install optional capacitor C6
on the bottom side of DC2220A or connect additional
capacitor bank to terminals VCAP (E8) and GND (E7).
200µs/DIV
1V/DIV
DC2220 F03a
VLOAD
VIN
PFI
3a
50ms/DIV
3b
1V/DIV
DC2220 F03b
VLOAD
VIN
PFI
LOAD CURRENT (A)
EFFICIENCY (%)
96
94
90
88
92
95
93
89
87
91
86
DC2220 F04
0 2.5 321 1.50.5
Figure3. Power interruption, VLOAD 5.0V, ILOAD 0.5A
Figure4. Efficiency vs Load, VCAP 12V, LOAD 5.0V, Step-Down Mode
8. Repeat steps 1 to 7 for different load currents and VIN
voltages.
9. You can measure voltage regulation and ripple in
backup mode on VLOAD terminals.
10. Make sure that input voltage on VIN terminals does not
exceed 17V and VCAP voltage is not set above 40V.
Figure 3 illustrates power interruption. In the beginning of
the process VIN (yellow) is 5.5V and supplies LOAD rail,
PFI signal is low and step-down converter is OFF. Once
VIN value is reduced to 4.75V, PFI signal changes state
to high, the step-down converter turns ON and starts to
supply the LOAD rail by 5.0V taking energy from the storage
capacitor C5. The efficiency curve is presented in Figure 4.
The efficiency measurement was conducted in step-down
mode. A constant DC voltage of 12V was applied to the VCAP
and GND terminals with the input voltage disconnected
from the VIN and GND terminals.
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dc2220afb
DEMO MANUAL DC2220A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 CAP., X7R, 0.1µF, 25V, 10%, 0603 AVX, 06033C104KAT2A
2 1 C2 CAP., X5R, 4.7µF,16V, 10%, 0805 TDK C2012X5R1C475K
3 1 C3 CAP., C0G, 470pF 50V, 5%, 0603 AVX, 06035A471JAT2A
4 1 C4 CAP., C0G, 22pF, 25V, 5%, 0603 AVX, 06033A220JAT2A
5 1 C5 CAP., ALUM., ELECT., 1000µF, 50V, 16x16.5 PANASONIC, EEEFK1H102AM
6 2 C9, C11 CAP., POS 47µF, 20V, 20%,TQC-D2 PANASONIC, 20TQC47MYF
7 1 C10 CAP., X7R, 4.7µF, 50V, 10%,1210 AVX, 12105C475KAT2A
8 3 C12, C13, C14 CAP., X7R, 10µF, 50V, 10%, 210 AVX, 12105C106KAT2A
9 1 C15 CAP., X7S, 1µF, 100V, 10%, 0805 TDK C2012X7S2A105K
10 1 L1 IND, 7.2µH POWER SUMIDA, CDEP105NP-7R2MC-88
11 1 Q1 MOSFET, P-CHN, 30V, LFPAK VISHAY, Si4491EDY-T1-GE3
12 1 R1 RES., CHIP, 511k, 1/10W, 1%, 0603 VISHAY, CRCW0603511KFKEA
13 1 R2 RES., CHIP, 0.01, 1/4W, 1%, 1206 VISHAY, WSL1206R0100FEA
14 1 R3 RES., CHIP, 133k, 1/16W, 1%, 0603 VISHAY, CRCW0603133KFKEA
15 1 R4 Res., CHIP, 1MEG, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA
16 1 R5 RES., CHIP, 37.4k, 1/10W, 1%, 0603 VISHAY, CRCW060337K4FKEA
17 2 R6, R11 RES., CHIP, 5.11k, 1/10W, 1%, 0603 VISHAY, CRCW06035K11FKEA
18 2 R7, R8 RES., CHIP, 510k, 1/10W, 1%, 0603 VISHAY, CRCW0603510KFKEA
19 1 R9 RES., CHIP, 402k, 1/10W, 1%, 0603 VISHAY, CRCW0603402K0FKEA
20 1 R10 RES., CHIP, 332k, 1/10W, 1%, 0603 VISHAY, CRCW0603332KFKEA
21 1 U1 I.C., LTC3643EUDD, QFN24UDD-3X5 LINEAR TECH., LTC3643EUDD#PBF
Additional Demo Board Circuit Components
1 C6 CAP., ALUM. OPTION,16X16.5 OPT
2 C7, C8 CAP., OPTION, 0603 OPT
3 R12 RES., OPTION, 0603 OPT
Hardware: For Demo Board Only
1 10 E1 – E10 TP, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 HEADER, 1X3, 0.079 SINGLE ROW WURTH, 620-003-111-21
3 1 JP2 HEADER, 1X4, 0.079 SINGLE ROW WURTH, 620-004-111-21
4 2 XJP1, XJP2 SHUNT, 0.079" CENTER WURTH, 608-002-134-21
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dc2220afb
DEMO MANUAL DC2220A
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.
Figure5. DC2220A Demo Circuit Schematic
SCHEMATIC DIAGRAM
5
5
4
4
3
3
2
2
1
1
D
D
C
C
B
B
A
A
LOAD
3V - 17V
VIN
GND
GND
50V
1. ALL RESISTORS AND CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
CAPGD
/PFO
40V BACKUP
5V SYSTEM BUS
GND
CAP
GND
100V
40V MAX
PFI
INTVCC
INTVCC
INTVCC
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
VK
PRODUCTION 51-10-92
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
VK
PRODUCTION 51-10-92
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
VK
PRODUCTION 51-10-92
SIZE
DATE:
.VER.ON CI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Tuesday, September 01, 2015
1 1
BIDIRECTIONAL HIGH VOLTAGE BACKUP CONVERTER
LT
VK
N/A
LTC3643EUDD
DEMO CIRCUIT 2220A
SIZE
DATE:
.VER.ON CI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Tuesday, September 01, 2015
1 1
BIDIRECTIONAL HIGH VOLTAGE BACKUP CONVERTER
LT
VK
N/A
LTC3643EUDD
DEMO CIRCUIT 2220A
SIZE
DATE:
.VER.ON CI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Tuesday, September 01, 2015
1 1
BIDIRECTIONAL HIGH VOLTAGE BACKUP CONVERTER
LT
VK
N/A
LTC3643EUDD
DEMO CIRCUIT 2220A
E8
R1
511K
R7
510K
U1
LTC3643EUDD
CAP 3
INDIS 17
PFI
13 BOOST 15
INDIS 16
INTVCC 14
SW 18
NC 22
PGND
1
SW 20
SW 19
ILIM 21
CLP
24
PGND
2NC 23
IN
5
FBCAP 9
/PFO
12
ITH 10
CAPGD
11
GATE
6
FBSYS
8
IN
4
RUN
7
PGND
25
E3
E6
C12
10uF
1210
+
C6
OPT
C7
OPT
E4
JP1
ON
OFF
RUN
1
3
2
C14
10uF
1210
R4
1MEG
C15
1uF
0805
C3
470pF
R6
5.11K
+
C9
47uF
+
C5
1000uF
C8
OPT
E5
E2
E7
R12
OPT
C1
0.1UF
C13
10uF
1210
C10
4.7uF
1210
R2
0.01
1210
C4
22pF R11
5.11K
E1
+
C11
47uF
R10
322K
JP2
2A
3A
4A
ILIM_BUCK
1
2
3
4
R9
402K
L1
7.2uH
E9
R5
37.4K
R8
510K
Q1
SI4491EDY
1
2
5
3
4
C2
4.7uF
0805
R3
133K
E10
6
dc2220afb
DEMO MANUAL DC2220A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
LINEAR TECHNOLOGY CORPORATION 2015
LT 0116 REV B • 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 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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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
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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 applica-
tion engineer.
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