DC1 1 2 3
Q U ICK S TA R T G U IDE
LTC3 5 6 2
L in e a r U S B B a tte ry Ch a rg e r w ith Du a l B u c k R e g u la to rs
DESCRIPTION
Demonstration circuit 1123 is a Linear USB Battery
Charger w ith Dual Buck Regulators featuring the
LTC3562. The LTC3562 is a quad high efficiency mono-
lithic synchronous step-dow n regulator w ith an I2C inter-
face. Tw o regulators are externally adjustable and can
have their feedback voltages programmed betw een
425mV and 800mV in 25mV (Type A). The other tw o
regulators are fixed output regulators w hose output volt-
ages can be programmed betw een 600mV and 3.775V in
25mV steps (Type B). All four regulators operate inde-
pendently and can be put into pulse skip, LDO, Burst
M ode operation or forced Burst M ode operation through
I2C control. The Type A regulators have separate RUN
pins that can be enabled if I2C control is unavailable.
At low output load conditions, the regulators can be
sw itched into LDO, Burst M ode operation or forced Burst
M ode operation, extending battery life in portable sys-
tems. The quiescent current drops to under 100µA w ith
all regulators in LDO mode and under 0.1µA w hen all
regulators are shut dow n
Sw itching frequency is internally set to 2.25M Hz, allow -
ing the use of small surface mount inductors and capaci-
tors. All regulators are internally compensated.
The LTC3562 is offered in a low profile 3mm
QFN package.
4
3mm
Design files for this circuit board are available. Call
the LTC factory.
The 2.85V to 5.5V input range makes the LTC-3562 ide-
ally suited for single Li-ion battery pow ered applications.
L
, LTC, LTM , LT, Burst M ode, are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective ow ners.
TABLE 1. Typical Specifications (25°C)
2.85V to 5.5V (Subject to dropout)
0.96V to 1.82V, 600mA (M ax)
1.20V to 3.775V, 600mA (M ax)
0.80V to 1.51V, 400mA (M ax)
0.60V to 3.775V, 400mA (M ax)
Input Voltage Range: V
P600A
CC
P600B
P400A
P400B
OPERA TING PRINCIPLES
The LTC3562 is a highly integrated pow er management
IC that contains four I2C controllable, monolithic, high
efficiency step-dow n regulators. Tw o regulators pro-
vide up to 600ma of output current and the other tw o
regulators produce up to 400ma. All four regulators
are 2.25M Hz, constant-frequency, current mode
sw itching regulators that can be independently con-
trolled through I2C. All regulators are internally com-
pensated eliminating the need for external compensa-
tion components.
The LTC3562 offers tw o different types of adjustable
step-dow n regulators. The tw o Type A regulators
(R600A, R400A) can have the feedback voltage ad-
justed from 425mv to 800mv in 25mv increments. The
tw o Type B regulators (R600B, R400B) can have the
1
DC1123 QUICK START GUIDE
17. Set Load1 and Load2 to 450mA. Set Load3 and
Load4 to 300mA. Adjust PS1 over the operating range
and observe line regulation.
input damping netw ork w ill likely not be required.
Please note that the in-circuit capacitance of the
specified 10uF, 0805 ceramic capacitor for C1 and C2
is less than 5uF each w ith VIN greater than 4.25 Volts.
For good transient response and stability the output
capacitor each buck regulator should retain at least
4uF of capacitance over the operating temperature
and voltage range.
A PPLICA TION INFORM A TION
This demo circuit is designed to demonstrate the full
capability of the LTC3562 I2C Quad Synchronous
Step-Dow n DC-DC Regulator. Not all components are
required in all applications. The critical circuit com-
ponents are on the top of the board near the IC and
listed in the Required Circuit Components section of
the Bill of M aterials, in Figure 5.
The output inductors for the OUT600A and OUT600B
are the recommended values of 3.3uH w hile the
OUT400A and OUT400B are 4.7uH.
Resistors R4 and R6 are to adjust the output voltage
seen on the OUT600A output w hile R3 and R4 w ill set
the voltage on the OUT400A output.
The input capacitor netw ork of C1 and R1 is used to
dampen source lead inductances that commonly oc-
cur in laboratory setups w ith tw isted leads and a
bench pow er supply. W hen using a USB cable this
3
DC1123 QUICK START GUIDE
Figure 1. Proper M easurem ent Equipm ent Setup
Figure 2. M easuring Input or Output Ripple
4
DC1123 QUICK START GUIDE
Figure 3.
Figure 3. Graphical User Interface
5
DC1123 QUICK START GUIDE
Figure 4. Circuit Schem atic
6
DC1123 QUICK START GUIDE
Item Qty
Reference - Des
Part Description
Manufacturer, Part #
REQUIRED CIRCUIT COMPONENTS:
CAP, CHIP X5R, 10uF, 10V, 0805
1
2
3
4
5
6
7
8
9
1
4
2
2
2
1
1
1
1
2
C2
C4,C7,C8,C9
C5,C6
L2,L4
L1,L3
R3
Murata, GRM21BR61A106KE19
TDK, C1608X5R0J106M
Murata, GRM1557U1H100JZ01D
TOKO, 1098AS-3R3M
CAP, CHIP,X5R, 10uF, 6.3V, 0603
CAP, CHIP, COG, 10pF, 50v, 0402
INDUCTOR, 3.3uH, 0.120 Ohms, 1.0A
INDUCTOR, 4.7uH, 0.155 Ohms, 0.88A
RES, 0402, 475K OHMS, 1%, 1/16w
RES, 0402, 634K OHMS, 1%, 1/16w
RES, 0402, 536K OHMS, 1%, 1/16w
RES, 0402, 499K OHMS, 1%, 1/16w
TOKO, 1098AS-4R7M
VISHAY, CRCW0402475KFKED
VISHAY, CRCW402634KFKED
VISHAY, CRCW402536KFKED
VISHAY, CRCW0402499KFKED
VISHAY, CRCW04023M30JNED
R4
R5
R6
10
R12,R13
RES, 0402, 3.3M OHMS, 5%, 1/16w
I2C QUAD SYNCHRONOUS STEP-DOWN
DC/DC REGULATOR
11
1
U1
LINEAR TECH, LTC3562EUD
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS:
1
2
3
4
5
6
7
2
1
1
1
4
1
1
C10,C11
CAP, CHIP, X5R, 0.1uF, 10V
CAP, CHIP,X5R, 10uF, 10V
RES, 0402, 0.0 Ohms, 1/16w
RES, 0402, 100K Ohms, 5%, 1/16w
RES, 0402, 5.1K OHMS, 5%, 1/16w
RES, 0402, 1 OHM, 5%, 1/16w
SERIAL EEPROM
TDK, C1005X5R1A104K
C1
R7
R2
TDK, C2012X5R0J106M
VISHAY, CRCW04020000Z0ED
VISHAY, CRCW0402100KJNED
VISHAY, CRCW04025K1JNED
VISHAY, CRCW04021R00JNED
MICROCHIP, 24LC025-I/ST
R8,R9,R10,R11
R1
U2
HARDWARE FOR DEMO BOARD ONLY:
HEADER,3 PINS, 2mm
1
2
3
4
2
2
1
1
JP1,JP2
JP1,JP2
J1
SAMTEC, TMM-103-02-L-S
SAMTEC, 2SN-BK-G
TYCO, 1734035-2
MOLEX/WALDEN, 87831-1420
SHUNT, 2mm
CONN, USB MINI-B
HEADER, 2X7 PIN, 0.079CC
J2
E1,E5,E6,E7,E8,
E9,E15,E16,E17,
E18
5
10
TURRET, 0.09 DIA
MILL-MAX, 2501-2
E2,E3,E4,E10,E11,
E12,E13,E14
6
7
8
4
TURRET, 0.061 DIA
MILL-MAX, 2308-2
STAND-OFF, NYLON 0.25" tall (SNAP ON)
KEYSTONE, 8831 (SNAP ON)
Figure 5. Bill of M aterials
7
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