Linear Technology DC1296A Quick Start Manual

DESCRIPTION
Demonstration Circuit DC1296A is a High Efficiency
USB Power Manager + Dual Buck + Buck-Boost Con-
verters featuring the LTC
highly integrated power management and battery
charger IC for Li-Ion/polymer battery applications. It
includes a high efficiency current limited switching
PowerPath manager with automatic load prioritization,
a battery charger, an ideal diode and three general
purpose synchronous step-down switching regulators.
Designed specifically for USB applications, the
LTC3556's switching power manager automatically
limits input current to a maximum of either 100mA or
500mA for USB applications or 1A for AC-powered
applications. Unlike linear PowerPath controllers, the
LTC3556's switching input stage transmits nearly all of
the 2.5W available from the USB port to the system
PERFORMANCE SUMMARY
SYMBOL PARAMETER
VBUS Bus Input Voltage Range
LDO3V3 3.3V LDO Output Voltage Range
VBAT Battery Float Voltage
I Battery Charge Current
BAT
V Regulator 1 Output Voltage
OUT1
V Regulator 2 Output Voltage
OUT2
V Regulator 3 Output Voltage
OUT3
OPERATING PRINCIPLES
The LTC3556 is a Li-Ion battery charger/power manager
with two Buck regulators and Buck-Boost regulator. The
LTC3566 also contains an integrated Buck regulator that
can provide the pre-regulation function, called Bat-
Track™, from the USB input supply. This allows for
minimal power dissipation in the charger. The load pre-
sented to the USB port can be programmed to comply
Arrow.com.
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®
3556. The LTC3556 is a
Specifications are at T
CONDITIONS
Constant Voltage Mode
Constant Current Mode, R
IOUT1 ≤ 400mA
IOUT2 ≤ 400mA
IOUT3 ≤ 1A
DEMO CIRCUIT DC1296A
QUICK START GUIDE
LTC3556EUFD: High Efficiency
USB Power Manager with Dual Buck
and Buck-Boost DC/DCs
load with minimal power wasted as heat. This feature
allows the LTC3556 to provide more power to the ap-
plication and eases the constraint of thermal budgeting
in small spaces. The two buck switching regulators
can provide up to 400mA while the buck-boost regula-
tor can deliver 1A. The output voltage of one buck and
the buck-boost can be adjusted, over a 2 to1 range, via
2
the I C channel. The entire product can be started from
an external push button and subsequently controlled
2
via I C. The LTC3556EUFD is available in a 28-pin
(4mm × 5mm × 0.75mm) QFN surface mount pack-
age. Design files for this circuit board are available,
call the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation. PowerPath is a
trademark of Liner Technology Corporation.
= 25°C
A
= 2.00k
PROG
with the USB standards. This load can be set to 100mA,
or 500mA, as negotiated with the USB host, and is pro-
grammed using the I
sistance.
The current that the charger supplies to the battery is
also programmable via the PROG pin resistance. The
current available, simultaneous to charging the battery, is
MIN TYP MAX
4.35 6
3.1 3.4
4.15 4.23
485 515
0.8 1.6
1.7 1.8 1.9
2.65 3.3
2
C channel and the CLPROG pin re-
UNITS
V
V
mA
mA
V
V
V