LTC3556_15 Datasheet, PDF (1/36 Pages) Linear Technology – High Effi ciency USB Power Manager with Dual Buck and Buck-Boost DC/DCs

FEATURES
POWER MANAGER
n _{High Efficiency Switching PowerPath}^TM _Controller
with Bat-Track^TM Adaptive Output Control
n _{Programmable USB or Wall Current Limit}
(100mA/500mA/1A)
n _{Full Featured Li-Ion/Polymer Battery Charger}
n _{Instant-On Operation with a Discharged Battery}
n _{1.5A Maximum Charge Current}
n _{Internal 180mΩ Ideal Diode Plus External Ideal Diode}
Controller Powers Load in Battery Mode
n _{Low No-Load IQ when Powered from BAT (<30μA)}
DC/DCs
n _{Dual High Efficiency Buck DC/DCs (400mA/400mA IOUT)}
n _{High Efficiency Buck-Boost DC/DC (1A IOUT)}
n _{All Regulators Operate at 2.25MHz}
n _{Dynamic Voltage Scaling on Two Buck Outputs}
n _I²_{C Control of Enables, Mode, Two VOUT Settings}
n _{ENALL Pin with Power-Up Sequence Control}
n _{Low No-Load Quiescent Current: 20μA Each}
APPLICATIONS
n _{HDD-Based MP3 Players, PDAs, GPS, PMPs}
n _{Other USB-Based Handheld Products}
LTC3556
High Efficiency USB Power
Manager with Dual Buck
and Buck-Boost DC/DCs
DESCRIPTION
The LTC^®3556 is a highly integrated power management
and battery charger IC for Li-Ion/Polymer battery applica-
tions. It includes a high efficiency current limited switching
PowerPath manager with automatic load prioritization, a
battery charger, an ideal diode, and three synchronous
switching regulators (two bucks and one buck-boost).
Designed specifically for USB applications, the LTC3556’s
switching power manager automatically limits input cur-
rent to a maximum of either 100mA or 500mA for USB
applications or 1A for adapter-powered applications.
The LTC3556’s switching input stage transmits nearly all of
the 2.5W available from the USB port to the system load
with minimal power wasted as heat. This feature allows
the LTC3556 to provide more power to the application and
eases the constraint of thermal budgeting in small spaces.
The two buck regulators can provide up to 400mA each
and the buck-boost can deliver 1A.
The LTC3556 is available in the low profile 28-pin (4mm
× 5mm × 0.75mm) QFN surface mount package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. PowerPath
and Bat-Track are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 6522118 and 6404251.
TYPICAL APPLICATION
High Efficiency PowerPath Manager, Dual Buck, Buck-Boost and LDO
USB/WALL
4.5V TO 5.5V
CHARGE
ENALL
SEQ
3
I²C
USB COMPLIANT
STEP-DOWN
REGULATOR
CC/CV
BATTERY
0V
CHARGER
LTC3556
ALWAYS ON LDO
DUAL HIGH EFFICIENCY ¹
BUCKS
2
HIGH EFFICIENCY
BUCK-BOOST
3
I²C PORT
TO OTHER
LOADS
OPTIONAL
+
T
Li-Ion
3.3V/25mA
0.8V TO 3.6V/400mA
0.8V TO 3.6V/400mA
RTC/LOW
POWER LOGIC
MEMORY
CORE
μP
2.5V to 3.3V/1A
PGOODALL
HDD/IO
3556 TA01
Battery Charge Current
vs Battery Voltage
700
BATTERY CHARGE CURRENT
600 _{EXTRA CURRENT}
FOR FASTER CHARGING
500
500mA USB CURRENT LIMIT
400
300
200
V_BUS = 5V
100 5X MODE
BATTERY CHARGER PROGRAMMED FOR 1A
0
2.8 3 3.2 3.4 3.6 3.8 4 4.2
BATTERY VOLTAGE (V)
3556 TA01b
3556f
1