LTC3557 Datasheet, PDF (1/28 Pages) Linear Technology – USB Power Manager with Li-Ion Charger and Three Step-Down Regulators

LTC3557/LTC3557-1
USB Power Manager with
Li-Ion Charger and Three
Step-Down Regulators
FEATURES
■ _{Seamless Transition Between Input Power Sources:}
Li-Ion Battery, USB, 5V Wall Adapter or High
Voltage Buck Regulator with Bat-Track^TM
■ _{200mΩ Internal Ideal Diode Plus Optional External}
Ideal Diode Controller Provides Low Loss Power
Path When Input Current is Limited or Unavailable
■ _{Triple Adjustable High Efficiency Step-Down}
Switching Regulators (600mA, 400mA, 400mA I_OUT)
■ _{Pin Selectable Burst Mode}^® _Operation
■ _{Full Featured Li-Ion/Polymer Battery Charger}
■ _{1.5A Maximum Charge Current with Thermal Limiting}
■ _{Battery Float Voltage:}
4.2V (LTC3557)
4.1V (LTC3557-1)
■ _{Low Profile 4mm × 4mm 28-Pin QFN Package}
APPLICATIONS
■ _{HDD-Based MP3 Players}
■ _{PDA, PMP, PND/GPS}
■ _{USB-Based Handheld Products}
DESCRIPTION
The LTC^®3557/LTC3557-1 is a highly integrated power
management and battery charger IC for single cell Li-Ion/
Polymer battery applications. It includes a PowerPath^TM
manager with automatic load prioritization, a battery
charger, an ideal diode and numerous internal protection
features. Designed specifically for USB applications, the
LTC3557/LTC3557-1 power manager automatically limits
input current to a maximum of either 100mA or 500mA
for USB applications or 1A for wall adapter powered
applications. Battery charge current is automatically
reduced such that the sum of the load current and the
charge current does not exceed the programmed input
current limit. The LTC3557/LTC3557-1 also includes three
adjustable synchronous step-down switching regulators
and a high voltage buck regulator output controller with
Bat-Track that allows efficient charging from supplies as
high as 38V. The LTC3557/LTC3557-1 is available in a low
profile 4mm × 4mm × 0.75mm 28-pin QFN package.
, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology
Corporation. Bat-Track and PowerPath are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6522118, 6700364. Other patents pending.
TYPICAL APPLICATION
HV SUPPLY
8V TO 38V
(TRANSIENTS
TO 60V)
USB OR
5V ADAPTER
CHARGE
RST
HIGH VOLTAGE
BUCK DC/DC
100mA/500mA
1000mA
0V
CC/CV
CHARGER
LTC3557/LTC3557-1 NTC
ALWAYS ON LDO
TRIPLE HIGH EFFICIENCY
STEP-DOWN
SWITCHING REGULATORS
35571 TA01a
V_OUT
+ _{SINGLE CELL}
Li-Ion
3.3V/25mA
0.8V to 3.6V/600mA
0.8V to 3.6V/400mA
0.8V to 3.6V/400mA
Input and Battery Current vs Load Current
600 _{RPROG = 2k}
500 ^{RCLPROG = 2k}
I_IN
400
I_LOAD
300
200
I_BAT
(CHARGING)
100
0
I_BAT
WALL = 0V
(DISCHARGING)
–100
0 100 200 300 400 500 600
I_LOAD (mA)
35571 TA01b
35571fc
1