LTC4097_15 Datasheet, PDF (1/20 Pages) Linear Technology – USB/Wall Adapter Standalone Li-Ion/Polymer Battery Charger

FEATURES
■ _{Charges Single-Cell Li-Ion/Polymer Battery from}
Wall Adapter and USB Inputs
■ _{Automatic Input Detection (Wall Adapter Input has}
Charging Priority)
■ _{Charge Current Programmable up to 1.2A from}
Wall Adapter Input
■ _{Programmable Charge Current Termination}
■ _{NTC Thermistor Input for Temperature Qualified}
Charging
■ _{Independent DC, USB Charge Current Programming}
■ _{Preset Float Voltage with ±0.6% Accuracy}
■ _{Thermal Regulation Maximizes Charge Rate Without}
Risk of Overheating*
■ _{Charge Status Output}
■ _{Automatic Recharge}
■ _{20µA Charger Quiescent Current in Shutdown}
■ _{Available in a Thermally Enhanced, Low Profile}
(0.75mm) 12-Lead (3mm × 2mm) DFN Package
APPLICATIONS
■ _{Cellular Telephones}
■ _{MP3 Players}
■ _{Portable Handheld Devices}
LTC4097
USB/Wall Adapter
Standalone Li-Ion/Polymer
Battery Charger
DESCRIPTION
The LTC^®4097 is a standalone linear battery charger that
is capable of charging a single-cell Li-Ion or Li-Polymer
battery from both wall adapter and USB inputs. The charger
can detect power at the inputs and automatically select
the appropriate power source for charging.
No external sense resistor or blocking diode is required
for charging due to the internal MOSFET architecture.
Internal thermal feedback regulates the battery charge
current to maintain a constant die temperature during high
power operation or high ambient temperature conditions.
The float voltage is fixed at 4.2V and the charge current
is programmed with an external resistor. The LTC4097
terminates the charge cycle when the charge current drops
below the user programmed termination threshold after
the final float voltage is reached. The LTC4097 can be put
into shutdown mode reducing the DCIN supply current to
20µA, the USBIN supply current to 10µA, and the battery
drain current to less than 2µA even with power applied
to both inputs.
Other features include trickle charge, automatic recharge,
undervoltage lockout, charge status output, an NTC therm-
istor input used to monitor battery temperature and VNTC
power present output with 120mA drive capability.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by U.S. Patents including 6522118.
TYPICAL APPLICATION
Dual Input Battery Charger for Single-Cell Li-Ion Battery
WALL
ADAPTER
USB
PORT
1µF
LTC4097
BAT
DCIN
VNTC
USBIN HPWR
1µF
IUSB
NTC
2k
IDC
ITERM
1% _1.24k
GND
1%
800mA (WALL)
100mA/500mA (USB)
+ ^4.2V
SINGLE CELL
Li-Ion BATTERY
2k
T
1%
4097 TA01
Complete Charge Cycle (1100mAh Battery)
1000
800
600
400
200
0
4.2
4.0
3.8
3.6
3.4
5.0
2.5
0
CONSTANT VOLTAGE
USBIN = 5V
T_A = 25°C
R_IDC = 1.24k
R_IUSB = 2k
HPWR = 5V
0 0.5 1.0 1.5 2.0 2.5 3.0
TIME (HR)
4097 TA01b
4097f
1