LTC4054-4.2/LTC4054X-4.2
Standalone Linear
Li-Ion Battery Charger with
Thermal Regulation in ThinSOT
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FEATURES
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Programmable Charge Current Up to 800mA
No MOSFET, Sense Resistor or Blocking
Diode Required
Complete Linear Charger in ThinSOTTM Package for
Single Cell Lithium-Ion Batteries
Constant-Current/Constant-Voltage Operation with
Thermal Regulation* to Maximize Charge Rate
Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly
from USB Port
Preset 4.2V Charge Voltage with ±1% Accuracy
Charge Current Monitor Output for Gas
Gauging*
Automatic Recharge
Charge Status Output Pin
C/10 Charge Termination
25µA Supply Current in Shutdown
2.9V Trickle Charge Threshold (LTC4054)
Available Without Trickle Charge (LTC4054X)
Soft-Start Limits Inrush Current
Available in 5-Lead SOT-23 Package
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APPLICATIO S
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Cellular Telephones, PDAs, MP3 Players
Charging Docks and Cradles
Bluetooth Applications
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The LTC®4054 is a complete constant-current/constantvoltage linear charger for single cell lithium-ion batteries.
Its ThinSOT package and low external component count
make the LTC4054 ideally suited for portable applications.
Furthermore, the LTC4054 is specifically designed to work
within USB power specifications.
No external sense resistor is needed, and no blocking
diode is required due to the internal MOSFET architecture.
Thermal feedback regulates the charge current to limit the
die temperature during high power operation or high
ambient temperature. The charge voltage is fixed at 4.2V,
and the charge current can be programmed externally with
a single resistor. The LTC4054 automatically terminates
the charge cycle when the charge current drops to 1/10th
the programmed value after the final float voltage is
reached.
When the input supply (wall adapter or USB supply) is
removed, the LTC4054 automatically enters a low current
state, dropping the battery drain current to less than 2µA.
The LTC4054 can be put into shutdown mode, reducing
the supply current to 25µA.
Other features include charge current monitor, undervoltage
lockout, automatic recharge and a status pin to indicate
charge termination and the presence of an input voltage.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
*U.S.Patent No. 6,522,118
Complete Charge Cycle (750mAh Battery)
TYPICAL APPLICATIO
700
600mA Single Cell Li-Ion Charger
1µF
4
VCC
BAT
LTC4054-4.2
PROG
GND
3
600mA
5
1.65k
4.2V
Li-Ion
BATTERY
2
CONSTANT
POWER
500
4.25
400
4.00
300
3.75
3.50
200
VCC = 5V
θJA = 130°C/W
RPROG = 1.65k
TA = 25°C
100
0
405442 TA01a
4.50
CONSTANT
VOLTAGE
0
CHARGE
TERMINATED
BATTERY VOLTAGE (V)
VIN
4.5V TO 6.5V
4.75
CONSTANT
CURRENT
600
CHARGE CURRENT (mA)
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DESCRIPTIO
3.25
3.00
0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0
TIME (HOURS)
405442 TAO1b
405442xf
1
