LTC4068-4.2 Datasheet, PDF (1/12 Pages) Linear Technology – Standalone Linear Li-Ion Battery Charger with Programmable Termination

FEATURES
■ _{Programmable Charge Current Up to 950mA}
■ _{Complete Linear Charger in DFN Package}
■ _{No MOSFET, Sense Resistor or Blocking Diode}
Required
■ _{Thermal Regulation Maximizes Charge Rate}
Without Risk of Overheating*
■ _{Charges Directly from a USB Port}
■ _{Programmable Charge Current Termination}
■ _{Preset 4.2V Charge Voltage with ±1% Accuracy}
■ _{Charge Current Monitor Output for Gas Gauging*}
■ _{Automatic Recharge}
■ _{Charge Status Output}
■ _{“AC Present” Output}
■ _{2.9V Trickle Charge Threshold (LTC4068)}
■ _{Available Without Trickle Charge (LTC4068X)}
■ _{Soft-Start Limits Inrush Current}
■ _{Low Profile (3mm × 3mm × 0.75mm) DFN Package}
U
APPLICATIO S
■ _{Cellular Telephones, PDAs, MP3 Players}
■ _{Bluetooth Applications}
LTC4068-4.2/LTC4068X-4.2
Standalone Linear
Li-Ion Battery Charger with
Programmable Termination
DESCRIPTIO
The LTC^®4068 is a complete constant-current/constant-
voltage linear charger for single cell lithium-ion batteries.
Its DFN package and low external component count make
the LTC4068 ideally suited for portable applications. Fur-
thermore, the LTC4068 is designed to work within USB
power specifications.
No external sense resistor or external blocking diode are
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 conditions. The charge voltage is fixed at
4.2V and the charge current is programmed with a resis-
tor. The LTC4068 terminates the charge cycle when the
charge current drops below the programmed termination
threshold after the final float voltage is reached.
When the input supply (wall adapter or USB supply) is
removed, the LTC4068 enters a low current state dropping
the battery drain current to less than 2µA. Other features
include charge current monitor, undervoltage lockout,
automatic recharge and status pins to indicate charge
termination and the presence of adequate input voltage.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Protected by U.S. Patents, including 6522118.
TYPICAL APPLICATIO
Single Cell Li-Ion Battery Charger with C/5 Termination
V_IN
4.5V TO 6.5V
V_CC
BAT
LTC4068-4.2
600mA
CHRG
+ ^1-CELL
ACPR ^ITERM
Li-Ion
BATTERY
EN PROG
825Ω
1µF
GND
1.65k
406842 TA01
Complete Charge Cycle (750mAh Battery)
700
CONSTANT
CURRENT
600
500
4.75
4.50
CONSTANT
VOLTAGE 4.25
400
4.00
300
3.75
200 V_CC = 5V
3.50
θ_JA = 40°C/W
100 ^RPROG ^{= 1.65k}
3.25
R_TERM = 825Ω
0 ^{TA = 25°C}
3.00
0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25
TIME (HOURS)
406842 TA02
406842fa
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