LTC4065-4.4
Standalone 750mA Li-Ion
Battery Charger in 2 × 2 DFN
U
FEATURES
DESCRIPTIO
The LTC®4065-4.4 is a complete constant-current/con-
stant-voltage linear charger for high capacity single-cell
lithium-ion batteries with a 4.4V float voltage. Its 2mm ×
2mm DFN package and low external component count
make the LTC4065-4.4 especially well-suited for portable
applications. Furthermore, LTC4065-4.4 is specifically
designed to work within USB power specifications.
■
Complete Linear Charger in 2mm × 2mm DFN
Package
■
C/10 Charge Current Detection Output
■
Timer Termination
■
Charge Current Programmable Up to 750mA with
5% Accuracy
■
No External MOSFET, Sense Resistor or Blocking
Diode Required
The CHRG pin indicates when charge current has dropped
to ten percent of its programmed value (C/10). An internal
timer terminates charging according to battery manufac-
turer specifications.
■
Preset 4.4V Float Voltage with 0.6% Accuracy
■
Constant-Current/Constant-Voltage Operation with
Thermal Feedback to Maximize Charging Rate
Without Risk of Overheating
■
Charge Current Monitor Output for Gas Gauging
No external sense resistor or blocking diode is required due
to the internal MOSFET architecture. Thermal feedback regu-
lates charge current to limit the die temperature during high
power operation or high ambient temperature conditions.
■
Automatic Recharge
■
Charges Single-cell Li-Ion Batteries Directly from
USB Port
■
20µA Supply Current in Shutdown Mode
When the input supply (wall adapter or USB supply) is
removed, the LTC4065-4.4 automatically enters a low cur-
rent state, dropping battery drain current to less than
1µA. With power applied, LTC4065-4.4 can be put into shut-
down mode, reducing the supply current to less than 20µA.
■
Soft-Start Limits Inrush Current
■
Tiny 6-Lead (2mm × 2mm) DFN Package
U
APPLICATIO S
■
Wireless PDAs
The full-featured LTC4065-4.4 also includes automatic
recharge, low-battery charge conditioning (trickle charg-
ing) and soft-start (to limit inrush current).
■
Cellular Phones
■
Portable Electronics
, 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, 6700364.
The LTC4065-4.4 is available in a tiny 6-lead, low profile
(0.75mm) 2mm × 2mm DFN package.
U
Complete Charge Cycle (1100mAh Battery)
TYPICAL APPLICATIO
550
500
450
400
350
300
250
200
150
100
50
4.5
4.4
4.3
4.2
4.1
4.0
3.9
3.8
3.7
3.6
3.5
3.4
CONSTANT-CURRENT
Standalone Li-Ion Battery Charger
CONSTANT-
VOLTAGE
500mA
V
IN
4.5V TO
5.5V
V
BAT
CC
R1
510Ω
LTC4065-4.4
CHRG PROG
CHRG
TRANSITION
4.4V
+
Li-Ion
EN
GND
C1
1µF
BATTERY*
R3
2k
CHARGE
TERMINATION
4065 TA01
V
CC
= 5V
= 2K
R
PROG
0
*E.G. SANYO BATTERIES: UF553436T OR UF553450T
0
1
1.5
2
2.5
3
3.5
4
4.5
5
0.5
TIME (HOURS)
4065 TA01b
406544f
1