LTC4059 Datasheet, PDF (1/12 Pages) Linear Technology – 900mA Linear Li-Ion Battery Chargers with Thermal Regulation in 2 ´ 2 DFN

LTC4059/LTC4059A
900mA Linear Li-Ion
Battery Chargers with
Thermal Regulation in 2 × 2 DFN
FEATURES
DESCRIPTIO
s _{Programmable Charge Current Up to 900mA}
s _{Charge Current Monitor Output for Charge}
Termination*
s _{Constant-Current/Constant-Voltage Operation with}
Thermal Regulation to Maximize Charging Rate
Without Risk of Overheating*
s _{Constant-Current Source Mode for Charging}
Nickel Batteries (LTC4059 Only)
s _{ACPR Pin Indicates Presence of Input Supply}
(LTC4059A Only)
s _{No External MOSFET, Sense Resistor or Blocking}
Diode Required
s _{Operating Supply Voltage from 3.75V to 8V}
s _{Charges Single Cell Li-Ion Batteries Directly from}
USB Port
s _{Preset 4.2V Charge Voltage with 0.6% Accuracy}
s _{10µA Supply Current in Shutdown Mode}
s _{Tiny 6-Lead (2mm × 2mm) DFN Package}
U
APPLICATIO S
s _{Wireless PDAs}
s _{Cellular Phones}
s _{Portable Electronics}
s _{Wireless Headsets}
s _{Digital Cameras}
The LTC^®4059/LTC4059A are constant-current/constant-
voltage linear chargers for single cell lithium-ion batteries.
Their 2mm × 2mm DFN package and low external compo-
nent count make these chargers especially well suited for
portable applications. Furthermore, they are designed to
work within USB power specifications.
No external sense resistor, MOSFET or blocking diode is
required. Thermal feedback regulates the charge current
to limit the die temperature during high power operation or
high ambient thermal conditions. The charge voltage is
fixed at 4.2V and the charge current is programmable.
When the input supply (wall adapter or USB supply) is
removed, the LTC4059/LTC4059A automatically enter a low
current state, dropping the battery current drain to less than
1µA. With power applied, they can be put into shutdown
mode, reducing the supply current to 10µA.
The LTC4059A features an open-drain status pin to indi-
cate the presence of an input voltage. The LTC4059 can be
used as a constant-current source to charge Nickel cells.
Other features include undervoltage lockout protection
and a current monitor pin which can indicate when to
terminate a charge cycle.
The LTC4059/LTC4059A are available in a 6-lead, low
profile (0.8mm) 2mm × 2mm DFN package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
*US Patent 6,522,118
TYPICAL APPLICATIO
V_IN
4.5V TO 8V
1µF
V_DD
50k
V_CC ACPR
LTC4059A 600mA
EN
BAT
GND PROG
+
2k
4059 TA01
µP
4.2V
Li-Ion
BATTERY
Complete Charge Cycle (800mAh Battery)
700
CONSTANT
CURRENT
600
4.4
CONSTANT
VOLTAGE
4.2
500
4.0
400
3.8
300
3.6
200
100
V_CC = 5V
R_PROG = 2k
T_A = 25°C
0
0
0.5
1
1.5
TIME (HOURS)
3.4
3.2
3.0
2
2.5
4059 TA02
4059fa
1