LTC1731-4.2_15 Datasheet, PDF (1/12 Pages) Linear Technology – Single Cell Lithium-Ion Linear Battery Charger Controllers

FEATURES
s _{Complete Linear Charger Controller for}
1-Cell Lithium-Ion Batteries
s _{1% Voltage Accuracy}
s _{Programmable Charge Current}
s _{C/10 Charge Current Detection Output}
s _{Programmable Charge Termination Timer}
s _{Space Saving 8-Pin MSOP Package}
s _{Automatic Sleep Mode When Input Supply}
is Removed (7µA Battery Drain)
s _{Automatic Trickle Charging of Low Voltage Cells}
s _{Programmable for Constant-Current-Only Mode}
U
APPLICATIO S
s _{Cellular Phones}
s _{Handheld Computers}
s _{Charging Docks and Cradles}
s _{Programmable Current Source}
LTC1731-4.1/LTC1731-4.2
Single Cell Lithium-Ion Linear
Battery Charger Controllers
DESCRIPTIO
The LTC^®1731 is a complete constant-current/constant-
voltage linear charger controller for single cell lithium-ion
batteries. Nickel-cadmium (NiCd) and nickel-metal-hy-
dride (NiMH) batteries can also be charged with constant
current using external termination. The external sense
resistor sets the charge current with 5% accuracy. An
internal resistor divider and precision reference set the
final float potential with ±1% accuracy. The output float
voltage is set internally to 4.1V (LTC1731-4.1) or 4.2V
(LTC1731-4.2).
When the input supply is removed, the LTC1731 automati-
cally enters a low current sleep mode, dropping the battery
drain current to typically 7µA. An internal comparator
detects the end-of-charge (C/10) condition while a pro-
grammable timer, using an external capacitor, sets the
total charge time. Fully discharged cells are automatically
trickle charged at 10% of the programmed current until
cell voltage exceeds 2.457V.
The LTC1731 is available in the 8-pin MSOP and SO
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
500mA Li-Ion Battery Charger
V_IN = 6V
MBRM120T3
CHARGE
STATUS
C_TIMER
0.1µF
7
1k
V_CC
8
SENSE
2
CHRG
DRV ⁶
LTC1731-4.2
3
TIMER
1
BAT
5
PROG
GND
4
R_PROG*
19.6k
R_SENSE
0.2Ω
Q1
Si9430DY
I_BAT = 500mA
+ _Li-ION
CELL
1µF
10µF
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
1731 TA01
1