LTC1732-8.4_15 Datasheet, PDF (1/12 Pages) Linear Technology – Lithium-Ion Linear Battery Charger Controller

FEATURES
s _{Complete Linear Charger Controller for 2-Cell}
Lithium-Ion Batteries
s _{Preset Charge Voltage with ±1% Accuracy}
s _{Programmable Charge Current}
s _{C/10 Charge Current Detection Output}
s _{Programmable Charge Termination Timer}
s _{Small, Thin 10-Pin MSOP Package}
s _{Input Supply (Wall Adapter) Detection Output}
s _{8.8V to 12V Input Voltage Range}
s _{Automatic Sleep Mode When Input Supply}
Is Removed (Only 10µA Battery Drain)
s _{Automatic Trickle Charging of Low Voltage Cells}
s _{Programmable for Constant-Current-Only Mode}
s _{Battery Insertion Detect and Automatic Charging}
of Low-Battery
s _{Automatic Battery Recharge}
U
APPLICATIO S
s _{Cellular Phones}
s _{Handheld Computers}
s _{Charging Docks and Cradles}
s _{Digital Cameras and Camcorders}
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTC1732-8.4
Lithium-Ion Linear
Battery Charger Controller
DESCRIPTIO
The LTC^®1732-8.4 is a complete constant-current/con-
stant-voltage linear charge controller for lithium-ion
(Li-Ion) batteries. Nickel-cadmium (NiCd) and nickel metal-
hydride (NiMH) batteries can also be charged with con-
stant current using external termination. Charge current
can be programmed with ±7% accuracy using external
sense and program resistors. An internal resistor divider
and precision reference set the final float voltage with ±1%
accuracy.
When the input supply is removed, the LTC1732-8.4
automatically enters a low current sleep mode, dropping
the battery drain current to 10µA. 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
battery voltage exceeds 4.9V.
The LTC1732-8.4 begins a new charge cycle when a
discharged battery is connected to the charger or when the
input power is applied. In additon, if the battery remains
connected to the charger and the cell voltage drops below
8.05V, a new charge cycle will begin.
The LTC1732-8.4 is available in the 10-pin MSOP package.
TYPICAL APPLICATIO
400mA 2-Cell 8.4V Li-Ion Battery Charger
V_IN = 10V
MBRM120T3
R1
1k
C_TIMER
0.1µF
R2
2
1k SEL
3
CHRG
8
V_CC
9
SENSE
DRV ⁷
LTC1732-8.4
10
ACPR
1
BAT
4
6
TIMER PROG
GND
5
R_PROG*
19.6k
R_SENSE
0.25Ω
1µF
Q1
Si9430DY
I_BAT = 400mA
10µF
+ 8.4V
Li-Ion
BATTERY
*SHUTDOWN INVOKED BY FLOATING THE PROG PIN
1732-8.4 TA01
Typical Li-Ion Charge Cycle
9
CONSTANT
CONSTANT
CURRENT
VOLTAGE
BATTERY VOLTAGE
400
8
400mA HR BATTERY
300
CHARGE CURRENT
200
7
CHRG
LED OFF _TIMER
100
STOPS
0
6
0 0.5 1.0 1.5 2.0 2.5 3.0
TIME (HOURS)
1732-8.4 TA01b
17328f
1