LTC1734L_15 Datasheet, PDF (1/12 Pages) Linear Technology – Lithium-Ion Linear Battery Charger in ThinSOT

FEATURES
s _{Low Profile (1mm) ThinSOT}^TM _Package
s _{Programmable Charge Current: 50mA to 180mA}
s _{No Blocking Diode Required}
s _{No Sense Resistor Required}
s _{1% Accurate Preset Voltage: 4.2V}
s _{Charge Current Monitor Output}
for Charge Termination
s _{Automatic Sleep Mode with Input Supply Removal}
s _{Manual Shutdown}
s _{Negligible Battery Drain Current in Shutdown}
s _{Undervoltage Lockout}
s _{Self Protection for Overcurrent/Overtemperature}
U
APPLICATIO S
s _{Cellular Telephones}
s _{Handheld Computers}
s _{Digital Cameras}
s _{Charging Docks and Cradles}
s _{Low Cost and Small Size Chargers}
s _{Programmable Current Sources}
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
80mA Li-Ion Battery Charger
V_IN
5V
1µF
3
V_CC
1
I_SENSE
2 ^LTC1734L 6
GND DRIVE
4
PROG
R_PROG
4.7k
5
BAT
UMT4403
I_BAT = 80mA
+
10µF
SINGLE
Li-Ion
BATTERY
1734 TA01
LTC1734L
Lithium-Ion Linear
Battery Charger in ThinSOT
DESCRIPTIO
The LTC^®1734L is a low cost, single cell, constant-current/
constant-voltage Li-Ion battery charger controller. When
combined with a few external components, the SOT-23
package forms a very small, low cost charger for single cell
lithium-ion batteries. The LTC1734L is a lower charge
current version of the LTC1734.
The LTC1734L provides a fixed float voltage of 4.2V with
1% accuracy (for 4.1V and 4.15V float voltages, contact
LTC Marketing). Constant current is programmed using a
single external resistor between the PROG pin and ground.
Manual shutdown is accomplished by floating the pro-
gram resistor while removing input power automatically
puts the LTC1734L into a sleep mode. Both the shutdown
and sleep modes drain near zero current from the battery.
Charge current can be monitored via the voltage on the
PROG pin allowing a microcontroller or ADC to read the
current and determine when to terminate the charge cycle.
The output driver is both current limited and thermally
protected to prevent the LTC1734L from operating outside
of safe limits. No external blocking diode is required.
The LTC1734L can also function as a general purpose
current source or as a current source for charging nickel-
cadmium (NiCd) and nickel-metal-hydride (NiMH) batter-
ies using external termination.
PROG Pin Indicates Charge Status
5V
V_BAT
4V
3V
CONSTANT
2V CURRENT
CONSTANT
VOLTAGE
1.5V
V_PROG
1V
0V
CHARGING
BEGINS
CHARGING
COMPLETE
1734 TA01b
1734lf
1