LTC1733
1
sn1733 1733fs
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
■
Cellular Telephones
■
Handheld Computers
■
Digital Still Cameras
■
Charging Docks and Cradles
■
Complete Linear Charger for 1-Cell Lithium-Ion
Batteries
■
Thermal Regulation Maximizes Charging Rate
without Risk of Overheating*
■
No External MOSFET, Sense Resistor or Blocking
Diode Required
■
Up to 1.5A Charge Current
■
Preset Charge Voltage with 1% Accuracy
■
Programmable Charge Current with 7% Accuracy
■
Programmable Charge Termination Timer
■
Tiny Thermally Enhanced 10-Pin MSOP Package
■
Charge Current Monitor Useful for Gas Gauging*
■
C/10 Charge Current Detection Output
■
Automatic Recharge
■
Thermistor Input for Temperature Qualified Charging
■
AC Present Logic Output
■
4.1V/4.2V Pin Selectable Output Voltage
Monolithic Linear
Lithium-Ion Battery Charger with
Thermal Regulation
The LTC
®
1733 is a standalone constant-current/
constant-voltage linear charger for lithium-ion batteries
with an on-chip power MOSFET. Internal thermal feedback
regulates the charge current to limit die temperature
during high power operation or high ambient temperature
conditions. This feature allows the user to program a high
charge current without risk of damaging the LTC1733 or
the handheld product.
No external current sense resistor is needed and no
blocking diode is required due to the internal MOSFET
architecture. The charge current and charge time can be
set externally with a single resistor and capacitor, respec-
tively. When the input supply (wall adapter) is removed,
the LTC1733 automatically enters a low current sleep
mode, dropping the battery drain current to less than 5µA.
The LTC1733 also includes NTC temperature sensing,
C/10 detection circuitry, AC present logic, 4.1V/4.2V pin
selectability and low battery charge conditioning (trickle
charging).
The LTC1733 is available in a 10-pin thermally enhanced
MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Charge Current vs Battery Voltage
Standalone Li-Ion Battery Charger
BATTERY VOLTAGE (V)
2
CHARGE CURRENT (mA)
3.5
1733 TA01b
2.5 3 4 4.5
1200
1000
800
600
400
200
0
TRICKLE
CHARGE
CONSTANT
CURRENT
CONSTANT
VOLTAGE
CONSTANT
POWER
T
A
= 40°C
T
A
= 0°C
V
IN
= 5V
θ
JA
= 40°C/W
T
A
= 25°C
*Patent Pending
BAT
PROG
TIMER
GND
V
CC
V
IN
= 5V
1.5k
1%
4.7µF
0.1µF
I
BAT
= 1A
1733TA01
LTC1733
4.2V
1-CELL
Li-Ion
BATTERY*
*AN OUTPUT CAPACITOR MAY BE REQUIRED
DEPENDING ON BATTERY LEAD LENGTH
28
9
7
5
NTC
6
4
SEL