LM3647 Datasheet, PDF (1/17 Pages) National Semiconductor (TI) – Universal Battery Charger for Li-Ion, Ni-MH and Ni-Cd Batteries

PRELIMINARY
March 2000
LM3647
Universal Battery Charger
for Li-Ion, Ni-MH and Ni-Cd Batteries
1.0 General Description
The LM3647 is a charge controller for Lithium-Ion (Li-Ion),
Nickel-Metal Hydride (Ni-MH) and Nickel-Cadmium (Ni-
Cd) batteries. The device can use either a pulsed-current
charging or a constant-current charging technique. The
device can also be configured to discharge before charg-
ing. Throughout the charging sequence the LM3647 mon-
itors voltage and/or temperature and time in order to
terminate charging.
s Negative delta voltage (-∆V)
s Maximum voltage
s Optional: Delta temperature/delta time (∆T/∆t)
s Optional: Maximum temperature
s Backup: Maximum time
If both voltage and temperature fail to trigger the termina-
tion requirements, then the maximum time (configured by
external hardware) steps in which terminates the charging.
In Ni-Cd/Ni-MH mode, four different charging stages are
used:
s Soft-start charge
s Fast charge
s Topping charge
s Maintenance charge
In Li-Ion mode, four different charging stages are used:
s Qualification
s Fast Charge Phase 1, Constant Current
s Fast Charge phase 2, Constant Voltage
s Maintenance charge
The charge current of the LM3647 is configured via exter-
nal resistors, which in turn controls the duty cycle of the
PWM switching control output. For cost-sensitive applica-
tions, the LM3647 charge controller can be configured
without a temperature sensor and to use an external cur-
rent source.
When using an external current source, the current is con-
trolled by the LM3647 which turns the current source on
and off. The LM3647 automatically detects the presence of
a battery and starts the charging procedure when the bat-
tery is installed. Whenever an error occurs (e.g., short cir-
cuit, temperature too high, temperature too low, bad
battery, charge time over, etc.) the LM3647 will stay in error
mode until the battery is removed or it gets within the al-
lowed charging temperature range. The LM3647 is avail-
able in a standard 20-lead SOIC surface mount package.
Key Features
s Auto-adaptive fast charge
s High-resolution, accurate voltage monitoring prevents
Li-Ion undercharge or overcharge
s Fast charge, pre-charge and maintenance currents are
provided. Different currents are selectable via external
resistors.
s Fast-charge termination by ∆ temperature/∆ time, maxi-
mum voltage, maximum temperature, negative ∆ volt-
age and maximum time
s Dynamically detects battery insertion, removal, short
circuit and bad battery without additional hardware
s Supports charging of battery packs with 2-8 cells of Ni-
Cd/Ni-MH or 1-4 cells of Li-Ion
s Three LED indicators and Buzzer output indicate oper-
ational modes
s Ni-MH/Ni-Cd charge mode, Li-Ion charge mode or dis-
charge mode can be selected manually
s PWM switching controller
Applications
s Battery charging systems for:
— Portable consumer electronics
— Audio/video equipment
— Communications equipment
— Point of sale devices
— Power tools
— Personal convenience products
©2000 National Semiconductor Corporation
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