LM3647 Reference Design
User’s Manual
GENERAL DESCRIPTION
The LM3647 is a charge controller for Nickel-Cadmium
(Ni-Cd), Nickel-Metal Hydride (Ni-MH) or Lithium-Ion (Li-Ion)
batteries. The device uses a pulsed-current charging or a
constant-current charging technique. The device can also be
configured to discharge before charging. Throughout the
charging sequence the LM3647 monitors voltage and/or
temperature and time in order to terminate charging.
•
Negative delta voltage (−
∆
V)
•
Maximum voltage
•
Optional: Delta temperature/delta time (
∆
T/
∆
t)
•
Optional: Maximum temperature
•
Backup: Maximum time
The
LM3647
is
user
configurable
for
three
battery
chemistries: Ni-Cd, Ni-MH or Li-Ion.
In Ni-Cd/Ni-MH mode, four different charging phases are
used:
•
Softstart charge
•
Fast charge
•
Topping charge
•
Maintenance charge
In Li-Ion mode, four different charging stages are used:
•
Qualification
•
Fast Charge Phase 1, Constant Current
•
Fast Charge phase 2, Constant Voltage
•
Maintenance charge
KEY FEATURES
•
Auto-adaptive fast charge
•
High-resolution, accurate voltage monitoring prevents
Li-Ion under-charge or overcharge
•
Fast charge, pre-charge and maintenance currents are
provided. Different currents are selectable via external
resistors
•
Fast-charge termination by temperature/time, maximum
voltage, maximum temperature and maximum time
•
Dynamically detects battery insertion, removal, short
circuit and bad battery without additional hardware
•
Supports charging of battery packs with 2-8 cells of
Ni-Cd, Ni-MH or 1-4 cells of Li-Ion
•
Three LED indicators and one Buzzer output indicate
operational modes
•
Ni-MH/Ni-Cd charge mode, Li-Ion charge mode or
discharge mode can be selected manually
•
PWM switching controller
DOCUMENTATION INFORMATION
The following documentation describes how to use the
LM3647 demo-board and also gives a few tips on design
calculations. Please note that not all components on the
demo-board are used when designing a charger
application. The demo-board has extra components to
make it simple for the user to try out different batteries and
configurations. There are actually two different charge
current regulation methods and these are referred to as fast
and slow (LM317).
JUMPER SETTINGS
J5
Type Select
V
CC
Ni-MH
GND
Ni-Cd
Hi-Z
Li-Ion
J2
Charge Mode
V
CC
No discharge
GND
Maintenance charge only
Hi-Z
Discharge before charge
J2
Maintenance Mode
V
CC
Charge indefinitely
GND
No charge and restart fast-charge if battery
becomes discharged
Hi-Z
Charge indifinitely and restart fast-charge if
battery becomes discharged
J5
J6
J7
Regulation Method / Cell
Voltage
V
CC
V
CC
GND
Fast
Slow
LM3647 controls charge current
External (LM317) charge control
GND
V
CC
GND
Fast
Slow
LM3647 controls charge current
External (LM317) charge control
Hi-Z
V
CC
GND
Fast
Fast
4.2V/Cell Li-Ion
4.1V/Cell Li-Ion
Timeout
Timeout settings J18 (set according to charge-rate C), See
Section 3.0 for more information.
Temperature Input
The optional Temperature input is connected to J3 and if not
used Short J8.
Voltage Regulation Range
Voltage regulation loop setting J14 (not used with external
LM317 regulation I.e. J7 = slow), defines maximum voltage
output. See also Section
3.0
LM3647 REFERENCE
DESIGN DEMO-BOARD.
Voltage Measurement
The battery voltage is selected with the Voltage jumpers J11
& J12 depending on number of cells/chemistry. For instance,
a 9V Ni-Cd block battery has 6 cells in it and therefore needs
the jumper at
″
Ni 6-Cells
″
on J11 and J12:
National Semiconductor
Application Note 1164
March 2001
LM3647
Reference
Design
User’s
Manual
AN-1
164
© 2001 National Semiconductor Corporation
AN101315
www.national.com
