QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC708
LITHIUM-ION LINEAR BATTERY CHARGER WITH THERMAL REGULATION
1
LTC4064EMS-4.0
Demonstration circuit DC708 is a complete constant-
current, constant-voltage battery charger designed to
charge one Lithium-Ion cell used in battery backup ap-
plications or applications that require greatly increased
cycle life at the expense of battery capacity. The
LTC4064EMS-4.0 used on this demo circuit features an
internal P-channel power MOSFET with a unique thermal
feedback loop that reduces the output current under
high ambient temperature and/or high power dissipation
conditions. This feature allows the charger to provide
higher charge currents under normal conditions and still
provide safe charging under abnormal conditions such
as high ambient temperature, high input voltage or low
battery voltage. The IC is available in a 10-pin MSOP
thermally enhanced package featuring an exposed bot-
tom-side metal pad for soldering to the PC board.
Other Features include:
•
Preset float voltage of 4.0V±1%.
•
Greatly increased cycle life when used for charging
4.1V or 4.2V batteries.
•
1A and 0.5A Constant Current selected by a jumper.
•
Capable of charging directly from USB power.
•
3-hour charge termination timer. This timer can be set
for other time periods through a capacitor change.
For instance, you may want to use a much shorter pe-
riod (on the order of 30 seconds) when evaluating the
board with a battery simulator instead of a real Li-Ion
battery.
•
Charge Current Monitor Output can be used for gas
gauging.
•
Manual Shutdown
•
Low battery drain current when input supply is re-
moved
•
No isolation diode or current sense resistor required.
•
C/10 Trickle charge for deeply discharged batteries
•
Auto recharge when battery voltage drops below pre-
set threshold
•
Input Power OK LED indicator (ACPR)
•
C/10 Charge LED indicator (CHRG)
•
Fault LED indicator for “out of temp range” (FAULT)
Small surface mount components are used to minimize
board space and height with the circuitry occupying ap-
proximately 0.15 square inches of board space with a
height of 0.054 inches (1.4mm).
Table 1. Typical Demo Board Specifications
Input Voltage Range V
IN
4.25V to 7V (upper
range limited by PC
board dissipation)
Output Voltage V
BAT
(constant
voltage mode)
4.0V ±1%
Output Current I
BAT
(constant
current mode)
1 A ± 8%, 0.5A ± 8%
••••••••••••••••••
(se
lected by jumper)
Current Monitor Output
1.5V±5% @ Full Cur-
rent
Output Current I
BAT
(trickle
current mode)
100mA ± 20%, 50mA ±
20%
C/10 CHRG LED Threshold Level 100mA ± 25%. 50Ma ±
25%
Circuit Board Temperature in
Thermal Feedback Mode
60°C to 70°C
Trickle Charge Threshold
Voltage
2.457V
Battery Drain Current with
V
IN
Removed
<1µA
