QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC606
LI-ION BATTERY CHARGER IN SOT-23
1
LTC4056-4.2
DESCRIPTION
Demonstration circuit DC606 is single cell Li-Ion
linear charger in a SOT-23. Charge rates as high
as 700mA can be achieved. The user is provided
with two control jumpers to select between
ON/OFF and 450mA/700mA charge rates. The
reduced charge rate is suitable for USB applica-
tions. A charge LED illuminates while the charger
is charging the battery.
Design files for this circuit board are available.
Call the LTC factory.
Table 1. Performance Summary
PARAMETER CONDITION VALUE
Input Voltage 4.25V - 6.5V
Iout 450mA selected Vbat=3.6V 450mA +- 7%
Iout 700mA selected Vbat=3.6V 700mA +-7%
Float Voltage Vin =5V 4.20v+-1%
Trickle Charge Threshold V
IN
= 5V 2.9V +-0.05V
Recharge Threshold Vin 5V 4.05V+-50mV
OPERATING PRINCIPLES
Demo DC606 is a simple single cell Li-Ion
charger. The demo features the LTC4056-4.2
charger IC. This charger implements a constant
current, and constant voltage charge scheme.
Charge termination is based on a timer. A topping-
off charge will be applied if the cell voltage falls to
4.05V to insure long-term charge maintenance.
Deeply discharged cells are conditioned with a low
C/50 trickle current until the cell voltage reaches
2.9V whereupon full charge current is applied. A
charge LED is provided that illuminates every time
the charger is charging the battery. The peak
charge current is jumper selectable at either
700mA or 450mA. The 450mA rate is intended for
USB applications.
QUICK START PROCEDURE
Demonstration circuit 606 is easy to set up to
evaluate the performance of the LTC4056-4.2. Re-
fer to Figure 1 for proper measurement equipment
setup and follow the procedure below:
1.
Use the jumper provided to select the desired
charge rate 450mA or 700mA. Verify that the
Charger Enable jumper is set to the ON posi-
tion.
2.
With power off, connect the meters and input
power supply as shown in Figure 1.
3.
Connect the demo board to the battery simula-
tor as shown in Figure 1.
4.
Set the battery simulator voltage to zero, slowly
increase the input voltage. When the supply
voltage exceeds 4.5V the charger should acti-
vate and the charge LED will illuminate.
NOTE:
Make sure that the input voltage does
not exceed 6.5V.
5.
Note that so long as the battery voltage is under
the Trickle Charge threshold of 2.9V the charge
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC606
LI-ION BATTERY CHARGER IN SOT-23
2
current is about 2% of the selected charge cur-
rent
6.
Increase the battery voltage to about 3V and
note that the charge current has increased to
the jumper programmed current, either 450 or
700mA. This is the constant current region of
the charging cycle
7.
Continue to increase the battery voltage, as the
battery voltage approaches the float voltage of
4.2V the charge current will begin to drop. This
is the constant voltage region of operation.
8.
Wait 3 hours. The LED will extinguish as the
charger terminates. The termination timeout
can be reduced to 18 minutes by substituting a
100nF cap for C2.
9.
Now slowly decrease the battery voltage as the
battery voltage reaches about 4.05V, a new
charging cycle should begin.
10.
Place the Charger Enable jumper in the OFF
position. Note that the battery current draw is
extremely low (approx 1uA) and that the supply
current draw is low (approx 35uA).
QUICK START GUIDE FOR DEMONSTRATION CIRCUIT DC606
LI-ION BATTERY CHARGER IN SOT-23
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