QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 763
650MA STANDALONE LI-ION BATTERY CHARGER
1
LTC4065EDC
DESCRIPTION
Demonstration circuit DC763 is a complete constant-
current, constant-voltage battery charger designed to
charge single-cell lithium-ion batteries. DC763 is
based on the LTC4065 that is available in a 2mm
×
2mm DFN package featuring an exposed bottom-side
metal pad for soldering to the PC board. The LTC4065
features an internal MOSFET with thermal feedback
loop that regulates the charge current to limit the die
temperature during high power operation or high am-
bient thermal conditions. The preset float voltage is
4.2V with 0.6% accuracy and the constant charge
current is 650mA. The DC763 has a jumper for ena-
bling the charger (JP1). Placing the jumper to “OFF”
turns off the charger and jumper to “ON” enables the
charger. The full-featured DC763 also includes auto-
matic recharge, low–battery charge conditioning
(trickle charging), soft-start (to limit inrush current)
and a C/10 charge LED indicator. Small surface
mount components are used to minimize board space
and height.
Design files for this circuit board are available. Call
the LTC factory.
LT is a registered trademark of Linear Technology Corporation
Table 1.
Performance Summary
PARAMETER
CONDITION
VALUE
Input Voltage
3.75-5.25V
I
BAT
(constant current mode)
Vin=5V, Vbat=3.6V
650mA +/-5%
Float Voltage
Vin=5V
4.20V +/-0.6%
Trickle Charge Threshold
2.9V +/-0.15V
I
BAT
(trickle current mode)
65mA +/-20mA
QUICK START PROCEDURE
Demonstration circuit DC763 is easy to set up to
evaluate the performance of the LTC4065. Refer to
Figure 1. for proper measurement equipment setup
and follow the procedure below:
1
.
Set jumper JP1 to the ‘‘ON’’ position.
Adjust
the output voltage of the input power supply
to 0V and then connect the power supply to
the Vin and GND pins of the demo board.
2
.
Set the battery simulator to 0V, and then con-
nect it to the BAT and GND pins.
3
.
Connect the digital voltmeters as shown in the
setup diagram to measure the input voltage
V
IN
, charger voltage (VBAT) and the charge
current (IBAT).
4
.
Begin increasing the input voltage to 5V and
keep the battery simulator power supply at
0V. The CHRG LED should be on, and the
charge current should be approximately
65mA.
This is the trickle charge mode for a
deeply discharged battery.
Typically, a bat-
tery that has not been charged for a long time.
5
.
Starting from 0V, slowly increase the battery
simulator power supply (VBAT), observing the
charger’s output voltage on the DVM. When
the charger’s output voltage exceeds ap-
proximately 2.9V, the charger will enter the
Constant Current mode of the charge cycle
with the charge current (IBAT) increased to
the programmed value of approximately
650mA.
This is the Constant Current mode.
6
.
Continue to slowly increase the battery simu-
lator power supply, thus simulating a battery
accepting charge. The charge current should
remain at the programmed value of 650mA
until the charger output voltage is within
