Data Sheet

VIN
1K
CN3083
1st power
supply
M1
D1
2nd power
supply
Figure 6 Combining 2 Input Power Supply
Battery Temperature Sense
To prevent the damage caused by the very high or very low temperature done to the battery pack, the CN3083
continuously senses battery pack temperature by measuring the voltage at TEMP pin.
If V
TEMP
<(46%×VIN) for 0.15 seconds, it indicates that the battery temperature is too high or too low and the
charge cycle is suspended. If V
TEMP
>(46%×VIN) for 0.15 seconds, the charge cycle resumes.
The battery temperature sense function can be disabled by connecting TEMP pin to GND.
Recharge
After a charge cycle has terminated, if the battery voltage drops below the recharge threshold of 4.1V, a new
charge cycle will begin automatically.
Constant-Current/Constant-Voltage/Constant-Temperature
The CN3083 use a unique architecture to charge a battery in a constant-current, constant-voltage, constant
temperature fashion as shown in Figure 3. Amplifiers Iamp, Vamp, and Tamp are used in three separate
feedback loops to force the charger into constant-current, constant-voltage, or constant-temperature mode,
respectively. In constant current mode the charge current delivered to the battery equal to 1800V/R
ISET
. If the
power dissipation of the CN3083 results in the junction temperature approaching 115℃, the amplifier Tamp will
begin decreasing the charge current to limit the die temperature to approximately 115℃. As the battery voltage
rises, the CN3083 either returns to constant-current mode or it enters constant voltage mode straight from
constant-temperature mode.
Open-Drain Status Outputs
The CN3083 have 2 open-drain status outputs: OK and CK. CH is pulled low when the charger is in charging
status, otherwise CH becomes high impedance. OK is pulled low if the charger is in charge termination status,
otherwise OK becomes high impedance.
When the battery is not present, the charger charges the output capacitor to the regulation voltage quickly, then
the BAT pin’s voltage decays slowly to recharge threshold because of low leakage current at BAT pin, which
results in a 100mv ripple waveform at BAT pin, in the meantime, CH pin outputs a pulse to indicate that the
battery’s absence. The pulse’s frequency is around 10Hz when a 4.7uF output capacitor is used.
The open drain status output that is not used should be tied to ground.
V
IN
Bypass Capacitor C
IN
Many types of capacitors can be used for input bypassing, C
IN
is typically a 22uF capacitor.
For the consideration of the bypass capacitor, please refer to the Application Note AN102 from our website.
Stability
Typically a 4.7uF capacitor from BAT pin to GND is required to stabilize the feedback loop.
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