Datasheet

LTC4062
12
4062fb
METHOD
Charge
Time
Termination
Mode
Charge
Current
Termination
TIMER
0.1µF to
GND
I
DET
R
DET
to
GND
CHARGER DESCRIPTION
Charges for 3 Hours. After 3 Hours, the Charger
Stops Charging and Enters Standby Mode.
Recharge Cycles Last for 1.5 Hours.
Charges for 3 Hours. After 3 Hours, the Charger
Stops Charging and Enters Standby Mode.
Recharge Cycles Last for 1.5 Hours.
Charges Until Charge Current Drops Below
I
DET
, Then Enters Standby Mode.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
CHRG OUTPUT DESCRIPTION
Pull-Down State While I
BAT
> I
DET
. High Impedance
State While I
BAT
< I
DETECT
or When Charging Is Stopped.
Pulsing State Available When NTC Is Used and
Is Still Charging.
Pull-Down State While I
BAT
> I
DETECT
. High Impedance
State While I
BAT
< I
DETECT
or When Charging Is Stopped.
Pulsing State Available When NTC Is Used and
Is Still Charging.
0.1µF to
GND
GND R
DET
to
GND
User
Selectable
Charge
Termination
V
CC
R
DET
to
GND
Charges Indefinitely.
Charges Indefinitely.
SmartStart Is Disabled.
V
CC
NC
Charges Indefinitely.
SmartStart Is Disabled.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
Pull-Down State When Charging. High Impedance State
When Charging Is Stopped. Pulsing State Available
When NTC Is Used and Is Still Charging.
GND NC
NC
APPLICATIO S I FOR ATIO
WUUU
Table 1
Programming Charge Termination
The LTC4062 can terminate a charge cycle using one of
several methods, allowing the designer considerable flex-
ibility in choosing an ideal charge termination algorithm.
Table 1 shows a brief description of the different termina-
tion methods and their behaviors.
Charge Time Termination
Connecting a capacitor (C
TIMER
) to the TIMER pin enables
the timer and selects charge time termination. The total
charge time is set by:
TIME HOURS
C
F
HOURS
TIMER
()
.
•=
µ01
3
When the programmed time has elapsed, the charge cycle
terminates and the charger enters standby mode. Subse-
quent recharge cycles terminate when 50% of the pro-
grammed time has elapsed. The I
DET
pin determines the
behavior of the CHRG output. Connecting a resistor (R
DET
)
from the I
DET
pin to ground sets the charge current
detection threshold, I
DETECT
:
I
R
R
I
V
R
or
R
V
I
DETECT
PROG
DET
CHG
DET
DET
DETECT
==
=
10
100
100
•
When the charge current (I
BAT
) is greater than
I
DETECT
, the CHRG output is in its pull-down state. When
the charger enters constant voltage mode operation and
the charge current falls below I
DETECT
, the CHRG output
becomes high impedance, indicating that the battery is
almost fully charged. The CHRG output will also become
high impedance once the charge time elapses. If the I
DET
pin is not connected, the CHRG output remains in its pull-
down state until the charge time elapses and terminates
the charge cycle.
Figure 2 shows a charger circuit using charge time termi-
nation that is programmed to charge at 500mA. Once the
charge current drops below 100mA in constant voltage
mode (as set by R
DET
), the CHRG output turns off the LED.
This indicates to the user that the battery is almost fully
charged and ready to use. The LTC4062 continues to