Datasheet

7
4009fd
LTC4009
LTC4009-1/LTC4009-2
pin FuncTions
CLN (Pin 1): Adapter Input Current Limit Negative Input.
The LTC4009 senses voltage on this pin to determine if
the charge current should be reduced to limit total input
current. The threshold is set 100mV below the CLP pin. An
external filter should be used to remove switching noise.
This input should be tied to CLP if not used. Operating
voltage range is (CLP – 110mV) to CLP.
CLP (Pin 2): Adapter Input Current Limit Positive Input.
The LTC4009 also draws power from this pin, including
a small amount for some shutdown functions. Operating
voltage range is GND to 28V.
DCIN (Pin 3): DC Power Input. The LTC4009 draws power
from this pin when an external DC power source is present.
This pin is typically isolated from the CLP pin by a diode
and should be bypassed with a capacitance of 0.1µF or
more. Operating voltage range is GND to 28V.
ICL (Pin 4): Active-Low Input Current Limit Indicator Out-
put. This open-drain output pulls to GND when the charge
current is reduced because of AC adapter input current
limiting. This output should be left floating if not used.
DCDIV (Pin 5): AC Adapter Present Comparator Input. The
LTC4009 senses voltage on this pin to determine when an
adequate DC power source is present, or if an overvoltage
condition exists. An external resistor divider programs
these threshold levels relative to DCIN. Operating voltage
range is GND to INTV
DD
.
SHDN (Pin 6): Active-low Shutdown Input. Driving SHDN
below 300mV unconditionally forces the LTC4009 into the
shutdown state. This input has a 50kΩ internal pull-down
to GND. Operating voltage range is GND to INTV
DD
.
ACP (Pin 7): Active-Low AC Adapter Present Indicator
Output. This open-drain output pulls to GND when adequate
AC adapter (DC) voltage is present, based on the DCDIV
input. This output should be left floating if not used.
CHRG (Pin 8): Active-Low Charge Indicator Output. This
open-drain output provides three levels of information
about charge status using a strong pull-down, 25µA weak
pull-down or high impedance. Refer to the Operation and
Applications Information sections for further details. This
output should be left floating if not used.
FBDIV (Pin 9, LTC4009): Battery Voltage Feedback Resis-
tor Divider Source. The LTC4009 connects this pin to BAT
when charging is in progress. FBDIV is an open-drain
PFET output to BAT with an operating voltage range of
GND to BAT.
Battery Shutdown CurrentPWM Frequency vs Charge Current
CHARGE CURRENT (A)
0
0
PWM FREQUENCY (kHz)
100
200
300
400
600
0.5
1.0 1.5 2.0
4009 G13
2.5 3.0
500
BAT = 14.5V
BAT = 12V
BAT = 5V
CLP = 15V
R
SENSE
= 33mΩ
R
IN
= 3.01k
BATTERY VOLTAGE (V)
0
BATTERY CURRENT (µA)
15
20
25
20
4009 G14
10
5
0
5
10
15
25
DC1104 WITH
SSB44 INPUT
DIODE
LTC4009
ALL PINS
Typical perForMance characTerisTics
(T
A
= 25°C unless otherwise noted. D
IN
= SSB44, L = IHLP-2525 6.8µH)