11
LTC4414
4414fc
V
IN
GND
CTL
SENSE
GATE
STAT
7
3
2
6
8
1
LTC4414
P-CHANNEL
MOSFET
SUPPLY
INPUT
LOGIC
INPUT
C
OUT
*
TO LOAD
4414 F07
*DRAIN-SOURCE DIODE OF MOSFET
0.1µF
V
IN
GND
CTL
SENSE
GATE
STAT
7
3
2
6
8
1
LTC4414
TO LOAD OR
PowerPath
CONTROLLER
TO LOAD OR
PowerPath
CONTROLLER
STATUS IS HIGH
WHEN BAT1 IS
CHARGING
STATUS IS HIGH
WHEN BAT2 IS
CHARGING
470k
4414 F06
V
CC
*
*
BAT1
BATTERY
CHARGER
INPUT
470k
V
CC
BAT2
V
IN
GND
CTL
SENSE
GATE
STAT
7
3
2
6
8
1
LTC4414
*DRAIN-SOURCE DIODE OF MOSFET
0.1µF
Battery Load Sharing
Figure 5 illustrates an application circuit for dual battery
load sharing with automatic switchover of load from
batteries to wall adapter. Whichever battery can supply the
higher voltage will provide the load current until it is
discharged to the voltage of the other battery. The load will
then be shared between the two batteries according to the
capacity of each battery. The higher capacity battery will
provide proportionally higher current to the load. When a
wall adapter input is applied, both MOSFETs will turn off
and no load current will be drawn from the batteries. The
STAT pins provide information as to which input is supply-
ing the load current. This concept can be expanded to
more power inputs.
TYPICAL APPLICATIO S
U
Figure 7. Logic Controlled High Side Power Switch
CTL pin input can be used with a microcontroller and
back-to-back MOSFETs as shown in Figure 4. This allows
complete control for disconnection of the charger from
either battery.
High Side Power Switch
Figure 7 illustrates an application circuit for a logic con-
trolled high side power switch. When the CTL pin is a
logical low, the LTC4414 will turn on the MOSFET. Be-
cause the SENSE pin is grounded, the LTC4414 will apply
maximum clamped gate drive voltage to the MOSFET.
When the CTL pin is a logical high, the LTC4414 will turn
off the MOSFET by pulling its gate voltage up to the supply
input voltage and thus deny power to the load. The
MOSFET is connected with its source connected to the
power source. This disables the drain-source diode from
supplying voltage to the load when the MOSFET is off. Note
that if the load is powered from another source, then the
drain-source diode can forward bias and deliver current to
the power supply connected to the V
IN
pin.
Figure 6. Automatic Dual Battery Charging
from Single Charging Source
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
Figure 5. Dual Battery Load Sharing with Automatic
Switchover of Load from Batteries to Wall Adapter
Multiple Battery Charging
Figure 6 illustrates an application circuit for automatic
dual battery charging from a single charger. Whichever
battery has the lower voltage will receive the charging
current until both battery voltages are equal, then both will
be charged. When both are charged simultaneously, the
higher capacity battery will get proportionally higher cur-
rent from the charger. For Li-Ion batteries, both batteries
will achieve the float voltage minus the forward regulation
voltage of 20mV. This concept can apply to more than two
batteries. The STAT pins provide information as to which
batteries are being charged. For intelligent control, the
V
IN
GND
CTL
SENSE
GATE
STAT
7
3
2
6
8
1
LTC4414
C
OUT
TO LOAD
STATUS IS HIGH
WHEN BAT1 IS
SUPPLYING
LOAD CURRENT
WHEN BOTH STATUS LINES ARE
HIGH, THEN BOTH BATTERIES ARE
SUPPLYING LOAD CURRENTS. WHEN
BOTH STATUS LINES ARE LOW, THEN
WALL ADAPTER IS PRESENT
STATUS IS HIGH
WHEN BAT2 IS
SUPPLYING
LOAD CURRENT
47k
4414 F05
V
CC
BAT1
WALL
ADAPTER
INPUT
V
IN
GND
CTL
SENSE
GATE
STAT
7
3
2
6
8
1
LTC4414
47k
V
CC
BAT2
*
*
*DRAIN-SOURCE DIODE OF MOSFET
