LTC4413_15 Datasheet, PDF (10/12 Pages) Linear Technology – Dual 2.6A, 2.5V to 5.5V, Ideal Diodes

LTC4413
APPLICATIONS INFORMATION
WALL
ADAPTER
R1
1000k
R2
200k
BATA
1-CELL Li-Ion
BATB
1-CELL Li-Ion
MP1 FDR8508
C1
10μF
2 _ENBA
4 _ENBB
3,11 _GND
9
STAT
LTC4413
IDEAL
1 INA OUTA 10
R_STAT
470k
IDEAL
5 INB OUTB 6
C1:C1206C106K8PAC
C2:C1206C475K8PAC
C2
4.7μF
4413 F03
TO
LOAD
Figure 3
batteries according to the capacity of each battery. The
higher capacity battery provides proportionally higher
current to the load. When a wall adapter input is applied,
the voltage divider formed by R1 and R2 disables the
LTC4413, causing the STAT pin voltage to fall, turning on
MP1. At this point the load is powered by the wall adapter
and both batteries may be removed without interrupting
the load voltage. When the wall adapter is removed, the
output voltage droops until the voltage divider turns on the
LTC4413, at which point the batteries revert to providing
load power. The status signal can also be used to provide
information as to whether the wall adapter (or BATB) is
supplying the load current.
Automatic PowerPath Control
Figure 4 illustrates an application circuit for microcon-
troller monitoring and control of two power sources. The
PRIMARY
POWER
AUX
POWER
MICROCONTROLLER
R_STAT
470k
C_A
10μF
C_B
10μF
2 _ENBA
4 _ENBB
3,11 _GND
9
STAT
LTC4413
IDEAL
1 INA OUTA 10
IDEAL
5 INB OUTB 6
STAT
TO
LOAD
C1
4.7μF
4413 F04
Figure 4
10
microcontroller’s analog inputs (perhaps with the aid of a
resistor voltage divider) monitors each supply input and
the LTC4413 status, and then commands the LTC4413
through the two ENBA/ENBB control inputs.
Automatic Switchover from a Battery to an Auxiliary
Supply or a Wall Adapter
Figure 5 illustrates an application for implementing the
function of automatic switchover from a battery to either
an auxiliary supply or to a wall adapter using the LTC4413.
The LTC4413 automatically senses the presence of a wall
adapter as the ENBB pin voltage is pulled higher than its
rising turn-off threshold of 550mV through resistive divider
(R2 and R3). This disables the AUX input from powering
the load. If the AUX is not present when a wall adapter is
attached (i.e., the BAT is supplying load current), as the
wall adapter voltage rises, the body diode in MP1 forward
biases, pulling the output voltage above the BAT voltage.
The LTC4413 senses a reverse voltage of as little as 10mV
and turns off the ideal diode between INA and OUTA. This
causes the STAT voltage to fall, turning on MP1. The load
then draws current from the wall adapter, and the battery is
disconnected from the load. If the AUX is not present when
the wall adapter is removed, the load voltage droops until
the BAT voltage exceeds the load voltage. The LTC4413
senses that the BAT voltage is greater, causing the STAT
voltage to rise, disabling MP1; the BAT then provides
power to the load.
WALL
ADAPTER
AUX
ADAPTER
MP1 FDR8508
C1
10μF
R1
1Ω
R2
1000k _{4 ENBB}
9
STAT
R3
LTC4413
100k
IDEAL
1 INA OUTA 10
R_STAT
470k
BAT
3,11 _GND
IDEAL
5 INB OUTB 6
R4
1000k ₂
ENBA
R5
500k _{C1:C0805C106K8PAC}
C2:C1206C475K8PAC
C2
4.7μF
4413 F05
TO
LOAD
Figure 5
4413fc