LTC4413-2 Linear Technology, LTC4413-2 Datasheet - Page 14

• Manufacturer Part Number: LTC4413-2
• Description: Fast Ideal Diodes
• Manufacturer: Linear Technology

LTC4413-1/LTC4413-2
APPLICATIONS INFORMATION
In the event that a low power external PFET is used for
the external overvoltage protection device, care must be
taken to limit the power dissipation in the external PFET.
The operation of this circuit is identical to the “Automatic
Switchover from a Battery to a Wall Adapter” application
shown on the fi rst page of this data sheet. Here, however,
the ideal diode from INA to INB is disabled by pulling up
on ENBA whenever an overvoltage condition is detected.
This channel is turned-off using a resistor connected to
OVP along with a 5.6V zener diode, ensuring the absolute
maximum voltage at ENBA is not exceeded during an
overvoltage event. When the overvoltage condition ends,
14
ADAPTER
INPUT
WALL
0.1μF
1Ω
10nF
C2
FDR8508
C1: C0805C106K8PAC
C2: C0403C103K8PAC
C
OUT
R
560k
: C1206C475K8PAC
ENBA
+
BAT
C1
10μF
D1
OPTIONAL
D2
5.6V
Figure 7
STAT IS HIGH WHEN WALL ADAPTER IS
SUPPLYING LOAD CURRENT
OVP IS HIGH WHEN WALL ADAPTER
VOLTAGE > 6V
INA
ENBA
GND
ENBB
INB
the OVP voltage drops slowly, depending on the gate
charge of the external PFET. This causes the external PFET
to linger in a high R
a signifi cant amount of heat depending on the load cur-
rent. To avoid dissipating heat in the external PFET, this
application delays turning on the ideal diode from INA to
OUTA, until the gate voltage of the external PFET drops
below V
out of the high R
be used on either channel of the LTC4413-2.
LTC4413-2
IDEAL
IDEAL
ENBIL
OUTB
OUTA
STAT
OVP
OVI
, where the external PFET should safely be
DS(ON)
441312 F07
V
DS(ON)
CC
R
470k
region. This soft-start scheme can
STAT
C
4.7μF
OUT
region where it can dissipate
STAT
OVP
TO LOAD
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