Datasheet

LTC4360-1/LTC4360-2
8
436012fa
Figure 3. MOSFET Configurations
GATEP
SUPPLY
IN
OVERVOLTAGE, REVERSE
CURRENT PROTECTION
NEGATIVE
VOLTAGE
PROTECTION
GATE
OVERVOLTAGE, REVERSE
CURRENT PROTECTION
GATE
GATE
GATEP
436012 F03
OVERVOLTAGE
PROTECTION
OVERVOLTAGE
PROTECTION
NEGATIVE
VOLTAGE
PROTECTION
GATE
OUT
SUPPLY
IN
OUT
SUPPLY
IN
OUT
SUPPLY
IN
OUT
M1
M1 M3
M1M2
M1M2
M3
APPLICATIONS INFORMATION
MOSFET Configurations and Selection
The LTC4360 can be used with various external MOSFET
configurations (see Figure 3). The simplest configuration is
a single N-channel MOSFET. It has the lowest R
DS(ON)
and
voltage drop and is thus the most power efficient solution.
When GATE is pulled to ground, the MOSFET can isolate
OUT from a positive voltage at IN up to the BV
DSS
of the
MOSFET. However, reverse current can still flow from OUT
to IN via the parasitic body diode of the MOSFET.
For near zero reverse leakage current protection when GATE
is pulled to ground, back-to-back N-channel MOSFETs can
be used. Adding an additional P-channel MOSFET controlled
by GATEP (LTC4360-2) provides negative input voltage
protection down to the BV
DSS
of the P-channel MOSFET.
Another configuration consists of a P-channel MOSFET
controlled by GATEP and a N-channel MOSFET controlled
by GATE. This provides protection against overvoltage and
negative voltage but not reverse current.
Input Transients
Figure 4 shows a typical set-up when an AC wall adaptor
charges a mobile device. The inductor L
IN
represents the
lumped equivalent inductance of the cable and the EMI filter
found in some wall adaptors. R
IN
is the lumped equivalent
resistance of the cable, adaptor output capacitor ESR and
the connector contact resistance.