Datasheet

LTC4227
7
422712fa
For more information www.linear.com/LTC4227
pin FuncTions
CPO1, CPO2: Charge Pump Output. Connect a capacitor
from CPO1 or CPO2 to the corresponding IN1 or IN2 pin.
The value of this capacitor is approximately 10× the gate
capacitance (C
ISS
) of the external MOSFET for ideal diode
control. The charge stored on this capacitor is used to pull
up the gate during a fast turn-on. Leave this pin open if
fast turn-on is not needed.
DGATE1, DGATE2: Ideal Diode MOSFET Gate Drive Out
-
put. Connect this pin to the gate of an external N-channel
MOSFET for ideal diode control. An internal clamp limits
the gate voltage to 12V above and a diode voltage below
IN. During fast turn-on, a 1.5A pull-up charges DGATE from
CPO. During fast turn-off, a 1.5A pull-down discharges
DGATE to IN.
D2ON: On Control Input. A voltage below 1.145V allows
the external ideal diode MOSFET in the IN2 supply path
to turn on and a voltage above 1.235V turns it off. Con
-
nect this pin to an external resistive divider from IN1 to
make IN1 the higher priority input supply when IN1 and
IN2 are equal.
EN (UFD Package): Enable Input.
Ground this pin to enable
Hot Swap control. If this pin is pulled high, the MOSFET
is not allowed to turn on. A 10µA current source pulls this
pin up to a diode below INTV
CC
. Upon EN going low when
ON is high, an internal timer provides a 100ms start-up
delay for debounce, after which the fault is cleared.
Exposed Pad (UFD Package): Exposed pad may be left
open or connected to device ground.
FAULT (UFD Package): Fault Status Output. Open-drain
output that is normally pulled high by a 10µA current
source to a diode below INTV
CC
. It may be pulled above
INTV
CC
using an external pull-up. It pulls low when the
circuit breaker is tripped after an overcurrent fault timeout.
Leave open if unused.
GND: Device Ground.
HGATE: Hot Swap MOSFET Gate Drive Output. Connect
this pin to the gate of the external N-channel MOSFET for
Hot Swap control. An internal 10µA current source charges
the MOSFET gate. An internal clamp limits the gate volt
-
age to 12V above and a diode voltage below OUT. During
turn-off, a 300µA pull-down discharges HGATE to ground.
During an output short or INTV
CC
undervoltage lockout, a
fast 200mA pull-down discharges HGATE to OUT.
IN1, IN2: Positive Supply Input and MOSFET Gate Drive
Return. Connect this pin to the power input side of the
external ideal diode MOSFET. The 5V INTV
CC
supply is
generated from IN1 and IN2 via an internal diode-OR. The
voltage sensed at this pin is used to control DGATE. The
gate fast pull-down current returns through this pin when
DGATE is discharged.
INTV
CC
: Internal 5V Supply Decoupling Output. This pin
must have a 0.1µF or larger capacitor. An external load of
less than 500µA can be connected at this pin.
NC (UFD Package): No Connection. Not internally
connected.
ON: On Control Input. A rising edge above 1.235V turns on
the external Hot Swap MOSFET and a falling edge below
1.155V turns it off. Connect this pin to an external resistive
divider from SENSE
+
to monitor the supply undervoltage
condition. Pulling the ON pin below 0.6V resets the elec
-
tronic circuit breaker.
OUT: MOSFET Gate Drive Return. Connect this pin to the
output side of the external Hot Swap MOSFET. The gate
fast pull-down current returns through this pin when
HGATE
is discharged.
PWRGD: Power Status Output. Open-drain output that is
normally pulled high by a 10µA current source to a diode
below INTV
CC
. It may be pulled above INTV
CC
using an
external pull-up. It pulls low when the MOSFET gate drive
between HGATE and OUT exceeds the gate-to-source volt
-
age of 4.2V. Leave open if unused.
SENSE
+
: Positive Current Sense Input. Connect this pin
to the diode-OR output of the external ideal diode MOS
-
FETs and input of the current sense resistor. The voltage
sensed at this pin is used for monitoring the current limit
and also to control DGATE for forward voltage regulation
and reverse turn-off. This pin has an undervoltage lockout
threshold of 1.9V that will turn off the Hot Swap MOSFET.
SENSE
–
: Negative Current Sense Input. Connect this pin
to the output of the current sense resistor. The current