Datasheet

LTC4224-1/LTC4224-2
5
422412fa
PIN FUNCTIONS
SENSE1, SENSE2 (Pins 1,10): Current Sense Input. Con-
nect this pin to an external sense resistor. The current limit
circuit controls GATEn to limit the voltage between V
CCn
and SENSEn to 25mV. An Electronic Circuit Breaker (ECB)
is active during current limiting and trips after 5ms. To
disable current limit, connect this pin to V
CCn
.
V
CC1
, V
CC2
(Pins 2, 9): Supply Voltage and Current Sense
Input. An undervoltage lockout circuit disables the part
until V
CC
, the higher of V
CC1
and V
CC2
, exceeds 2.4V. The
lower supply is disabled until it exceeds 0.8V.
GATE1, GATE2 (Pins 3, 8): Gate Drive for External N-channel
MOSFET. A charge pump sources 10µA from GATE to turn
on the external MOSFET. An internal clamp limits the gate
voltage to 5.5V above the higher of V
CC1
and V
CC2
. During
turn-off, a 1.5mA pulldown current discharges GATE to
ground. During short-circuits, a 125mA pulldown current
is activated to discharge GATE to ground.
FAULT (Pin 4): Fault Status Output. Open-drain output
that is normally pulled high to V
CC1
or V
CC2
by an exter-
nal resistor. It is pulled low when the ECB trips due to an
overcurrent condition at either supply. This pin may be
left open if unused.
ON1, ON2 (Pins 5, 6): On Control Input. A falling edge
turns on the external N-channel MOSFET and a rising edge
turns it off. A low to high transition on this pin resets an
ECB fault for the corresponding channel. Internally pulled
up to V
CC
by a 10µA current source.
GND (Pin 7): Device Ground.
Exposed Pad (DFN Package Only): Exposed Pad may be
left open or connected to device ground.
FUNCTIONAL DIAGRAM
CHARGE
PUMP
422412 FD
0.8V
0.8V
2.4V
V
CC
–
+
–
+
–
+
–
+
–
+
+
–
+
–
CHARGE
PUMP
–
+
GATE
PULLDOWN
LOGIC
CONTROL
GATE
PULLDOWN
0.8V
–
+
0.8V
V
CC1
V
CC2
10µA
10µA
GATE1
GATE2
ON1
FAUL T
ON2
SENSE2
SENSE1
GND
ACL1
ACL2
10µA
10µA
5.5V
5.5V
ON2
ON1
ECB1
ECB2
V
CC1
UV
V
CC2
UV
25mV
25mV
V
CC
V
CC
V
CC
V
CC