Datasheet

6
LTC1422
1422fb
PIN FUNCTIONS
UUU
GATE (Pin 6): The high side gate drive for the external
N-Channel. An internal charge pump guarantees at least
10V of gate drive when V
CC
is 5V. The slope of the voltage
rise or fall at the GATE is set by an external capacitor
connected between GATE and GND, and the 10µA charge
pump output current. When the circuit breaker trips, the
undervoltage lockout circuit monitoring V
CC
trips, or the
ON pin is pulled low for more than 40µs, the GATE pin is
immediately pulled to GND.
SENSE (Pin 7) : Circuit Breaker Set Pin. With a sense
resistor placed in the supply path between V
CC
and SENSE,
the circuit breaker will trip when the voltage across the
resistor exceeds 50mV for more than 10µs. If the circuit
breaker trip current is set to twice the normal operating
current, only 25mV is dropped across the sense resistor
during normal operation. To disable the circuit breaker,
V
CC
and SENSE can be shorted together.
V
CC
(Pin 8): The positive supply input, ranging from 2.7V
to 13.2V for normal operation. I
CC
is typically 0.6mA. An
undervoltage lockout circuit disables the chip until the
voltage at V
CC
is greater than 2.47V.
–
+
1.232V
REFERENCE
20µs GLITCH
FILTER
10µs
FILTER
2.47V
UVL
+
–
50mV
8
REF
5
FB
1
RESET
4
GND
COMP 3
V
CC
7
SENSE
6
GATE
–
+
COMP 1
REF
–
+
COMP 2
2µA
12µA
–
+
COMP 4
REF
TIMER
1422 BD
3
ON
2
Q1 Q2
LOGIC
CHARGE
PUMP
Q3
BLOCK DIAGRA
W