LT1910 Linear Technology, LT1910 Datasheet - Page 5

• Manufacturer Part Number: LT1910
• Description: Protected High Side MOSFET Driver
• Manufacturer: Linear Technology

PI FU CTIO S
GND (Pin 1): Common ground.
TIMER (Pin 2): A timing capacitor C
to ground sets the restart time following overcurrent
detection. Upon detection of an overcurrent condition, C
is rapidly discharged to less than 1V and then recharged
by a 14 A nominal current source back to the 2.9V timer
threshold, whereupon the restart is attempted. Whenever
TIMER pulls below 2.9V, the GATE pin pulls low to turn off
the external switch. This cycle repeats until the overcur-
rent condition goes away and the switch restarts success-
fully. During normal operation the pin clamps at 3.5V
nominal.
FAULT (Pin 3): The FAULT pin monitors the TIMER pin
voltage and indicates the overcurrent condition. When-
ever the TIMER pin is pulled below 3.3V at the onset of a
current limit condition, the FAULT pin pulls active LOW.
The FAULT pin resets HIGH immediately when the TIMER
pin ramps above 3.4V during autorestart. The FAULT pin
is an open-collector output, thus requiring an external
pull-up resistor and is intended for logic interface. The
resistor should be selected with a typical 1mA pull-up at
low status and less than 2mA under worst-case condi-
tions.
IN (Pin 4): The IN pin threshold is TTL/CMOS compatible
and has approximately 200mV of hysteresis. When the IN
pin is pulled active HIGH above 2V, an internal charge
pump is activated to pull up the GATE pin. The IN pin can
be pulled as high as 15V regardless of whether the supply
is on or off. If the IN pin is left open, an internal 75k pull-
down resistor pulls the pin below 0.8V to ensure that the
GATE pin is inactive LOW.
U
U
U
T
from the TIMER pin
T
GATE (Pin 5): The GATE pin drives the power MOSFET
gate. When the IN pin is greater than 2V, the GATE pin is
pumped approximately 12V above the supply. It has
relatively high impedance (the equivalence of a few hun-
dred k ) when pumped above the rail. Care should be
taken to minimize any loading by parasitic resistance to
ground or supply. The GATE pin pulls LOW when the
TIMER pin falls below 2.9V.
SENSE (Pin 6): The SENSE pin connects to the input of a
supply-referenced comparator with a 65mV nominal off-
set. When the SENSE pin is taken more than 65mV below
supply, the MOSFET gate is driven LOW and the timing
capacitor is discharged. The SENSE pin threshold has a
0.33%/ C temperature coefficient (TC), which closely
matches the TC of the drain sense resistor formed from the
copper trace of the PCB.
For loads requiring high inrush current, an RC timing delay
can be added between the drain sense resistor and the
SENSE pin to ensure that the current-sense comparator
does not false trigger during start-up (see Applications
Information). A maximum of 10k can be inserted be-
tween a drain sense resistor and the SENSE pin. If current
sensing is not required, the SENSE pin is tied to supply.
V
for the LT1910, the V
connection for the current sense comparator. The V
must be connected to the positive side of the drain sense
resistor for proper current sensing operation.
+
(Pin 8): In addition to providing the operating current
+
pin also serves as the Kelvin
LT1910
sn1910 1910fs
+
5
pin