During normal operation, the Input pin is
electrically connected to the gate of the internal
power MOSFET. The device then behaves like a
standard power MOSFET and can be used as a
switch from DC to 50 KHz. The only difference
from the user’s standpoint is that a small DC
current (I
iss
) flows into the Input pin in order to
supply the internal circuitry.
The device integrates:
- OVERVOLTAGE CLAMP PROTECTION:
internally set at 42V, along with the rugged
avalanche characteristics of the Power
MOSFET stage give this device unrivalled
ruggedness and energy handling capability.
This feature is mainly important when driving
inductive loads.
- LINEAR CURRENT LIMITER CIRCUIT: limits
the drain current Id to Ilim whatever the Input
pin voltage. When the current limiter is active,
the device operates in the linear region, so
power dissipation may exceed the capability of
the heatsink. Both case and junction
temperatures increase, and if this phase lasts
long enough, junction temperature may reach
the overtemperature threshold T
jsh
.
- OVERTEMPERATURE AND SHORT CIRCUIT
PROTECTION: these are based on sensing
the chip temperature and are not dependent on
the input voltage. The location of the sensing
element on the chip in the power stage area
ensures fast, accurate detection of the junction
temperature. Overtemperature cutout occurs at
minimum 150
o
C. The device is automatically
restarted when the chip temperature falls
below 135
o
C.
- STATUS FEEDBACK: In the case of an
overtemperature fault condition, a Status
Feedback is provided through the Input pin.
The internal protection circuit disconnects the
input from the gate and connects it instead to
ground via an equivalent resistance of 100 Ω.
The failure can be detected by monitoring the
voltage at the Input pin, which will be close to
ground potential.
Additional features of this device are ESD
protection according to the Human Body model
and the ability to be driven from a TTL Logic
circuit (with a small increase in R
DS(on)
).
PROTECTION FEATURES
VNP14N04
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