FAN3100T Fairchild Semiconductor, FAN3100T Datasheet - Page 15

• Manufacturer Part Number: FAN3100T
• Description: The FAN3100 2A gate driver is designed to drive an N-channel enhancement-mode MOSFET in low-side switching applications by providing high peak current pulses during the short switching intervals
• Manufacturer: Fairchild Semiconductor

© 2007 Fairchild Semiconductor Corporation
FAN3100 • Rev. 1.0.3
closest to the VDD and GND pins to carry the higher-
frequency components of the current pulses.
Layout and Connection Guidelines
The FAN3100 incorporates fast reacting input circuits,
short propagation delays, and powerful output stages
capable of delivering current peaks over 2A to facilitate
voltage transition times from under 10ns to over 100ns.
The following layout and connection guidelines are
strongly recommended:
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Figure 43 shows the pulsed gate drive current path
when the gate driver is supplying gate charge to turn the
MOSFET on. The current is supplied from the local
bypass capacitor, C
the MOSFET gate and to ground. To reach the high
peak currents possible, the resistance and inductance in
the path should be minimized. The localized C
contain the high peak current pulses within this driver-
MOSFET circuit, preventing them from disturbing the
sensitive analog circuitry in the PWM controller.
Keep high-current output and power ground paths
separate from logic input signals and signal ground
paths. This is especially critical when dealing with
TTL-level logic thresholds.
Keep the driver as close to the load as possible to
minimize the length of high-current traces. This
reduces the series inductance to improve high-
speed switching, while reducing the loop area that
can radiate EMI to the driver inputs and other
surrounding circuitry.
The FAN3100 is available in two packages with
slightly different pinouts, offering similar
performance. In the 6-pin MLP package, Pin 2 is
internally connected to the input analog ground and
should be connected to power ground, Pin 5,
through a short direct path underneath the IC. In the
5-pin SOT23, the internal analog and power ground
connections are made through separate, individual
bond wires to Pin 2, which should be used as the
common ground point for power and control signals.
Many high-speed power circuits can be susceptible
to noise injected from their own output or other
external sources, possibly causing output re-
triggering. These effects can be especially obvious
if the circuit is tested in breadboard or non-optimal
circuit layouts with long input, enable, or output
leads. For best results, make connections to all pins
as short and direct as possible.
The turn-on and turn-off current paths should be
minimized as discussed in the following sections.
BYP
, and flows through the driver to
BYP
acts to
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Figure 43. Current Path for MOSFET Turn-On
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