IntelliMAX™ switches don’t require an input capacitor.
To reduce device inrush current, a 0.1 µF ceramic
capacitor, CIN, is recommended close to the VIN pin. A
higher value of CIN can be used to further reduce the
voltage drop experienced as the switch is turned on into
a large capacitive load.
IntelliMAX™ switches work without an output capacitor.
If the applications parasitic board inductance forces
VOUT below GND when switching off, a 0.1 µF capacitor,
COUT, should be placed between VOUT and GND.
Device output fall time can be calculated based on RC
constant of external components as follows:
tF RL CL 2.2
where tF is 90% to 10% fall time, RL is output,
load and CL is output capacitor.
The same equation works for a device with a pull-down
output resistor, then RL is replaced by a parallel
connected pull-down and external output resistor
combination, as follows:
where tF is 90% to 10% fall time, RL is output load,
RPDis output pull-down resistor (65 typical, and CL
is the output capacitor.
Recommended Land Pattern and Layout
For best thermal performance and minimal inductance
and parasitic effects, it is recommended to keep input
and output traces short and the capacitors as close to
the device as possible. Below is a recommended layout
for this device to achieve optimum performance.
Figure 24. Recommended Land Pattern and Layout
© 2012 Fairchild Semiconductor Corporation
FPF1504 / FPF1504L • Rev. 1.11