[sdiy] What's all this decoupling cap business??

[Ray Wilson]

A little more on this...

Here are a couple of quotes from National Semiconductor app notes that may
prove useful in this regard.

Power Supply Decoupling
In order to reduce noise within the IC, most of National
Semiconductor's TCONs (timing controllers) use at least two separate power
supplies and numerous power supply pins. It is recommended
that every power supply pin should have its own
decoupling capacitor as close as possible to the pin, and at
least one of the power supply pins of each type should have
multiple decoupling capacitors attached. A good default capacitor
value is 0.1µF, and if multiple capacitors are to be
attached, it may help to have a range of values. Three
capacitors of 100pF, 0.1µF, and 22µF will work well for most
applications.

Power Supply Decoupling
Like the timing controller, the column driver should have
decoupling capacitors located as close as possible to each
of the power pins. Typically, a 0.1µF capacitor on each power
pin will meet the decoupling needs of the system.

RSDST Flat Panel Display
Design Guidelines Part 1

National Semiconductor
Application Note 1234
Craig Zajac
May 2002


Tantalum capacitors are often recommended for power supply bypass
applications because of a useful value of series resistance.
These capacitors will often stop high frequency parasitic
oscillations that involve resonant circuits in the power supply
lines because the series resistance of the capacitor reduces
the Q of the high frequency parasitic resonant circuits.

Tom M. Frederiksen, Intuitive IC Op Amps