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Creating Your Own Options Board
TM8000 3DK Hardware Developer’s Kit
Application Manual
September 2003
© Tait Electronics Ltd
Power Supply
Decoupling
Power supply decoupling is most effective when the decoupling is placed
close to the load. For high-impedance loads, some resistance in series with
the load can be beneficial. For most applications a single 100nF capacitor is
sufficient to remove high-frequency noise.
For high-speed digital designs, the use of a power plane for each digital
supply rail is strongly recommended. The power plane enables many
decoupling capacitors and device power pins to be connected together with
very low impedance. The inter-plane capacitance is usually not sufficient by
itself for decoupling. Low ESR tantalums for low-frequency decoupling are
recommended. Multiple ceramic 100 nF capacitors are recommended for
high-frequency decoupling. Design analysis should be undertaken to ensure
that decoupling is effective up to at least 500 MHz.
Separate power supply rails for digital and analog circuitry are
recommended.
Note
High-speed digital design requires a high level of design experi-
ence, appropriate design tools and high bandwidth test equipment
to be successful. This should not be undertaken without all of the
above.