PL123E-05SC Datasheet, PDF (3/10 Pages) Micrel Semiconductor – Low Skew Zero Delay Buffer

LAYOUT RECOMMENDATIONS
(P P reliminary) L123E-05
Low Skew Zero Delay Buffer
The following guidelines are to assist y ou with a performance optimized PCB design:
Signal Integrity and Termination
Considerations
- Keep traces short!
- Trace = Inductor. With a capacitive load this
equals ringing!
- Long trace = Transmission Line. Without proper
termination this will cause reflections ( looks like
ringing ).
- Design long traces as “striplines” or “microstrips”
with defined impedance.
- Match trace at one side to avoid reflections bounc-
ing back and forth.
Decoupling and Power Supply
Considerations
- Place decoupling capacitors as close as possible to
the VDD pin(s) to limit noise from the power supply
- Addition of a ferrite bead in series with VDD can
help prevent noise from other board sources
- Value of decoupling capacitor is frequency de-
pendant. Typical values to use are 0.1F for de-
signs using frequencies < 50MHz and 0.01F for
designs using frequencies > 50MHz.
Typical CMOS termination
Place Series Resistor as close as possible to CMOS output
CMOS Output Buffer
( Typical buffer impedance 20 
50 line
To CMOS Input
Connect a 33 series
resistor at each of the output
clocks to enhance the
stability of the output signal
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax [phone] • www.micrel.com Rev 12/13/11 Page 3