Micrel, Inc.

PL135-27

September 8, 2014

4

Revision 2.0

Layout Recommendations

The following guidelines are to assist you 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 bouncing

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

• Multiple VDD pins should be decoupled separately for

best performance.

• Addition of a ferrite bead in series with VDD can help

prevent noise from other board sources

• Value of decoupling capacitor is frequency dependent.

Typical value to use is 0.1µF.