EN6337QI/EN6347QI
Evaluation Board User Guide
Nov 2010
Page 5 of 9
For spread spectrum operation the input clock frequency may be swept between two
frequencies that are within the lock range. The sweep (jitter) repetition rate should be
limited to 10 kHz. The radiated EMI spectrum may be now measured in various states –
free running, phase locked to a fixed frequency and spread spectrum. Before measuring
radiated EMI, place a 10uF/0805, X7R capacitor at the input and output edges of the
PCB (footprint already provided on the board), and connect the input power and the
load to the board at or near these capacitors.
The added capacitor at the input edge is
for high-frequency decoupling of the input cables. The one added at the output edge is
meant to represent a typical load decoupling capacitor.
Figure 4: Evaluation Board Layout Assembly Layer
