Micrel, Inc.

SM803020

July 22, 2013

10

Revision 1.0

hbwhelp@micrel.com or (408) 955-1690

Application Information

Input Reference

When operating with a crystal input reference, do not apply

a switching signal to a REF_IN.

Crystal Layout

Keep the layers under the crystal as open as possible and

do not place switching signals or noisy supplies under the

crystal.

Crystal load capacitance is built inside the die so no

external capacitance is needed. See the Selecting a

Quartz Crystal for the Clockworks Flex I Family of

Precision Synthesizers application note for more details.

Contact Micrel’s HBW applications group if you need help

selecting a suitable crystal for your application at:

hbwhelp@micrel.com.

Power Supply Filtering Recommendations

Figure 1. Recommended Power Supply Filtering

•

Use the power supply filtering shown in Figure 1 for

VDDAP1, VDDAP2, VDDI1 and VDDI2.

•

Connect the VDDO and VDD pins directly to the VDD

power plane.

•

Connect all VSS pins directly to the ground power

plane.

Figure 2. Duty Cycle Timing

Figure 3. All Outputs Rise/Fall Time