(Preliminary)

PL680-37/38/39

38-640MHz Low Phase Noise XO

47745 Fremont Blvd., Fremont, California 94538 Tel (510) 492-0990 Fax (510) 492-0991 www.phaselink.com Rev 11/28/05 Page 3

FREQUENCY SELECTION TABLE

SEL2

SEL1

SEL0

Selected Multiplier/Output Frequency

0

0

0

VCO Max*

0

0

1

VCO Min*

0

1

0

Reserved

0

1

1

Reserved

1

0

0

Fin x 2

1

0

1

Fin x 8

1

1

0

Fin x 16

1

1

1

Fin x 4

All SEL pads have internal pull-ups (default value is ‘1’). Bond to GND to set to 0.

* Special Test Modes to help selecting the inductor value for the target output frequency.

PERFORMANCE TUNING & INDUCTOR VALUE SELECTION

Please refer to PhaseLink’s ‘PhasorV Tuning Assistance’ software to automatically calculate the optimum inductor

values. In addition, the chart below could be used as a reference for quick inductor value selection.

Use the special test modes “VCO Max” and “VCO Min” to determine the optimum inductor value. “VCO Max”

represents the high end of the VCO range and “VCO Min” represents the low end of the VCO range. The output

frequency in the “VCO Max” and “VCO Min” test modes is VCO/16. This means that the output frequencies are

around the crystal frequency that will be used. The optimum inductor value is where the target crystal frequency

is closest to the middle between the “VCO Max” and “VCO Min” output frequencies. In this case the VCO will lock

in the middle of its tuning range with maximum margin on either side.