VCT2001A Datasheet, PDF (1/5 Pages) CTS Corporation – HCMOS Output-Dual Input Clock Generator

PRELIMINARY
Module Data Sheet: VCT2001A 77.760 MHz
Application: HCMOS Output-Dual Input Clock Generator
1.0 DESCRIPTION AND APPLICATION
The VCT2001A is a dual reference input 3.3V clock generator module with an
HCMOS output. Reference inputs are selectable by a one-bit select control input.
An alarm output can be used to detect a problem on the selected reference, such as
a loss of lock or a loss of reference. A logic level “1” is indicated from the alarm pin
when there is a problem with the selected reference. The unit operates in the free run
mode when there is a problem with the selected reference, or when free run is invoked by
enabling the forced free run input. Free run accuracy will keep the output to within 20
ppm. The reference will not automatically switch upon loss of reference. Also, all
outputs may be tri-stated for external testing purposes with a signal to the Tri-State/Reset
input.
The Loss of Reference alarm detects a missing rising edge within 100 nS of the
missing edge. This is usually around 70 nS.
The 8kHz output is divided from the on-board low jitter oscillator. Output phase
coherence is maintained during reference switching rearrangement, so the output phase
will not necessarily be the same as the reference being used.
The dimensions of the low jitter module are 0.78” x 0.83” x 0.29” mounted on a
castellated pin FR-4 board.
FEATURES:
• Output jitter below 1 ps from 12 kHz to 20 MHz
• Two Selectable References @ 8 kHz
• Alarm Output Detecting Loss of Reference or Loss of Lock
• Tri-Statable Outputs
• Force Free Run Function
• Automatic Free Run Operation upon loss of both references
• Rising Edge Phase Detector allows for any Duty Cycle Reference Input
• 3.3 Volt Regulated Power Supply
• Small Size: 0.78” x 0.83” x 0.29”
• Surface Mount with Castellated Pins
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Rev. “4” 3/28/03