VCT2001A

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 VCT2001A 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 of VCT2001A 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.

VCT2001A 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.