S4503

The S4503 is a clock synthesizer which utilizes phase-locked loop technology to provide two (2) independently selectable output frequencies in the 10 MHz to 300 MHz range. A reference input may be provided by either a low cost crystal or a TTL frequency source.

The first of the two (S4503) output frequency groups consists of a pair of differential PECL (Positive referenced ECL) outputs which will operate up to 300 MHz. The second group (TTL) consist of two outputs with selectable frequency, up to 80 MHz.

The final frequency of S4503 for each group is digitally selected via three programmable counters. One counter is used to set the internal VCO frequency between 150 MHz to 300 MHz, and the others are used to divide the VCO frequency from 2 thru 16 (TTL) and 1, 2 or 4 (PECL).

All phase-locked loop elements of S4503 are provided on chip with the exception of the passive components needed for the loop filter function and VCO.