SP8854D

The SP8854D is one of a family of parallel load synthesisers containing all the elements apart from the loop amplifier to fabricate a PLL synthesis loop. Other parts in the series are the SP8852D which is fully programmable requiring two 16 word bit words to set the RF and reference counters, and the SP8855D which is programmed by hard wired links or switches.

The SP8854D is programmed using a 16 bit parallel data bus. This Data is stored in an internal buffer. The 10 bit programmable reference divider is programmed by connecting the 10 programming pins either to ground or +5V. The device can therefore be programmed with a single transfer from the control microprocessor. Hard wired inputs can also control the F_pd and F_ref outputs and the control sense of the loop.