SP8855D

The SP8855D 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 a fully programmable device requiring two 16 bit words to set the RF and reference counters, and the SP8854D which has hard wired reference counter programming and requires a single bit word to program the RF divider.

The SP8855D is intended for applications where a fixed synthesiser frequency is required although it can also be used where frequency selection is set by switches. In general the device will be programmed by connecting the programming pins to either V_CC or ground. Additional hard wired inputs can be used to control the F_pd and F_ref outputs, set the control direction of the loop and select the phase detector gain. Another input may be used to disable the phase detector output