View sp5510 datasheet:

JUNE 1995 ADVANCE INFORMATION 2184-3.2 SP5510 1·3 GHz BIDIRECTIONAL I2C BUS CONTROLLED SYNTHESISER (Supersedes version in April 1994 Consumer IC Handbook, HB3120 - 2.0) The SP5510 is a single-chip frequency synthesiser designed for TV tuning systems. Control data is entered in the standard I2C BUS format. The device has four addressable current- limited output ports (P0-P3) and four bi-directional open- collector ports (P4-P7), one of which (P6) is also a 3-bit 5-level ADC input. The information on these ports can be read via the I2C BUS. The SP5510S is a variant in a 16-lead miniature plastic package, without P0-P2 but functionally identical in other respects. Both variants have one fixed I2C BUS address and three programmable addresses, allowing two or more synthesisers