The MC44827/27B are tuning circuits for TV and VCR tuner applications. They contain on one chip all the functions required for PLL control of a VCO. The integrated circuits also contain a high frequency prescaler and thus can handle frequencies up to 1.3 GHz. The MC44827 has programmable 512/1024 reference divider while the MC44827B has a fixed reference divider of 1024. The MC44827/27B offer the same features as MC44817/17B but has improved sensitivity performance and reduced power dissipation. The low frequency preamplifier has been removed and the operational amplifier pullup resistor has been increased to 60 k. The MC44827/27B are controlled via a 3wire bus. The MC44827/27B have the same functions as the MC44828 which is I2C bus controlled. The MC44827/27B and the MC44828 can be exchanged to allow conversion between 3wire bus and I2C bus control. The MC44827/27B are manufactured on a single silicon chip using Motorola's high density bipolar process, MOSAICTM (Motorola Oxide Self Aligned Implanted Circuits).