PLL Tuning Circuit with DC-DC Converter, I2C Bus and ADC

The MC44871 is a tuning circuit for TV, VCR and Multimedia tuner applications. This device contains on one chip all the functions required for PLL control of a VCO. This integrated circuit also contains a high frequency prescaler and thus can handle frequencies up to 1.3 GHz.

The MC44871 has an integrated dc/dc converter to generate the 30 V supply voltage for the tuning amplifier on the chip. A tuner using the MC44871 does not require an external 30 V supply.

The MC44871 is controlled by a I2C bus, and has a chip address function. The MC44871 data format is the same as the MC44818.

The MC44871 is manufactured on a single silicon chip using Motorola’s high density bipolar process, MOSAIC (Motorola Oxide Self Aligned Implanted Circuits).

• The Pin Called VCC2 for the MC44818 is Now Called CP (Charge

Pump). This Pin is the Output of the DC/DC Converter; a 1.0 nF

Capacitor Replaces the Need for an External 30 V Supply

• High Speed I2C Bus (up to 800 kHz)

• I2C Bus Read Mode for Lock Detector and AFC Level

• HF Input is Balanced

• MC44871 has Three PNP High Current (30 mA) Band Buffers (B0, B1, B2) and One NPN Low Current (5.0 mA) Band Buffer (B4)

• VCC Internally Supplies PNP Band Buffers

• The Tuning Voltage is Generated Through an External Pull–Up Resistor (750 kΩ)

• Less Phase Comparator Output Current

• Single 5.0 V Supply Operation