GENERAL DESCRIPTION
The TEA6845 is a single IC with car radio tuner for AM and FM intended for microcontroller tuning with the I2C-bus. It provides the following functions:
• AM double conversion receiver for LW, MW and SW (31 m, 41 m and 49 m bands) with IF1 = 10.7 MHz and
IF2 = 450 kHz
• FM single conversion receiver with integrated image rejection for IF = 10.7 MHz capable of selecting US FM,
US weather, Europe FM, East Europe FM and Japan FM bands.

FEATURES
• FM mixer for conversion of FM RF from 65 to 108 MHz to IF of 10.7 MHz; the mixer provides inherent image rejection
• FM RF mixer can be set to receive weather band radio up to 162.55 MHz; weather band radio flag output
• AM mixer 1 for conversion of AM RF to AM IF1 of 10.7 MHz
• LC tuner oscillator providing mixer frequencies for FM mixer and AM mixer 1
• AM mixer 2 for conversion of AM IF1 to AM IF2 of 450 kHz
• Crystal oscillator providing mixer frequencies for AM mixer 2 and reference for synthesizer PLL, IF count, timing for Radio Data System (RDS) update and reference frequency for car audio signal processor ICs
• Fast synthesizer PLL tuning system with local control for inaudible RDS updating
• Timing function for RDS update algorithm and control signal output for car audio signal processor ICs (TEA688x, SAA77xx) or car radio integrated signal processor IC (TEF6890H)
• Digital auto alignment circuit for conversion of LC oscillator tuning voltage to controlled alignment voltage of FM antenna tank circuit
• AGC PIN diode drive circuit for FM RF AGC; AGC detection at FM mixer input; the AGC PIN diode drive can be activated by the I2C-bus as a local or distance function; AGC threshold is a programmable and keyed
function switchable via the I2C-bus
• FM IF linear amplifiers with high dynamic input range
• FM quadrature demodulator with automatic centre frequency adjustment and Total Harmonic Distortion
(THD) compensation