1. General description
The TEF6862 is a single-chip car radio tuner for AM, FM and weather band reception
providing AM double conversion for LW, MW and full range SW (11 m to 120 m bands)
with IF1 = 10.7 MHz and IF2 = 450 kHz.
FM double conversion to IF1 = 10.7 MHz and IF2 = 450 kHz with integrated image
rejection for both IF1 and IF2; integrated IF filter with variable bandwidth and automatic
bandwidth control algorithm with flexibility via the I2C-bus; capable of US FM, Europe FM,
Japan FM, East Europe FM and weather band reception; all FM bands can be selected
using high injection LO or low injection LO in the FM mixer 1.
Tuning system including crystal oscillator, VCO, PLL synthesizer and state machine for
timing uncritical control of search, preset change and AF check via microcontroller.
2. Features
n High dynamic range FM front-end mixer for conversion of FM RF (65 MHz to 108 MHz
and USA weather band) to an IF frequency of 10.7 MHz; mixer provides inherent
image rejection which can be switched from low injection LO to high injection LO via
the I2C-bus
n FM front-end AGC PIN diode drive circuit; AGC detection at the FM font-end mixer
input and the IF filter input; AGC threshold for detection at the mixer input is
programmable and keyed AGC function can be selected via the I2C-bus; the AGC PIN
diode drive can be activated by the I2C-bus for a search tuning in local mode; in
AM mode the AGC PIN diode drive can be activated by the I2C-bus if required;
information on amount of PIN diode AGC is available via the I2C-bus
n FM front-end mixer includes +6 dB gain setting via the I2C-bus
n FM second mixer for conversion of IF1 10.7 MHz to IF2 450 kHz including inherent
image rejection; the gain can be controlled via the I2C-bus
n Integrated FM channel selection filter with continuous variable bandwidth providing
simultaneous low distortion and high selectivity with only one external ceramic filter;
improved sensitivity with dynamic threshold extension can be enabled via the I2C-bus
n Fully integrated FM demodulator with very low distortion
n Digital bandwidth control algorithm with detection on adjacent channel information,
deviation, detuning and level with customer flexibility via the I2C-bus
n Digital alignment circuit for bus controlled adjustment of oscillator tuning voltage to two
FM antenna tank circuit tuning voltages; AM and FM level start and slope alignment;
IF filter and demodulator center frequency alignment
n AM and FM level detection (signal strength indication)
n Separate RF input to FM front-end mixer for weather band
n Flag or voltage output indicators for actual IF bandwidth information