TEA6848H
1 FEATURES
· FM mixer 1 for conversion of FM RF (65 to 108 MHz
and US weather band) to IF of 10.7 MHz; the mixer
provides inherent image rejection; for European and
US FM band/WB (weather band) the mixer is driven with
a ‘high’ injection Local Oscillator (LO); in Japan
FM band and East Europe FM band the mixer is driven
with a ‘low’ injection LO
· 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 FM 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, TEF689x)
· Digital alignment circuit for bus controlled matching of
oscillator tuning voltage to FM antenna tank circuit
tuning voltage
· 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 function for
search tuning; AGC threshold is a programmable and
keyed function switchable via the I2C-bus
· FM IF linear amplifier with high dynamic input range
· FM mixer 2 for conversion of FM IF1 to FM IF2 of
450 kHz with inherent image rejection
· Fully integrated dynamic selectivity and
FM demodulator at IF2; improved sensitivity with
dynamic threshold extension; centre frequency of IF2
selectivity alignment via the I2C-bus
· Level detector for AM and FM with temperature
compensated output voltage; starting point and slope of
level output is programmable via the I2C-bus
· AM cascode AGC stage and RF PIN diode drive circuit;
AGC threshold detection at AM mixer 1 and IF2 AGC
input; threshold for detection at mixer 1 input is
programmable via the I2C-bus
· AM IF2 AGC and demodulator
· AM AF output switchable to provide AM IF2 for
AM stereo decoder
· AM noise blanker with detection at IF1 and blanking at
AM IF2
· Software controlled flag output
· Buffer output for weather band flag
· Adjacent channel detector, modulation detector and
frequency offset for instantaneous bandwidth control of
the integrated filter
· Flag and voltage output indicating the actual bandwidth
· I2C-bus alignment of centre frequency and gain variation
as functions of bandwidth of the IF2 filter and centre
frequency of the offset detector.
2 GENERAL DESCRIPTION
The TEA6848H is a single IC with car radio tuner for AM,
FM and Weather Band (WB) 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 double conversion receiver with integrated image
rejection for IF1 and for IF2 capable of selecting US FM,
US weather, Europe FM, East Europe FM and
Japan FM bands; fully integrated dynamic selectivity at
450 kHz FM IF2; FM demodulator with dynamic
threshold extension; centre frequency alignment of IF2
selectivity via the I2C-bus
· The tuning system includes VCO, crystal oscillator and
PLL synthesizer on one chip.
