tea5766uk NXP Semiconductors, tea5766uk Datasheet - Page 8

• Manufacturer Part Number: tea5766uk
• Description: Tea5766uk Stereo Fm Radio + Rds
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA5766UK_1
Product data sheet
7.10.1 IF counter correct channel checking
7.10.2 IF counter count time
7.12.1 Soft mute
7.10 IF counter
7.11 Level voltage generator and level analog-to-digital converter
7.12 Mute
7.8 IF filter
7.9 FM demodulator
Fully integrated IF filter with a center frequency of 225 kHz.
Fully integrated FM quadrature demodulator.
The received RF signal is converted down to a 225 kHz Intermediate Frequency (IF). The
IF is measured by means of a frequency counter. A correct IF frequency measurement
result indicates that the radio is tuned to a valid channel and not to an image or a channel
with high interference. The 7-bit IF counter output can be read via the control interface.
The IF counter is continuously active and can be read at any time via the bus. It also
activates a flag when the IF count result is outside the IF count valid result window; see
also
Before a tuning cycle is initiated the IF count period can be set to 2 ms or to 15.6 ms with
bit IFCTC in register TNCTRL (see
initiating the tuning algorithm with a preset (SM = 0) will always give an RDS update as
shown in
Section 7.20
The level voltage reflects the received field strength at the antenna. The analog level
voltage is digitized to 4 bits by the level Analog-to-Digital Converter (ADC). This level ADC
is continuously active and the output can be read at any time via the control interface. The
level ADC information is used during search as well as preset tuning to compare the
received signal strength with a search stop level (see
indicate that the level voltage is reduced below a programmable threshold value (see
Section
between the search stop level and the threshold level can be selected by bit LHSW (see
Table
When the ADC level is set to its minimum value 3, the search algorithm will only stop at
channels having an RF level higher than or equal to ADC level 3. After completing the
search algorithm and being tuned to a station, due to the hysteresis the effective limit will
be set to 0. This means that the continuous ADC level check will never set the LEVFLAG.
The low-pass filtered level voltage drives the softened attenuator. At low RF input levels,
the audio output is faded and hence also the noise. The softened function can be turned
on/off via the control interface, bit SMUTE in register TNCTRL (see
Section
19,
8.2.5). The threshold value is relative to the search stop level. The hysteresis
Section
Table 20
8.2.4.
is used. Once tuned, the IF count period is always 15.6 ms.
7.21. In case the IF count time is set to 15.6 ms the tuning flowchart of
and
Rev. 01 — 22 March 2007
Section
8.2.5).
Table
16). When the IF count period is set to 2 ms,
Section
8.2.5). A flag will be set to
TEA5766UK
Stereo FM radio + RDS
Table
© NXP B.V. 2007. All rights reserved.
16).
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