tea5761uk NXP Semiconductors, tea5761uk Datasheet - Page 8

• Manufacturer Part Number: tea5761uk
• Description: Tea5761uk Low-voltage Single Chip Fm-stereo Radio
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13451
Product data sheet
8.13.1 Soft mute
8.10 FM demodulator
8.11 IF counter
8.12 Voltage level generator and analog-to-digital converter
8.13 Mute
8.7 RF AGC
8.8 Local or long distance receive
8.9 IF filter
The RF AGC prevents overloading and limits the amount of intermodulation products
created by strong adjacent channels. The RF AGC is on by default and can be turned off
via the I
The TEA5761UK also has an in-band AGC to prevent overloading by the wanted channel.
The in-band AGC is always turned on.
If bit LDX = 1, the LNA gain is reduced by 6 dB to prevent distortion when a transmitter is
very near. If bit LDX = 0, the LNA gain is normal to receive long distance (DX) stations.
A fully integrated IF filter with a center frequency of 225 kHz is built-in.
The FM quadrature demodulator has an integrated resonator to perform the phase shift of
the IF signal.
The received signal is mixed to an IF of 225 kHz. The result of the mixing is counted. A
good IF count result indicates that the radio is tuned to a valid channel instead of an
image or a channel with much interference. The IF counter outputs a 7-bit count result via
the I
I
window; see
bit IFCTC.
The voltage level indicates the field strength received by the antenna. The voltage level is
analog-to-digital converted to a 4-bit word and output via the I
continuously active and can be read at any time via the I
when the voltage level falls under a predefined selectable threshold. Bit LHSW allows
either large or small hysteresis steps to be chosen; see
The low-pass filtered level voltage drives the soft mute attenuator at low RF input levels:
the audio output is faded and hence also the noise (curves 1 and 2 of
The soft mute function can also be toggled via the I
2
C-bus. It also activates a flag when the IF count result is outside the IF count valid result
2
C-bus. The IF counter is continuously active and can be read at any time via the
2
C-bus.
Section
9.2.2. The IF count period can be set to 1.953 ms or 15.625 ms by
Rev. 01 — 2 August 2006
Low voltage single-chip FM stereo radio
2
C-bus, using bit SMUTE.
Table 21
2
C-bus. It also activates a flag
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
2
C-bus. The ADC level is
TEA5761UK
and
Section
Figure
12).
9.2.3.
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