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TEA5764HN_2
Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Product data sheet
Rev. 02 — 9 August 2005
8 of 64
Philips Semiconductors
TEA5764HN
FM radio + RDS
The result found using
Equation 1
or
Equation 2
must always be rounded to the lowest
integer value. If rounded down to the lowest integer value of N
DEC
= 12246, the PLL word
becomes 2FD6h.
This value can be written to register FRQSETLSB or FRQSETMSB via the I
2
C-bus and
the IC will then either start an autonomous search at this frequency or go to a preset
channel at this frequency. When the application is built according to the block diagram
shown in
Figure 1
, and with the preferred components, the PLL will settle to the new
frequency within 5 ms. The most accurate tuning is accomplished when a search is
followed by a preset to the same frequency.
The PLL is triggered by writing to any one of the bytes FRQSETMSB, FRQSETLSB,
TNCTRL1, TNCTRL2, TESTBITS, TESTMODE.
Accurate validation of the PLL locking on the new frequency can take 2 ms to 10 ms.
When a lock is detected, bit LD is set.
8.6 Band limits
The TEA5764HN can be switched either to the Japanese FM-band or to the US/Europe
FM-band. Setting bit BLIM to logic 0 the band range is 87.5 MHz to 108 MHz; setting bit
BLIM to logic 1 selects the Japanese band range of 76 MHz to 90 MHz.
8.7 RF AGC
The RF AGC (or wideband 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
2
C-bus.
The TEA5764HN also has an in-band AGC to prevent overloading by the wanted channel.
The in-band AGC is always turned on.
8.8 Local or long distance receive
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.
8.9 IF filter
A fully integrated IF filter is built-in.
8.10 FM demodulator
The FM quadrature demodulator has an integrated resonator to perform the phase shift of
the IF signal.
8.11 IF counter
The received signal is mixed to produce 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
2
C-bus. The IF counter is continuously active and can be read at any time
via the I
2
C-bus. It also activates a flag when the IF count result is outside the IF count
valid result window; see
Section 9.1.4.4
.