tea5766uk NXP Semiconductors, tea5766uk Datasheet - Page 12

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

NXP Semiconductors
TEA5766UK_1
Product data sheet
7.20.1 Auto high-side and low-side injection stop switch
7.20.2 Muting during search or preset
Table 5.
[1]
The channel quality can sometimes be improved in case of image frequency interference.
This can be achieved if the Local Oscillator (LO) injection is positioned at the opposite
side of the wanted channel (see
be derived from the IF frequency counter. To enable this feature the AHLSI bit must be set
to logic 1.
The search/preset algorithm will stop and generate an interrupt event after the detection
of a valid RSSI level in combination with a frequency outside the IF frequency window.
The host processor can detect this state by reading the interrupt register. Swap of the LO
injection is achieved by inversion of bit HLSI in combination with a new tuning word for the
changed oscillator frequency (see
During preset and search the tuner is always muted, which is done by the algorithm itself.
When the AHLSI bit is set and the tuner has stopped during a preset or a search because
of a wrong IF count, the tuner keeps muted and generates an interrupt event. In this way
the host processor can switch the high or low setting quietly and waits for the new result.
All these mute actions are done by blocking the audio signal and the audio output will
keep its DC level and stay in low-impedance state i.e. 50
with the MU bit will cause a plop.
Bit
IFFLAG
1
1
1
Fig 3. Switch LO from high-side injection to low-side injection using the HLSI bit
This table is valid until 31.25 ms after the tuning cycle has completed. It shows the outcome of the flag
register when a read is done after INTX has gone LOW with the condition that no other mask bits are set
than shown in the table.
Tuner truth table
BLFLAG
0
1
1
image on low-side
Rev. 01 — 22 March 2007
FRRFLAG
1
0
1
[1]
…continued
Figure
switch LO from high-side to low-side
Comment
a preset or search has been done, but the wanted channel
has a valid RSSI level but fails the IF count; when AHLSI
was set HLSI must be toggled and a new PLL value must be
programmed; FRRMSK set
not a valid state
band limit is reached during search; no valid channel found;
BLMSK or FRRMSK set
Section
3). Indication for image frequency interference can
wanted channel
7.5).
image on high-side
(see
TEA5766UK
Table
Stereo FM radio + RDS
001aab460
4). A hard mute
© NXP B.V. 2007. All rights reserved.
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