Datasheet

TEF6901A_3 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 03 — 20 March 2008 28 of 107
NXP Semiconductors
TEF6901A
Integrated car radio
Since buffer mode (bits MODE[2:0] = 000) does not change any tuner action or register
other then those defined by the I
2
C-bus write transmission it generally is the mode used
for writing outside the buffered subaddress range (i.e. bits SA[4:0] = 06h to 1Fh). Writing
in the subaddress range of 06h to 1Fh is executed immediately and is not controlled by
the state machine. Load mode does not interrupt a state machine process, the preload
action changes the content of the BUFFER register which may interfere with a tuner
action in progress.
When a new state machine tuning action is started during a mute state of the state
machine, the new action skips the unnecessary activation of mute and starts immediately
with the actions that follow the mute period in the standard sequence. In this way fastest
timing is possible e.g. for search tuning (see Figure 14, Figure 16, Figure 20 and
Figure 22). When AF update mode is started during a mute state only the return tuning
action will be performed; in combination with check mode an AF update can be created
with the AF sampling time defined by I
2
C-bus control (see Figure 18).
The FM IF2 signal path contains a digital controlled AGC function with a maximum AGC
decay time of 13 ms to realize sufficient AM suppression during changing signal
conditions and high modulation situations. During the settling of the AGC (e.g. after a
tuning action), the gain of the FM path and the level detection can be affected. To get
correct signal quality information, a minimum time of 13 ms should be used between two
tuning actions.
Table 25. Tuning action modes
MODE2 MODE1 MODE0 Symbol Description
0 0 0 buffer write BUFFER register, no state machine action, no
register swap; see
Figure 9
0 0 1 preset tune to new program with 60 ms mute control; swap;
see
Figure 13 and Figure 14; BUFFER is preloaded with
CONTROL register; immediate swap; see
Figure 11
0 1 0 search tune to new program and stay muted (to release use
end); swap; see
Figure 15 and Figure 16; BUFFER is
preloaded with CONTROL register; see
Figure 11
0 1 1 AF update tune to AF program; check AF quality and tune back to
main program; two register swap operations;
see
Figure 10, Figure 17 and Figure 18
1 0 0 jump tune to AF program in minimum time; register swap;
see
Figure 10, Figure 19 and Figure 20
1 0 1 check tune to AF program and stay muted (to release use end);
register swap; see
Figure 10, Figure 21 and Figure 22
1 1 0 load write CONTROL register via BUFFER; no state machine
action; BUFFER is preloaded with CONTROL register;
immediate swap; see
Figure 12
1 1 1 end end action; release mute; no register swap; see
Figure 9
and
Figure 23