TDA7478
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Figure 4. RDS timing diagram
3 OUTPUT TIMING
The RDS (1187.5Hz) output clock on RDCL line is synchronized to the incoming data. According to the internal
PLL lock condition data change can result on the falling or on the rising clock edge. (see Fig. 1)Whichever clock
edge is used by the decoder (rising or falling edge) the data will remain valid for 416.7
µ
s after the clock transi-
tion.
4 OSCILLATOR CONTROLS (FSEL, OSEL)
Two different crystal frequencies can be used. The adaption of the internal clock divider to the external crystal
is achieved via the input pin FSEL. See the following table for reference:
Table 6.
A special mode is introduced to reduce EMI. With pin OSEL connected to GND the internal oscillator is switched
off and an external sinusoidal frequency could be applied on OSCIN. The peak to peak voltage of this signal
can be reduced down to 60mV.
In this mode the frequency selection via FSEL is still active.
Suggested values of C1 and C2 are shown in the following table:
Table 7.
Crystal FSEL (pin configuration)
4.332MHz
8.664MHz
connected to GND or open
connected to Vs
Crystal C1 C2
4.332MHz
8.664MHz
27pF
27pF
47pF
-
CLOCK
LINE
DATA
LINE
