BU8874 Datasheet, PDF (7/10 Pages) Rohm – DTMF receiver for telephones

Communication ICs
FApplication example
BU8874 / BU8874F
FSelecting attachment components
(1) Power supply components
(2) Oscillation components
C502 : This is the VDD bypass capacitor, and is normally
100µF.
JP501 : This is normally shorted. To test the current con-
sumption of the IC (at the point where the power
down mode is entered), insert a DC ammeter in
place of JP501.
X501 :
Use a crystal or ceramic resonator with an os-
cillation frequency of 4.194304MHz. If using a
ceramic resonator, there may be problems with
the precision of the oscillation frequency, so we
recommend using one of the ceramic resona-
tors listed below.
C591 :
If you are using a dedicated resonator X501de-
signed for DTMF receivers, capacitor C591
should be left open. If you are injecting an exter-
nal clock, X501 should be omitted and DC
blocking capacitor C591 used in its place. Typi-
cally, this capacitor should be 47µnF.
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