BU8871F Rohm, BU8871F Datasheet - Page 8

• Manufacturer Part Number: BU8871F
• Description: DTMF receiver for telephones
• Manufacturer: Rohm

FSelecting attached components
(1) Power supply components
(2) Oscillation components
(3) DTMF input
C501 : This is the DC blocking capacitor. Select a ca-
Communication ICs
pacitor that will pass DTMF signals (greater
than 697Hz) without significantly attenuating
the signals.
C502 : This is the V
JP501 : This is normally shorted. To test the current con-
X501 : Use a crystal or ceramic resonator with an os-
C591 : If you are using the X501 dedicated resonator
JP592 : If DTMF signals are being input directly, both
Q591
R591 X R595
C592, C593
100 F. The maximum recommended operating
power supply voltage is 5.25V, so a voltage
withstand value of 6.3V is sufficient.
sumption of the IC, insert a DC ammeter in place
of JP501.
cillation frequency of 4.194304MHz. If using a
ceramic resonator, there may be problems with
the precision of the oscillation frequency, so
please consult the manufacturer of the resona-
tor to make sure problems will not occur.
designed for DTMF receivers, capacitor C591
should be left open.
If you are injecting an external clock, X501
should be omitted and DC blocking capacitor
C591 used in its place. Typically, this capacitor
should be 47nF.
ends should be shorted.
Use these to increase the sensitivity of
the DTMF receiver.
DD
bypass capacitor, and is normally
BU8871F
187