198

Communication ICs

BU8872 / BU8872FS

FOperation notes

(1)

(2)

If using a pin-type ceramic resonator, connect a CH class capacitor between the OSCIN and OSCOUT pins and

the GND.

(3)

This LSI is not equipped with the power-on reset function. Also, since the internal circuit (flip-flop circuit) becomes

unstable at the rising edge of the power supply, the internal circuit is initialized as shown below by the first DTMF se-

quence received after the rising edge of the power supply. Therefore, input four dummy ACK pulses before the DTMF

reception.

FSelecting attached components

(1) Power supply components

100

µF.

JP501 : This is normally shorted. To test the current con-

sumption of the IC, insert a DC ammeter in place

of JP501.

(2) Oscillation components

X501, C551, and C552 : Use a crystal or ceramic resona-

tor

with

an

oscillation

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 resonators listed below.

X501

C551

C552

Murata CSA4.19MG

30pF

30pF

CST4.19MGW213 (internal capacitors)

Matsushita EFOEN4194

33pF

33pF

EFOEC4194

(internal capacitors)

TDK FCR4.19M5

33pF

33pF

FCR4.19MC5

(internal capacitors)

Kyocera KBR-4.19MSK

33pF

33pF

KBR-4.19MKS

(internal capacitors)

Fujitsu FAR-C4

j

(internal capacitors)

B-04194-K00

ROHM SFR3AU 4194

(internal capacitors)

C591 : If you are using a dedicated resonator designed

for DTMF receivers, such as the X501, C551, or

C552, capacitor C591 should be left open. If you

are injecting an external clock, X501 should be

omitted and capacitor C591 used in its place.

Typically, this capacitor should be 47nF.