SAA7284GP データシートの表示（PDF） - Philips Electronics

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SAA7284GP

Terrestrial digital sound decoder for conventional intercarrier PLL-IF systems

Philips Electronics 

Philips Semiconductors

Terrestrial digital sound decoder for

conventional intercarrier PLL-IF systems

Preliminary specification

SAA7284

DAIE

When set HIGH this bit switches in the Digital Audio

Interface output to the DOBM pin. When set LOW the

DOBM output is 3-stated. Power-on resets to HIGH.

FM3 TO FM0

These bits set the level of attenuation of the FM audio

signal (see Table 9). Power-on resets 0000 = 0 dB

attenuation.

ASYS

When this bit is HIGH it activates the automatic standard

switch mode. When set LOW, the standard must be set by

the BG/I bit. Power-on resets to HIGH.

BG/I

When this bit is HIGH it switches the DQPSK demodulator

to system BGH and attenuates the digital audio level by

4.6 dB (if NICLEV is set HIGH). When LOW, the DQPSK

demodulator switches to system I (with no 4.6 dB

attenuation). Power-on resets to HIGH.

NICLEV

When this bit is set LOW it overrides the 4.6 dB NICAM

audio level compensation, irrespective of whether the

device is in automatic or manual system mode. When set

HIGH the 4.6 dB compensation level is applied in

system BGH. Power-on resets to HIGH.

STLOCK

When STLOCK is set HIGH it will stop the automatic

system switch after the device has achieved an INSYNC

condition, should the demodulator lose lock at any time.

This minimizes the re-acquisition time. When set LOW the

device will be permitted to change system after an

INSYNC condition has been reached. Power-on resets to

LOW.

Table 5 Output as a function of M1/M2 and DMSEL

DMSEL

0

0

1

1

M1/M2

0

1

0

1

FUNCTION

selects DIGITAL; L = M2, R = M2

selects DIGITAL; L = M1, R = M1

selects DIGITAL; L = M2, R = M1

selects DIGITAL; L = M1, R = M2

Table 6 Port 2 control

PORT2

0

1

PIN OUTPUT STATE

LOW

HIGH

Table 7 SSWIT signal states and function

SSWIT3

0

0

0

0

1

1

SSWIT2

0

0

1

1

X(1)

X

SSWIT1

FUNCTION

0 NICAM source de-emphasis switched out, no gain

1 NICAM source de-emphasis switched in, no gain

0 NICAM source de-emphasis switched in, +6 dB gain; power-on reset when

PORA = HIGH

1 NICAM source de-emphasis switched in, +12 dB gain; power-on reset when

PORA = LOW

0 external inputs switched in, no change to previous de-emphasis/gain setting

1 FM inputs switched in, no change to previous de-emphasis/gain setting

Note

1. Where X = don’t care.

1996 Oct 24

14

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