TDA9614H datasheet(9/60 Pages) PHILIPS

9 / 60 page

1995 Mar 21

Philips Semiconductors

Preliminary speciﬁcation

Audio processor for VHS hi-ﬁ

and linear audio

TDA9614H

6.1

Audio I/O switching

6.1.1

INPUT SELECT (INPUTSEL)

For the audio FM circuitry eight different audio signals can

be selected. The selection made here for hi-fi is also

available for the linear audio circuitry.

1. TUNER (stereo input; internal tuner of VCR).

2. CINCH (stereo input; connection to hi-fi set).

3. EXT1 (stereo input; TV SCART1).

4. EXT2 (stereo input; decoder, 2nd VCR SCART2).

5. EXT3 (stereo input; front CINCH for e.g. camcorder).

6. SAP (mono input; ‘Second Audio Program’ audio

carrier for NTSC or conventional FM carrier with

NICAM reception).

7. NORMAL (linear audio; [playback] signal of linear

audio).

When inserting a new video signal in an old

audio/video recording the hi-fi audio track is erased.

This setting can keep the current audio available on

the hi-fi track by copying the (playback) linear audio

signal to the hi-fi track during video insert.

8. EXT3/ST (input mix; mono EXT3 on left, mono hi-fi on

right channel).

For linear audio use see Section 6.1.2.

6.1.2

NORMAL SELECT (NORMSEL)

For linear audio four settings can be selected:

1. INPUTSEL (mono signal from input select).

This is the ‘standard’ setting. The signal source

selected with the input select is led to the linear audio

circuit. The linear audio AGC should be switched on.

2. VOLUME (mono signal from [hi-fi] volume control).

The signal source selected with the input select has

now volume control, the linear audio AGC should be

switched off. This setting is for use with ‘audio

dubbing’: inserting a new audio signal on the linear

track in an old audio/video recording. A special audio

dubbing feature is now possible by selecting ‘input mix’

EXT3/ST in the input select. This setting enables us to

use the VCR as a mixer console: an audio source

connected to EXT3 (front CINCH) can be adjusted and

mixed together with the original hi-fi playback signal,

using the left (EXT3) and right (hi-fi playback) volume

controls.

3. SAP (SAP input).

This setting enables simultaneous recording of the

NTSC SAP signal on the linear track and TUNER

stereo on the audio FM track. When receiving a

NICAM audio signal, the linear audio can be used as a

‘backup’ track when received television signals are

weak.

4. TUNER LEFT (left channel [language 1] of TUNER

input).

When receiving dual language transmissions the main

language (language 1) can be recorded on linear

audio. Note that if the SAP input is not used it can be

connected to the right TUNER channel, enabling

language selection for linear audio.

6.1.3

VOLUME L/R; AGC

The volume controls are mainly intended for level

adjusting of the audio signals to be recorded on the hi-fi

track, however using the ‘VOLUME’ setting in the Normal

Select it can also be used to control linear audio. The

volume controls have a control range of +14 dB to

−49 dB

in 1 dB steps and a full mute. Because the volume controls

are I2C-bus controlled their actual behaviour is defined by

the VCR’s software. For instance user control can be

‘volume only’, ‘left + right’, ‘volume + balance’ or the

setting can be defined by a ‘digital AGC’ software loop

using the signals at the DC (VU meter) outputs.

The linear audio level can be controlled by an AGC circuit,

which can be switched off when desired. In most cases the

AGC should be used at all settings of the Normal Select

except for ‘VOLUME’.

6.1.4

AUDIO FM OUTPUT MUTE (AFOMUTE);

NORMAL OUTPUT MUTE (NOMUTE)

The audio output signal of the audio FM circuit can be

muted with AFOMute, the linear output signal can be

muted using NOMute. If one of these signals is not used

as an output (or input) signal it is best muted to further

minimize crosstalk.

6.1.5

OUTPUT SELECT (OUTSEL)

This block is the ‘main’ output select function, possibly

functional on all outputs. Each output however has some

means to override this selection for its own output signal,

to implement extra features. Eight selections are possible

and they are shown in Table 1.

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