tda9610h NXP Semiconductors, tda9610h Datasheet - Page 7

• Manufacturer Part Number: tda9610h
• Description: Audio Fm Processor For Vhs Hi-fi Audio
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FUNCTIONAL DESCRIPTION
The IC is intended for use within the audio FM system of
VHS video recorders. Three modes of operation can be
distinguished:
Switching and control of the three modes is done by the
I
Record mode
The audio signal, selected from the four stereo audio
inputs (EXT1L, EXT1R, EXT2L, EXT2R, CINL, CINR,
TUNL and TUNR), is fed to the volume control stage
(separate for left [L] and right [R]). The information for
LINOUT is, after summing of L and R, derived from either
one of the four stereo inputs or the volume control output
or one of the mono inputs (EXN1 and EXN2). After the
Low-Pass Filter (LPF) and signal compression in the noise
reduction (NR) and filter block the audio signal is available
at AFOUTL and AFOUTR. The compressed signal is now
FM modulated on a RF carrier in the PLL block. After
low-pass filtering and summation of both RF carriers
(L and R) the signal is available at FMOUT.
The output select block offers the possibility to choose
eight different audio signal modes:
1. Stereo.
2. Left.
3. Right.
4. Mono.
5. Normal.
6. Mixed stereo (stereo + LININ).
7. Mixed left (left + LININ).
8. Mixed right (right + LININ).
These audio signal modes are selectable for the output
stages LINEL, LINER and MODOUT. The standard audio
output is LINEL and LINER, e.g. for SCART output.
MODOUT is a mono audio output, with an
overload-protecting AGC, to drive an external
RF modulator.
1995 Mar 21
2
C-bus.
Record mode
Playback mode
Loop-through mode.
Audio FM processor for VHS hi-fi audio
7
The headphone select block offers the possibility to
choose either the output select signal or four independent
audio signal modes (stereo, left, right and normal) for the
output stages HPOUTL and HPOUTR.
HPOUTL and HPOUTR, with common volume control for
L and R, is suitable for direct headphone drive.
DCOUTL and DCOUTR are intended for VU meter drive.
It is connected to the selected stereo audio input after the
volume control block. The output signal at
DCOUTL and DCOUTR is proportional to the square root
of the recorded audio signal (see Fig.3).
Playback mode
The two FM modulated RF carriers, present at the two
FMINL and FMINR inputs after being band-pass filtered,
are demodulated in the PLL block. The LF audio signal is
fed through a sample-and-hold circuit to suppress
head-switching noise. The demodulated audio signal is
available at AFOUTL and AFOUTR. The audio signal is
low-pass filtered and expanded in the noise reduction (NR)
and filter block. The resulting audio signal is available after
the output and headphone select blocks for all four output
stages (LINEL, LINER, MODOUT, HPOUTL, HPOUTR,
DCOUTL and DCOUTR). The functionality of the output
and headphone select blocks is identical to the record
mode. During playback DCOUTL and DCOUTR are
connected to the headphone select block.
The functionality of the input and normal select blocks is
also identical to record mode (see Fig.3), which offers the
possibility to control (other) audio signals independently
for LINOUT (see Fig.4).
Loop-through mode
This mode is similar to the record mode (see Fig.3), except
for the FMOUT pin, which is inactive, and the RAF output
which is active LOW (see Fig.5).
Product specification
TDA9610H