TDA9821 datasheet(4/16 Pages) PHILIPS

4 / 16 page

1996 Nov 20

Philips Semiconductors

Product speciﬁcation

Dual channel TV FM intercarrier

sound demodulator

TDA9821

PINNING

SYMBOL

DESCRIPTION

IN1(B/G)

intercarrier input 1 at 5.5 MHz

n.c.

not connected

n.c.

not connected

n.c.

not connected

n.c.

not connected

n.c.

not connected

VAF2

audio output voltage 2

VAF1

audio output voltage 1

decoupling capacitor 1

decoupling capacitor 2

VCOref

VCO reference

CSTAB

supply voltage stabilization

GND

ground

supply voltage

IN2(B/G)

intercarrier input 2

n.c.

not connected

Fig.2 Pin configuration.

handbook, halfpage

TDA9821

MHA531

IN1(B/G)

n.c.

VAF2

VAF1

n.c.

IN2(B/G)

CSTAB

VCOref

GND

FUNCTIONAL DESCRIPTION

The complete circuit consists of two separate channels,

each consisting of a limiter-amplifier, FM demodulator and

AF amplifier. Circuit operation is also described in Fig.1.

FM demodulators

The intercarrier signal is fed through external ceramic

band-pass filters which are tuned to the sound carrier

frequencies.

Each limiter-amplifier is AC-coupled into a

FM demodulator. The integrated FM demodulator PLLs

are alignment-free. The FM demodulator outputs are

amplified to 500 mV (RMS value). High amplification and

DC error signals of the PLLs, which are superimposed on

the FM demodulator outputs, require DC decoupling at

pins 9 and 10 of the AF amplifier inputs.

Stereo channel separation adjustment (optional)

Optimal stereo channel separation is achieved by

adjusting VAF1 (pin 8) and VAF2 (pin 7) as follows:

1. VAF1 by a resistor in series with the DC decoupling

capacitor at pin 9

2. VAF2 by a variable resistor in series with the

DC decoupling capacitor on pin 10 to the same

voltage as VAF1.

Normally stereo channel separation is adjusted in the

stereo decoder for the B/G standard.

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