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TDA9851T/V1

I2C-bus controlled economic BTSC stereo decoder

Philips Electronics 

Philips Semiconductors

I2C-bus controlled economic BTSC stereo

decoder

Product specification

TDA9851

FUNCTIONAL DESCRIPTION

Stereo decoder

The composite signal is fed into a pilot detector/pilot

cancellation circuit and into the MPX demodulator.

The main L + R signal passes a 75 µs fixed de-emphasis

filter and is fed into the dematrix circuit. The decoded

sub-signal L − R is sent to the VCA circuit. To generate the

pilot signal the stereo demodulator uses a PLL circuit

including a ceramic resonator.

an input voltage range between 0.1 to 1.1 V (RMS).

The circuit adjusts variations in modulation during

broadcasting and because of changes in the programme

material. The function can be switched off. To avoid

audible plops during the permanent operation of the AVL

circuit a soft blending scheme has been applied between

the different gain stages. A capacitor (4.7 µF) at pin CAV

determines the attack and decay time constants.

In addition the ratio of attack and decay times can be

changed via the I2C-bus.

Mode selection

The L − R signal is fed via the internal VCA circuit to the

dematrix/switching circuit. Mode selection is achieved via

the I2C-bus.

Automatic volume level control

The automatic volume level stage controls its output

voltage to a constant level of typically 200 mV (RMS) from

Integrated filters

The filter functions necessary for stereo demodulation are

provided on-chip using transconductor circuits. The filter

frequencies are controlled by the filter reference circuit via

the external resistor R4.

LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 134).

SYMBOL

PARAMETER

CONDITIONS

VCC

VSDA, VSCL

Vn

Tamb

Tstg

Ves

supply voltage

voltage of SDA and SCL to GND

voltage of all other pins to GND

operating ambient temperature

storage temperature

electrostatic handling

VCC < 9 V

VCC ≥ 9 V

Tj < 125 °C

note 1

Note

1. Machine model class B.

MIN.

0

0

0

0

−20

−65

−

MAX.

9.9

VCC

9

VCC

+70

+150

−

UNIT

V

V

V

V

°C

°C

V

THERMAL CHARACTERISTICS

SYMBOL

Rth(j-a)

PARAMETER

CONDITIONS

thermal resistance from junction to ambient in free air

TDA9851 (SOT234-1; SDIP24)

TDA9851T (SOT137-1; SO24)

VALUE

55

90

UNIT

K/W

K/W

1997 Nov 12

6

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