Tuner AGC

It sinks a current to control the gain of the tuner RF

amplifier. Its starting point is adjusted by an external

potentiometer (Pin 1).

AFC Circuit

It is a FM demodulator stage which delivers on

Pin 19 a current proportional to the frequency dif-

ference between the IF input signal and the refer-

ence IF frequency of the external LC on Pin 20. This

current is converted into a voltage by means of a

resistor network.

FM Demodulation

It consists of a three stage limiter amplifier in order

to reject the amplitude modulation and a quadra-

ture demodulator. The deemphasis filter is built

with an internal resistor and an external capacitor

on Pin 11.

Mute Function

It is an internal switch to cut-off the internal audio

signal. It acts when a level below 2.1V is applied

on Pin 15. When no mute, the Pin 15 must be driven

with a high DC impedance.

Video and Audio Switches

They are both controlled by the Pin 21 voltage.

Internal sources or external sources can be sent to

the outputs (Pin 12 for video and Pin 8 for audio).

The internal signals are selected by a control level

below 2.5V on Pin 21, the external ones by a control

level above 5V.

The gain of the video switch is 6dB for both internal

and external signals.

The gain of the audio switch is 0dB for the maxi-

mum volume.

ABSOLUTE MAXIMUM RATINGS

Symbol

Parameter

Value

Unit

Supply Voltage

13.5

V

Tuner AGC Voltage

V

Storage Temperature

-40, +150

Operating Temperature

0, +70

THERMAL DATA

Symbol

Parameter

Value

Unit

Junction-ambient Thermal Resistance

Max.

75

ELECTRICAL CHARACTERISTICS

∆f = ± 25kHz,

Ω, unless otherwise specified)

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

SUPPLY

Voltage Operating Range

8.1

9

12.6

V

Supply Current

24

38

52

mA

IF AMPLIFIER

Input Sensitivity

Refer to test circuit

70

µV

Differential Input Resistance

1.5

k

Ω

Differential Input Capacitance

2

pF

Gain Control Range

64

dB

DEMODULATED VIDEO OUTPUT (Pin 18)

Amplitude

Top sync to white

1.8

2.1

2.4

Top Sync Level

without output filter

1.6

1.9

2.2

V

BW

Bandwidth

See Figure 1

5

7

MHz

TDA8222

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