TEA6843 Просмотр технического описания (PDF) - Philips Electronics

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TEA6843

New In Car Entertainment (NICE) extended car radio

Philips Electronics 

Philips Semiconductors

New In Car Entertainment (NICE)

extended car radio

Product specification

TEA6843HL

7 FUNCTIONAL DESCRIPTION

7.1 Oscillators

7.1.1 VCO

The L and C tuned VCO provides the local oscillator signal

for both FM and AM mixer 1. It has a frequency range of

151.2 to 248.2 MHz.

7.1.2 CRYSTAL OSCILLATOR

The crystal oscillator provides a 20.5 MHz signal that is

used for:

• Reference frequency for frequency synthesizer PLL

• Local oscillator for AM mixer 2

• Reference frequency for the IF counter

• Timing signal for the RDS update algorithm

• Reference frequency (75.368 kHz) for the TEA688x (car

audio signal processor - CASP) or TEF689x (car radio

integrated signal processor - CRISP).

7.1.3 PLL

Fast synthesizer PLL tuning system with local control for

inaudible RDS updating.

7.2 FM signal channel

7.2.1 DAA

FM RF Digital Auto Alignment (DAA) circuitry for the

conversion of the VCO tuning voltage to a controlled

alignment voltage for the FM antenna tank circuit.

7.2.2 FM I/Q MIXER

FM quadrature mixer converts FM RF (65 to 162.55 MHz)

to IF of 10.7 MHz. The FM mixer provides inherent image

rejection and high RF sensitivity.

It is capable of tuning the US FM, US weather,

Europe FM, Japan FM and East Europe FM bands:

• US FM = 87.9 to 107.9 MHz

• US weather FM = 162.4 to 162.55 MHz

• Europe FM = 87.5 to 108 MHz

• Japan FM = 76 to 91 MHz

• East Europe FM = 65.8 to 74 MHz.

7.2.3 FM KEYED AGC

The AGC threshold is programmable and the keyed AGC

function is switchable via the I2C-bus.

If the keyed AGC function is activated, the AGC function is

keyed by the narrow band level (IF).

The AGC PIN diode drive can be set via the I2C-bus to

local function for search tuning.

7.2.4 FM IF AMPLIFIERS

The two FM IF amplifiers provide 10 dB and 8.5 dB

amplification with high linearity and dynamic range.

7.2.5 FM DEMODULATOR

The FM quadrature demodulator includes automatic

centre frequency adjustment and THD compensation.

7.2.6 FM MPX SOFT MUTE

Muting depth and start of muting are adjustable via the

I2C-bus.

7.3 AM signal channel

7.3.1 AM TUNER

The AM tuner is realized in a double conversion technique

and is capable of selecting LW, MW and SW bands.

AM mixer 1 converts AM RF to IF1 of 10.7 MHz, while

AM mixer 2 converts IF1 of 10.7 MHz to IF2 of 450 kHz:

• LW = 144 to 288 kHz

• MW = 522 to 1710 kHz (European and US AM band)

• SW = 5.85 to 9.99 MHz (including the 31 m, 41 m and

49 m bands).

7.3.2 AM RF AGC AND IF2 AGC

The AM RF includes a PIN diode drive circuit. The

threshold detection points for AM AGC are performed at

AM mixer 1 and AM IF2. AGC thresholds are

programmable at AM mixer 1 input via the I2C-bus.

7.3.3 AM AF OR IF2 SWITCH

The AM output provides either a demodulated AM Audio

Frequency (AF) or the corresponding AM IF2 signal. The

IF2 signal can be used for AM stereo decoder processing.

7.3.4 AM SOFT MUTE

The AM detector output is either not muted or signal

strength dependent soft muted audio. The soft mute

function can be switched off via the I2C-bus.

2003 Dec 19

9

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