TEA6840 Просмотр технического описания (PDF) - Philips Electronics

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TEA6840

New In Car Entertainment (NICE) car radio

Philips Electronics 

Philips Semiconductors

New In Car Entertainment (NICE) car radio

Preliminary specification

TEA6840H

FUNCTIONAL DESCRIPTION

FM mixer 1

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

to an 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 = 162.4 to 162.55 MHz

• Europe FM = 87.5 to 108 MHz

• Japan FM = 76.0 to 91 MHz

• East Europe FM = 65.8 to 74 MHz.

VCO

The L and C tuned VCO provides the Local Oscillator (LO)

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

range of 151.2 to 248.2 MHz.

Crystal oscillator

The crystal oscillator provides a 20.5 MHz signal that is

used for:

• Reference frequency for frequency synthesizer PLL

• LO for 2nd AM mixer

• Reference frequency for the IF counter

• Timing signal for the RDS update algorithm

• Reference frequency (75.4 kHz) for the TEA6880H.

PLL

Fast synthesizer PLL tuning system with local control for

inaudible RDS updating.

DAA

Digital Auto Alignment circuitry (FM RF DAA) for the

conversion of the VCO tuning voltage to a controlled

alignment voltage for the FM antenna tank circuit.

FM keyed AGC

FM contains keyed wide-band RF AGC. AGC detection

occurs at the FM mixer. The wide-band RF signal switches

a narrow band signal (IF) from the FM IF level detector

circuitry that controls the FM RF AGC block.

It includes an AGC pin diode drive circuit for the FM RF

AGC. The pin diode drive can be activated via the I2C-bus

as a local/distance function.

The AGC threshold is programmable and the keyed AGC

function is switchable via the I2C-bus.

FM IF amplifiers

The two FM IF amplifiers provide 10 dB and 4 dB

amplification with high linearity and dynamic range.

FM demodulator

The FM quadrature demodulator includes automatic

centre frequency adjustment and THD compensation.

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 an IF1 of 10.7 MHz, while

AM mixer 2 converts 10.7 MHz IF1 to 450 kHz IF2.

• LW = 144 to 288 kHz

• MW = 530 to 1710 kHz (US AM band)

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

49 m bands).

AM RF 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 via the I2C-bus.

AM detector

The AM detector provides AM level information and AM AF

or AM IF2.

AM AF/IF2 SWITCH

The AM output provides either a detected AM Audio

Frequency (AF) or the corresponding AM IF2 signal.

The IF2 signal can be used for AM stereo decoder

processing.

AM noise blanker

The detection point for the AM noise blanker is the output

stage of AM mixer 1, while blanking is realized at the

output of the 2nd mixer.

Trigger sensitivity can be modified by changing the resistor

value at pin 46.

1999 Jul 12

9

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