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TEA6840 Scheda tecnica(PDF) 9 Page - NXP Semiconductors |
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TEA6840 Scheda tecnica(HTML) 9 Page - NXP Semiconductors |
9 / 44 page 1999 Jul 12 9 Philips Semiconductors Preliminary specification New In Car Entertainment (NICE) car radio 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. |
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