Os motores de busca de Datasheet de Componentes eletrônicos |
|
TDA9820 Folha de dados(PDF) 5 Page - NXP Semiconductors |
|
TDA9820 Folha de dados(HTML) 5 Page - NXP Semiconductors |
5 / 20 page 1996 Nov 20 5 Philips Semiconductors Product specification Multistandard/dual channel TV FM intercarrier sound demodulator TDA9820 FUNCTIONAL DESCRIPTION The complete circuit consists of two separate channels, each consisting of a limiter-amplifier, FM demodulator and AF amplifier. Circuit operation is also described in Fig.1. Source selector The intercarrier signal is fed through external ceramic band-pass filters which are tuned to the sound carrier frequencies. One of the four filtered sound carriers from pins 1, 2, 3 or 16 is fed to limiter-amplifier 1 via the appropriate electronic switch in the source selector. The electronic switch of the sound carrier is selected by the control unit (see Table 1). The second sound carrier of the intercarrier signal is directly fed from pin 15 to limiter-amplifier 2. FM demodulators Each limiter-amplifier is AC-coupled into a FM demodulator. The integrated FM demodulator PLLs are alignment-free. The FM demodulator outputs are amplified to 500 mV (RMS value). High amplification and DC error signals of the PLLs, which are superimposed on the FM demodulator outputs, require DC decoupling at pins 9 and 10 of the AF amplifier inputs. Stereo channel separation adjustment (optional) Optimal stereo channel separation is achieved by adjusting VAF1 (pin 8) and VAF2 (pin 7) as follows: 1. VAF1 by a resistor in series with the DC decoupling capacitor at pin 9 2. VAF2 by a variable resistor in series with the DC decoupling capacitor on pin 10 to the same voltage as VAF1. Second sound carrier mute The output of the second FM demodulator is muted when the signal level (signal and/or noise) at pin 15 is less than typically 0.5 mV (RMS value). This avoids an incorrect stereo or dual sound identification when a mono signal is transmitted. Therefore, with a mono transmission, there is no audio output at pin 7. When the signal level at pin 15 is greater than typically 1.0 mV (RMS value) mute is switched off. Control unit The control unit selects the required sound standard according to the voltages on pin 5 and pin 6. The control unit performs the following: 1. selects the free-running frequencies of VCO1 and VCO2 2. switches the source selector (the four possible combinations are shown in Table 1). Table 1 Logic table; note 1 Note 1. In columns S1 and S2: 0 = LOW and 1 = HIGH. STANDARD S1 (PIN 5) S2 (PIN 6) FREQUENCY VCO1 (MHz) FREQUENCY VCO2 (MHz) SOURCE SELECTOR CONNECTION B/G 1 1 5.5 5.74 pin 1 M 1 0 4.5 4.72 pin 3 I 0 1 6.0 off pin 16 D/K 0 0 6.5 6.74 pin 2 |
Nº de peça semelhante - TDA9820 |
|
Descrição semelhante - TDA9820 |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | Lista de Fabricantes All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |