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Datenblatt-Suchmaschine für elektronische Bauteile |
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Datenblatt-Suchmaschine für elektronische Bauteile |
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TDA9873H Datenblatt(PDF) 8 Page - NXP Semiconductors |
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TDA9873H Datenblatt(HTML) 8 Page - NXP Semiconductors |
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8 / 40 page  2000 Apr 04 8 Philips Semiconductors Product specification Multistandard dual carrier stereo sound decoder TDA9873H In the following dematrix, the modes stereo, mono and dual are processed for the different standards. The 6 dB level difference between B/G and M standard is automatically compensated in the dematrix, therefore no further level adaption is needed. De-emphasis is performed by two RC low-pass filter networks with internal resistors and external capacitors. The time constant is automatically switched to 50 µs or 75 µs according to the chosen standard. Due to some frequency response peaking of the FM demodulation, compensation is necessary. This is done by having a slightly larger time constant for the de-emphasis. All other settings such as AF switch, stereo channel adjustment values or default corrections have to be controlled via the I2C-bus depending on the identification or user definition. AF switch The circuit incorporates a single stereo and mono AF output. Using rail-to-rail operational amplifiers, the clipping level is set to 1.4 V (RMS) for VCC =5V. As well as the internal stereo decoder output signal, one external stereo and one mono input can be switched to the AF outputs. Both the mono and stereo outputs can be switched independent of the internal or external sources (see Tables 13 and 25). Fig.6 shows the switch configurations. A nominal gain of 0 dB for the signals from the external inputs to the outputs is built-in. Stereo/dual sound identification The pilot signal is fed to the input of a NBPLL. The PLL circuit generates the synchronized pilot carrier. This carrier is used for the synchronous AM demodulation to get the low-pass filtered identification signal. A Schmitt trigger circuit performs pulse shaping of the identification signal when the signal level is higher than the Schmitt trigger threshold. For smaller signal levels there is no AC output signal, thus protecting against mis-identification caused by spurious signal components. The identification stages consist of two digital PLL circuits and digital integrators to generate the stereo or dual sound identification bits, which can be read out via the I2C-bus. A 4 MHz crystal oscillator provides the reference clock frequency. The corresponding detection bandwidth is larger than ±50 Hz for the pilot carrier signal, so that fpilot variations from the transmitter can be tracked in the event of missing synchronization with the horizontal frequency fH. However, the detection bandwidth for the identification signal is limited to approximately ±1 Hz for high identification reliability. I2C-bus transceiver The TDA9873H is microcontroller controlled via a 2-wire I2C-bus. Two wires, serial data (SDA) and serial clock (SCL) carry information between the devices connected to the bus. The TDA9873H has an I2C-bus slave transceiver with auto-increment. To avoid conflicts in applications with other ICs providing similar or complementary functions, two slave addresses are available, selected on the pin MAD. A slave address is sent from the master to the slave receiver. In the TV sound processor family several devices are available. To identify the TDA9873H device, the master sends a slave address with R/W bit = 0. The slave then generates an acknowledge and the master sends the data subaddress 254 to the slave, followed by an acknowledge from the slave to the master. The master then sends the slave address with R/W bit = 1. The slave then transmits the device identification code 80H to the master, followed by an acknowledge NOT and a STOP condition generated by the master. Control ports Two digital open-collector output ports P1 and P2 provide external switching functions in the receiver front-end or IF demodulators. The ports are controlled by the I2C-bus (see Tables 22 and 23) and are freely programmable. |
Ähnliche Teilenummer - TDA9873H |
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Ähnliche Beschreibung - TDA9873H |
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