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TDA8395 数据表(PDF) 4 Page - NXP Semiconductors |
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TDA8395 数据表(HTML) 4 Page - NXP Semiconductors |
4 / 10 page October 1991 4 Philips Semiconductors Preliminary specification SECAM decoder TDA8395 FUNCTIONAL DESCRIPTION The TDA8395 is a self-calibrating SECAM decoder designed for use with a baseband delay circuit. During frame retrace a 4.433619 MHz reference frequency is used to calibrate the filters and the demodulator. The reference frequency should be very stable during this period. The Cloche filter is a gyrator-capacitor type filter the resonance frequency of which is controlled during the calibration period and offset during scan; this ensures the correct frequency during calibration. The demodulator is a Phase-Locked Loop (PLL) type demodulator which uses the frequency reference and the bandgap reference to force the PLL to the required demodulation characteristic. The low frequency de-emphasis is matched to the PLL and is controlled by the tuning voltage of the PLL. A digital identification circuit scans the incoming signal for SECAM (only line-identification is implemented). The identification circuit needs to communicate with the TDA8362 to guarantee that the output signal from the decoder is only available when no PAL signal has been identified. If a SECAM signal is decoded a request for colour-on is transmitted to pin 1 (current is sunk). If the signal request is granted (i.e. pin 1 is HIGH therefore no PAL) the colour difference outputs ( −(B−Y) and −(R−Y)) from the TDA8362 are high impedance and the output signals from the TDA8395 are switched ON. If no SECAM signal is decoded during a two-frame period the demodulator will be initialized before another attempt is made also during a two-frame period. The CD outputs will be blanked or high-impedance depending on the logic level at pin 1. A two-level sandcastle pulse generates the required blanking periods and, also, clocks the digital identification pulse on the falling edge of the burst gate pulse. To enable the calibration period to be defined the vertical retrace is discriminated from the horizontal retrace, this is achieved by measuring the width of the blanking period. LIMITING VALUES In accordance with the Absolute Maximum System (IEC 134) SYMBOL PARAMETER MIN. MAX. UNIT VP positive supply voltage − 8.8 V Tstg storage temperature range −25 +150 °C Tamb operating ambient temperature range −25 +70 °C |
类似零件编号 - TDA8395 |
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类似说明 - TDA8395 |
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