原标题：NXP TDA8296模拟电视和FM收音机通用数字低IF解调方案

　　nxp 公司的TDA8296是模拟电视和FM收音机通用数字低IF信号PLL解调器，适合所有的模拟TV标准，包括M/N, B/G/H, D/K, I, L 和 L音标准。器件通过两个DAC还提供CVBS和 SSIF/单频音频。TDA8296特别适合和NXP的硅调谐器TDA1827x.配合使用。所有的处理都在数字域完成，主要应用在TV，录音机和PC TV。本文介绍了TDA8296主要特性和优势，功能方框图，典型应用电路图以及多种IF输入电路。

　　TDA8296：Digital global standard low IF demodulator for analog TV and FM radio

　　The TDA8296 is an alignment-free digital multistandard vision and sound low IF signal PLL demodulator for positive and negative video modulation including AM and FM mono sound processing. It can be used in all countries worldwide for M/N, B/G/H, I, D/K, L and L-accent standard. CVBS and SSIF/mono audio are provided via two DACs. FM radio preprocessing is included for simple interfacing with demodulator/stereo decoder backends.

　　The IC is especially suited for the application with the NXP Silicon Tuner TDA1827x. All the processing is done in the digital domain.

　　The chip has an ‘easy programming’ mode to make the I2C-bus protocol very simple. In principle, only one bit sets the proper standard with recommended content. However, if this is not suitable, free programming is always possible.

　　TDA8296主要特性和优势：

　　Digital IF demodulation for all analog TV standards worldwide (M/N, B/G/H, D/K, I, L and L-accent standard)

　　Multistandard true synchronous demodulation with active carrier regeneration

　　Alignment-free

　　16 MHz typical reference frequency input (from low IF tuner) or operating as crystal oscillator

　　Internal PLL synthesizer which allows the use of a low-cost crystal (typically 16 MHz)

　　Especially suited for the NXP Silicon Tuner TDA1827x

　　No SAW filter needed

　　Low application effort and external component count in combination with the TDA1827x

　　Simple upgrade of TDA8295 possible

　　12-bit low power IF ADC on chip running with 54 MHz or 27 MHz

　　Two 10-bit DACs on chip for CVBS and SSIF or audio

　　Easy programming for I2C-bus

　　High flexibility due to various I2C-bus programming registers

　　I2C-bus interface and I2C-bus feed-through for tuner programming

　　Four I2C-bus addresses selectable via two external pins

　　Gated IF AGC acting on black level by using H/V PLL or peak IF AGC (I2C-bus selectable)

　　Internal digital logarithmic IF AGC amplifier with up to 48 dB gain and 68 dB control range

　　Peak search tuner IF AGC for optimal adaptive drive of the IF ADC

　　Switchable IF PLL and IF AGC loop bandwidths

　　Precise AFC and lock detector

　　Accurate group delay equalization for all standards

　　Very robust IF demodulator coping with adverse field conditions

　　Wide PLL pull-in range up to ±1 660 kHz (I2C-bus selectable)

　　CVBS and SSIF or audio output with simple postfilter (capacitor only)

　　CVBS gain levelling stage to provide nearly constant signal amplitude during over modulation

　　Video equalizer with eight settings

　　Nyquist filter in video baseband

　　Excellent video S/N (typically 60 dB weighted)

　　High selectivity video low-pass filter for all standards

　　Low video into sound crosstalk

　　SSIF AGC

　　Sound performance comparable to QSS single reference concepts

　　AM/FM mono sound demodulator

　　Switchable de-emphasis

　　Excellent FM sound

　　Good AM sound

　　High FM Deviation mode for China

　　Preprocessing of FM radio (mono and stereo) with highly selective digital band-pass filter

　　No ceramic filter or external components needed for FM radio

　　FM radio available in mono

　　Automatic or forced mute for mono sound

　　Automatic or forced blank for video

　　Mostly digital FIR filter implementation (NSC notches and video low-pass filters)

　　Three GPIO pins

　　Power-On Reset (POR) block for reliable power-up behavior

　　Very low total power dissipation (typically 150 mW)

　　No power sequence requirement

　　Standby mode (typically 5 mW)

　　40-pin HVQFN package

　　CMOS technology (0.090um 1.2 V and 3.3 V)

　　TDA8296应用：

　　TV applications

　　Recording

　　PC TV applications

　　图1。TDA8296功能方框图

　　图2。TDA8296典型应用电路图

　　图3。和TDA1827x接口的TDA8296 IF中频输入电路图

　　图4。TDA8296 IF输入应用

　　图5。TDA8296 75欧姆缓冲器应用电路