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Whether driven by Moore's Law or consumer demand, the current TV requirements for performance have increased dramatically. It has a 1,080-pixel high-definition (HD) format with 6 times the data processing capacity of standard definition (SD) TV format, managing DTV, IPTV and video conferencing broadcasts, processing Dolby AC-3, MPEG and other audio formats, etc. It has quickly become a must-have feature of digital TV (DTV).In addition to the technical requirements related to audio and video and input signal formats, digital TV also involves several display methods: front projection, rear projection, DLP, LCD, plasma and CRT. Whether you're watching TV through the watch's built-in 1-inch monitor or using a projection system that uses the entire wall as a display, this combination of display size and performance is versatile.
Although each digital TV currently sold differs in size, shape, and size, the salesperson's introduction to different models is quite different, but the basic structure inside the digital TV is very similar. In general, DTV can be roughly divided into the following main parts: display (and drive), kernel media engine, audio decoding and processing, video decoding and processing, tuner circuits, interface modules and power supplies.
Figure 1 is a basic block diagram of a high definition digital television (HDTV) at the semiconductor functional level. Most of these components are available from the same company, enabling faster design cycles and faster time-to-market while ensuring compatibility. Texas Instruments not only provides almost all of the semiconductor components needed to develop HDTV, but also has set up a dedicated working group to advance the development of audio and video and DLP technology to improve the user's TV experience. TI's TMS320DM644x family, DaVinci digital media processors and other core processing functions, as well as a rich set of high-performance analog components, are highly integrated, flexible, and easy to use to meet the needs of the rapidly growing DTV market. Leveraging high-performance audio and video codecs, graphics acceleration, communications and support services is critical to developing converged applications that meet the needs of the home entertainment experience.
| Figure 1: A typical digital TV system can be broadly divided into main parts such as display (and drive), kernel media engine, audio decoding and processing, video decoding and processing, tuner circuits, interface modules, and power supplies. |
Video solution
Perhaps the most important thing consumers watch when watching TV shows is the video experience. The resolution, brightness, contrast, sharpness and other factors of the picture will affect the user's real experience. Whether the TV supports multiple ATSC DTV formats, NTSC and PAL decoding, composite video signal and S video signal input, and 2D adaptive filtering technology are also critical. With the continuous development of HDTV technology, support for 1080i resolution and 3D adaptive filtering will also become standard features. In the scheme in Figure 1, TI offers a variety of video decoder families (such as TVP5160), analog-to-digital converters (ADCs) (such as TVP7001), and video buffers (such as TIV7327) to provide high performance while meeting system cost targets. Performance of the product.
Figure 2 shows the data flow path for the TVP5160 video decoder, which handles signals in NTSC, PAL, SECAM, S-Video, SCART, YpbPr, RGB, 480p, and other input formats. DTV should have this flexibility to ensure that one model of product fits into any set of realities. Typical features of the DTV decoder include synchronization, blanking, field, active video window, horizontal and vertical sync, clock, genlock (for downstream video encoder synchronization), host CPU interrupts, and programmable logic I/O signals. These are functions that should be available in addition to video data output and advanced field blanking period (VBI) data recovery. Some of TI's video decoders also have the feature of supporting the VBI Data Processor (VDP) for segmentation, resolution and troubleshooting of TV teletext, closed caption (CC) and other VBI data. The built-in FIFO can not only store up to 11 lines of TV text broadcast data, but also use the appropriate host port sync signal to perform full-screen TV text broadcast search. The TVP5146M2 decoder can transmit twice the original sampled luminance data through the output formatter for host VBI processing.
The TVP700x family of ADCs offers several advantages in terms of ADCs in the signal chain. They not only reduce jitter, improve the graphics quality of video systems, but also support the higher bandwidth required for PC and HD video output. With an output speed of up to 165Msps and a rich video capability, this 8/10-bit, three-channel ADC is ideal for applications such as commercial projectors, televisions, and set-top boxes.
Finally, we also need to match the output resolution of the video signal chain to the display's function and the resolution of the input signal to optimize the video design. In the past, for lower resolution CRT TVs, the use of lower performance front ends is still acceptable, but in terms of the resolution of the current display, the noise or distortion of any analog front end will be on the DTV screen. The image has a noticeable effect.
Figure 2: Block diagram of the decoder data stream.
Audio solution
In the past, consumers might have connected their TVs to their home audio systems to improve their audio, especially when watching movies. Now, with the development of audio solutions, the location of the TV is likely to be far from the home stereo system, and many DTVs are wall mounted, which requires the integration of advanced audio solutions directly into the DTV. In addition, speaker technology has evolved to make the entire screen a part of the speaker. But whether it's a flat speaker or a traditional speaker, the audio signal chain plays a vital role in maximizing the audio experience.
The performance of audio solutions involves a multitude of factors, including audio processing power, audio output power, cooling, and overall power consumption. Traditional audio solutions include two to three speakers driven by Class AB audio power amplifiers. However, the Class AB amplifier generates a lot of heat during operation relative to the total audio output power, which makes Class AB amplifiers unsuitable for thin flat-panel TVs because Class AB amplifiers typically require larger heat sinks to function properly. To solve this problem, the industry uses Class D amplifier technology in its design (Figure 3). The output FET of a Class D amplifier switches between the cut-off and saturation regions and is more efficient than a Class AB amplifier. TI also offers the PurePath Digital audio solution, which not only maximizes audio efficiency, but also improves sound processing with a signal-to-noise ratio (SNR) greater than 110dB.
Whether it is a 6-channel PurePath Digital solution such as the TAS5086 and TAS5186, or an audio codec such as PCM3794 and a Class D audio amplifier such as the TPA3100D2, TI offers a wide range of audio solutions and professional technical support to optimize DTV solutions.
| Figure 3: Basic Class D audio amplifier topology. |
The essential component audio processing of DTV helps to further characterize audio quality. In addition to more advanced audio functions such as surround sound virtualization, bass boost, and other well-known audio operations, audio processing enables standard sound modes such as movies, news, music, and more.
Interface circuit and power management
Since DTV is the center of the home communication portal, DTV and set-top boxes are adding new interfaces in addition to basic audio and video functions. DTV has and will continue to support VGA and component video signal inputs (which usually include output), and some even support HDMI. In addition, they support other interfaces such as DVI, S-Video terminals, IEEE1394, USB and LAN connections.
TI provides interface products in all of these areas, and is designed to support new protocols such as IEEE1394 and older protocols such as RS232. In addition, TI's low-power wireless product line recently added Chipcon series technology and introduced devices such as CC2500, which simplifies design requirements for remote control and wireless connectivity.
Including the AD/DC converter circuit that provides the main power supply for the DTV itself, almost all functional modules in the TV require specific power solutions, such as DLP lamps, LCD bias or backlight power for the display, main processor and DDR. The core and I/O power of the memory, as well as the power supply for the tuner and video/analog signal chain. Figure 4 shows the basic power distribution diagram of the DTV.
Figure 4: Almost all functional modules in a digital TV require a specific power solution.
However, in today's era of energy conservation, governments are constantly promulgating new policies to further rigorously regulate standby power consumption and the efficiency of consumer products. At present, almost all TV design regulations are voluntary, but mandatory regulations may appear soon. For example, to qualify for Energy Star certification, digital TV must consume less than 3W in standby mode. Power-saving mode flyback converters such as PFC and UCC28600 help minimize power loss in standby mode. The UCC28600 enters burst mode under light load conditions and can signal during standby to disable the bias supply of the PFC controller.
TI offers Swift, 40k, modules and other point-of-load power solutions, as well as AC/DC power conversion and power factor correction devices, providing all the necessary technologies for today's DTV power supply designs. TI provides power modules to help manufacturers quickly bring products to market, and also provides board-level semiconductor solutions to meet the cost requirements of the DTV consumer market.
to sum up
In addition to specific solutions for video, audio, interfaces and power supplies, TI offers a broad product portfolio for temperature sensing, fan control, system clocking, general logic and linear solutions. In addition, TI supports the development of custom solutions through the power and signal chain reference design team, providing you with the best and most extensive technology for developing DTV, and will also provide specific assistance during your design process.
Regardless of whether HDTV will continue to follow the path we are foreseen in the future, or move towards a new field (for example, to present stereoscopic images through 3D holographic projection in a room), TI will continue to provide technology and advance technology. Development, turning people's dreams into reality.
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