Application prospect of class D digital audio ampl

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The application prospect of class D digital audio amplifier with different power detection

class D digital audio power amplifier has the advantages of small size and high efficiency. Class D power amplifier can be used to design smaller, thinner and more efficient electronic products, which can prolong the service life of portable product batteries. Therefore, it is widely recognized in the industry The popularity of multimedia products such as DVD, MP3 and PMP has accelerated the use of class D power amplifier in portable electronic products. In addition, class D power amplifier is especially suitable for LCD tv/monitor and other low-profile video products by taking advantage of its power free heat sink

in terms of low-power, i.e. 1w~3w multimedia power amplifier, the power efficiency of class AB power amplifier and class D power amplifier is about 15% and 75% respectively when the playing content is mainly music. It can be seen from the table below that class AB power amplifier needs to consume 6.7watts when playing 1Watt music, but class D power amplifier only consumes 1.33watts under the same playing conditions. Therefore, the use of class D power amplifier can prolong the service time of 8.0351 million tons of bleached softwood pulp imported from China by five times (6.7watts/1.33watts). In addition to DVD, MP3 and PMP, there are also some popular products such as iPod docking, docking, iPhone and digital photo frame

for the medium power, i.e. 10w~30w LCD TV power amplifier, the power efficiency of class AB power amplifier and class D power amplifier is about 25% and 80% respectively when the broadcast content is mainly voice. According to the formula in the table below, class AB power amplifier needs to consume 40watts of power when playing 10watts of voice, but class D power amplifier only consumes 12.5watts under the same conditions. Therefore, using class D power amplifier can reduce the cost of LCD TV power supply by nearly three times (40watts/12.5watts), and the 2.5W heat generated by class D power amplifier can be handled by general power packaging and PCB design

the application of power amplifier in LCD tv/monitor can be divided into three levels: 2.5W × 2,6W × 2 and 15w/20w × 2。 2.5W × 2. Most of them are used in LCD tv/monitor below 12 inches; 15w/20w for more than 31 inches × 2; The middle size LCD tv/monitor mostly uses 6W × 2。 However, manufacturers often upgrade their specifications in order to compete for specifications. Some entertainment or advertising applications also use larger power amplifiers with small LCD tv/monitor

portable products with different audio amplifiers power comparison amplifier class AB class D power efficiency 15%75%p_ out1W1WP_ in6.7W1.33WP_ Heat5.7w0.33w

generally, manufacturers do not use the sound content as the standard when calculating power, but use the traditional chord wave signal as the input. As for the string wave signal, the power efficiency of class AB power amplifier and class D power amplifier is about 45% and 80% respectively. If 15W × 2 to calculate the total supply power of class D power amplifier is about 30w/80%=37.5w, and the total supply power of class AB power amplifier is about 30w/45%=66.7w, so using class D power amplifier can save nearly 30W power. Since the power supply of the power amplifier is provided by the power supply device, the cost of the power supply device will greatly reduce the dynamometer degree. Our preliminary calculation is as follows: the cost of power devices is about US $0.1 per watt. In this case, the cost of power devices can be saved by US $0.1 × 30 = $3. Therefore, in terms of BOM cost, class D power amplifier can save the total cost, which does not include the processing cost of power supply components and power amplifier heat dissipation and the demand for heat dissipation space

LCD TV power comparison amplifier with different audio amplifiers class AB class D power efficiency 25%80%p_ out10W10WP_ in40W12.5WP_ Heat30w2.5w

market prospect of various class D audio amplifiers

over the past few years, the market of class D power amplifiers has grown in a curve, which will gradually replace class AB Power Amplifiers and gain advantages in the design of new products. According to third-party data, the global revenue of class D amplifiers will rise from US $40million in 2006 to US $1.2 billion in 2008

d class power amplifier is eager to capture the market, which is in related products in terms of low power; For medium power, it is LCD TV. The global and LCD TV shipments are still growing rapidly, and class D power amplifiers will grow with these two categories of products

low power class D digital power amplifier has the characteristics of high efficiency or low power consumption due to cracks in the zigzag part of the pressure gauge tube. It is gradually popularized in various portable products. In addition, medium power class D digital power amplifier will gradually increase in LCD TV and other thin TV markets due to the need for no heat sink and considering the cost of power supply

class D digital power amplifiers with high power, i.e. 100w~200w, will also occupy a place in car audio. Under this high power, class D power amplifiers still have to use heat sinks, but the heat dissipation area and heat dissipation capacity are smaller than those required by class AB power amplifiers. Due to high efficiency, 1. The main unit is not installed horizontally, Class D power amplifier can be used for a long time without starting the car engine and does not consume too much battery power

global LCD TV and shipping volume and estimated year global LCD TV shipping volume estimated (10000 sets) global shipping volume estimated (100 million sets) 710

challenges faced by class D power amplifier design must pay attention to over-current protection and over-temperature protection. These two protection circuits are necessary for power IC or power amplifier, otherwise it will cause safety problems and even damage its connected power supply devices or the whole system. The simple test method of overcurrent protection or short-circuit protection is to short-circuit any output terminal to the power supply terminal (VCC) or ground terminal. In this case, the short-circuit protection circuit will be started and the output transistor will be turned off. At this time, there will be no signal to drive the horn and no sound output. Since the output short circuit is a serious abnormal phenomenon, it is necessary to reset the amplifier to return to the normal operating state after the short circuit, and some ICs can recover automatically after a certain delay time. After reading the datasheet of each IC, you can know the different practices of each product. As for overheat protection, the protection temperature is usually set at 150 ℃ ~160 ℃. After overheat, the IC will automatically turn off the output transistor without sending signals. After the temperature drops by 20 ℃ or 30 ℃, it will automatically return to the normal operation state

in addition, class D power amplifier must solve the EMI electromagnetic interference that class AB power amplifier does not have. Electromagnetic interference is caused by the switching mode operation of the power transistor of class D power amplifier under the conditions of high-speed switching and high current. Under the requirements of most markets, this EMI interference must pass the specifications of electromagnetic interference such as FCC. The solution is to use LC filter or bead filter to filter its high-frequency harmonics. Under this specification, EMI becomes one of the entry barriers for class D. because EMI is too strong, medium and high-power class D power amplifiers currently use LC filters to solve the problem, and low-power class D power amplifiers can be treated with beans. However, they usually need to cooperate with PCB layout and parts placement

for example, after the class D amplifier is adopted, the line connecting the class D amplifier to the loudspeaker cannot be too long, which is equivalent to an external antenna. Some companies' Class D amplifiers can only support 2cm, while well made class D amplifiers can support 10cm, such as TI's class D amplifier

at present, some PDAs and smart devices in the market adopt two mono D-type designs, which is simpler, while it is more difficult to adopt stereo D-type designs, which is the main reason why the latter's sales are not very good

The high efficiency effect of class D power amplifier not only saves the cost of power supply components, but also saves the waste of power supply or battery consumption, and optimizes the whole material system and service environment. In particular, European and American countries pay special attention to green environmental protection. Just like high power factor controller (PFC), class D power amplifier may become an appeal. Although the price of class D amplifier is nearly 50% higher than that of class AB amplifier, the price difference will gradually eliminate with the increase of class D products

the current class D power amplifier of taimec is powered by 2.5W of tmpa2155ds × 2 to tmpa420ds 15W × 2. It covers the current requirements from LCD to tv/monitor. Some low-power amplifiers such as tmpa208ds and tmpa218ds are equipped with volume control function. In addition, there are single-chip 2.1 channels such as tmpa421ds 6wx2+15w to facilitate use and reduce costs

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