Monday, January 25, 2010

class d audio amplifier

class d audio amplifier
A Class D audio amplifier is basically a switching amplifier or PWM amplifier. There are a number

of different classes of amplifiers. This application note takes a look at the definitions for the main

Class D Amplifier
A Class D amplifier or switching amplifier is an electronic amplifier which, in contrast to the active resistance used in linear mode AB-class amplifiers, uses the switching mode of transistors to regulate power delivery. The amplifier, therefore, features high power efficiency (low energy losses), which additionally results in lower weight by eliminating bulky heat sinks. Additionally, if voltage conversion is necessary, the on-the-way high switching frequency allows the bulky audio transformers to be replaced by small inductors. Low pass LC-filtering smoothes the pulses out and restores the signal shape on the load.

Class D Audio Amplifiers
Class D amplifiers, first proposed in 1958, have become

increasingly popular in recent years. What are Class D amplifiers?

How do they compare with other kinds of amplifiers? Why is

Class D of interest for audio? What is needed to make a “good”

audio Class D amplifier? What are the features of ADI’s Class D

amplifier products? Find the answers to all these questions in the

following pages.
UM10155 Discrete Class D High Power Audio Amplifier
Class D Audio Amplifier, Universal Class D, UcD, PWM Audio Amplifier, .... The ' High Power Class D Audio Amplifier Demonstrator Board.
Class D Audio Amplifier Output Filter Optimization
This application note examines the effect of the output filter on audio Class D amplifier performance. Switch-mode amplifiers such as the MAX4295 and MAX4297 offer improved efficiency over their more traditional Class AB counterparts. By understanding the operation of these devices, the modulation noise spectrum and the loudspeaker loads they are required to drive, it is possible to completely eliminate the output filter while retaining the efficiency benefits of Class D amplifiers.
How Class D audio amplifiers work
A Class D audio amplifier is basically a switching amplifier or PWM amplifier. There are a number of different classes of amplifiers. We will take a look at the definitions for the main classifications as an introduction.
Class D Audio Amplifiers - Theory and Design
A completely new technology for audio amplification has been evolving during the last 15-20 years that has a clear benefit over current widespread Class-A, and AB topologies. We are talking about the so-called “Class-D”. This benefit is mainly its high power efficiency. Figure 1 shows typical efficiency curves vs. Output power for Class-B and Class-D designs.
170W Class D Audio Amplifier Solution
The LM4651 is a fully integrated conventional pulse width modulator driver IC. The IC contains short circuit, under voltage, over modulation, and thermal shut down protection circuitry. The LM4651also contains a standby function which shuts down the pulse width modulation minimizing supply current. The LM4652 is a fully integrated H-bridge power MOSFET IC in a TO-220 power package. The LM4652 has a temperature sensor built in to alert the LM4651 when the die temperature of the LM4652 exceeds the threshold. Together, these two IC's form a simple, compact high power audio amplifier solution complete with protection normally seen only in Class AB amplifiers. Few external components and minimal traces between the IC's keep the PCB area small and aids in EMI control.

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