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Audio Design

Design of audio amplifiers: selection guide for Class-D audio amplifier and circuit ideas

Introduction

If you already know about class A, B, and AB, they are all linear amplifiers with constant gain where the audio is fed to the base of a transistor. The latest class D audio amplifier is switch type amplifier by using Pulse Width Modulator (PWM) amplifier. In class A, B and AB type amplifiers which are linear amplifiers, the gain is constant irrespective of bus voltage variations but the gain is proportional in class D amplifiers. Class D amplifiers are much efficient than linear amplifiers.
The lower power consumption of Class D amplifiers make them suitable for audio amplifier design. Class D is more relevent for battery operated devices such as phones and notebooks, netbooks and tablets due to low power consumption.

Class D amplifier market: Due to the power performance of Class D amplifiers, its market is growing around 20- 30% on average.


Drawback: The drawback of class D amp is, switching of the outputs in the Class D amplifiers causes EMI and hence in most applications which require EMI certification need to be dealt cautiously.

Class D amplifiers are used in designing audio amplifiers in many applications, including powered subwoofers, powered speakers, mobile applications (to save battery power), and bass amplifiers.

Here below we provide a list of class D amplifiers from leading semicoductor vendors.

Parts selection table from key vendors of anlog ICs

Manufacturer Name Part Number Description
International Rectifier AUIRS2092S Automotive Audio Amplifier
Intersil ISL99201IRTAZ-TK Filterless High Efficiency 1.5W Class D Mono Amplifier
Maxim Integrated Products MAX98304EWL+ Mono 3.2W Class D Amplifier
Monolithic Power Systems, Inc. MP1720 2.7W Mono Class-D Low-EMI High-Efficiency Audio Amplifier
Monolithic Power Systems, Inc. MP7747 20W Class-D Mono Single Ended Audio Amplifier
National Semiconductor (now Texas Instruments) LM48310SDX/NOPB Ultra-Low EMI, Filterless, 2.6W, Mono, Class D Audio Power Amplifier with E2S
On Semiconductor NCP2824FCT2G Class D Audio Power Amplifier with AGC
RoHM BD5460GUL-E2 Small Class-D speaker amplifier
STMicroelectronics TDA7498 100-watt + 100-watt dual BTL class-D audio amplifier
Analog Devices SSM2380CBZ-REEL7 2 x 2 W, Filterless, Stereo, Class-D Audio Amplifier with ALC + I2C
Maxim Integrated Products MAX98306ETD+ Stereo 3.7W Class D Amplifier
National Semiconductor (now Texas Instruments) LM48520TLX/NOPB Boosted Stereo Class D Audio Power Amplifier with Output Speaker Protection and Spread Spectrum
NXP Semiconductors TDA8932BT High-efficiency class D amplifier
NXP Semiconductors TDA8932BTW High-efficiency class D amplifier
NXP Semiconductors TDA8933BTW High-efficiency class D amplifier
NXP Semiconductors TFA9810T Stereo full-bridge audio amplifier 2 x 12 W
On Semiconductor 4904V-TLM-E 10W x 2ch, Class-D, Power Amplifier IC for TVs and Home Audios
STMicroelectronics TDA7491HV 20W+20W dual BTL class-D audio amplifier
STMicroelectronics TS2012IQT Filter-free stereo 2 x 2.8 W class D audio power amplifier
Maxim Integrated Products MAX9776ETJ+ 2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier
Cirrus Logic CS4412A-CNZ Audio Power Amplifier
Maxim Integrated Products MAX13301AUM/V+ 4 Channel, Automotive Class D Audio Amplifier
Texas Instruments TAS5630DKD Analog input 300W Stereo class D amplifier with integrated feedback
Texas Instruments TAS5176DDWG4 100-W (5.1 Channel) Digital Amplifier Power Stage

 

Manufacturer Part Number Output Type Efficiency PSSR (dB) Output power (W)
AUIRS2092S 1 channel 65 500
ISL99201IRTAZ-TK 1 channel 86% 65 1.4
MAX98304EWL+ 1 channel 93% 90 2.6
MP1720 1 channel 90% 60 2.7
MP7747 1 channel 91% 59 20
LM48310SDX/NOPB 1 channel 88% 82 2.6
NCP2824FCT2G 1 channel 90% 80 2
BD5460GUL-E2 1 channel 53 850m
TDA7498 1 channel 90% 100
SSM2380CBZ-REEL7 2 channels 93% 85 2.5
MAX98306ETD+ 2 channels 92% 83 2.4
LM48520TLX/NOPB 2 channels 78% 82 1.1
TDA8932BT 2 channels 92% 15
TDA8932BTW 2 channels 92% 18
TDA8933BTW 2 channels 89% 10
TFA9810T 2 channels 89% 9
4904V-TLM-E 2 channels 85% 10
TDA7491HV 2 channels 90% 20
TS2012IQT 2 channels 81% 70 2.8
MAX9776ETJ+ 3 channels 79% 68 1.5
CS4412A-CNZ 4 channels 85% 30
MAX13301AUM/V+ 4 channels 88% 70 66
TAS5630DKD 4 channels 88% 80 300
TAS5176DDWG4 6 channels 90% 100

 

Part Number Load Impedance Operating Temperature Supply Voltage
AUIRS2092S 4 ohm -40 to 125 C 10 to 18V
ISL99201IRTAZ-TK 8 ohm -40 to 85 C 2.4 to 5.5V
MAX98304EWL+ 4 ohm -40 to 85 C 2.5 to 5.5V
MP1720 4 ohm 2.5 to 5.5V
MP7747 4 ohm 9.5 to 36V
LM48310SDX/NOPB 4 ohm -40 to 85 C 2.7 to 5.0V
NCP2824FCT2G 4 ohm -40 to 85 C 2.5 to 5.5V
BD5460GUL-E2 8 ohm -40 to 85 C 2.5 to 5.5V
TDA7498 6 ohm -40 to 85 C 14 to 39V
SSM2380CBZ-REEL7 4 ohm -40 to 85 C 2.5 to 5.5V
MAX98306ETD+ 4 ohm -40 to 85 C 2.6 to 5.5V
LM48520TLX/NOPB 8 ohm -40 to 85 C 2.7 to 5.0V
TDA8932BT 4 ohm -40 to 85 C 10 to 36V
TDA8932BTW 4 ohm -40 to 85 C 10 to 36V
TDA8933BTW 8 ohm -40 to 85 C 10 to 36V
TFA9810T 8 ohm -40 to 85 C 8 to 20V
4904V-TLM-E 8 ohm -30 to 70 C 8 to 20V
TDA7491HV 8 ohm -40 to 85 C 5 to 18V
TS2012IQT 4 ohm -40 to 85 C 2.5 to 5.5V
MAX9776ETJ+ 4 ohm -40 to 85 C 2.7 to 5.5V
CS4412A-CNZ 4 ohm -10 to 70 C 8 to 18V
MAX13301AUM/V+ 4 ohm -40 to 125 C 6 to 25.5V
TAS5630DKD 4 ohm 0 to 70 C 0V to 52.5V, 10.8V to 13.2V
TAS5176DDWG4 3 ohm 0 to 125 C 0V to 34V, 10.8V to 13.2V

 

Suggestion on some specific ICs:

  • Maxim's MAX98314 is a 3.2W class D amplifier integrated with input coupling capacitors built by using the 3D chip assembly.

  • NXP's TFA9881 and TFA9882 are the smallest digital-in mono class D audio amplifier which delivers up to 3.4W of power with power consumption of 6.5mW.

  • NXP offers class-D amplifiers with a range from 0.4W to 200W in both analogue and digital inputs. NXP also offers class D car radio amplifiers that deliver up to 2 x 135 W in to 4 ohm loads.

  • On Semi's NCS8353 stereo audio amplifier can deliver continuous output power up to 20 W per channel in to an 8 ohm bridge tied load(BTL) can be suitable for flat panel TVs.

  • ST Micro's TDA7498E dual-BTL class D amplifier exhibits unparalleled power density of 3.2W/mm2.

  • · Texas Instriment's TPA3116D2, TPA3118D2, TPA3130D2 and TPA3131D2 are medium-power, analog-input Class-D speaker amplifiers while TPA2011D1/37D1/39D1 and TPA2015D1 are low-power, analog-input, Class-D speaker amplifiers.

  • International Rectifier's class D driver + digital audio MOSFETs such as IRS4301(1 channel), IRS2052(2 channels), IRS2053(3 channels), IRS2093(4 channels), etc., provide output power from few tens of Watts up to 500 W. IR also provides Integrated class D audio amplifiers in trade name called PowlRaudio, such as IR4301, IR4311, IR4302, etc.,

  • National's LM48901 is a quad class D amplifier (spatial array) configured through an I2C compatible interface with superior click and pop suppression.

  • Texas Instruments made LM48901 quad Class D spatial array employ distributed sound processing coupled with loudspeaker array technology to produce an immersive audio experience for space-constrained applications.

  • Texas Instruments' LM49251's Class G headphone amp dynamically reduces the supply voltage to lower power consumption and extend audio (MP3, movies, etc.) playback time. The loudspeaker's ALC provides designers with several options to control audio distortion levels and prevent speaker damage.|

  • Maxim's MAX98304 is the smallest Class D amplifier at 1mm x 1mm. This amplifier increases output power by 23% to 3.2W and reduces noise by 39% to 19µVRMS, as compared to Maxim's previous-generation device.

  • The MAX98400 from Maxim is filterless Class D amplifiers available in 2 x 12W, 2 x 20W, and 1 x 40W configurations. The MAX98400 amplifiers ideal for TVs, notebooks, and all-in-one desktop applications.

  • MAX98300/MAX98302 from Maxim are mono/stereo 2.4W/channel Class D amplifiers which do not need EMI-suppression components. The MAX98300/MAX98302 consume supply current of 700µA/channel. Maxim's MAX98500, is a boosted 2.2W Class D amplifier designed for battery-operated portable devices. This device integrates a boost converter to provide a constant output power and, therefore, louder audio output over a wide range of battery supply voltages.

  • The TS4999 from STMicroelectronics is a two-channel, 2.8W class D stereo audio amplifier IC featuring 3D audio effects that improves sound quality from portable equipment.

  • ST's TDA7498 is suggested for equipments such as DVD and Blu-ray players, home theater, active speakers, and docking stations.

  • Texas Instruments suggests its TPA2015D1 allows more than twice the battery life compared to the nearest competing amplifier and is available in a compact 2-mm x 2-mm WCSP package for space-constrained applications including smart phones, notebooks, portable navigation devices, portable docking station and portable DVD players. In addition, the amplifier incorporates battery monitoring automatic gain control (AGC) and SpeakerGuard technology.

  • The TPA2028D1 and TPA2026D2 from TI incorporate DRC to boost soft volumes automatically, allowing designers to compress the dynamic range of the audio to match the dynamic range of the speaker.

  • MAX97000/MAX97001*/MAX97002 feature Class D mono speaker amplifier with distortion limiter; a DirectDrive II Class H stereo headphone amplifier; and an ultra-low-noise, analog bypass switch.

  • WM9081 from Wolfson packs DAC and class D amplifier in single chip.

  • The SSM2517 Class D audio amplifier from Analog devices also combines on a single chip an audio DAC (digital-to-analog converter), power amplifier, and a PDM digital interface.

  • A new LM4675 mono, 2.65W, Class D Boomer audio amplifier from Texas Instruments reduces electromagnetic interference (EMI) more than 11 dB below the United States Federal Communications Commission (FCC) limit to lower system noise in portable devices including cell phones, smart phones, music players, notebook computers, DVD players, gaming devices and other portable electronics.

  • The TAS5414 and TAS5424 Class D amplifiers from TI introduce the power efficiency of digital amplification for automotive audio applications, such as head units and external amplifiers.

  • MAX9708 from Maxim is a Class D amplifier optimized for flat-panel display applications including LCD and PDP televisions and home audio equipment. This is a filterless amplifier that requires very few external components.

For learning audio amplifier design and for circuit ideas using class D amp visit below sites:

1. http://www.irf.com/product-info/audio/classdtutorial.pdf

2. http://www.ti.com/lit/an/sloa031/sloa031.pdf

3. http://www.wpi.edu/Pubs/E-project/Available/E-project-041808-145643/unrestricted/report.pdf

4. http://www.nxp.com/documents/user_manual/UM10155.pdf

5. http://www.analog.com/library/analogDialogue/archives/40.../class_d.pdf

        More> > page 2 - More Recently released class D amplifier ICs

Note: The data given in this is only a reference for the clarification of data and specs consult the manufacturer of the part.


 

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