Infineon Technologies

MERUS™ - The new benchmark in Class D amplifiers

For all who love audio!

For many years already Infineon has wowed audio customers all over the world with its advanced technologies and products. For an even stronger and more impactful presence in the class D audio market it is now time to elevate the excellence to the next level. In order to maximize product portfolio transparency and initiate unprecedented value creation for its existing customer base and potential future customers, Infineon introduces its category brand, MERUS™.

  • One roof under which the already successfully established audio portfolio is complemented by newly added high-performance class D amplifier solutions.
  • One brand name synonymous for unbeatable audio experience throughout all premium class D audio applications.
  • One range of technically advanced audio amplifiers playing in a league of their own when it comes to power efficiency, output power and audio performance while ensuring fast time to market and greatest possible design freedom.

At Infineon we believe the best audio amplifiers must …
COOLER … produce sound in speakers, instead of heat to the surroundings.
SMALLER & LIGHTER … be heard, not seen. Bulky and heavy is history.
ROBUST & FLEXIBLE … not be delicate and demanding.

And because we at Infineon also believe that our customers deserve only the best, we are producing them. Discover MERUS™ - the new industry benchmark … for all who love audio!

Three pillars of success – Build on what makes the difference

Infineon’s MERUS™ class D amplifier solutions will take root in the audio market fast and become renowned for incomparable supremacy based on three fundamental pillars

* The MERUS™ MA12070 4 – 26 V ultra-efficient audio amplifier was the first amplifier to receive the “WiSA endorsed” certification in the market (Dec, 2018)

Class D Audio Applications

MERUS™ is more than a brand! It is the gateway to excellence in class D audio application designs.

As such, Infineon strives to support its existing and future audio customers with all their projects throughout the main three categories in this field: home, portable / battery powered, and professional audio applications.

Home Audio

Infineon’s audio experts understand that solutions for home audio applications have to not only fulfill the request for exceptional sound quality but also the way audio devices are designed and fit to the rest of the interior will impact a consumer’s buying decision. This was taken into account when developing MERUS™ audio amplifiers. They fully eliminate the need for bulky and expensive LC output filters and heatsinks. Infineon made the impossible possible. Form factors and shapes unknown to the industry so far are now available to audio designers who turn to MERUS™.

Target applications:

  • Multi-room systems
  • Home hubs
  • TVs
  • Sound bars
  • Home theater systems
  • Smart speakers

Portable / Battery Powered Audio

Over the past years the audio industry has transformed into one where the terms “battery powered” and “portable / mobile / handheld” are making a substantial difference. Namely, in what is expected from the new generation of audio devices like MP3 players, portable docking stations, smartphones, etc. Power consumption is more in focus than ever before. Reducing the amount of power consumed by a device is key to increase battery life. And yet consumers nowadays are not willing to compromise enjoying the best audio experience on the go for a longer lasting listening time. MERUS™ audio amplifiers satisfy both expectations. Battery playback time is doubled compared to standard solutions. Audio performance and sound quality remain at best-in-class level.

Target applications:

  • Battery-operated speakers
  • On-the-go Bluetooth speakers
  • Docking speakers
  • Boom boxes
  • Wearable speakers

Professional Audio

With MERUS™ the topic of revolutionizing professional audio electronics is no longer only found on future agendas. Big, heavy, and non-energy-efficient is history. Maximizing output power and power density is what counts for those who endeavor to be one step ahead - already today. Class D audio application optimized driver-transistor-combinations turn this new concept into reality. Discrete audio amplifier driver ICs can be combined with a set of power MOSFETs what results in an advantageous scalability of output power levels. Not to forget the fact: size matters! With smaller parts and BOM count reduction the footprint is also decreased. MERUS™ makes compact designs go hand-in-hand with high power efficiency and sound quality of professional standard – relentlessly perfect.

Target applications:

  • Power-over-ethernet (PoE)
  • Audio systems
  • Touring amplifiers
  • Active speakers
  • Public announcement 70-100 V systems
  • Music instrument amplifiers

Product Portfolio Overview - MERUS™ Class D Audio

The product portfolio reflects the “One brand for all class D audio applications” approach that Infineon uses to position itself with MERUS™ in the global class D audio amplifier industry. It stretches from fully integrated single-chip audio solutions to discrete audio solutions with highly scalable driver and power MOSFET combinations. As such, we now offer compelling class D audio solutions that are ideally suited for a broad range of class D audio applications with output power levels starting at 20 W - going all the way up to over 2000 W per channel.

 

  • Integrated Audio Solutions »
  • Discrete Audio Solutions »
  • Evaluation Board & Reference Design »

Integrated Audio Solutions

  • Maximized power efficiency (high dynamic range and low idle power), audio performance and design freedom
  • High power density in compact, thermally efficient PQFN packages - no need for mechanical heatsinks
  • Primary target applications: portable / battery powered audio applications and applications with challenging thermal conditions

Low power audio solutions (< 40 V)

Monolithic multilevel class D amplifier ICs enable optimization of audio systems for size, performance, and system cost

MERUS™ multilevel technology outperforms traditional class D amplifier ICs

In principle, multilevel amplifiers do the same as class D amplifier ICs, but they do it smarter:
Whereas a traditional class D IC produces only two voltage output levels, multilevel amplifier ICs use additional on-chip MOSFETs and capacitors to produce outputs with a higher signal granularity i.e. higher switching frequencies and/or multiple output signal levels (typically up to five voltage levels).

The multiple output levels are generated by unique output stages which consist of multiple stacked MOSFETs in combination with a so called fly-cap to store the additional voltage levels.

Multilevel switching is a technology that is also applied in other electronic fields such as solar power panels, power inverters, and the like. Infineon is the first company to apply the multilevel principles to class D audio amplifier products what positively affects the most important amplifier evaluation parameters compared to traditional class D amplifiers:

  • power consumption
  • solution size
  • audio performance
  • electromagnetic interference
  • and BOM cost

Along the above listed, potential LC filter removal (the higher signal granularity means that the load impedance is typically enough to smoothen out the signal), low THD+N and cooler operation are some of the primary advantages of the MERUS™ integrated multilevel audio amplifier ICs.

The higher power efficiency and reduced power consumption are especially significant at the average output power of music signals with low to moderate volume settings.

Power consumption advantage

Traditional class D amplifiers are only efficient at highest music volume levels (with high THD which renders this quality less useful for practical implementations). In realistic audio playback situations they consume significantly more input power (~1 W on average) than MERUS™ first generation integrated multilevel audio amplifier ICs (~0.25 W).

Technology breakthrough with MERUS™ integrated multilevel audio amplifier ICs

Even in idle and near idle mode, traditional class D amplifiers continue to have a lot of switching activity. In other words, each half-bridge in the output stage changes the duty cycle to create the desired output level. Considering that internal switching activity does not stop when no output is produced (i.e. no sound is coming out of the speakers) the resulting switching losses unnecessarily increase the power consumption.

MERUS™ integrated multilevel audio amplifier ICs use scalable signal “granularity” to keep the power loss extremely low. Due to the proprietary circuits architecture, there is virtually no switching loss measurable in idle mode - one of the parameters where MERUS™ integrated multilevel audio amplifier ICs excel.

Efficiency where it matters for audio reproduction

The leading thought behind the development of the MERUS™ integrated multilevel audio amplifier ICs was: amplifier efficiency at average output power is key!

The graph below shows efficiency as function of output power for a number of different amplifier architectures. Music is typically in the grey range and the average output power for music playback is lower than one may expect.

Highlight products – MERUS™ integrated multilevel audio amplifierICs

Currently, Infineon offers four fully integrated monolithic amplifier ICs:
Two versions, MA12040 and MA12040P, with 2x40 W peak output (with a maximum PVDD of 18 V) and either an I2S digital input or analog input with a pre-selectable gain.
Two versions, MA12070 and MA12070P, with 2x80 W peak output (with a maximum PVDD of 26 V) and the same two input options as the two slightly lower power versions.
Common to all four integrated multilevel audio amplifiers is unparalleled power efficiency and exceptional audio quality.

Output power: The four afore-described parts are specified for producing a continuous output power that is 1/8th of their maximum peak output power. In case of MA12070P this means, for example, that it will have 2x10 W continuous output power whereas the maximum peak output power is 2x80 W. However, the specification depends on PVDD, load impedance and PCB properties as well as on the respective board layout.

Integrated DSP: There is a small digital signal processor (DSP) integrated in the front-end of MA12040P or MA12070P. The DSP can perform simple tasks such as volume control and limiter / dynamic range compression (DRC). The DSP does not allow for equalization (EQ). Integrated DSP/EQ functionality will become available in subsequent product releases.

Output configuration: All devices can be configured as bridge-tied-load (BTL), parallel bridge-tied-load (PBTL), or single-ended (SE). As such, each IC can provide up to four SE channels, one BTL and two SE channels, two BTL channels or one PBTL channel.

Device configuration: The highly configurable MERUS™ integrated multilevel audio amplifiers use I2C as communication protocol. Hence, setting different configurations is typically done by using a microcontroller (MCU) as system manager in the audio system.

Protection: All four MERUS™ integrated multilevel audio amplifiers feature:

  • under voltage lockout (UVLO)
  • over temperature warning and error
  • short-circuit / over current protection
  • DC protection

MERUS™ multilevel amplifier ICs add value to your audio designs because of three convincing reasons:

1. Power efficiency: Superior power efficiency allows designing products that run cooler and with an extended battery playback time.
2. Sound quality: Even when playing music really loud there will be no power waste and best-in-class THD+N remains. With multilevel technology the rail voltage will be high enough to provide the extended dynamic range that is associated with excellent sound quality.
3. System level benefits: BOM reductions are achieved through filterless, heatsink-free operation, decreasing overall system cost.

Each of them being a substantial argument for those not fully satisfied with currently used solutions to consider switching to MERUS™.

 

High power (100 V – 600 V): Multi-chip modules (MCMs)

Modules include a PWM controller and power MOSFETs in a single package leading to a reduction in component count, consequently shrinking the PCB size up to 70 percent and simplifying class D amplifier designs

MERUS™ integrated audio amplifier multi-chip modules are perfect for designers seeking devices integrating a PWM controller and power MOSFETs in a single package. Such highly efficient, compact solutions do not only simplify class D amplifier designs but also reduce component count and shrink PCB size by up to 70 percent.
Improved efficiency, THD, and EMI are the result of combining an advanced audio controller IC with MOSFETs that have been fully optimized according to audio performance parameters. That is why the MERUS™ integrated audio amplifier MCMs operate without a mechanical heatsink over a wide power supply range - on either a single or a split power supply. And reliable operation over various environmental conditions is ensured by high voltage ratings together with noise immunity.

Should designers opt for one of the devices in the current product portfolio they will enjoy the flexibility and convenience of building stereo amplifier and multi-channel designs in various channel configurations. Moreover, 5x6 mm and 7x7 mm PQFN packages let them utilize a smaller class D topology.

Discrete Audio Solutions

  • driver-transistor-combinations optimized for class D applications
  • achieving output power scalability by choosing from a wide variety power MOSFETs in order to flexibly combine the MOSFET with dedicated audio amplifier driver ICs
  • best-in-class power efficiency
  • unified design platform

High power (100 V – 600 V): Audio amplifier driver ICs + power MOSFETs

Identification of the desired output level and speaker resistance forms basis of selecting the matching power MOSFET and combining it with the respective audio amplifier driver IC that works within a specified power range / up to a specified maximum power level

All those dealing with any kind of class D audio application and seeking high scalability in output power levels are invited to turn to Infineon’s MERUS™ discrete audio amplifier driver IC portfolio and accompanying assortment of power MOSFETs. For the sake of simplicity, the same driver can be used with a variety of MOSFETs making them scalable to various output power levels. Replacing the external MOSFET with another matching one is enough to trigger an alteration in the chipset’s output power level. The extensive range of power MOSFETs (through-hole, DirectFET™) is optimized around audio performance critical parameters (i.e. on-state resistance (RDS(on)), gate charge (QG), and reverse recovery charge (Qrr)) with the purpose of maximizing efficiency, THD, and EMI. Infineon’s class D discrete audio solutions are smaller in size than comparable class AB designs enabling a reduction in the board size. Most importantly, the high efficient design with class D application specific drivers and MOSFETs allows for superior audio performance and enhanced reliability.

MERUS™ discrete audio amplifier driver ICs

Power MOSFETs

DirectFET™ - Special package leveraging performance

DirectFET™ has a uniquely simple construction that provides breakthroughs in die free package resistance, parasitic package inductance and heat dissipation capabilities. Compared to standard discrete packages the DirectFET™ metal construction enables dual-side cooling to effectively increase the efficiency and current carrying capability of the device in a given footprint. DirectFET™ is compatible with today's high volume manufacturing processes and is the recommended package for surface mount discrete MOSFET designs.

Together with the latest MOSFET silicon technology, this packaging type is the right choice for those class D audio applications where thermal behavior, energy efficiency and power density are in focus.

Evaluation Board and Reference Design

EVAL_AUDIO_MA12070P - Class D Audio Evaluation Kit

This audio evaluation kit contains all hardware and software elements that are needed to evaluate the highly power efficient digital input integrated multilevel class D amplifier IC, MA12070P (2x80 W). The IC has been specifically developed for high performance filterless and heatsink-free audio applications.

Target applications: home, portable, and professional audio applications

View Details

 

IRAUDAMP21 - Class D Audio Reference Design

This reference design is a two-channel (90 W/channel) half-bridge class D audio power amplifier. It demonstrates how to use the integrated IR4321M IC, implement protection circuits, and design an optimum PCB layout. Mechanical heatsink or fan cooling is not required for normal operation. The board has been developed for applications with low impedance speaker loads typically seen in car audio amplifiers or sub-woofers.

Target applications:home, professional, and aftermarket car audio applications

View Details

 

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