Infineon’s MERUS Class D Audio Solution Integrates Multilevel Amplifier ICs

May 2, 2019 Alix Paultre

Infineon Technologies MERUS line unites the existing portfolio of multi-chip modules and discrete audio products under one umbrella, with a family of power-efficient monolithic class D audio amplifier solutions. Building on multilevel switching technology for class D audio amplifiers impacts parameters such as power consumption, solution size, audio performance, electromagnetic interference, and BOM cost.

With up to five levels of output signal modulation, multilevel amplifiers use additional on-chip MOSFETs and capacitors to produce outputs with higher signal granularity. Providing higher switching frequencies and scalable output-signal levels, the topology results in a small form factor and virtually no switching loss measurable in idle mode.

The initial products are four integrated multilevel audio amplifiers, the MA12040/P and the MA12070/P in two versions, respectively, with power consumption in the 250mW range. Traditional class D amplifiers are only efficient at highest music volume levels resulting in high THD, which renders quality less useful for practical implementations. In realistic audio playback situations they consume significantly more input power (~1 W on average) than the first generation of MERUS integrated multilevel audio amplifier ICs (~0.25 W).

The newly introduced devices support up to four channels, which can be configured in parallel bridge-tied-load (PBTL), in bridge-tied-load (BTL) or in single-ended (SE) mode. As such, a single IC can output up to 160 W peak (16 A max) in a single PBTL channel or, for instance, it can be set up as a 2.1 system with 2 x 20 W tweeters as SE channels and 1 x 40 W woofer speaker as BTL channel. In addition, the products feature an advanced digital power management scheme, low THD+N (0.003 percent) and low EMI emissions.

Offering heatsink-free operation without filters, the MA12040/P and the MA12070/P feature several protection modes such as undervoltage lockout, short-circuit/overcurrent and DC protection, and over-temperature warning and error. The MERUS integrated multilevel class D audio amplifier ICs come in a 64-pin thermally enhanced QFN package with exposed thermal pad (EPAD).

The family of fully integrated ICs from the MERUS class D audio portfolio consists of the analog audio input versions, MA12040 and WiSA™ Endorsed MA12070, and the I2S digital audio input versions, the MA12040P and the MA12070P.

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