Maxim launches dual-mode H-class headphone amplifier MAX97200, which is designed for a battery-powered portable device. This amplifier uses Maxim proprietary DirectDrive II technology to construct a high efficiency H-class architecture. The efficiency of the MAX97200 is almost twice the AB amplifier, which can effectively extend the audio playback time. In addition, the device's uninterrupted switch architecture and free / sprinkle performance can provide a more abundant audio experience for end users. The size of this IC is only 2mm2, which is the smallest stereo headphone amplifier on the market. The MAX97200 is ideal for cellular phones, portable media players (PMP), laptops, and other battery-powered audio applications.
Faced Challenge: Improve amplifier efficiency
Today's portable consumer electronics supports a variety of multimedia features, but this will also affect battery life. This issue has highlighted in every new design, because designers are constantly integrating camera modules, HD video, web browsing, and several other features based on demands into a new generation device. In order to maintain this "function extension" capability, system designers must find new ways to extend battery life.
Choosing the appropriate amplifier is critical to saving electricity. For example, the AB class amplifier is known as low efficiency, regardless of the size of the audio signal level, the maximum supply voltage is powered. This approach results in only 13% to 15% of the efficiency of only 13% to 15% under normal listening levels (2MW to 5 mW power to 16Ω).
Instead, the H-class amplifier (referred to as a G class in Europe) can switch between a plurality of internal generated power supplies depending on the amplitude of the output signal. By quickly selecting the power supply voltage, the H class amplifier can reduce the dynamic distortion of the output stage while increasing efficiency. The MAX97200 efficiency can be increased by 97% compared to the AB amplifier. Within 2 mW to 5 mW output power range, the MAX97200 can reach 20% to 29%.
DirectDrive II technology can construct the low power consumption H class architecture
Maxim's DirectDrive II technology uses an internal dual-mode charge pump that generates ± pvin and ± pvin / 2 power supplies from the external 1.8V regulator source. The MAX97200 is powered by ± pvin / 2 power supply when the output signal is low, and only when the load needs to be larger output power, the power is switched to the ± 1.8V power supply. Since most of the audio signals are low, the power consumption of the MAX97200 is comparable to the power consumption of the traditional ± 0.9V DirectDrive amplifier. To further save power, the current loss in turn-off mode is less than 1μA, and the current is only 1.15mA (typ) when the current is operating.
No interference audio performance
One challenge for H-class architecture is to switch the power supply before the output signal changes to a larger value, otherwise the audio output will have a significant clipping effect, resulting in dynamic distortion. Maxim's H-class has a unique tracking function, which provides seamless adjustment of the audio signals to achieve seamless adjustment of the power supply. This approach ensures that the signal is continuous, and there will be no common interference signals in the same class competition amplifier.
The MAX97200 has industry-leading clicked / 噼噼 performance in entering and exiting the shutdown mode, because the device has a very low output offset voltage. Since the DirectDrive II architecture generates an export of ground reference when power is powered, the large-scale inch flow capacitance that is usually required between the amplifier output and the headphone load is omitted. This feature ensures that you don't produce a boring click, thus providing a better auditory experience for end users.
In addition, the MAX97200 has a higher signal-to-noise ratio (SNR = 105dB) to ensure the high fidelity sound of the system. The output noise of the device is only 5.6 μV, improves the overall audio noise index, and does not create a snap when there is no signal.
Optimization for small size packages
The MAX97200 is a minimal high-efficiency earphone amplifier in the market, which is reduced by 25% of the nearest competitive product with minimal (1.27 mm x 1.65mm), 12 solder ball wafer level package (WLP). Since the MAX97200 does not need to induct, its overall scheme is reduced by 30% in the competition device.
The MAX97200 is powered by a 1.8V single power supply, which provides 34MW output power for 32Ω load. The device operates in -40 ° C to + 85 ° C extension level temperature range. Provide * Estimate to speed up design processes, more information, please visit China.maxim-ic.com/class-h-amp. :, Read more
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