EYE on NPI – Analog Devices’ MAX98365 14 V plug-and-play digital Class-D amplifier #EYEonNPI @ADI_News @DigiKey @Adafruit
This week’s EYE ON NPI (video) is bumpin’ the tunez, it’s Analog Devices (nee Maxim) MAX98365 Amplifier, a 14 V plug-and-play digital Class-D amplifier with a highly flexible digital audio interface that supports just about any kind of digital encoding.
This amplifier has a wide input power range, wide logic voltage range, and can handle just about any digital audio formatting you want to throw at it:
The digital audio interface is highly flexible. The devices support I2S, left-justified, and 8-channel TDM data formats. The digital audio interface accepts 8 kHz, 16 kHz, 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, and 192 kHz sample rates. Data words can be 16-bit, 24-bit, or 32-bit in I2S and left-justified modes and 16-bit or 32-bit in TDM mode. Digital audio interface input thresholds are ideal for interfacing to 1.2 V and 1.8 V logic. The devices can tolerate logic input voltages up to 5.5 V.
The NPI’s part number, the MAX98365, sounds similar to an I2S amp chip we’ve been using for a while – the MAX98357 – and to no surprise, this chip seems to be an upgrade to the original amp.
Both are single, class-D amplifiers, but the new chip has much better power supply range: 3V to 14V instead of 3 to 5V, which also allows it to max out the speaker power at around 14 W into a 4 or 8Ω load with 10% Total Harmonic Distortion (THD). For 1% THD you can go up to 14W in 4Ω or 8W into 8Ω.
The nifty thing this chip can do is swap formats based on the kind of signal it gets – which means you can use it in a range of designs. Most folks tend to use I2S, but left-justified or 8-channel TDM is also supported. It does this by auto-detecting the signal frequencies and pulse types. It also has the nicety of no MCLK pin required – which will be nice to hear for folks using this with single board Linux computer like Raspberry Pi that do not have MCLK output. Also, you get to save a pin if you are using I2S on a microcontroller!
OK, so this chip is quite magical, but there’s one thing to watch for – it’s only available in a chip-wafer-scale BGA package with 0.4mm pitch. This makes it great for embedding in tiny devices, but rough for prototyping. So you may want to check out the MAX98365AEVSYS eval board which can at least get you set up before you start routing. Next up, even if you are not too scared of 0.4mm pitch, the gain select pin is in the center, which means you can at least avoid plugged vias if you’re willing to live with a fixed gain.
If you want a itsy-bitsy-tiny-winy amplifier with great output, wide support for different formats, and class-D efficiency, the Analog Devices MAX98365 Amplifier is a great pick! And, best of all, it’s in stock right now for immediate shipment from Digi-Key. Order today and you will be blasting the hit song of the summer by tomorrow afternoon
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