Atmel 's latest audio component is the AT73C240, an audio companion ic for portable multimedia applications that integrates a 20bit stereo DAC and an up to 1W audio power amplifier.
The AT73C240's stereo DAC, which delivers a 90dB dynamic range, comprises a sigma-delta modulator with dither, continuous time analog filters and analog output drive circuitry. The master clock is 256 or 384 times the sampling frequency, allowing for a choice of input data rate up to 50 kHz, including standard audio rates of 48, 44.1, 32, 16 and 8 kHz.
The DAC is followed by a stereo 32Ohm headset driver with programmable volume control and mute function. There is also a mixer buffer stage for a pair of stereo inputs. The mono buffer stage can also receive the mixing of the stereo inputs as well as the differential monaural auxiliary input (which can be, for example, from a voice CODEC output driver in a mobile phone).
The audio power amplifier is a dual-mode AB class amplifier with differential output and programmable volume control. In full power mode, it is capable of driving an 8Ohm loudspeaker at maximum power of 1W at 5.5V supply and 440mW at 3.6V supply. The volume, mute, power down, de-emphasis controls and 16-, 18-, 20-bit audio formats are digitally programmable via a 4-wire SPI bus and the digital audio data is provided through a multi-format I2S interface.
Manufactured on Atmel's mainstream CMOS process, the AT73C240 is a smaller packaged and lower price follow-up to Atmel's AT73C213 audio DAC. Packaged in a 5x5mm, 32pin QFN, production quantities are already available, as is a reference design. For more information, visit: Atmel's website
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