TRAXMOD:DAC Selection
From K9spud
There are a plethora of DAC and audio CODEC chips available on the market. With so much variety, which DAC should we choose for a production portable audio player today? Let's examine some top contenders:
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PCM1770
Cost: $1.75 (100 qty)
Sample Rate / Resolution: 5KHz to 50KHz, 24 bit
Signal to Noise Ratio (16 ohm headphone output): 90dB minimum, 98dB typical.
Dynamic Range (16 ohm headphone output): 90dB minimum, 98dB typical.
Power Consumption: 12mW maximum, 6.5mW typical.
Package: 16 pin TSSOP (0.5mm pin pitch)
This chip is currently my top choice for the TRAXMOD project. It's small, cheap, simple, and provides great audio that can directly drive headphones. It has a master mode for providing most of the I2S clock signals by itself, making it easy to interface this chip to slave mode SPI ports of cheap microcontrollers. The only downside to this chip that I can see is that it will not support higher sampling rates of 96KHz and 192KHz for future high definition audio standards. For standard audio CD sampling rates, this seems like the best chip available.
WM8759
Cost: $0.96 (100 qty)
Distributors: Mouser
Sample Rate / Resolution: 8KHz - 192KHz, 24 bit
Signal to Noise Ratio (48KHz, 3.3V): 95dB typical.
Total Harmonic Distortion (16 ohm headphone output): -72dB typical.
Power Consumption: ~52.8mW (? AVdd current at 3.3V operation is not specified in datasheet)
Package: 14 pin SOIC (0.05" pin pitch)
This chip provides access to 192KHz/24-bit audio in a low cost DAC with integrated headphone amplifier. It supports a wide operating voltage range from 2.7V to 5.5V, however, audio performance specs suffer as operating voltage is lowered. Power consumption of this DAC seems rather high. This DAC does not provide master mode capability, which may affect audio quality and/or complicate hardware design with low cost microcontrollers that lack native I2S features. This DAC does not provide digital volume control, instead the amplitude of the AVdd power level determines the volume level, which complicates its use considerably.
TLV320AIC23B
Cost: $4.05 (100 qty)
Sample Rate / Resolution: 8KHz to 96KHz, 24 bit
Signal to Noise Ratio (headphone output): 90dB minimum, 97dB typical.
Signal to Noise Ratio (line output): 90dB minimum, 100dB typical.
Dynamic Range (line output): 85dB minimum, 90dB typical.
Power Consumption: 23mW typical.
Package: 28 pin TSSOP (PW) or 28 pin QFN (RHD), both 0.5mm pin pitch
With 97dB SNR typical at the head phone output, this one might get close to the PCM1770 in sound quality. This chip supports master mode audio data transfers, so it should be easy to interface to a slave mode SPI port of low cost microcontrollers. It has some flexible clock options, allowing 96KHz and 44,118KHz playback from a 12MHz system clock input. Used with this 12MHz clock, it would not produce exactly 44.1KHz, but it is pretty close and no crystals would have to be physically swapped out to get to 48KHz or 96KHz sampling rates. Another feature is it includes crystal driver circuitry on chip, so you don't need an external U04 inverter for clock generation.
TLV320DAC23
Cost: $2.80 (100 qty)
Sample Rate / Resolution: 8KHz to 96KHz, 24 bit
Signal to Noise Ratio (headphone output): 90dB minimum, 97dB typical.
Signal to Noise Ratio (line output): 90dB minimum, 100dB typical.
Dynamic Range (line output): 85dB minimum, 90dB typical.
Power Consumption: 18mW typical.
Package: 28 pin TSSOP (PW) or 28 pin QFN (RHD), both 0.5mm pin pitch
Appears to be exactly the same chip as TLV320AIC23B, but with the analog to digital converter section cut off to produce a lower cost part.
TLV320AIC3106
Cost: $5.20 (100 qty)
Sample Rate / Resolution: 8KHz to 96KHz, 24 bit
Dynamic Range (16 ohm headphone output): 92dB typical.
Signal to Noise Ratio (16 ohm headphone output): 96dB typical.
Signal to Noise Ratio (line output): 90dB minimum, 102dB typical.
Dynamic Range (line output): 99dB typical.
Power Consumption: 14mW typical.
Package: 48 pin QFN (0.5mm pin pitch)
My eye was drawn to this chip because TI markets this chip as having a 102dB SNR DAC, but when you get down into the datasheet, you can see that the actual SNR specification for the headphone output is lower (96dB). The slightly higher power consumption, lower audio performance (on 16 ohm head phone output), dual voltage supply requirement, and higher cost of this chip makes it a lesser contender in my opinion. The only reason I can see to consider this chip over PCM1770 is the support for 96KHz sampling rates and the ADC feature (this is an audio CODEC chip, not just a DAC). It still won't support 192KHz, so this chip isn't future proof despite the 96KHz improvement.
