audio/videoZONE Products for the week of November 15, 2004
Texas Instruments Says . . .
PCM4202/04: High-Performance 2-/4-Channel Professional/Broadcast
audio ADCs
Texas Instruments Incorporated introduced a pair of high-performance, 24-bit audio analog-to-digital converters (ADCs) designed for professional and broadcast audio applications. The PCM4202 (2-channel) and PCM4204 (4-channel) feature 118dB dynamic range, -105dB total harmonic distortion and up to 216kHz sampling rate.
"The PCM4204 combines superior performance and integration with the lowest power consumption of any high-performance audio ADCs on the market," said Mike Centorino, marketing manager for TI's Burr-Brown Pro Audio products. The low power consumption (150mW per channel) helps reduce the overall power budget required for the analog-to-digital conversion subsystem, which is ideal for high channel count systems.
The devices target a wide variety of high-performance audio applications, such as digital mixing consoles, digital effects processors, multi-track recorders, broadcast studio equipment, surround sound encoders, audio test equipment and high-end A/V receivers. The PCM4202 and PCM4204 are ideally suited for use with TI´s complementary professional audio devices, such as the PGA2500 digitally controlled microphone/ADC preamplifier and TMS320C6713TM Audio Digital Signal Processor (DSP).
The PCM4202 and PCM4204 architecture utilizes a delta-sigma ADC per channel
incorporating a novel density modulated dither topology for improved dynamic
performance. Both devices support 24-bit linear PCM output data, with sampling
frequencies up to 216kHz, and can be configured to output either 64x or
128x oversampled, 1-bit direct stream digital (DSD) data for each channel.
The DSD input mode allows 1-bit DSD to 24-bit PCM data format conversion
by utilizing the internal digital decimation filter.
analogZONE Says...
The professional audio group at TI's Burr-Brown is very proud of its products, and rightly so. Here, particularly with the 4-channel PCM4204, they have done themselves proud yet again. This is the first 4-channel part that I have seen with numbers even approaching those here. The two-channel part may be compared to the raw numbers of AKM's AKM5394A, but there are many added features in TI's offering, and one is that the AKM doesn't have the TDM output option, which is a really slick way to think; there aren't going to be many applications where your digital output wouldn't go straight into a processor.
The PCM4204 has a 1-bit delta-sigma in each channel and TI claims a "novel density modulated dither system for improved dynamic performance." One presumes this is some kind of clock dithering system but hey, whatever, the numbers are way up in that "how do you measure these" stratosphere: dynamic range 118 dB, THD -105 dB on a 24-bit PCM output, slightly lower on a 1-bit DSD output. But what screamed out of the data sheet at me was the incredibly low power consumption, 615 mW typical at 192 kHz sampling frequency, the sort of number I would say was very good in a 2-channel part!
The filter characteristics are incredibly good and you can see the design signature that was used in the ADS1271 at work again.
24-bit support is up to 216 kHz sampling on the PCM output and 64 Fs and 128 Fs on the DSD output, with DSD inputs also allowed for. The PCM output, as well as providing the TDM option, can be left and right justified and I2S. The analog rail needs to be between +4.75 V and +5.25 V, and the digital rail can be between +3.0 V and +3.6 V to be compatible with 3.3-V logic families. There is a power-down mode where the quiescent drops to a maximum of 10 mA on the analog side and 2 mA on the digital.
The full-scale differential input is typically 6.0 Vp-p with a 3 kilohm average input impedance (that might challenge the average designer, but not the guys in the fields where these parts are going into) with a typical CMRR of 85 dB. I didn't see a PSRR quoted.
I know the team in Tucson is going to take any criticism of this part very personally but I have to say that I am surprised that they didn't provide a separate reference for each channel. There are two references on-chip (with common-mode output voltage as well as providing voltages for the modulators) one for each pair of channels, which is a no brainer.
These parts will find homes in broadcast and high-end studio equipment, in the recorders, desks and the encoders for multi-channel processing like surround sound. And the team at TI can carry their heads high, yet again. These parts are also very reasonably priced.
The PCM4202 and PCM4204 are both in production with the former in a SSOP-28 priced at $7.95 in 1000-piece lots, and the latter in a thermally-ehanced TQFP-64 priced at $14.95, also in 1000-piece lots. Evaluation modules are available.