Help! PCM1792 issue.

Luke Lu

Intellectual 815 points

Other Parts Discussed in Thread: PCM1792, DSD1792, PCM1792A, DSD1792A

HI , can anyone shed some light please:

Our customer developed a Portable audio player ,using PCM1792. and there are still some confusions.

[1] what's the difference between PCM1792 and DSD1792 ?

Dose PCM1792 support DSD64，DSD128,DSD256 ? if not ,which DAC product of TI can support ?

[2] When testing Idle Channel Noise , the results are quite different under test condition: ( 22Hz，22KHz，A-weighted ) and (22Hz，20KHz AES17).

And Under 22Hz，20KHz AES17 test condition, the Idle channel noise of TI's PCM1792 EVM is -111dB, while customer's device is only -108dB.

[3] When testing THD+N, only a few devices can reach 0.0004%, while most devices only 0.001%.

The testing signal is 1KHz , 24Bit , 0dBfs，44.1KHz sample rate Sine Wave.

FFT-LCH:

FFT-RCH:

signal:

THD+N:

Idle channel nosie under 22Hz-22KHz-A

Idle channel nosie under 22Hz-20KHz AES17

over 8 years ago

0 Don Dapkus over 8 years ago

TI__Guru**** 189399 points

Hi, Luke,

It seems both these devices are NRND. I assume the customer is actually using the "A" versions, right?

In order to achieve the rated performance, you need to have a really good PCB layout and external components. I suggest that you try to copy the EVM as closely as possible to get the same level of performance.

-d2

0 Luke Lu over 8 years ago in reply to Don Dapkus

TI__Intellectual 815 points

Hi , Don,
That is very kind of you! Thanks! As you say, Our customer is using the "A" versions.
I still wonder Why the price of PCM1792A (7.08 | 1ku) is so much cheaper than DSD1792A(13.32 | 1ku).
Does the PCM1792A support DSD128 or DSD256?

0 Justin Bohr over 8 years ago in reply to Luke Lu

TI__Mastermind 27850 points

Hi Luke,

Yes the PCM1792A can operate in DSD64, while the system clock can go to 11.2896 MHz, the sampling rate is guaranteed to be able to operate at 2.8224 MHz.

Justin

Audio

Audio forum

Help! PCM1792 issue.