PCM1795 accepting higher rates than it's spec.

[stevo]

The DAC in my amplifier (Denon PMA-1600NE) is based around the Texas Instruments PCM1795 chip that is a 32bit/192kHz DAC capable according to Texas Instruments spec sheet. So how is it that it accepts 32bit/384kHz signals? It is also listed as being able to accept DSD at 2.6MHz, yet in this amplifier it accepts DSD at up to 11.sMHz.

 

So firstly how is this possible given the chips spec, and what is the point? What am I missing here?

[mansr]

The PCM1795 supports higher input rates with filter bypass and DSD up to 11.29 MHz (DSD256), all according to the datasheet. I'll admit, it's not the clearest datasheet I've seen.

[stevo]

Really? I can see the clock frequency goes very high, (Both PCM to 768kHz and DSD to 11.2MHz) but not the sampling frequency?

 

[mansr]

30 minutes ago, stevo said:

Really? I can see the clock frequency goes very high, (Both PCM to 768kHz and DSD to 11.2MHz) but not the sampling frequency?

You need to look at sections 8.2.2 Application for External Digital Filter Interface and 8.2.3 Application for DSD Format (DSD Mode) Interface. The system clock frequency doesn't need to be a high multiple of the sample rate in these modes. In external filter mode, the system clock is only 4x or 8x the sample rate. In DSD mode the bit clock is the system clock, which is possible since no digital processing takes place.

[stevo]

OK got it, thanks.