Hello all,
I want to build a DAC based on PCM1792 and I need to reduce by hardware Iout response from DAC, modifying Iref.
Accordingly with data sheet, a 10k resistor is used to obtain a DAC Iout response between -2.3mA to -10.1mA (7.8mAp-p), with center point at -6.2mA.
What happening if I use 20K Iref resistor? The center current (digital 0) point will be translated up at -3.1mA with Iout response between -1.15 to -5.05mA (3.9mAp-p)?
In other words, is possible to manipulate Iref for analog out attenuation?
Thank you
I want to build a DAC based on PCM1792 and I need to reduce by hardware Iout response from DAC, modifying Iref.
Accordingly with data sheet, a 10k resistor is used to obtain a DAC Iout response between -2.3mA to -10.1mA (7.8mAp-p), with center point at -6.2mA.
What happening if I use 20K Iref resistor? The center current (digital 0) point will be translated up at -3.1mA with Iout response between -1.15 to -5.05mA (3.9mAp-p)?
In other words, is possible to manipulate Iref for analog out attenuation?
Thank you
I think the guys at TI figured out that 10k was the value to use to get the best specs, so I think you'll be better of by changing the volume in or after the I/V section.
I don't want to make volume control over Iref. All I want is to reduce with 6dB Iout. At that level, the I/V converter has the best THD and dynamic range.
What I/V stage do you intend on using?
Can't you just change a resistor value? It is easier to get better snr with higher currents...
Can't you just change a resistor value? It is easier to get better snr with higher currents...
cviller said:
Yes, better SNR with higher current CAPABILITYS from I/V stage but with smaller imput currents.
The I/V stage is proprietary and can not be published 😡
Do you have a board with the iv section already? You could use pcm1798, which is basically the same chip as they (www.audiokit.ro) use together with the IV you posted. If you want to get the better specs from 1794 you'll need to use their recommended values.
Otherwise you might be able to change dynamic range with the value of R1... (just a guess - you could try with a simulator to see what you have to change to lower the gain. )
Otherwise you might be able to change dynamic range with the value of R1... (just a guess - you could try with a simulator to see what you have to change to lower the gain. )
There is a spice model for PCM1792/4?
I have the Rockna RD2 DAC and I will copy their I/V stage in my DAC based on SRC4392 and PCM1792
I have the Rockna RD2 DAC and I will copy their I/V stage in my DAC based on SRC4392 and PCM1792
I was thinking you could use a current generator and feed it into the a simulated I/V stage. Then you might be able to guess how to change some values to match the larger current.
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