SV: Re: [sdiy] 16bit DC, DAC, SPI!

[karl dalen]

--- Eric Brombaugh <ebrombaugh at earthlink.net> skrev:

> ...And if I'd been reading the Subject: line more carefully I would have 
> realized that this wasn't what you wanted.
> 
> Sorry for the noise. I'll go stand in the corner now...
> 
> Eric

I found the mail:

The thing is im using a PCM56 and i suspect its going EOL.
Old as my grannie but net since its rellay fast and infact it was
cheap untill recently TI more then doubbled its price and that 
may be a a sign something is about to happend with the device. 

Anyhow does sigma delta ripple at DC by default/design?

KD
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Adam Schabtach wrote:
>> I've had great luck with the Cirrus/Crystal CS43XX series of 
>> I2S stereo DACs.
> 
> Have you tried using these to generate DC control voltages? The spec sheet
> implies that they work down to 0Hz, but I have it in my head that
> sigmal-delta DACs don't do DC.

I've used the CS4334 (5V, 8-pin SOIC) and CS4344 (3.3V 10-pin TSSOP) and 
they both work down to DC. Or close enough that I can't tell - I've used 
them for LFOs with periods ~30 seconds with no visible distortion or 
attenuation. Based on that I can't imagine that they wouldn't hold a 
voltage indefinitely.

The main problem with the CS4334 is that the voltage you get for data = 
0x0000 (Vq) is internally generated and isn't available on a pin, so if 
you want to DC couple it you need to guess at what to subtract out. It's 
not too big a deal though.

The CS4344 fixes this problem by providing Vq on a pin so you can use 
that as the 0 reference in a downstream buffer stage to get a true 
bipolar signal.

Eric
> 



	
	
		
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