ODP: A Few Simple Questions

[Roman Sowa]

> -----Oryginalna wiadomość-----
> Od:	inman at interpath.com [SMTP:inman at interpath.com]
> Wysłano:	9 marca 1999 16:48
> Do:	synth-diy at mailhost.bpa.nl
> Temat:	A Few Simple Questions
> 
> Would someone please define these terms / answer these questions?
> 
> Rail to Rail
	[Roman Sowa]  
	there is input rail to rail and output rail to rail, and, of course,
there are
	opamps which do both. It means that signal (input or output) can be
anywhere between power supply *rails* of such opamp. Sometimes input rail to
rail exceedes power supply range by about 0.5V. Output rail to rail
	can be as close as few tens of mV apart from power supply, but only
for
	not so big currents. 
	You can not get all-in-one, I mean good behaving opamp and
rail-to-rail.
	There is always a compromise for speed, accuracy or distortion. And
most of them seem to be only 5V devices

> What does it mean to say an AD/DA converter is 2 or 4 or 8 channels?
> Are these inputs summed in the output or sent in parallel?
	[Roman Sowa]  
	Means it has 2,4 or 8 inputs/outputs. Multichannel ADCs usualy have
	mux and single ADC, while DACs are mostly really multi DACs in
	single package accessed as a memory (address and data) or serially.
	As for codecs, they can mix few inputs and then convert with single
ADC

> Is there a simple 8-bit DAC with parallel in?  Is there an 8-bit DAC
> for dummies?  
	[Roman Sowa]  
	Yes, there are a few. Mostly obsolete ones. Very old and nice DAC08,
	and few others which names can't recall. You can make a good DAC
	yourself - it may suffer small linearity problems, but will be very
fast.
	HC241 (for example) as a buffer and R-2R resistor ladder. Worked
fine
	for me many times.
	And search Analog Devices or Texas Instruments websites.