[sdiy] AD/DA schematics? quantizers,etc

Jerry Gray-Eskue jerryge at cableone.net
Thu May 14 06:17:06 CEST 2009


In the data sheet you will find a section:

Absolute Maximum Ratings

Supply Voltage (VCC) (Note 3) 6.5V
Voltage at Any Pin ?0.3V to (VCC
+0.3V)
Except Control Inputs
Voltage at Control Inputs ?0.3V to +15V
(START, OE, CLOCK, ALE, ADD A, ADD B, ADD C)


Range of VCC 4.5 VDC to 6.0 VDC

vref+ should be 5v or less but above 0v, Vref- should be 0v or more but less
than 5v.

If you Scale your 10v input to 5 volts you are good with a 5v vref+
Digital conversions use Scaling both IN and OUT to set the voltage levels to
and from whatever voltage is needed.

The Converters ( and all other Electronic Devices ) must operate within
their Absolute Maximum Ratings, within their Safe Operating Area, or they
will Fail sooner or later depending on how badly they are abused.



-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Dan Snazelle
Sent: Wednesday, May 13, 2009 10:39 PM
To: sdiy
Subject: RE: [sdiy] AD/DA schematics? quantizers,etc



ok



i feel like a fool

in all my reading and testing today i had somehow missed the fact that
on an ADCchip, the vref cant go below grnd (or not much below)



so i am confused. usually when i see a - sign i think of putting the
negative rail. but in this case it seems you pick a top voltage and a
you pick a bottom but that has to be within 0-vref



is this correct? and the vcc is always 5volts?



how high can the vref be?



a few people have mentioned that for cv, i want a 10v vref.



would a high vref be useful for audio as well? or a lower vref useful even?



thanks

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