At 10:31 PM 5/27/97 +0200, you wrote:
>Antonio Almeida wrote:
>>
>> I am looking for some serial DAC with bipolar output ? Speed is not
>> important, but price is.
>>
>
>would be also interessted in a realy cheap
>DAC, 10 or 12 bit
>
>Thanks.
>St.
>
Antonio..

To achieve your goal of bipolar, I have a dirty trick you can try to get
around a 'special' DAC.  Use a unipolar device, and then add a sign amp on
the other end.  Take a 'good' IE. OP07 amp, set it up like a classic diff
amp with four resistors, tie the two incoming resistors together to the
signal, and replace the resistor that goes from the + pin to ground with an
open collector to ground instead.  It has been a while since I worked on
this circuit, and I only sketched it out on paper, but I think the premise
is sound.  For a descent DAC, try the Linear Tech LTC145X.  I used it's
predecessor, the LTC1257, with good results.  Try to avoid that MA**M
company, my experience is historically that they had horible delivery
times.  That may have changed, but old impressions die hard.  Don't forget
to use a good reference!

Chris Eddy, PE
Pioneer Microsystems, Inc.
Pittsburgh, PA