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current output DAC's

Hi,

I am hooking up a 12bit current output DAC (DAC7811)

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with a 0V to 5V output voltage range.

I am putting an opamp I to V converter on the output of this current output DAC.

The datasheet shows these two hookups:

  1. negative voltage output Vout = -Vref * Code/4096

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  1. positive voltage output

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I would like the positive voltage output but it requires a -2.5V reference. What would be the best way to hook this DAC up for a 0V to 5V output range?

If I use a a -5V reference instead of the -2.5V reference will this provide a 0V to 5V output range? Does the output opamp need a bipolar supply as well for this?

cheers, Jamie

Reply to
Jamie Morken
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It's a bit late so maybe I'm missing something, but why don't you just use a voltage output DAC?

Reply to
Dave

I took a look at the TI datasheet. It seems to me the -5V reference should do the trick. I don't know about that trick to make a positive reference into a negative reference. Obviously from an ideal op amp, the scheme works, but I wonder about stability.

Reply to
miso

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Most of the serial interface DAC's I've seen that have a fast enough settling time ie. 0.2us, seem to be current output.

cheers, Jamie

Reply to
Jamie Morken

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Perhaps because voltage output DACs are current DACs with an opamp buffering the output? Just a guess. The CCD I'm using has a current output too. I assumed it was for the same reason (the opamp would be superfluous).

--
Keith
Reply to
krw

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