Re: trying to understand the REF pin on a DAC

On Mon, 29 Oct 2007 17:53:10 -0000, kasterborus@xxxxxxxxx wrote:

Wow thanks - that makes sense...

I was reading the data*** for the chip and I have a question...
http://focus.ti.com/lit/ds/symlink/tlv5618a.pdf

At one point it says that the maximum ref voltage is Vdd + 0.3, then
later is says the maximum recommended Vref is Vdd-1.5.
Would it be OK just to tie this pin to the 5v I'm using to power the
chip?

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No.
---

I want the output to be 0-5v.

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Look at the top of page 11 of the data *** and you'll see:

"The output voltage (full scale determined by the reference) is
given by:

CODE
2 REF ------ [V]"
2^n

which means that if your code is hex fff and 2^n = 4096, (which it
does since it's a 12 bitDAC) then with a reference voltage of 2.5V
your output will go from zero volts with an input of 0x000 to 5V
with an input of 0xfff.


--
JF
.