Dac-vref connected to ground?

[span]

Hi


I am using DAC7800(12 bit),i connected vref to ground and operating voltage of DAC is 5v.whether it is correct?
If it is correct means what will be analog voltage,if all bits are set to 1.

 

[Embedded Partner]

no................
connect Vref Vdd to +5V
and ground pin to ground

 

[span]

Hi

can you explain importance of vref in DAC
any formula ....can you explain with example.....
thanks you much

 

[Embedded Partner]

Hi

can you explain importance of vref in DAC
any formula ....can you explain with example.....
thanks you much

input digital data is refered with Vref

and compares and then convert it in to analog

for more information search in wikipedia

i hope it may help u...........

 

[alexan_e]

when the input will have the same voltage as the vref value the output will be all 1s (this depends on the adc and if it supports negative values).
In general for a 10 bit adc you have 1023 different values so each step will be vref/1023

for example if vref=5v then 5/1023=0.0049v
so if the input is 0.0049v the output will be 0000000001
if the input is 0.0098v the output will be 0000000010
if the input is 2.5v the output will be 1000000000
if the input is 5v the output will be 1111111111

Alex

 

[span]

Hi

I am using DAC7800(12 bit),i connected vref to -5v and operating voltage of DAC is 5v.I want to know what is the formula to calculate the voltage.....
whether output voltage will be in positive or in negative......
can anyone tell me

 

[alexan_e]

In my previous email i was actually talking about a ADC converter.

In the DAC converts the digital input in converted to a current and then its up to the external opamp circuit to convert this current to a voltage.

Page 9 and 10 of the datasheet has two output circuit, unipolar and bipolar and for each one the input/output table.
In these tables there is a -Vref and Vref, I'm not sure but i assume that if your Vref pin is connected to -5v then in these tables
-Vref = -(-5v) which is 5v
and Vref= -5v

Alex