finding current from capacitance ... and voltage

[taupune]

Hi,
I have been looking for some current source DAC, and have found a few types but I am having issue reading the datasheet.
Some of them give the output min and mac I that the DAC can provide, which makes sense to me but other give input capacitance and "some type" of voltage.


Can you have a look at this datasheet please:
http://www.analog.com/static/imported-files/data_sheets/AD5428_5440_5447.pdf

the specs for output are on the 3 page.

First question would be: Why do I need the input capacitance when I am interested for the output current.
How can I find this current when I am given only voltage and the chip is said to be a current source?

Are there any multiple channel DAC with 0 mA to several mA available on the market?

Thank you in advance
Tau

[berkeman]

Hi,
I have been looking for some current source DAC, and have found a few types but I am having issue reading the datasheet.
Some of them give the output min and mac I that the DAC can provide, which makes sense to me but other give input capacitance and "some type" of voltage.


Can you have a look at this datasheet please:
http://www.analog.com/static/imported-files/data_sheets/AD5428_5440_5447.pdf

the specs for output are on the 3 page.

First question would be: Why do I need the input capacitance when I am interested for the output current.
How can I find this current when I am given only voltage and the chip is said to be a current source?

Are there any multiple channel DAC with 0 mA to several mA available on the market?

Thank you in advance
Tau

The "input capacitance" specs are for the chip's digital inputs. Irrelevant for your analog output considerations.

[taupune]

Thanks for the reply.
so how can I find the output current when only the output voltage is given, knowing that the DAC is a current source.

[berkeman]

Thanks for the reply.
so how can I find the output current when only the output voltage is given, knowing that the DAC is a current source.

From the first page of the datasheet:

The applied external reference input voltage (VREF) determines the full-scale output current. An integrated feedback resistor (RFB) provides temperature tracking and full-scale voltage output when combined with an external I-to-V precision amplifier.

Look at the application circuits near the end of the datasheet to see how they are connecting the I-to-V opamp circuit.