Finding current from capacitance and voltage

AI Thread Summary
Input capacitance in the DAC datasheet pertains to the digital inputs and is not relevant for determining output current. The output current can be calculated using the external reference input voltage (VREF), which sets the full-scale output current. An integrated feedback resistor (RFB) and an external I-to-V precision amplifier are crucial for achieving accurate output. Application circuits in the datasheet provide guidance on connecting the I-to-V opamp circuit for proper functionality. Multiple channel DACs with current outputs ranging from 0 mA to several mA are available on the market.
taupune
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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
 
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taupune said:
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.
 
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.
 
taupune said:
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.
 
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