Programmed current source

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Anonymous
Not applicable

What is a good way to implement a programmed (firmware modulated) current source (<50 mA) using PSoC 5 with no or minimum external parts?

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Bob_Marlowe
Level 10
Level 10
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There is an IDAC component which is a Digital-toAnalog-Converter delivering a programmed current (not a voltage). Have a look at the IDAC datasheet to see, if it suits your needs.

   

 

   

Bob

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Bob_Marlowe
Level 10
Level 10
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There is an IDAC component which is a Digital-toAnalog-Converter delivering a programmed current (not a voltage). Have a look at the IDAC datasheet to see, if it suits your needs.

   

 

   

Bob

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Anonymous
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According to the CY8C55 Family Data Sheet the built-in IDAC has a widest range of 0-2.04mA.  So, the question remains.

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Anonymous
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Hi MichaelSu,

   

 

   

It is possible to use 4 available current sources in parallel to obtain higher current (4 times 2.04mA). However, this will still not meet your requirement of 50mA.

   

Is there any specific application which requires a current source of range close to 50mA?

   

 

   

You can build a current source using internal components available in PSOC along with external (active / passive) components. The sourcing and sinking ability of the PSoC GPIOs are 4mA and 8mA respectively. And that of SIOs are 4mA and 25mA respectively. Care should be taken that these max ratings is not exceeded.

Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

...and I am still convinced that 2mA < 50mA. (broad smile)

   

You will have to use external components as FETs to accomplish your needs.

   

 

   

Bob

Anonymous
Not applicable

Thank you all, 

   

Seems that the best idea is to add an external voltage-controlled current source.

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HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

You might want to look at Dave Jones' µSupply video series (http://www.eevblog.com/projects/usupply/ ) where he talks about the design of a digitally programmable PSU using the LT3080. It might be a little bit of overkill (the LT3080 can deliver up to 1 amp), but might still be helpful to see how to design a current source.