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PSoC™ 4

ToVa_285016
Contributor

Hi,

   

I have a motor controller that takes  a 0-10V input for control.  The DAC I usually use is an I2C 0-5V version.  Can I use the on board current DAC to create this 0-10V output?  Am I better off using a PSOC 5 with a VDAC and an op amp?

   

Can the setup on page 5 here create a 0-10V signal?

   

http://www.cypress.com/documentation/application-notes/an60305-using-psoc-3-and-psoc-5lp-idacs-build...

   

Thank you for your input,

   

Regards,

   

Tom

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8 Replies
ETRO_SSN583
Esteemed Contributor

The IDAC compilance range is maxed out with the Vdda

   

supply, so no to 10V. You could use an external OpAmp

   

to G up the slope of the onboard DAC, or just use an external

   

part that can handle the voltage range needed.

   

 

   

Regards, Dana.

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ToVa_285016
Contributor

Hi,

   

Thank you for the feedback.

   

Can I use the internal opamp, or is it also limited to Vdda?

   

Regards,

   

Tom

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ToVa_285016
Contributor

One other thing - with the 10,000 opamps out there, any recommendations on where to start for choosing one?

   

Regards,

   

Tom

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ETRO_SSN583
Esteemed Contributor

You could setup PSOC IDAC as source, feeding external mirror

   

to handle the voltage. In its collector use any value scaling R,

   

within leakage constraints, to gte the V you need. But problem

   

is it is un-buffered approach, regarding load effects.

   

 

   

Mirrors, I think a couple of semi manufacturers make them or

   

you buy matched transistors.

   

 

   

Regards, Dana.

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ETRO_SSN583
Esteemed Contributor

Internal OpAmp also constrained to Vdda.

   

 

   

10,000 opamps, you are right about that. The good old LM324 or

   

its variant will do for most applications. If trying to get to the rails

   

with its output then there are lots of R-R solutions, look carefully

   

at what load the OpAmp can tolerate to meet R-R.

   

 

   

Regards, Dana.

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ToVa_285016
Contributor

Thank you for the advice, I will try the LM324.
Regards,

   

Tom

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ETRO_SSN583
Esteemed Contributor

One source for a current mirror -

   

 

   

http://www.nxp.com/products/bipolar_transistors/general_purpose_bipolar_transistors/matched_pair_tra...

   

 

   

Regards, Dana.

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Anonymous
Not applicable

You can use this board, it has a 12bit DAC, Rail to rail amp and a boost converter to provide 10V.

https://store.ncd.io/product/1-channel-0-10v-dac-digital-analog-converter-i%C2%B2c/

This has i2c port, so you can interface it wilt any micro controller which has i2c.

PR46-15-MCP4725-I2CDAC_2.png