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PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

 hi developers,

   

 can you suggest me any application note which explains how to configure a switched capacitor block as an analog integrator. my prime need is that once started,this integrator should operate concurrently with other modules. it should not use CPU.

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JoMe_264151
Expert II

When you type the word "integrtator" just into the search-field located at the top of this page you will get a lot of application-notes offered. My favorit on is http://www.cypress.com/?rID=2630 because it gave me some insight in these "switched" thing I did not understand at first, although it shows just the other way round: using an integrator as an op-amp.

   

 

   

Bob

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11 Replies
JoMe_264151
Expert II

When you type the word "integrtator" just into the search-field located at the top of this page you will get a lot of application-notes offered. My favorit on is http://www.cypress.com/?rID=2630 because it gave me some insight in these "switched" thing I did not understand at first, although it shows just the other way round: using an integrator as an op-amp.

   

 

   

Bob

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Anonymous
Not applicable

 bob,

   

            i read that app note already. as you said it is the other way around. it does not give a working example with parameter settings. moreover it says that a switched capacitor is by default an integrator. how can that be. can you please provide a basic working integrator example with parameter setting.(only a list of parameter settings) so that i can tweak various parameters and try to understand the SC block  better? 

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JoMe_264151
Expert II

Did you have a look at AN 2041 (to be found here http://www.cypress.com/?docID=29017 ?)

   
   

 

   
   

Bob

Anonymous
Not applicable

 bob,

   

      i have gone through the basics of switched capacitor blocks too. the app note just gives the theory. i am actually trying out the sc block as an integrator with some arbitrary settings based on what i understood from the app note and am tweaking each of the parameters keeping others constants but i am still far from interpreting the results. can you please provide me with the list of SC block parameter settings with which i can generate a ramp signal from its o/p going straight to saturation. 

   

for your information these are the settings i have made and i am giving a dc input in port_2_1. when the DC input is near zero or equal to zero i am getting a fast saturation towards 5v. when it is kept near 5 V dc the output is a single pulse of amplitude 2.5v and lasting 100us. the clock i have chosen is VC1 which is 24Mhz/16.

   

the input i have chosen is(i.e. ACmux ) port_2_1

   

and the scond input (Bmux i).e. port_2_3 is grounded externally.

   

FSW1 is on

   

FSW0 is off

   

Power is set to high

   

AREFMUX set to AGND

   

Ccap set to 31

   

autozero is on

   

analogoutbus_0 is chosen and the output is taken at port0_3

   

Bcap value is set to zero

   

Acap value is set to 31

   

Asign is negative

   

clockphase is normal

   

Fcap is 16

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JoMe_264151
Expert II

At first sight...

   

Have a look at the datasheet for the SCBLOCK, it states that the input clock maximum should be 2mHz. considering that the SC-inputclock is divided by the module by 4, the applied clock should not be higher than 8MHz.

   

 

   

Bob

JoMe_264151
Expert II

And here is (a rather old) AN http://www.khalus.com.ua/psoc/pdf/appnotes/an2115.pdf using an integrator. Do not get confused about the pictures of PSoC Designer, I suppose it is a pre-4 version. The math is rather simple and is mostly controlled by the input-frequency.

   

 

   

Bob

Anonymous
Not applicable

 hi bob,

   

           thanks a lot for that application note. that was just what i wanted. hope you can help me out with some more clarifications. the settings given in the app note is generating a ramp. but i could not control the starting level of it .it starts somewhere around 1.5 v and rises to saturation. moreover the level at the Bmux input is not affecting the output level at all. can you correlate the pins of this SC block with a standard op amp integrator pins for me. specifically i need .

   

which is the reference pin (the non inverting input of op amp in an integrator)

   

which is the signal input pin

   

what is the formula for gain( -Vin*time/RC) in standard op amp but here?

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Anonymous
Not applicable

 thanks bob once again, i understood the SC block further i will upload the wave forms soon

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Anonymous
Not applicable

 This is for u bob.

   

hope you will enjoy the beautiful waveforms i have generated using two SCblocks.

   

see the attachment 

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JoMe_264151
Expert II

Thank you, Prasanna, I've got a lot of different things as a "thanx", but no waveforms before.

   

 

   

Happy waving

   

Bob

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Anonymous
Not applicable

Quick settings for integrator and various other applications using SCBLOCK generic user module are given in Appendix G of application note AN2041. Here is the link-

   

http://www.cypress.com/?rID=2899 

   

 

   

-Rajiv Badiger

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