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PSoC 5, 3 & 1

BaDr_2102091
New Contributor

Hi,

I'm using the CY8C5868AXI-LP035.

I routed pin 9 (p6[7]) to analog input of power monitor (I know it is not recommended analog input, but I didnt have place).

Once I start the power monitor I measure with scope outside the device (on pin 9) the desired signal but the psoc also add a 300Hz "noise". It doesn't matter If I change any configuration of the power monitor, the problem remains.

If I don't start the power monitor, or start the power monitor but dont assign pin 9 everything ok.

Can you pls advise how can the device create a 300Hz interference?

BR,

Barak

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BaDr_2102091
New Contributor

I also see it on recommended pin for analog input.

During compilation when jtag is connected (before programming), problem disappeared. Then coming back after programming.

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Vasanth
Moderator
Moderator

Hi Barak,

Could you please be elaborate on the observation with JTAG connected. Could you please let me know more about the project and the configurations you have used? Will you able to share the project for us to have a look. In PSoC Creator ,  go to File -> Create Workspace Bundle -> Select minimal. Please attach the generated file. Meanwhile sharing hardware design guideline for reference.

Best Regards,
Vasanth

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BaDr_2102091
New Contributor

Hi,

I found similar issue in the forum:

https://community.cypress.com/thread/20584?start=0&tstart=0

I added opamp on input and it seems to work

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BaDr_2102091
New Contributor

The problem now, is that although i Don't see the 300Hz, which is good (I measure With scope) , the read from power monitor is not what I measure on scope.

Assuming i defined the opamp as follower &low power, should i i expect any gain ?

I connected for testing purpose the input of the opamp and the output of the opamp to the power monitor and i get different reads (it looks as if the opamp has a gain of 2).

With measuring only the opamp output it seems a gain of~8

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Vasanth
Moderator
Moderator

Hello Barak,

Does the input scaling factor same across these channels you have tested? How are you providing input to the power monitor ? Are they attenuated ?

Best Regards,
Vasanth

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BaDr_2102091
New Contributor

All scaling factors are 1. The input is not attenuated.

As I said I drive both the input and output of the opamp to the power monitor and get different voltage readings.

How can it be that input  & output of the opamp measure different values? (opamp in follower mode).

Any way, both of the opams  input and output measurements doesn't fit to what i measure on the external pin with scope.

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Vasanth
Moderator
Moderator

Hi Barak,

That seems to be an odd behavior. What is your opamp configuration? In the main loop did you just call Opamp_Start() ? You can eliminate any issues related to source also by providing an alternate tested input to the Opamp.

Best Regards,
Vasanth

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BaDr_2102091
New Contributor

Yes, I just used the opamp_start().

How do you recommend to proceed? (Which component can test internally the opamp))

BR,

Barak

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Vasanth
Moderator
Moderator

Hi Barak,

Additionally did you use the dedicated OPAMP output pin to tap the voltage ? In PSoC5 device those pins will be P0[0], P0[1], P3[6] and P3[7]. If any other pin is used for this purpose the routing resistance will come into picture.

If those are met, Could you try Isolating the issue as I suggested before ?

1) At source, give a known stable source and confirm whether the behavior is consistent.

2) Isolate only the opamp part and see whether OPAMP is giving proper output

3) If these are not met we can look into the Power Monitor component.

Best Regards,
Vasanth

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BaDr_2102091
New Contributor

Hi,

Did you mean to use vref as input to the op amp?

With a vref it doesnt work good also.

I have 22 supplies measured ok in the power mo itor, but this 23 input cant cant properly

Is there an option to speak over phone?

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Vasanth
Moderator
Moderator

Hi Barak,

Somehow I missed the previous response. As I asked,  is the Opamp output tapped on the dedicated pin? To understand the issue we may need to see the design.

Best Regards,
Vasanth

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BaDr_2102091
New Contributor

The opamp output is connected to the power monitor, it is all internally.

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BaDr_2102091
New Contributor

Can we speak over phone?

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BaDr_2102091
New Contributor

any answer?

Can we speak?

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