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Beginner
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VCCA and VCCD_PLL for Cyclone IVE

Hi,
I'm using Cyclone IVE device (EP4CE55F23). Here are my doubts:

(a) The VCCINT rail consumes 2.3A and VCCD_PLL rail consumes 42mA. I plan to supply both rails from a single power plane (without any ferrites) and limit the ac ripple to 15mV, giving a target impedance of about 13.25 milliohms. Is it okay to do so? What is the noise tolerance of VCCD_PLL rail?

(b) The VCCIO_2.5V rail consumes 125mA and VCCA rail consumes 47mA. I plan to supply both rails from a single power plane (without any ferrites) and limit the ac ripple to 15mV, giving a target impedance of about 123 milliohms. Is it okay to do so? What is the noise tolerance of VCCA rail?

(c) If I have to separate VCCIO_ 2.5V and VCCA, can I connect JTAG connector to VCCIO plane instead of VCCA plane?

Thanks.
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Moderator
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Re: VCCA and VCCD_PLL for Cyclone IVE

Hi Binayak Shrestha

Thanks for your inquiry. Allow me some time to look into the info you requested and get back to you.

 

Thanks. 

Eng Wei

 

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Moderator
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Re: VCCA and VCCD_PLL for Cyclone IVE

Hi Binayak Shrestha

Referring to pin connection guideline of doc below:

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/dp/cyclone-iv/pcg-01008.pdf

For question (a) and (b), referring to page 8, example 2 for Cyclone IV E:

"May be able to share VCCD_PLL with VCCINT with a proper isolation filter. With proper isolation filter, limit the VCCD_PLL power supply to ±3% maximum ripple voltage. Depending on the regulator capabilities this supply may be shared with multiple Cyclone IV devices. Use the Early Power Estimation (EPE) tool within Quartus II to assist in determining the power required for your specific design."

"If VCCIO requires 2.5 V, may be able to share VCCA with a common 2.5 V supply with a proper isolation filter. However, for any other VCCIO voltage you will require a 2.5 V regulator for VCCA. Use the EPE tool to assist in determining the power required for your specific design."

For question (c), we can refer to page2 of the same doc for jtag pin connection. 

Thanks.

Eng Wei

 

 

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Beginner
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Re: VCCA and VCCD_PLL for Cyclone IVE

Hi Eng Wei,

My main aim is to remove the isolation filters from VCCA and VCCD_PLL and still use the same power plane.

(a)  With VCCINT = 1.2V, the noise maximum noise ripple allowed on VCCD_PLL = 3% of VCCINT = 36mV. If I maintain a 10mV ( much less than 36mV) noise ripple across the power plane, can't I power both VCCINT and VCCD_PLL with the same power plane without using any isolation filter?

(b) Maximum allowed noise ripple on VCCA = 3% of 2.5V = 75mV. If I maintain a 10mV ( much less than 75mV) noise ripple across the power plane, can't I power both VCCIO_2.5V and VCCA with the same power plane without using any isolation filter?

(c) What I have understood is that both VCCA and JTAG power pins need 2.5V. It doesn't matter if they are powered from the same source or a different source.

 

Thanks,

Binayak 

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Moderator
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Re: VCCA and VCCD_PLL for Cyclone IVE

Hi Binayak 

Sorry for late response as I was getting around with more spec and discussion before getting back to you.

For 1st and 2nd question, the recommendation from the spec is always guaranteed by certain level of implementation validation and characterization for jitter performance. If we would like to have different implementation from the spec, due to design limitation, then we can utilize tools like Power Distribution Network (PDN) Design tools for analysis.

Unfortunately I couldn't find any better power isolation filters guideline for Cyclone family at the moment, but below doc can be use as reference (Stratix IV) for power isolation filter usage and analysis.

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/an/an583.pdf

 

For 3rd question regarding JTAG connection, yes, we can use any other 2.5V power supply as long it is supplying a stable 2.5V.

Here is the ref:

https://www.intel.com/content/altera-www/global/en_us/index/support/support-resources/knowledge-base...

 

Thanks.

Eng Wei

 

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Beginner
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Re: VCCA and VCCD_PLL for Cyclone IVE

Hello Eng Wei,

Thanks for clearing my doubts. However, the link to the appnote AN583 for isolation filter is dead. Has this appnote been removed?

 

Thanks and Regards,

Binayak

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