How to connect i/o DC supply voltage?

[aifi]

connect power to i/o pad

hi...

how to connect i/o DC supply voltage?

how to supply two difference voltage since we need a lower voltage to core compare to i/o pad.?

thanks

 

[jcchan]

Re: connect power to i/o pad

There must have two power pad, one is high voltage and another is low voltage power pad. The IO ring power is connected to high voltage power pad and core power is connected to low voltage power pad. A power cut cell must be placed between high voltage power ring and low power ring for ESD protect.

 

[aifi]

Re: connect power to i/o pad

what is cut cell? could u give me an example...

 

[leeenghan]

Re: connect power to i/o pad

Hi,

The pad library will have "pad-power pad", "pad-ground pad", "core-power pad" and "core-ground pad". Likely to have also "pad+core -ground pad" (i.e. the core ground and pad ground are shorted). There will also be other varitiy of power pad. For example, beside classify the power into pad-power and core power, there is also pre-driver power, ESD potection power, output-driving power.

I suggest you study the pad datasheet to see how many type of power pad are provided.

Cut cell (or diode-cut cell) is used when you have more than one pad power (for example, you have 3.3V pad power and 2.5V pad power in the same die. It is also okay just to leave a gap instead of using Cut cell. Cut cell become important when you have analog pad. Analog pad has weak ESD protection, so sometime it is connected to the digital pad with a cut cell.


Regards,
Eng Han
www.eda-utilities.com