Power Up Sequence Part Deux

Hi NathanT ,

Could you or your team help look into this query?

Thanks and regards,

Coco

Hi, RTWHIT04 .

In that section, it does pertain on how the trace on your board should happen. Here is a guide what does it mean:

Pin 2 should be supplied first or should be the nearest with the 2.5V source. But along on that line, succeeding pins of VDD2 should be connected in a single node or within the line of Pin 2. The gist, what it says is that all VDD 2 should be in a single line. And they should not be separated. 

On the other hand, when powering up the AD7626 device, first apply the 2.5 V VDD2 supply and VIO voltage to the device. After the VIO and 2.5 V VDD2 have been established, apply the 5 V VDD1 supply. If using an external reference with the AD7626, ensure that the EN0 and EN1 pins are connected to the correct logic values associated with the reference option of choice and then apply the external reference voltage. Finally, apply the analog inputs to the ADC

Regards,
Jo

Hey Nathan, thank you for confirming that the specification is intentional. I plan to use this component on a six layer board with a 2V5 power plane.

Do I need to take care to make sure that pin 2 is the closest to the power source even when using a power plane?

Hi, RTWHIT04 .

Yes. You are right. From its existing layout, that is how it was implemented. I think it is best way to follow that since it was already tested to be in its optimal performance.

Here is its User Guide you can use as a reference: EVAL-AD7625FMCZ/EVAL-AD7626FMCZ (Rev. A)

Regards,
Jo