PCB with no DDR. What to do with the different DDR pins?

[ninjanymo]

UG933 explains that VCCO_DDR should be tied to VCC_PAUX, while PS_DDR_VREF0/1 and PS_DDR_VRN/P should be left floating, which is fine.

Further, UG933 describes what to do with unused I/O pins in Table 5-5:

However, it seems as if Table 5-5 describes what to do with unused DDR I/O if some of them are used. In my use-case, none of them are used and that get's me confused when there are different guidelines for no-ECC and ECC.

So just to make sure:

Can I leave all DDR pins floating while enabling internal pull-ups on the pins described as I/O by Table 5-4 in UF933?

[gnarahar · Accepted solution]

@ninjanymo 

---

Can I leave all DDR pins floating 

---

Yes, if you are not using the PS DDR, leave the pins unconnected except for VCCO_DDR which is tied to VCCPAUX as mentioned in UG933 v1.13

[ninjanymo]

Great, thanks.

[ninjanymo]

I realized that I asked this in the wrong board (UltraScale architecture).

I am working with the Zynq-7000. Is it safe to assume that your answer still stands for that architecture?

[gnarahar]

@ninjanymo Yes, it still stands since the discussion was around UG933 which is the PCB design guide for Zynq-7000 device :) 

[rlindner3]

My application is an Ultrascale, specifically an XCZU3EG-SFVC784 and will not be using any DDR.

But VCCO_PSDDR is constrained to 1.5V where VCCAUX or VCC_PSAUX are 1.8V.

I am guessing these would not want to be connected. 

So, I need to know what to do with VCCO_PSDDR, VCC_PSDDR_PLL and VCC_PSINTFP_DDR to use the least possible quiescent power.

Thanks - Robert L

[gnarahar]

@rlindner3  This is an already closed thread and generally it is good to post your query in a new thread to gain traction and not get missed in the community. 

---

So, I need to know what to do with VCCO_PSDDR, VCC_PSDDR_PLL and VCC_PSINTFP_DDR to use the least possible quiescent power.

---

You can tie these pins to GND if DDR is not used. Please use XTP427 Schematic checklist and UG583 during your schematic and PCB design 

[rlindner3]

Thanks.

FMI - How can I tell whether a thread is closed.

[gnarahar]

@rlindner3 

---

FMI - How can I tell whether a thread is closed.

---

If the thread has an Accepted Solution. New posts made on these threads tend to get missed since the community sees the thread has a solution and may not look into it.