Forum Discussion
ContributorCyclone IV drop in replacement confirmations
Dear Altera,
If the BANK VCCIO is 1.8V and the same package but with different LE # FPGA is drop in replace.
Where the original pin is a VCCA while different LE size same pin is a IO.
With 1.8V on VCCIO and input fixed to VCCA aka 2.5V do this introduce any issue?
As we can see the datasheet mentioned the DC input accept 3.6 or below.
-> Table 1–4. Recommended Operating Conditions for Cyclone IV GX Devices (Part 2 of 2)
So the C4 device have a protection forward diode to clamp the voltage when IO is set to input?
As long as that pin is fixed to input state do this condition function properly?
Thanks,
Brian
11 Replies
FvMSuper Contributor
Hi Brian,
reading Cyclone IV datasheet strictly, Table 1-15 has also to be observed. It specifies Vinh,max of 2.25 V for 1.8 V banks. Don't no why and how the spec is related to general 3.6 Vin,max in table 1-3 and 1-4. According to device handbook, PCI diode isn't used vor 1.8 V and below I/O standards.
Regards Frank
BrianSune_FroumFvM
Well if you read from top to bottom:
The table for output uses VCCIO and input Max=3.6V ~ha!
If your statement holds, then the output should be a fixed number as well for generalized numbers.
My question is not about GPIO use cases, you might argue but ticket is about drop in replacement not standard signal goes high / low with current-limited driver.
I will prefer Altera staffs to handle my ticket.
Thank you- FvM
Hi Brian,
I apologize for not reading your question thoroughly. I didn't realize that you asked about feeding 2.5 VCCA supply to a 1.8 V GPIO due to migration compatible pin assignment. That should always work. To be sure, you can check the respective assignment in Quartus pinout table.
I checked that Quartus indicates connection of VCCA4 (PIN_L12) to 2.5 V for EP4CE10F17 if you select migration compatibility to CE22, no matter that's in a 1.8 V bank.
Regards Frank
- BrianSune_Froum
Interesting~
AqidAyman_AlteraRegular Contributor
Hi Brian,
Can you provide the OPN for both of the devices that you refer here?
Regards,
Aqid
- BrianSune_Froum
The question is not related to any specific Cyclone IV devices:
The question is about when VCCIO is driven from 1.8V or any voltage under the VCCA, do the input pins are allow to feed in 2.5V or 3.3V as datasheet marked with <3.6V on inputs?
When this question is answered there is no issue on the remains drop-in compatibilities.
Thanks,
Brian
- AqidAyman_Altera
Hi Brian,
These two devices should not be treated as drop-in replacements in this board condition. Cyclone IV supports vertical migration within the same package, but the migration devices must have compatible dedicated input pins, configuration pins, and power pins.
You can select migration devices in Quartus and check the Pin Migration view for pins whose functions change. The Fitter uses the selected migration-device list to restrict the design to compatible pins; pins that are power pins on one device should not be treated as usable user I/O across the migration path.
Reference: Device Migration Planning, AN 592: Cyclone IV Design Guidelines.
Maybe just for your information, I saw an old documentation, Quartus® II Handbook mentioning below statement:
Regards,
Aqid
