Hello, my name is Ume Onigiri.
We are going to build a digital clock using Altera's Cyclone® IV E in a fabrication exercise.
First of all, we need to figure out what kind of voltage should be supplied to the device.
We found that the Cyclone IV E has several power supplies: VCCINT, VCCIO, VCCA, and VCCD_PLL.
In this article, we will study the roles of these four power supplies.
VCCINT
VCCINT is the power supply for the device's internal logic.
The voltage to be supplied can be checked from Quartus® II's Assignments → Core Voltage of the device.
Note that the device used this time is EP4CE6E22C6, so 1.2 V is supplied to the VCCINT pin.
VCCIO
VCCIO is the power supply for I/O.
Cyclone IV E has 8 I/O banks, and each I/O bank can supply different power.
I/O banks can supply 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.0 V, or 3.3 V.
The voltage level can be selected for each I/O bank according to the board specifications.
Note, however, that the same voltage must be supplied to the VCCIO pins in the same I/O bank.
VCCA and VCCD_PLL
Both VCCA and VCCD_PLL are power supplies for the PLL.
In Cyclone IV E, VCCA must be supplied with 2.5 V and VCCD_PLL with the same voltage as VCCINT.
The digital clock design for this exercise does not use a PLL.
Therefore, I thought that VCCINT and VCCIO should be supplied with voltages, but VCCA and VCCD_PLL need not be supplied with voltages.
However, I thought it was not good to make a decision based on my own assumption, so I checked the Pin Connection Guidelines of Cyclone IV.
I found that both the VCCA and VCCD_PLL pins "must be connected even if the PLL is not used.
If I had ignored these two power supplies, I am afraid that I might have damaged the device.
Conclusion
Depending on the device family, some device families have power supplies that are different from the power supplies introduced here.
This time, we felt that it is important to check the Pin Connection Guidelines of the device to see if it is connected or not, even if it is not the power supply of the part to be used.
There were two devices, including a spare, that were provided for the production training.
If I break all of these two devices, will I have to buy new devices out of my own pocket?
With such anxiety, Ume Onigiri decided to check carefully.
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