Good morning ,
I'm working with CycloneV GX at AS (x1 and x4) Standard configuration.
I've read at CycloneV Handbook ,that MSEL(4:0) pins shall be connected to VCCPGM or GND directly. The Voltage value of VCCGM is 3.0/3.3V.
But at the scheme of Cyclone V SoC FPGA Development Kit Board, you can see MSEL(4:0) connected to VCCPGM=2.5V via resistors and switch.
Is it correct to connect MSEL pins to 2.5V?
N.B. I've attached print-screen from the scheme.
As per all the Intel recommendation documents, VCCPGM must be 3V/3.3V for AS x1, ASx4 configuration.
I am not sure why it is 2.5V in Cyclone V SoC kit. But, in Cyclone V GX Dev kit, VCCPGM is 2.5V, but no support for ASx1 and ASx4 mode.
It states that: Connect these pins to either a 1.8V, 2.5V, 3.0V, or 3.3V power supply
Thus, it is ok for VCCPGM to connect to 2.5V.
Hi @JwChin ,
The above document mentions the possible values for VCCPGM, but it does not talk about in conjunction with ASx1, ASx4 configuration mode.
https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-v/cv_5v2.pdf, page 244, Table 7-2: says that either 3.3V or 3.0V must be connected if Cyclone V platform supports ASx1, ASx4 mode of configuration.
This table in the handbook is the real cause for the confusion.
You are correct. VCCPGM for 2.5V and below is not supported for AS mode. I stand corrected for my previous answer.
I found a kdb that explains it:
Hope this clears all the doubts.
Thank you ,JwChin for answer about "CycloneV :MSEL(4:0) and VCCPGM voltage" issue!
The issue is clear.
Does your last answer "The RS and RP external resistors is to give an effective 100 ohm differential output impedance" is connected to this issue or to another?