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Different oscillator for FPGA system clock

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shawnmk123

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Hello,

I'm using the 576-4651-ND (Digikey Part Number) for my FPGA system clock.
The part is a differential oscillator. The input voltage is 3.3V. the output voltage swing is .35V.

I don't know what is a differential clock (i've never used it before). Anyways, I'm connecting it to 2 MRCC pins (Positive and Negative) of any Bank in XC7A35T-1FTG256.

What should the VCCO of that Bank be? 3.3V or something else.

Please help.

Thank you,
 

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VCCO of the bank should be set to 1.8 for LVDS, or 2.5V for LVDS_25, if you want to use the internal termination resistor (enabled with DIFF_TERM = TRUE, I recommended that you use it for best results).

If you use an external termination resistor you can use a VCCO that is different than the two mentioned but there are various criteria that must be met. Read UG471 - Rules for Combining I/O Standards in the Same Bank, starting at pg 97 if you plan on using a different VCCO voltage.
 

shawnmk123

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I'm referring to the NetFPGA 1G CML application schematic for building my custom FPGA board.
They are using the kintex 7.
They used a differential 200 MHz oscillator for their FPGA system clock.
(input VCC = 3.3V, output connected to bank with VCCO = 1.5V using a termination resistor).
the IO standard they used was the LVDS.
Did they connect the DIFF OSC (DSC1123AE1-200.0000T-ND) to a Bank with VCCO = 1.5V because the max output offset is 1.4V and pk to pk is 0.350V?

Can I connect the same DIFF OSC to a Bank with VCCO = 3.3V?

Thank you for your help.

- - - Updated - - -

VCCO of the bank should be set to 1.8 for LVDS, or 2.5V for LVDS_25, if you want to use the internal termination resistor (enabled with DIFF_TERM = TRUE, I recommended that you use it for best results).

If you use an external termination resistor you can use a VCCO that is different than the two mentioned but there are various criteria that must be met. Read UG471 - Rules for Combining I/O Standards in the Same Bank, starting at pg 97 if you plan on using a different VCCO voltage.

That was helpful to know.
 

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