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Altera_Forum's avatar
Altera_Forum
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11 years ago

Using LVDS channels in the same bank driven by separate PLLs

We are trying to make sure that our project satisfies one of the guidelines in the Cyclone V Device Handbook on pages 5-13 and 5-14. The guideline states: "You can use both corner PLLs to drive the LVDS channels simultaneously. You can use a corner PLL to drive all the transmitter channels and the other corner PLL to drive all the receiver channels in the same I/O bank. Both corner PLLs can drive duplex channels in the same I/O bank if the channels that are driven by each PLL are not interleaved. You do not require separation between the groups of channels that are driven by both corner PLLs."

What does "interleaved" mean, interleaved physical pins, interleaved pads, or something else?

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  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    11 years ago

    Basically, in an IO bank you have pins like:

    PLL_T

    0 <->

    1 <->

    2 <->

    3 <->

    PLL_B

    In this, all 0 to 3 RX channels can be driven by one PLL, and all of the TX channels can be driven by the other.

    Alternatively, channels 0 and 1 can be driven by PLL_T (both RX and TX). Channels 2 and 3 can be driven by PLL_B at the same time (both RX and TX)

    However, channels 0 and 2 can't be driven by PLL_T if channels 1 and 3 are being driven by PLL_B. In otherwords they can't be interleaved.

    So the following configurations work:

    (A)

    0 <=> PLL_T

    1 <=> PLL_T

    2 <=> PLL_T

    3 <=> PLL_T

    (B)

    PLL_B <= 0 <= PLL_T

    PLL_B <= 1 <= PLL_T

    PLL_B <= 2 <= PLL_T

    PLL_B <= 3 <= PLL_T

    (C)

    0 <=> PLL_T

    1 <=> PLL_T

    2 <=> PLL_B

    3 <=> PLL_B

    But the following will not work:

    (D)

    0 <=> PLL_T

    1 <=> PLL_B

    2 <=> PLL_T

    3 <=> PLL_B

    (E)

    0 <=> PLL_T

    1 <=> PLL_B

    2 <=> PLL_B

    3 <=> PLL_T