Instantiation of MMCM/BUFG - 3.6 English

7 Series FPGAs Transceivers Wizard (PG168)

Document ID
PG168
Release Date
2022-05-19
Version
3.6 English

The TX/RXOUTCLK are routed to the FPGA logic through a mixed-mode clock manager (MMCM) or BUFG. An MMCM is needed when the TXUSRCLK does not match TXUSRCLK2 and the RXUSRCLK does not match RXUSRCLK2. Table: MMCM for TX Buffer Bypass and Table: MMCM for RX Buffer Bypass capture various scenarios to instantiate an MMCM.

Table 3-4:      MMCM for TX Buffer Bypass

TX External Data Width

TX Internal Data Width

TX Buffer Bypassed

Source for TXOUTCLK

TXUSRCLK2

MMCM

16

16/20

No

TXOUTCLKPMA

TXUSRCLK

No

32

16/20

No

TXOUTCLKPMA

TXUSRCLK/2

Yes

32

32/40

No

TXOUTCLKPMA

TXUSRCLK

No

64

32/40

No

TXOUTCLKPMA

TXUSRCLK/2

Yes

20

20

No

TXOUTCLKPMA

TXUSRCLK

No

40

20

No

TXOUTCLKPMA

TXUSRCLK/2

Yes

40

40

No

TXOUTCLKPMA

TXUSRCLK

No

80

40

No

TXOUTCLKPMA

TXUSRCLK/2

Yes

16

16/20

Yes/No

Ref Clk

 

 If Refclk = TXUSRCLK2 then

 

Wizard chooses TXPLLREFCLK_DIV1

as TXOUTCLK

 

Else

Wizard chooses TXPLLREFCLK_DIV2

As TXOUTCLK

 

You should choose the appropriate REFCLK to meet the preceding criteria.

TXUSRCLK

No

32

16/20

Yes/No

TXUSRCLK/2

Yes

32

32/40

Yes/No

TXUSRCLK

No

64

32/40

Yes/No

TXUSRCLK/2

Yes

20

20

Yes/No

TXUSRCLK

No

40

20

Yes/No

TXUSRCLK/2

Yes

40

40

Yes/No

TXUSRCLK

No

80

40

Yes/No

TXUSRCLK/2

Yes

Table 3-5:      MMCM for RX Buffer Bypass

RX External Data width

RX Internal Data Width

RX Buffer Bypassed

Source for RXOUTCLK

RXUSRCLK2

MMCM

16

16/20

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK

No

32

16/20

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK/2

Yes

32

32/40

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK

No

64

32/40

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK/2

Yes

20

20

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK

No

40

20

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK/2

Yes

40

40

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK

No

80

40

No

RXOUTCLKPMA/TXOUTCLK/REFCLK

RXUSRCLK/2

Yes

16

16/20

Yes

RXOUTCLKPMA

RXUSRCLK

No

32

16/20

Yes

RXUSRCLK/2

Yes

32

32/40

Yes

RXUSRCLK

No

64

32/40

Yes

RXUSRCLK/2

Yes

20

20

Yes

RXUSRCLK

No

40

20

Yes

RXUSRCLK/2

Yes

40

40

Yes

RXUSRCLK

No

80

40

Yes

RXUSRCLK/2

Yes