Pin Description

The QSFP28 pin assignment is SFF-8679 compliant.

Pin

Symbol

Description

Pin

Symbol

Description

1

Ground

Ground

20

Ground

Ground

2

Tx2n

Connected to Port 1 lane Rx2
Inverted Data

21

Rx2n

Connected to Port 1 lane Tx2
Inverted Data

3

Tx2p

Connected to Port 1 lane Rx2
Non-Inverted Data

22

Rx2p

Connected to Port 1 lane Tx2
Non-Inverted Data

4

Ground

Ground

23

Ground

Grounds

5

Tx4n

Connected to Port 2 lane Rx2
Non-Inverted Data

24

Rx4n

Connected to Port 2 lane Tx2
Inverted Data

6

Tx4p

Connected to Port 2 lane Rx2
Inverted Data

25

Rx4p

Connected to Port 2 lane Tx2
Non-Inverted Data

7

Ground

Ground

26

Ground

Ground

8

Mod-SelL

Cable Select

27

ModPrsL

Cable Present

9

ResetL

Cable Reset

28

IntL

Interrupt

10

Vcc Rx

+3.3V Power supply receiver

29

Vcc Tx

+3.3V Power supply transmitter

11

SCL

2-wire serial interface clock

30

Vcc1

+3.3V Power Supply

12

SDA

2-wire serial interface data

31

LPMode

Low Power Mode

13

Ground

Ground

32

Ground

Ground

14

Rx3p

Connected to Port 2 lane Tx1
Non-Inverted Data

33

Tx3p

Connected to Port 2 lane Rx1

Non-Inverted Data

15

Rx3n

Connected to Port 2 lane Tx1
Inverted Data

34

Tx3n

Connected to Port 2 lane Rx1
Inverted Data

16

Ground

Ground

35

Ground

Ground

17

Rx1p

Connected to Port 1 lane Tx1
Non-Inverted Data

36

Tx1p

Connected to Port 1 lane Rx1
Non-Inverted Data

18

Rx1n

Connected to Port 1 lane Tx1
Inverted Data

37

Tx1n

Connected to Port 1 lane Rx1
Inverted Data

19

Ground

Ground

38

Ground

Ground

QSFP28 Module Pad Layout

image2021-9-19_16-54-21.png

Pin

Symbol

Description

Pin

Symbol

Description

1

Ground

Ground

20

Ground

Ground

2

Tx2n

Connected to lane Rx2
Inverted Data

21

Rx2n

Connected to lane Tx2
Inverted Data

3

Tx2p

Connected to lane Rx2
Non-Inverted Data

22

Rx2p

Connected to lane Tx2
Non-Inverted Data

4

Ground

Ground

23

Ground

Grounds

5

Not connected

Not connected

24

Not connected

Not connected

6

Not connected

Not connected

25

Not connected

Not connected

7

Ground

Ground

26

Ground

Ground

8

Mod-SelL

Cable Select

27

ModPrsL

Cable Present

9

ResetL

Cable Reset

28

IntL

Interrupt

10

Vcc Rx

+3.3V Power supply receiver

29

Vcc Tx

+3.3V Power supply transmitter

11

SCL

2-wire serial interface clock

30

Vcc1

+3.3V Power Supply

12

SDA

2-wire serial interface data

31

LPMode

Low Power Mode

13

Ground

Ground

32

Ground

Ground

14

Not connected

Not connected

33

Not connected

Not connected

15

Not connected

Not connected

34

Not connected

Not connected

16

Ground

Ground

35

Ground

Ground

17

Rx1p

Connected to lane Tx1
Non-Inverted Data

36

Tx1p

Connected to lane Rx1
Non-Inverted Data

18

Rx1n

Connected to lane Tx1
Inverted Data

37

Tx1n

Connected to lane Rx1
Inverted Data

19

Ground

Ground

38

Ground

Ground

QSFP28 Module Pad Layout

The pinout of the 50Gb/s ends of the cable is identical to the 100Gb/s end except that RF lanes 3 and 4 (pins 5, 6, 14, 15, 24, 25, 33, 34) are not connected.

image2021-9-19_16-53-53.png

© Copyright 2023, NVIDIA. Last updated on May 22, 2023.