QSFP28 carries 100GbE using four 25 Gbps lanes. Used in data center top-of-rack switches and 100G routers with SR4, LR4, and CWDM4 optical variants.
| Pin | Name | Function | Type |
|---|---|---|---|
| 1 | GND | Ground | GND |
| 2 | TX2n | TX lane 2 negative | BUS |
| 3 | TX2p | TX lane 2 positive | BUS |
| 5 | TX4n | TX lane 4 negative | BUS |
| 6 | TX4p | TX lane 4 positive | BUS |
| 8 | MOD_SEL# | Module select | I/O |
| 9 | RESET# | Module reset | I/O |
| 10 | VCC_TX | TX supply 3.3V | PWR |
| 11 | SCL | I2C clock | BUS |
| 12 | SDA | I2C data | BUS |
| 14 | RX3p | RX lane 3 positive | BUS |
| 15 | RX3n | RX lane 3 negative | BUS |
| 17 | RX1p | RX lane 1 positive | BUS |
| 18 | RX1n | RX lane 1 negative | BUS |
| 20 | ModPrsL | Module present active low | I/O |
| 22 | VCC_RX | RX supply 3.3V | PWR |