Specifications
Absolute maximum ratings are those beyond which the device may be damaged.
Parameter | Min | Max | Units |
Supply voltage | -0.3 | 3.6 | V |
Data input voltage | -0.3 | 3.6 | V |
Control input voltage | -0.3 | 3.6 | V |
This table shows the environmental specifications for the product.
Parameter | Min | Max | Units |
Storage temperature | -40 | 85 | °C |
This section shows the range of values for normal operation.
Parameter | Min | Typ | Max | Units |
Supply voltage (Vcc) | 3.135 | 3.3 | 3.465 | V |
Power consumption | --- | --- | 0.1 | W |
Operating case temperature for MAM1Q00A-QSA28_E | -10 | 85 | °C | |
Operating relative humidity | 5 | 85 | % |
Parameter | Min | Typ | Max | Units |
Characteristic Impedance | 90 | 100 | 110 | Ω |
The QSA28 adapter is used to connect an SFP28 module in a QSFP28 port. The QSA28 includes an EEPROM that can be accessed using I2C address 0x50. The EEPROM is selected when both the ResetL and the ModSelL control signals are asserted. The EEPROM main usage is to identify the QSA technology, the supported rates, and to distinguish between the QSA28 (25GbE) and QSA (10GbE).
The EEPROM is not write protected like the copper cables and the host needs to make sure not to write wrong data to the QSA.
The SFP EEPROM access is unchanged, ResetL is de-asserted, ModSelL is asserted, and using I2C address 0x50.
Memory Map QSFP28
Page 00h | Register Name | Value | Description |
0 | Identifier | 0xFF | |
1-3 | Signature | "QSA" | |
4 | Memory map revision | 0 | |
5 | QSA device ID | 0x1 | 0x0: QSA10 |
6-7 | Reserved | 0 | |
8 | Supported link modes | 0x07 | b0: 10Gbd NRZ / SDR-QDR, supported |
9 | Supported link modes | 0x00 | Reserved |
10-15 | Reserved for future link codes | 0 | |
24-25 | Nominal baud rate | 257 | 25.7GBd, in 100MBd units |
26-27 | Max baud rate | 281 | 28.1GBd, in 100MBd units |
28 | Max case temp | 70/85 | 70ºC: MAM1Q00A-QSA28 |
29 | Nominal encoding | 0 | 0x0: NRZ |
30-31 | Reserved | 0 | |
32 | Attenuation 2.5G | 03 | Typical attenuation in 1dB. |
33 | Attenuation 5G | 03 | |
34 | Attenuation 7G | 06 | |
35 | Attenuation 12G | 07 | |
36 | Attenuation 25G | 0xFF | |
37-63 | Reserved | ||
64-66 | Vendor OUI | 0x0002C9 | Mellanox IEEE company ID. |
67 | Reserved | ||
68-83 | Vendor name | 0x4D656C | “Mellanox” in ASCII |
84-99 | Serial number | MTYYWW | Written on backshell label. Refer to Table 10: Back-Shell Label Legend. |
100-115 | Part number | MAM1Q00A-QSA28 | ASCII. Written on backshell label |
116-117 | Product revision | ASCII. Written on backshell label | |
118-125 | Date code | YYMM | Written on backshell label (6 digits padded w 0xFF) |
126 | Reserved | ||
127 | Checksum | EEPROM checksum to detect invalid data (add mod 256). Written by production. |
This product is compatible with ESD levels in typical data center operating environments and certified in accordance with the standards listed in the Regulatory Compliance Section. The product is shipped with protective caps on all connectors to protect it during shipping. In normal handling and operation of high-speed cables and optical transceivers, ESD is of concern during insertion into the OSFP cage of the server/switch. Hence, standard ESD handling precautions must be observed. These include use of grounded wrist/shoe straps and ESD floor wherever a cable/transceiver is extracted/inserted. Electrostatic discharges to the exterior of the host equipment chassis after installation are subject to system level ESD requirements.
The figure below shows the dimensions of the QSA28.
The SFP28/SFP+/SFP mating paddle card dimension A10 (length of component/solder mask keep-out area, refer to SFF-8071) shall be >6.0mm instead of >5.5mm. The reason for this requirement is to prevent damaging the adapter when trying to insert an SFP upside down

Dimensions provided in parenthesis are informative only and not a controlled dimension
RF Connectivity
QSFP28 Side | SFP28 Side |
Tx1p/n | TD+/- |
Rx1p/n | RD+/- |
Tx2p/n | Terminated |
Rx2p/n | Terminated |
Tx3p/n | Terminated |
Rx3p/n | Terminated |
Tx4p/n | Terminated |
Rx4p/n | Terminated |
The following label is applied on the cable’s backshell:

(sample illustration)
Legend: COO – Country of Origin
Backshell Label SN (Serial Number) Legend
Symbol | Meaning | Notes |
SN – Serial Number | ||
MT | Manufacturer name | 2 characters, e.g. MT |
YY | Year of manufacturing | 2 digits |
WW | Week of manufacturing | 2 digits |
XX | Manufacturer site | 2 characters |
SSSSS | Serial number | 5 digits for serial number, starting from 00001. Reset at start of week to 00001. |
Miscellaneous | ||
ZZ | HW and SW revision | 2 alpha-numeric characters |
YYYY | Year of manufacturing | 4 digits |
MM | Month of manufacturing | 2 digits |
DD | Day of manufacturing | 2 digits |
COO | Country of origin | E.g. China or Malaysia |
![]() | Quick response code | Serial number (MTYYWWXXSSSSS) |
The required switch OS and adapter cards firmware versions are listed in the table below.
QSA28 OS/FW Software Requirements
OPN | Minimum OS/FW Version |
MSN2700 | OS 3.6.4006 or higher |
MSN2410 | OS 3.6.4006 or higher |
MSN2100 | OS 3.6.4006 or higher |
ConnectX-4 LX | FW 14.18.1000 or higher |
ConnectX-4 | FW 12.19.0080 or higher |
ConnectX-5 | FW 16.18.1000 or higher |
Safety: CB, CE
EMC: CE, FCC, ICES, RCM
Ask your NVIDIA FAE for a zip file of the certifications for this product.
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.