Translate Voltages for RGMII

RGMII is a high-bandwidth data bus protocol with very strict timing considerations. The following device recommendations are provided as a suggested solution as they can support the data rates required for RGMII interfaces; however, because the RGMII specification is defined without consideration for voltage level translation, board-level assessment of key timing parameters and assessment of performance within the system is encouraged.

Example of Using Voltage Translation with RGMII

Design Considerations

Board layout is critical to the success of RGMII translation; we recommend using signal integrity simulations and prototyping for any design
Use active translators for maximum data rate
Use one device for all TX signals and one for all RX signals to minimize channel-to-channel skew
See Low Voltage Translation For SPI, UART, RGMII, JTAG Interfaces for details regarding the performance of SN74AXC8T245 in RGMII applications
Place translators closest to the low-voltage device, if possible, to improve signal integrity
Consider source-terminating signals if sent over 12 cm (4700 mil) or longer traces
Need additional assistance? Ask our engineers a question on the TI E2E™ logic support forum

Recommended Parts

Part Number	Automotive Qualified	RGMII Voltage Translation Range	Device Maximum Data Rate (Mbps)	Features
SN74AXC8T245		2.5 V to 3.3 V	380 Mbps	Glitch-free power supply sequencing Outputs are disabled when either supply is 0 V Active translation architecture
SN74AXC8T245-Q1	✓	2.5 V to 3.3 V	380 Mbps
SN74AVC8T245		1.8 V to 3.3 V	320 Mbps	Active translation architecture
SN74AVC8T245-Q1	✓	1.8 V to 3.3 V	320 Mbps	Active translation architecture

For more devices, browse through the online parametric tool where you can sort by desired voltage, channel numbers, and other features.

IMPORTANT NOTICE AND DISCLAIMER

TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS.

These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these resources.

TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for TI products.