1 Introduction

Designers that build applications using USB redrivers expect to see consistent bit error free operation for different channel lengths, temperatures, data rates, or other conditions. When using a USB redriver with static equalization (EQ) settings, a significant amount of time is needed to determine an ideal fixed EQ level for the particular system design across these conditions. Even then, the ideal EQ level can not work error free in all practical cases. Many system designs cannot be limited to specific conditions, so the system design is stuck with an error prone solution. This case is where AEQ improves upon static EQ methodology.

AEQ adapts to the various system characteristics by automatically tuning the EQ settings of the redriver, resulting in bit error free operation under different system conditions. Historically, AEQ algorithms are reserved to retimer devices, but retimers are more expensive than redrivers in many applications. TI offers redriver products, like the TUSB1146, that feature AEQ functionality with better cost efficiency. The TUSB1146 redriver implements AEQ functionality at the downstream facing port USB Type-C® 3.2 receivers (RX1 and RX2). This application note discusses the value in using AEQ functionality over static EQ for the TUSB1146 with supporting tests.