JAJSKH4A April 2022 – May 2024 TUSB1104
PRODUCTION DATA
The purpose of receiver equalization is to compensate for channel insertion loss and inter-symbol interference in the system before the input of the TUSB1104. The receiver overcomes these losses by attenuating the low frequency components of the signals with respect to the high frequency components. The proper gain setting should be selected to match the channel insertion loss before the input of the TUSB1104 receivers. Two 4-level inputs pins enable up to 16 possible equalization settings when in pin-strap mode. The TUSB1104's USB 3.2 host, hub, and device receivers (SSTX1/2) and USB 3.2 USB connector receivers (CRX1/2) each have their own two 4-level inputs. The TUSB1104 also provides the flexibility of adjusting settings through I2C registers.
The TUSB1104's USB host, hub, and device facing port receiver (SSTX1/2) only support Fixed EQ (FEQ). The TUSB1104 implements three different equalizer features for the USB connector facing port receivers (CRX1 and CRX2): Fixed EQ (FEQ), Fast Adaptive EQ (Fast AEQ), and Full Adaptive EQ (Full AEQ). In Fixed EQ operation, a single setting is used for all possible devices (with and without cable) inserted into the USB receptacle. The Fast AEQ feature will distinguish between a short channel and a long channel. A short channel represents a low loss use case of a USB 3.2 device plugged directly into USB receptacle without a cable. A long channel represents the high loss use case of the USB 3.2 device plugged into the receptacle through a USB cable. In Fast AEQ mode, TUSB1104 will select between two pre-determined settings based on whether or not channel is short or long. When TUSB1104 is configured for Full AEQ, the TUSB1104 will automatically determine what it believes is the best equalization setting each time a USB device is inserted into the USB receptacle. In Full AEQ mode, the TUSB1104 will attempt to determine the best settings regardless if the channel is short, long, or somewhere in between.