SLLSFW6 March 2024 ISOUSB211-Q1
ADVANCE INFORMATION
The ISOUSB211-Q1 has inbuilt programmable receive equalization and transmit pre-emphasis to cancel signal loss caused by board traces, which helps in meeting USB2.0 high-speed TX and RX eye-diagram templates. These settings are controlled by EQ11 and EQ10 on side 1 and EQ21 and EQ20 on side 2. The EQxx pins can be connected to ground, connected to 3.3-V supply or left floating, together creating 9 different equalization levels. EQ11 and EQ10 can be chosen based on the length of D+/D- board trace and corresponding channel loss estimated on side 1, and similarly EQ21 and EQ20 for side 2. Typical 45-Ohm trace in FR4 has about 0.15 dB/inch for 480 Mbps signaling. Further adjustments to the EQ settings can be made by observing the transmit eye-diagram at the connector. If the trace lengths are very small, no equalization may be needed, and the EQxx pins can be connected to ground.
ISOUSB211-Q1 samples EQxx pins only at power up, so it is not recommended to change the EQxx settings on the fly after power up.