SLLA656 November   2024 TUSB1021-Q1 , TUSB521-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2TUSB521-Q1 Equalization Selection
  6. 3TUSB1021-Q1 Equalization Selection
  7. 4TUSB521-Q1 Placement Example
  8. 5TUSB521-Q1 Configuration Example
  9. 6Layout Guidelines
    1. 6.1 Ground Stitching
    2. 6.2 AC Coupling and Resistor Placement
  10. 7Summary
  11. 8References

6 Layout Guidelines

Use the following layout guidelines in routing the high-speed USB signals to and from the TUSB521-Q1 and TUSB1021-Q1:

  • Route the RXP/N and TXP/N pairs with a controlled 90Ω differential impedance (±15%).
  • Keep differential pairs away from other high-speed signals.
  • Keep intra-pair routing to within 2 mils.
  • Locate the differential pair length matching near the mismatch.
  • Separate each pair by at least 3 times the signal trace width.
  • Minimize the use of bends in differential traces. When bends are used, make the number of left and right bends as equal as possible and the angle of the bend is ≥135º. Bending the trace this way minimizes any length mismatch caused by the bends and minimize the impact bends have on the EMI.
  • Route all differential pairs on the same layer.
  • Minimize the number of vias to two or less.
  • Keep differential traces on layers adjacent to a ground plane.
  • Do not route differential pairs over any split plane.
  • If using a through-hole connector, route the high-speed signals on opposite side of the connector so that the connector pin does not create a stub in the transmission line.