Proper routing and placement is important to
maintain the signal integrity the USB2.0, SBU, CC line signals. The following
guidelines apply to the TPD4S480 device:
- Place the bypass capacitors
as close as possible to the VPWR pin, and ESD protection
capacitor as close as possible to the VBIAS pin. Capacitors must
be attached to a solid ground. This minimizes voltage disturbances during
transient events such as short-to-VBUS and ESD strikes.
- The USB2.0 and SBU lines must
be routed as straight as possible and any sharp bends must be
minimized.
Standard ESD recommendations apply to the C_CC1,
C_CC2, C_SBU1, and C_SBU2 as well:
- The optimum placement for the
device is as close to the connector as possible:
- EMI during an ESD
event can couple from the trace being struck to other nearby
unprotected traces, resulting in early system failures.
- The PCB designer must
minimize the possibility of EMI coupling by keeping any unprotected
traces away from the protected traces which are between the TPD4S480 device and the connector.
- Route the protected traces as
straight as possible.
- Eliminate any sharp corners
on the protected traces between the TVS and the connector by using rounded
corners with the largest radii possible.
- Electric fields tend
to build up on corners, increasing EMI coupling.