TDA2SA datasheet(364/427 Pages) TI2

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USB PHY

Connector

D+

D-

VBUS

GND

D-

D+

Cable

Connector

364

TDA2SX, TDA2SG, TDA2SA

TDA2HG, TDA2HV, TDA2HF, TDA2LF

SPRS951F – DECEMBER 2015 – REVISED MAY 2019

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Product Folder Links: TDA2SX TDA2SG TDA2SA TDA2HG TDA2HV TDA2HF TDA2LF

Applications, Implementation, and Layout

Figure 8-35. USB PHY Connector and Cable Connector

8.5.2.2.2.8 DP/DM Vias

When a via must be used, increase the clearance size around it to minimize its capacitance. Each via

introduces discontinuities in the signal’s transmission line and increases the chance of picking up

interference from the other layers of the board. Be careful when designing test points on twisted pair lines;

through-hole pins are not recommended.

8.5.2.2.2.9 Image Planes

An image plane is a layer of copper (voltage plane or ground plane), physically adjacent to a signal routing

plane. Use of image planes provides a low impedance, shortest possible return path for RF currents. For a

USB board, the best image plane is the ground plane because it can be used for both analog and digital

circuits.

•

Do not route traces so they cross from one plane to the other. This can cause a broken RF return path

resulting in an EMI radiating loop as shown in Figure 8-36. This is important for higher frequency or

repetitive signals. Therefore, on a multi-layer board, it is best to run all clock signals on the signal

plane above a solid ground plane.

•

Avoid crossing the image power or ground plane boundaries with high-speed clock signal traces

immediately above or below the separated planes. This also holds true for the twisted pair signals (DP,

DM). Any unused area of the top and bottom signal layers of the PCB can be filled with copper that is

connected to the ground plane through vias.

TDA2SA Datasheet(PDF) 364 Page - Texas Instruments