TUSB546AI-DCI datasheet(39/49 Pages) TI1

39 / 49 page

To USB Host

AC Coupling

capacitors

RX2

TX2

TX1

RX1

DP0

DP1

DP2

DP3

TUSB546A-DCI

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SLLSF14 – JUNE 2017

Product Folder Links: TUSB546A-DCI

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11 Layout

11.1 Layout Guidelines

1. RXP/N and TXP/N pairs should be routed with controlled 90-Ω differential impedance (±15%).

2. Keep away from other high speed signals.

3. Intra-pair routing should be kept to within 2 mils.

4. Length matching should be near the location of mismatch.

5. Each pair should be separated at least by 3 times the signal trace width.

6. The use of bends in differential traces should be kept to a minimum. When bends are used, the number of

left and right bends should be as equal as possible and the angle of the bend should be

≥ 135 degrees. This

will minimize any length mismatch causes by the bends and therefore minimize the impact bends have on

EMI.

7. Route all differential pairs on the same of layer.

8. The number of VIAS should be kept to a minimum. It is recommended to keep the VIAS count to 2 or less.

9. Keep traces on layers adjacent to ground plane.

10. Do NOT route differential pairs over any plane split.

11. Adding Test points will cause impedance discontinuity, and therefore, negatively impact signal performance.

If test points are used, they should be placed in series and symmetrically. They must not be placed in a

manner that causes a stub on the differential pair.

11.2 Layout Example

Figure 36. Layout Example

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