DRA790 Datasheet, PDF (393/436 Pages) Texas Instruments – Infotainment Applications Processor

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DRA790, DRA791
DRA793, DRA797
SPRS968A – AUGUST 2016 – REVISED FEBRUARY 2017
RF Return
Current
RF Return
Current
Slot in Image Plane
Slot in Image Plane
Bad
Better
Figure 7-29. Do Not Violate Image Planes
SPRS906_PCB_USB20_09
7.5.2.2.2.10 Power Regulators
Switching power regulators are a source of noise and can cause noise coupling if placed close to sensitive
areas on a circuit board. Therefore, the switching power regulator should be kept away from the DP/DM
signals, the external clock crystal (or clock oscillator), and the USB PHY.
7.5.2.3 References
• USB 2.0 Specification, Intel, 2000, http://www.usb.org/developers/docs/
• High
Speed
USB
Platform
Design
Guidelines,
http://www.intel.com/technology/usb/download/usb2dg_R1_0.pdf
Intel,
• Selection and Specification of Crystals for Texas Instruments USB 2.0 Devices (SLLA122)
2000,
7.5.3 USB 3.0 Board Design and Layout Guidelines
This section provides the timing specification for the USB3.0 (USB1 in the device) interface as a PCB
design and manufacturing specification. The design rules constrain PCB trace length, PCB trace skew,
signal integrity, cross-talk, and signal timing. TI has performed the simulation and system design work to
ensure the USB3.0 interface requirements are met. The design rules stated within this document are
targeted at DEVICE mode electrical compliance. HOST mode and/or systems that do not include the 3m
USB cable and far-end 11-inch PCB trace required by DEVICE mode compliance testing may not need
the complete list of optimizations shown in this document; however, applying these optimizations to HOST
mode systems will lead to optimal DEVICE mode performance.
7.5.3.1 USB 3.0 interface introduction
The USB 3.0 has two unidirectional differential pairs: TXp/TXn pair and RXp/RXn pair. AC coupling caps
are needed on the board for TX traces.
Figure 7-30 present high level schematic diagram for USB 3.0 interface.
Copyright © 2016–2017, Texas Instruments Incorporated
Applications, Implementation, and Layout 393
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