Datasheet AOZ8S321UD4-05 (Alpha & Omega) - 5

ALPHA & OMEGA
S E M I C O N D U C T O R
AOZ8S321UD4-05 High Speed PCB Layout Guidelines
ground bounce. The clamping performance of TVS diodes on a single ground PCB can be improved by minimizing the Printed circuit board layout is the key to achieving the highest impedance with relatively short and wide ground traces. The level of surge immunity on power and data lines. The location PCB layout and IC package parasitic inductances can cause of the protection devices on the PCB is the simplest and significant overshoot to the TVS’s clamping voltage. The most important design rule to follow. The AOZ8S321UD4-05 inductance of the PCB can be reduced by using short trace devices should be located as close as possible to the noise lengths and multiple layers with separate ground and power source. The AOZ8S321UD4-05 device should be placed on planes. One effective method to minimize loop problems is all data and power lines that enter or exit the PCB at the I/O to incorporate a ground plane in the PCB design. connector. In most systems, surge pulses occur on data and power lines that enter the PCB through the I/O connector. The AOZ8S321UD4-05 ultra-low capacitance TVS is Placing the AOZ8S321UD4-05 devices as close as possible designed to protect four high speed data transmission lines to the noise source ensures that a surge voltage will be from transient over-voltages by clamping them to a fixed clamped before the pulse can be coupled into adjacent PCB reference. The low inductance and construction minimizes traces. voltage overshoot during high current surges. When the voltage on the protected line exceeds the reference voltage In addition, the PCB should use the shortest possible the internal steering diodes are forward biased, conducting traces. A short trace length equates to low impedance, the transient current away from the sensitive circuitry. The which ensures that the surge energy will be dissipated by AOZ8S321UD4-05 is designed for ease of PCB layout by the AOZ8S321UD4-05 device. Long signal traces will act as allowing the traces to run underneath the device. The pinout antennas to receive energy from fields that are produced by of the AOZ8S321UD4-05 is designed to simply drop onto the ESD pulse. By keeping line lengths as short as possible, the IO lines of a High Definition Multimedia Interface (HDMI the efficiency of the line to act as an antenna for ESD related 1.4/2.0) or USB 3.0/3.1 design without having to divert the fields is reduced. Minimize interconnecting line lengths by signal lines that may add more parasitic inductance. Pins 1, placing devices with the most interconnect as close together 2, 4 and 5 are connected to the internal TVS devices and as possible. The protection circuits should shunt the surge pins 6, 7, 9 and 10 are no connects. The no connects was voltage to either the reference or chassis ground. Shunting done so the package can be securely soldered onto the PCB the surge voltage directly to the IC’s signal ground can cause surface. Clock Clock SSRX+ SSRX+ Data0 Data0 SSRX– SSRX– Ground Ground Ground Ground Data1 Data1 SSTX+ SSTX+ Data2 Data2 SSTX– SSTX–
Flow Through Layout for HDMI 1.4/2.0 Flow Through Layout for USB 3.0/3.1
Rev. 2.0 September 2020
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