If the common-mode voltage in the system is higher than 2 V, the coupling capacitors are placed on both sides

of the switch (shown in Figure 9-3). A biasing voltage of less than 2 V is required in this case.

Device/

Endpoint

RX

TX

Device/

Endpoint

RX

TX

Port A

Port A

Port B

Port B

System/Host

Controller

RX

TX

VBIAS

VBIAS

Figure 9-3. AC Coupling Capacitors on Both Sides of Switch

9.2 Typical Application

HD3SS212

HPDB

DAx (p)

HPDA

DAx (n)

HPDC

AUXAx

AUXCx

AUXBx

DCx (p)

DCx (n)

DBx (p)

DBx (n)

Control

AUX _SEL

Dx_SEL

Copyright © 2016, Texas Instruments Incorporated

GPU/

Source A

4

4

2

GPU/

Source B

GPU/

Source A

2

Sink/

Connector

4

4

4

4

2

Figure 9-4. Dual Source Connection Block Diagram

9.2.1 Design Requirements

Table 9-1 lists the design parameters.

Table 9-1. Design Parameters

DESIGN PARAMETERS

EXAMPLE VALUE

Input voltage range

3.3 V

Decoupling capacitors

0.1 µF

AC capacitors

75 nF – 200 nF (100 nF shown) USBAA TX p and

AC capacitors n lines require AC capacitors.

Alternate mode signals may or may not require AC

capacitors

9.2.2 Detailed Design Procedure

• Connect VDD and GND pins to the power and ground planes of the printed circuit board, with 0.1-µF bypass

capacitor

• Use +3.3-V TTL/CMOS logic level at SEL

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HD3SS212

SLAS822D – DECEMBER 2011 – REVISED DECEMBER 2020

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