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TUSB1002: Changes from Revision A (May 2016) to Revision B

ttd
Mastermind 7830 points
Part Number: TUSB1002

Dear Technical Support Team,

I have a question about  "Changes from Revision A (May 2016) to Revision B".

This was updated about RXP2 and RXN2 like adding capacitor and pulldown register.

What is the background of this changes?

I think that some connection is failed without capacitor for AC coupling and pulldown register(DC coupling).

So is it recommended from DC coupling to AC coupling,right?

■Changes from Revision A (May 2016) to Revision B Page

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• Added a capacitor to the RXP2 and RXN2 pins of the Simplified Schematic........................................................................ 1
• Added a capacitor to the RXP2 and RXN2 pins of Figure 17 .............................................................................................. 19
• Updated the A/C coupling Capacitor section of Table 4 ..................................................................................................... 19
• Changed text in the Detailed Design Procedure From: No A/C coupling capacitors are placed on the RX2P/N. To:
330nF A/C coupling capacitors along with 220k resistors are placed on the RX2P and RX2N. Inclusion of these
330nF capacitors and 220k resistors is optional but highly recommended. If not implemented, then RX2P/N should

be DC-coupled to the USB receptacle. ................................................................................................................................ 20
• Added 330nF AC capacitors (C12 and C13) on RX2P and RX2N in Figure 18 .................................................................. 20

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Best Regards,

ttd

  • 0
    TI__Guru**** 150215 points
    Capacitor on RX is USB spec ECN (Title: RX AC Coupling Capacitor Option).

    This capacitor is useful for ESD/EOS protection and remove unwanted bias level from Rx side. Because RX side of different UBS-SS system have variable common mode voltage (use different termination scheme), this option can remove unmatched bias level for interconnection logic. After adding this capacitor leakage current through RX pin can be ideally 0mA and it is helpful to prevent water corrosion. (Same as TX side)

    Adding external pulldown resistor is changing the biasing network to address non-detecting issue with some non-compliant USB devices on the market.

    Thanks
    David