AD8155 (XStream Switch) HOT, does not pass data

I'm using the AD8155 to split upstream and downstream USB 3.0 data for use as a USB 3.0 protocol analyzer analog front-end. I'm unable to get this to work. The current draw on the 3.3V rail is 1.1A @ 3.3V so the IC gets extremely hot. This is without any data passed through the device. It also does not pass data. I have reviewed schematics and replaced the AD8155 without luck. All power supplies are 3.3V. Resistance between the 3.3V rail and GND is about 6 ohm when measured with power off. The AD8155 is hard-strapped to do BICAST C => A/B.

Please see attached for schematics. Are there any gotchas I've missed?

Thanks,

John.

p.s.

Please note that the StdA_SSRX and StdB_SSRX inputs should be swapped (incorrect on schematics but fixed on actual prototype board). The idea is to route upstream USB 3.0 data from one connector, split in the AD8155 and pass on via the 2nd connector. Same for downstream data. Separate copies of the upstream/downstream data is then sent to USB 3.0 PHYs for protocol analysis.

AD8155Schematics.pdf
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  • Hi Jarrod,

    Thank you for your response.

    I can confirm that the package temperature went down from over 75 degrees C to about 65 degrees C when the inputs were left floating. The temperature is still rather high but I will change the VTTI/VTTO to 1.8V per your suggestion in the next board spin, which should bring it down additionally.

    Regards,

    /John.

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  • Hi Jarrod,

    Thank you for your response.

    I can confirm that the package temperature went down from over 75 degrees C to about 65 degrees C when the inputs were left floating. The temperature is still rather high but I will change the VTTI/VTTO to 1.8V per your suggestion in the next board spin, which should bring it down additionally.

    Regards,

    /John.

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