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Original question:

TUSB4041 GRSTz pin

TUSB4041I: TUSB4041 GRSTz pin and VDD33 and VDD power-on relationship

Anthony Triana
Prodigy 10 points
Part Number: TUSB4041I

In our application VDD3 is on first followed by a lowering of VDD3 and then VDD is sequenced on first with VDD3 following approximately 1 second later.

We experience no operational problems, but my question is:

With GRSTZ connected only to a capacitor, if VDD3 and VDD are not sequenced correctly (VDD must be stable minimum of 10 μs before the VDD33) is this just a violation of guaranteed operation or is the device subject to potential damage?

I am asking because we have experienced several failures of TUSB4041 in between manufacturing of a PCBA and the same PCBA's integration into a system in our factory.

Attached is image of sequencing:trace 1 is VDD3, trace 2 is VDD

TUSB4041 GRSTz pin

  • 0
    TI__Guru 60870 points
    Hi Anthony,

    I wouldn't expect the device to become damaged from power sequencing alone. An incorrect reset pulse would impact the device behavior (it likely would not connect to the upstream port and enumerate as a hub). Have you checked the failed units - are the power rails shorted or is the damage limited to specific ports?

    Regards,
    JMMN