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TUSB1142: TUSB1142 mit I²C

SimonF
Expert 3480 points

Part Number: TUSB1142
Other Parts Discussed in Thread: TPS25750, TPS26750

Hi Team,

We operate the TUSB1142 via pin-strap. This means we can only select a linear mode – then the LFPS output signal is too low (750 mVpp). The LINR_L3 value for the LFPS signal can only be set via I²C.

Following ideas:

Topology I The MCU sets the registers in the TUSB1142 via the PD controller TPS26750SRSMR during startup via I²C. Disadvantage: The MCU must manage the flip signal via I²C during runtime. Is there a ready application for this?

Topology II The TPS26750SRSMR sets configuration registers and flip command via I²C (without MCU).

From forum posts, this was possible with the old TPS25750 through workarounds: • The TPS sets the registers in the TUSB1142 via I²C during startup. • The flip command is sent from the TPS via I²C to the TUSB1142, triggered by a GPIO event trigger – as documented for a TI charge controller. Unfortunately, nothing is documented about this in the TPS26750SRSMR.

Do you have another idea that could solve our problems?

Best regards,

Simon

  • 0
    TI__Guru 51461 points

    Hi Simon,

    The LFPS signaling is at a much lower frequency than the SS+ USB signals. The TUSB1142 cannot boost the signal of LFPS by much as it is outside the target frequency of the TUSB1142. Its best to tune LFPS signaling on the SoC side. Its most likely that the incoming LFPS signal form the host/device does not have enough amplitude. 

    For more information regarding the TPS26750, please reach out to the PD team (IPP-PI)