CYW43907 power savings by floating USB pins...

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MichaelF_56
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Team,

I'm working with DavidD_91​ on a new opportunity where the customer is looking to save additional power by not using the USB interface on the CYW43907 under WICED.

Would you know if the following pins could be left floating to accomplish this goal?

  • USB2_AVDD33
  • USB2_AVDD33IO
  • USB2_AVDD33LDO

Thanks in advance for the guidance.

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Aditi_B
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Hello,

Thank you for your patience. This is what the product team replied-->

For all 43907 module designs (i.e. from Murata, USI or SPIL), only USB2_VDD_3V3 is available for which guidance is provided in the Eval User Guide to connect it to GND when USB is unused. USB2_AVDD33, USB2_AVDD33IO, USB2_AVDD33LDO --> these signals are not accessible at the output of any of these modules, thus no action is required in regards to these signals. So, even if you use the USB interface or not, it doesn't matter because these pins can't be accessed. Only this pin-->USB2_VDD_3V3 needs to be taken care of.

Thanks

Aditi

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Aditi_B
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Hello,

The USB2_AVDD33, USB2_AVDD33IO, USB2_AVDD33LDO pins as mentioned in the datasheet seems to be power (PWR) pins. In this case, I am not sure whether we can leave these pins floating or not. We are seeking clarifications from the product/hardware team and will revert on this.

The Evaluation Kit User Guide mentions CYW43907 Power Signals for Unused Interfaces (section 13), in which they recommend to connect the power signals of unused interfaces to GND. Though this mentions for USB_VDD_3V3 and not for USB2 pins, I think this is what the document recommends for power signals. I'll seek more clarifications on this. Incase if this needs to be connected to GND, that should be a stable GND to avoid leakage currents and thus can save power. I have attached the Kit User Guide for the reference.

Thanks

Aditi

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MichaelF_56
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Thanks for looking into this AditiB_81

Let me know what you hear back from the product/hardware team.

Mike

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Aditi_B
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500 replies posted 5 questions asked 250 replies posted

Hello,

Thank you for your patience. This is what the product team replied-->

For all 43907 module designs (i.e. from Murata, USI or SPIL), only USB2_VDD_3V3 is available for which guidance is provided in the Eval User Guide to connect it to GND when USB is unused. USB2_AVDD33, USB2_AVDD33IO, USB2_AVDD33LDO --> these signals are not accessible at the output of any of these modules, thus no action is required in regards to these signals. So, even if you use the USB interface or not, it doesn't matter because these pins can't be accessed. Only this pin-->USB2_VDD_3V3 needs to be taken care of.

Thanks

Aditi

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