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Hot!what are the proper connections for VBUS and VUSB3V3 in case the USB is not used?

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Mohammed_Hassan
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2019/03/19 09:18:13 (permalink)
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what are the proper connections for VBUS and VUSB3V3 in case the USB is not used?

Hello, 
I am currently working on PIC32MZ controller (PIC32MZ0512EFF064) and I will not use the USB.
 
What are the right connections for VBUS and VUSB3V3 pins?
In the datasheet the only information regarding the VUSB3V3 is: " USB internal transceiver supply. If the USB module is not used, this pin must be connected to VSS. When connected to VSS, the shared pin functions on USBID will not be available."
and I Have the fear from connecting a power pin(VUSB) to VSS causes any power problems! 
 
Thanks in advance for your help.
 
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    campbellCustom
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    Re: what are the proper connections for VBUS and VUSB3V3 in case the USB is not used? 2019/03/20 10:52:30 (permalink)
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    Yes, the datasheet will tell you to ground VUSB3V3. This will have the unusual side effect of lowering the maximum output voltage on the USBID pin. I was using USBID/PRF3/RF3 as an output, and had to change pins. Otherwise I have not observed any odd behavior. I am not sure why the data sheet suggest grounding that pin. I recall others on this forum leaving that pin open, though I cannot speak for them.
     
     
     
     
    #2
    malaugh
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    Re: what are the proper connections for VBUS and VUSB3V3 in case the USB is not used? 2019/03/20 11:13:34 (permalink)
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    We had the same problem. Connecting VUSB3V3 to ground means that you only get a ligic high voltage of 1.5v if you use the USB pins as GPIO.   Now we just connect it to 3.3v, even though we do not use the USB function.  Our design is AC powered so we do not really care about power consumption.
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    Larry.Standage
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    Re: what are the proper connections for VBUS and VUSB3V3 in case the USB is not used? 2019/03/20 13:05:48 (permalink)
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    You get slightly lower power consumption by grounding the VUSB3V3 pin, so it's really just a matter of whether the difference (IIRC, around 10mA) is important.
    #4
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