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possible solution for RPi USB hot plug problems

Former Member

Near the end of this page,

 

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=63&t=8591&start=100

 

is a successful report of adding a 1 Ohm quarter watt resistor over each

USB polyfuse, in order to prevent a voltage drop when a capacitor on the

USB device is recharged.

Parents

  • Or alternatively as mahjongg says, replace the two badly-specced USB polyfuses by ones with higher trip points as we said some weeks ago, so that they also have lower resistances.  That'll also stop the polyfuses making the USB Vcc drop out of spec so rapidly for power-hungry peripherals, so you kill two birds with one stone.

     

    This whole power management design saga is pretty funny.  The moral is, don't throw away several decades' worth of regulated supply practice just to save some pennies.  Toss the CSI/DSI connectors overboard first if you need a sacrifice.

     

    Morgaine.

  • in reply to morgaine

    Amen.

     

    I'm still trying to figure in which mind was that having those connectors was a good idea. I don't envision a large percentage of the R-Pi community ever use them.

     

    IMHO the entire power design on the R-Pi is flawed, plus to cut costs built with cheap knock-off components like the LDO's.

     

    I guess somebody was shopping on alibaba when they were putting together the BOM.

     

    -J

  • in reply to jamodio

    Jamodio,

     

    First of all the RPi is not made for most purposes the community uses it for.

    Officially it is created and designed for educational use. In education use these headers are usefull for expansion.

    And what is the problem with the LDO? I see no problems with them they are used in many designs without any problems, the USB should be used with keyboard and a mouse only and not for USB drives and so on.

    As stated earlier external storage should be powered through a USB HUB with external power supply.

  • in reply to MDeGrauw

    Sure, good for you. Read the "official" instruction manual ...

     

    -J

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