#10441 NORM Not Tri: XO-1 and XO-1.5 response to invalid USB cabling configuration differs

[Zarro Boogs per Child]

#10441: XO-1 and XO-1.5 response to invalid USB cabling configuration differs
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           Reporter:  Quozl      |       Owner:  wad          
               Type:  defect     |      Status:  new          
           Priority:  normal     |   Milestone:  Not Triaged  
          Component:  hardware   |     Version:  not specified
         Resolution:             |    Keywords:               
        Next_action:  never set  |    Verified:  0            
Deployment_affected:             |   Blockedby:               
           Blocking:             |  
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Comment(by Quozl):

 '''Research''': characterise the response to incorrect USB cabling
 configuration, where current is injected into the USB port, such as via a
 Y cable with type A plugs attached to an external USB power supply and the
 laptop.

 '''Method''': a variable DC current source, followed by a pushbutton
 switch, followed by a digital multimeter in current mode, is attached to
 the USB port power pins.  An LED with series resistor is attached to
 another USB port.  A digital multimeter in voltage mode is connected
 across the USB port power pins.  The voltage provided by the laptop is
 measured as V(host).  Current is injected momentarily, and the current
 raised until the threshold is found at which the laptop responds I(fail).
 Voltage is measured with the current in place.

 '''Result''':

 ||''Serial Number''||''V(host)''||''I(ok)''||''I(fail)''||''Comments''||
 ||SHC016013D9 XO-1.5 D4||5.00 V||100 mA||107 mA||USB voltage does not rise
 much when current injected||
 ||SHC93701192 XO-1.5 B2||5.02 V||107 mA||108 mA||||
 ||CSN748043BE XO-1||4.97 V||125 mA||-||USB voltage rises easily, 7.35V||
 ||SHC016013D9 XO-1.5 D4||5.00 V||22 mA||44 mA||Repeated test without LED
 load on other port||

 I(ok) was the current tested immediately prior that did not cause the
 symptom.

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Ticket URL: <http://dev.laptop.org/ticket/10441#comment:2>
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