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???
06/07/10 17:53
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 		 #176473 - Getting power from the USB port
Responding to: ???'s previous message
Raghunathan said:
I am trying to interface a 4-20mA two wire pressure transmitter ( loop powered ) to a USB data logger.

ANd hence the power drawn from the USB port will be about 20mA. Is this calculation right or do I need to add some more power value for the convertor to work ?

If the above is correct , will this be OK to load the USB port ( I have no information how much my Sony notebook can source)


PER THE USB SPEC:

You CANNOT hang something on a USB port without enumerating it as a device.

Don't do that.

Really. Just don't.

Thanks.

-a

List of 33 messages in thread
TopicAuthorDate
DC / DC Convertor            01/01/70 00:00      
   OK            01/01/70 00:00      
   that is not possible            01/01/70 00:00      
      Clarification            01/01/70 00:00      
         Select 9-12V with a capacity to supply up to 20mA            01/01/70 00:00      
            I think I see what is needed            01/01/70 00:00      
               Per forgot            01/01/70 00:00      
                  Incorrect....            01/01/70 00:00      
                     incorrect?            01/01/70 00:00      
   Getting power from the USB port            01/01/70 00:00      
      OK for Development            01/01/70 00:00      
         Required points clarified - thanks            01/01/70 00:00      
            trying again            01/01/70 00:00      
         re: OK?            01/01/70 00:00      
            The Curse Of Stuff That "Works" (sic)            01/01/70 00:00      
               USB has provisions for 1.8A from charger ports            01/01/70 00:00      
         I should know better, word of warning            01/01/70 00:00      
            Worse :(            01/01/70 00:00      
               Fuse?            01/01/70 00:00      
                  With picture            01/01/70 00:00      
                     And the external USB connectors?            01/01/70 00:00      
                     Is that really a PC motherboard?!            01/01/70 00:00      
                        Unusual USB connector.            01/01/70 00:00      
                           It all looks a bit "chunky"...            01/01/70 00:00      
                        It's a front panel board            01/01/70 00:00      
                     Both Ports??            01/01/70 00:00      
                        Yes, both ports            01/01/70 00:00      
                           Fusing S/B on main board            01/01/70 00:00      
                           Poor C6...            01/01/70 00:00      
               Bolt that stable door!            01/01/70 00:00      
      Really?            01/01/70 00:00      
         Standby?            01/01/70 00:00      
      RE: Getting power from the USB            01/01/70 00:00      

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