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Author Topic: USB Power standards was RE: ts-590  (Read 4664 times)
NV5E
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Posts: 20




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« Reply #30 on: July 10, 2013, 07:09:55 PM »

It seems like people are confusing USB Power Delivery (note capitals) specifications with USB power delivery specifications.  USB Power Delivery is a new (2012) spec that allows for up to 100W over special "PD Aware" USB cables.  Non PD Aware USB is limited to 500mA for USB 1 & 2.  All of that is in the document cited by KE3WD.  So, unless you have "USB Power Delivery" equipment and cables, then you're limited to 500mA (900 for USB 3).
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KD8MJR
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« Reply #31 on: July 10, 2013, 07:31:52 PM »

I don't know how many people will have to say it to him for him to believe it but thanks for jumping in.  It's sad to see that W8JX was taking such a beating while trying to help a fellow ham and that's why I jumped in. Once I agreed with 8JX he started pounding on me.
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K0BT
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Posts: 190




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« Reply #32 on: July 10, 2013, 10:57:09 PM »

NV5E has it right.  The original USB 1.0 aand 2.0 specifications called for 500mA and a new spec allows for up to 100W.  

References:
http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip defines the maximum current under the original specifications.  

http://www.usb.org/developers/docs/usb_20_070113.zip contains the USB 2.0 specifications.  In "Universal Serial Bus Specification" Rev 2.0, chapter 7, section 7.3.2 contains the electrical characteristics table.

The new USB Power Delivery specification is outlined in the http://www.usb.org/developers/docs/usb_20_070113.zip file under file name USB_PD_R1_0 V1.2_Final - 20130626.pdf.  Appendix A of this document describes the new USB Power Delivery profiles.  This is a revision to the original USB specification and is designed to address the proliferation of devices that use USB for power and battery charging.


Back to the original post.  The USB port on the TS-590 should draw 2.5mA or less while inactive.





« Last Edit: July 10, 2013, 11:54:02 PM by K0BT » Logged
KD8MJR
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Posts: 2523




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« Reply #33 on: July 11, 2013, 03:28:11 PM »

NV5E has it right.  The original USB 1.0 aand 2.0 specifications called for 500mA and a new spec allows for up to 100W.  

K0BT just out of curiosity, can you even buy the "USB Power Delivery system and cables" or is this just a proposal that they are trying to get adopted?  It would seem to me that something like this would have a very limited market since usb is a data connection first and foremost and not really made to be used as a Power Supply .
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K0BT
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Posts: 190




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« Reply #34 on: July 11, 2013, 04:23:21 PM »

NV5E has it right.  The original USB 1.0 aand 2.0 specifications called for 500mA and a new spec allows for up to 100W.  

K0BT just out of curiosity, can you even buy the "USB Power Delivery system and cables" or is this just a proposal that they are trying to get adopted?  It would seem to me that something like this would have a very limited market since usb is a data connection first and foremost and not really made to be used as a Power Supply .

I know of two companies (Obsidian Technology and Canova Tech) that are supposed to be releasing evaluation boards but I haven't come across any production devices that follow the new standards.

http://www.canovatech.com/ct20600.html
http://ot1.com/joomla2/products/usb-power-delivery
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KE3WD
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« Reply #35 on: July 11, 2013, 04:47:57 PM »

NV5E has it right.  The original USB 1.0 aand 2.0 specifications called for 500mA and a new spec allows for up to 100W.  

References:
http://www.usb.org/developers/devclass_docs/batt_charging_1_1.zip defines the maximum current under the original specifications.  

And, in this document, we find, on pg 25: 

Quote

3.5 Charging Current Limits

The standard-A connectors defined in the USB 2.0 specification are rated for 1500mA.  Charging ports are allowed to use standard-A connectors.  If a charging port is capable of outputting more than 1500mA, then that port shall use a version of the standard-A connector that can handle the maximum output current.  [/i]

emphasis added

Please explain why they would state the above last sentence if the power is limited to 500mA. 

And, this is referring to USB 2.0, check out the original, the USB "1" power spec. 

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K0BT
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Posts: 190




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« Reply #36 on: July 11, 2013, 05:53:45 PM »


And, in this document, we find, on pg 25: 

Quote

3.5 Charging Current Limits

The standard-A connectors defined in the USB 2.0 specification are rated for 1500mA.  Charging ports are allowed to use standard-A connectors.  If a charging port is capable of outputting more than 1500mA, then that port shall use a version of the standard-A connector that can handle the maximum output current.  [/i]

emphasis added

Please explain why they would state the above last sentence if the power is limited to 500mA. 

And, this is referring to USB 2.0, check out the original, the USB "1" power spec. 




I see where the confusion lies.  You are referring to a dedicated charging port or charger - not to the current limits on a USB host or hub data port.   

You are right if you are referring to dedicated battery chargers.  It sounds as though you work with devices that follow the battery charging specifications rather than the data port specifications.
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KE3WD
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Posts: 5689




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« Reply #37 on: July 11, 2013, 07:11:16 PM »

I'm not alone in this. 

Quote
High-speed, 480-Mbit/s USB 2.0 transfers are just the ticket for the USB104+PC/104Plus board. These include transfers from high-current-draw devices. Two downstream ports provide 500 mA, while the remaining two ports handle up to 2000 mA. Parvus' board costs $230, and it is compatible with a range of operating systems.

source: http://electronicdesign.com/boards/usb-20-adapter-handles-high-current-devices

There are at least several big brandname USB highend Audio Devices, such as those used for recording to pc, that also require darn near the full 2A as specified for the first USB.  Many of these, the only option to use them on a puter that does not meet the current requirement is to incorporate a powered USB hub. 

My particular design digitizes radar video signal and the A to D devices used, well, they are nothing but space heaters, really.  When we first started, we could use cards designed to insert into desktop slots.  Then came the clamor for having all those networked capabilities on the laptops and the darn laptop mfrs killed the pcmcia slots rather quickly, forcing the USB adaptors issue.  Add a chunk of smart software and they can overlay the radar right on top of the maps, scaled to suit.  Makes a radar reader out of just about anybody, it does.  At least as far as navigation goes.  Besides, it gives a warm fuzzy to see the radar's scan of a coastline where the coastline is on a map, all in one place, dontcha know.  Or, in the brownwater, a bridge, outcropping, etc. 


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