Author Topic: Description of CDP and DCP port at page 395  (Read 365 times)

jsjohnsen

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Description of CDP and DCP port at page 395
« on: September 19, 2016, 10:23:54 am »
When I read the description of CDP and DCP port at page 395, I get the understanding that the receptacle is a Standard-A.
In fact when I read the USB Power Delivery Rev. 2.0 the receptacle is called Standard-A PD and that is not the same. (USB_PD_R2_0 V1.2 -20160325 - ECN clean markup 20160802.pdf page 83)
Is that a mistake in the book, or am I reading the standard wrong?

(don't know if you want the comment here on in the USB section)

BR
Jesper Johnsen


Jan Axelson

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Re: Description of CDP and DCP port at page 395
« Reply #1 on: September 19, 2016, 08:32:39 pm »
The Battery Charging 1.2 spec predates USB Power Delivery 2.0 and thus doesn't mention PD connectors.

jsjohnsen

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Re: Description of CDP and DCP port at page 395
« Reply #2 on: September 20, 2016, 01:31:11 am »
Hi Jan.

I will take a look at the Battery Charging spec also.
I spend some time digging even further and that only contribute to the deception  ;D

Source: USB_PD_R2_0 V1.2 -20160325 - ECN clean markup 20160802.pdf page"  section 3.1 .1 page 65
Standard, non-PD, receptacles used in USB Power Delivery capable products are limited to a nominal vSafe5V at 1.5A as defined in [USB BC 1.2] .

vSafe5V is the VBUS definition of 4.75 to 5.5V, and the cable needed for 1.5A is however standard:

Source: USB_PD_R2_0 V1.2 -20160325 - ECN clean markup 20160802.pdf page"  section 3.1 .1 page 65
Non-marked Cable Assemblies 3.3.1
Limitations are placed on the use of legacy cable assemblies (i.e., ones not marked).
Legacy cable assemblies include all cable assemblies with USB 2.0 or USB 3.1 Standard-A Connectors, USB 2.0 or USB 3.1 Standard-B Connectors, USB 3.1 Powered-B Connectors, and USB 2.0 or USB 3.1 Micro-B Connectors.
Devices shall only use these non-marked legacy cable assemblies at vSafe5V and up to 1.5A as described by [USB 2.0], [USB 3.1] and [USB BC 1.2] .

So as long you stay below 1.5A (which is the spec for CDP and DCP according to your book), it could be ok.
If I have a device that can operate at 100 and 500mA, that connects to a CDP and follow the processes written in the Battery Charging spec.
Do the standards restrict me from using the extra current to other purposes than charging batteries?
1) to meet 500mA I have to disable features
2) my device can charge a headset with a battery

« Last Edit: September 20, 2016, 02:25:44 am by jsjohnsen »

Jan Axelson

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Re: Description of CDP and DCP port at page 395
« Reply #3 on: September 20, 2016, 12:50:41 pm »
Currents greater than 500 mA (USB 2.0) or 900 mA (USB 3.1) are legal only for charging or for other purposes as specified in the USB PD 2.0 spec.