The Exigo: A high performance USB charger

[brabus]

Last question: do you offer any form of warranty for damages caused by your out-of-spec charger?

What's out of spec about it?

(...)

Correct if I am wrong, but I remember a 5V nominal voltage with a +/- 5% tolerance, hence 5.25V maximum, isn't it?

[tszaboo]

2.0 is specified 5V +/- 5%
USB 3.0 is 5V +0,25V/-0,55V (Why USB-IF, WHY??)

[Monkeh]

Go fetch http://www.usb.org/developers/docs/usb20_docs/usb_20_081114.zip and read the VBUS ECN.

Yes, it's very recent.

[tszaboo]

Go fetch http://www.usb.org/developers/docs/usb20_docs/usb_20_081114.zip and read the VBUS ECN.

Yes, it's very recent.

This is interesting. Hovewer:
"OEM’s can design products that support the higher power levels of the Type-C connector and provide VBUS levels at or above 5.25V..."
So you need the type C connector for that.

[Monkeh]

Go fetch http://www.usb.org/developers/docs/usb20_docs/usb_20_081114.zip and read the VBUS ECN.

Yes, it's very recent.

This is interesting. Hovewer:
"OEM’s can design products that support the higher power levels of the Type-C connector and provide VBUS levels at or above 5.25V..."
So you need the type C connector for that.

No, you don't, and that's not the specification, that's a reasoning. VBUS has been raised to max 5.5V, simple as.

[Monkeh]

You mean like Samsung do with their 2A chargers?

No. Samsung increase current until the voltage starts to sag below a certain level. What I suggest is that you raise the voltage above 5V so that after loss in the cable the device sees 5.0V exactly.

That's what Samsung 2A chargers do, and I have tested this. The output voltage of the charger rises with increasing current to offset the volt drop of the supplied, characterized cable.

[marcan]

You mean like Samsung do with their 2A chargers?

No. Samsung increase current until the voltage starts to sag below a certain level. What I suggest is that you raise the voltage above 5V so that after loss in the cable the device sees 5.0V exactly.

That's what Samsung 2A chargers do, and I have tested this. The output voltage of the charger rises with increasing current to offset the volt drop of the supplied, characterized cable.

I must say this sounded way too smart for Samsung and you just made me test my 2A charger, but you're right. 5.01V at the port no load, 5.08V pulling ~1A. I'm not sure where I put the original cable right now, so I can't test it, but that sounds reasonable for a decent cable. Clever.

[grenert]

Ist kaputt:
https://www.kickstarter.com/projects/1386151743/exigo-usb-charger/posts

[amyk]

I must say this sounded way too smart for Samsung and you just made me test my 2A charger, but you're right. 5.01V at the port no load, 5.08V pulling ~1A. I'm not sure where I put the original cable right now, so I can't test it, but that sounds reasonable for a decent cable. Clever.

It's nothing more than a minor change to the regulation loop, even some of the cheap (but not cheapest) no-name adapters have it.

[tszaboo]

Ist kaputt:
https://www.kickstarter.com/projects/1386151743/exigo-usb-charger/posts

That is actually good. Looks like lesson leared.  Good luck with the redesign!

[marcan]

It's nothing more than a minor change to the regulation loop, even some of the cheap (but not cheapest) no-name adapters have it.

Oh, I know it's easy to implement, I'm just surprised they bothered/thought of it. I don't think any of my other adapters do it, but then again the rest are either cheapies or multiport ones (with shared regulation) where it wouldn't make sense.

[timb]

By the way, Mike was right about linear regulators being everywhere with regards to USB battery charging. LiPo charging chips come in two flavors: Linear and Switching. Go check out TI's product portfolio.

Increases voltage = increased heat = higher chance of things breaking.


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