Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
> The machine I'm using right now, which is just about a year old, is
> practically overflowing with USB-A ports. But it only has one USB-C
> port. How long has USB-C been around?

In my house just a couple of weeks - I used my first USB-C device
last month, via a cable to a USB-A plug. Another flimsy little
connector that I'm likely to break, like devices with MicroUSB
connectors, when I accidentally catch the cable with my arm and
yank them about.

The USB-PD standards are interesting. Upon first reading about them
I was keen to find/design a device to just break out the outputs
and have a mini variable power supply for general use, even battery
powered from one of those power bank devices. But as with most
things USB3/C it turns out the power supplies that are actually
available only implement the bare minimum range of voltage outputs
that the manufacturers think most people will need.

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On 2024-06-08, Computer Nerd Kev wrote:
> Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
>> The machine I'm using right now, which is just about a year old, is
>> practically overflowing with USB-A ports. But it only has one USB-C
>> port. How long has USB-C been around?
>
> In my house just a couple of weeks - I used my first USB-C device
> last month, via a cable to a USB-A plug. Another flimsy little
> connector that I'm likely to break, like devices with MicroUSB
> connectors, when I accidentally catch the cable with my arm and
> yank them about.
>
> The USB-PD standards are interesting. Upon first reading about them
> I was keen to find/design a device to just break out the outputs
> and have a mini variable power supply for general use, even battery
> powered from one of those power bank devices. But as with most
> things USB3/C it turns out the power supplies that are actually
> available only implement the bare minimum range of voltage outputs
> that the manufacturers think most people will need.

Mine here are all 5/9/15/20V. I "think" they're missing only 1 or 2
voltages, but that's enough for my laptops and cell phones. Not really
sure what'd ask for 9 or 15 volts ...

Bear in mind that it's ONE output, and you negotiate the voltage on the
wire as part of the connection handshaking (IIRC CC1/2 or maybe
something more active later on, been a bit since I read up on how PD
works)

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Dan Purgert <dan@djph.net> wrote:
> On 2024-06-08, Computer Nerd Kev wrote:
>> The USB-PD standards are interesting. Upon first reading about them
>> I was keen to find/design a device to just break out the outputs
>> and have a mini variable power supply for general use, even battery
>> powered from one of those power bank devices. But as with most
>> things USB3/C it turns out the power supplies that are actually
>> available only implement the bare minimum range of voltage outputs
>> that the manufacturers think most people will need.
>
> Mine here are all 5/9/15/20V. I "think" they're missing only 1 or 2
> voltages, but that's enough for my laptops and cell phones. Not really
> sure what'd ask for 9 or 15 volts ...

9V plugpacks are pretty common for stuff I use, it's typical for
devices that reduce that to 5V internally. Similarly 5V devices
generally use 3.3V internally. My laptop's power supply is 16V, so
15V might work.

But really what excited me were the newer PPS power supplies (USB-C
3.0 PD PPS, to use their full title). These are supposed to supply
a requested voltage in 20mV steps between 3.3V and 21V+. The idea
is to allow optimised battery charging by supplying a charge
voltage/current specific to the state of charge that the battery is
in. I just liked the idea of completely universal plugpacks, but
when I went shopping for them (and granted they're quite new to the
market in Australia) the models on offer had a much more limited
voltage/current range.

> Bear in mind that it's ONE output, and you negotiate the voltage on the
> wire as part of the connection handshaking (IIRC CC1/2 or maybe
> something more active later on, been a bit since I read up on how PD
> works)

Yes it's all rather complicated, but in theory a device to allow
manual control of the output could be quite cheap because there
are chips designed for doing that in relatively dumb USB-C-powered
devices. However I found a project online from someone who'd tried
making a bench power supply adapter from a wide-range USB-PD PPS
power supply and they found the outputs were so far off what was
requested that they ended up setting it to a fixed output and used
another regulator for the final output. So not using the voltage
programming ability of the USB power supply after all. I realised
then that I was probably wasting my time - it's a standard for a
perfect power supply, which might only be used to make
barely-good-enough-to-sell power supplies. I shouldn't really have
been surprised.

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On 2024-06-16, Computer Nerd Kev wrote:
> Dan Purgert <dan@djph.net> wrote:
>> On 2024-06-08, Computer Nerd Kev wrote:
>>> The USB-PD standards are interesting. Upon first reading about them
>>> I was keen to find/design a device to just break out the outputs
>>> and have a mini variable power supply for general use, even battery
>>> powered from one of those power bank devices. But as with most
>>> things USB3/C it turns out the power supplies that are actually
>>> available only implement the bare minimum range of voltage outputs
>>> that the manufacturers think most people will need.
>>
>> Mine here are all 5/9/15/20V. I "think" they're missing only 1 or 2
>> voltages, but that's enough for my laptops and cell phones. Not really
>> sure what'd ask for 9 or 15 volts ...
>
> 9V plugpacks are pretty common for stuff I use, it's typical for
> devices that reduce that to 5V internally. Similarly 5V devices
> generally use 3.3V internally. My laptop's power supply is 16V, so
> 15V might work.

Not sure what a "9v plugpack" is -- maybe something leaning a little
more "professional grade", like what photographers tend to carry about?
All of my "5v(tm) devices" are certainly running lower voltages inside
-- batteries are only 3.7 to 4.2 volts (or thereabouts) anyway, and I
know my phone has a lot of 1.8 volt things inside.

I was more saying that I couldn't really think of anything that'd take
the middle voltages, given what I'm familiar with.

>
> But really what excited me were the newer PPS power supplies (USB-C
> 3.0 PD PPS, to use their full title). These are supposed to supply
> a requested voltage in 20mV steps between 3.3V and 21V+. The idea
> is to allow optimised battery charging by supplying a charge
> voltage/current specific to the state of charge that the battery is
> in. I just liked the idea of completely universal plugpacks, but
> when I went shopping for them (and granted they're quite new to the
> market in Australia) the models on offer had a much more limited
> voltage/current range.
>
>> Bear in mind that it's ONE output, and you negotiate the voltage on the
>> wire as part of the connection handshaking (IIRC CC1/2 or maybe
>> something more active later on, been a bit since I read up on how PD
>> works)
>
> Yes it's all rather complicated, but in theory a device to allow
> manual control of the output could be quite cheap because there
> are chips designed for doing that in relatively dumb USB-C-powered
> devices. However I found a project online from someone who'd tried
> making a bench power supply adapter from a wide-range USB-PD PPS
> power supply and they found the outputs were so far off what was
> requested that they ended up setting it to a fixed output and used
> another regulator for the final output. So not using the voltage
> programming ability of the USB power supply after all. I realised
> then that I was probably wasting my time - it's a standard for a
> perfect power supply, which might only be used to make
> barely-good-enough-to-sell power supplies. I shouldn't really have
> been surprised.

Happen to have a link to the project? Or was it something you came
across ages ago?

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|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860

Dan Purgert <dan@djph.net> wrote:
> On 2024-06-16, Computer Nerd Kev wrote:
>> Dan Purgert <dan@djph.net> wrote:
>>> On 2024-06-08, Computer Nerd Kev wrote:
>>>> The USB-PD standards are interesting. Upon first reading about
>>>> them I was keen to find/design a device to just break out the
>>>> outputs and have a mini variable power supply for general use,
>>>> even battery powered from one of those power bank devices. But as
>>>> with most things USB3/C it turns out the power supplies that are
>>>> actually available only implement the bare minimum range of
>>>> voltage outputs that the manufacturers think most people will
>>>> need.
>>>
>>> Mine here are all 5/9/15/20V. I "think" they're missing only 1 or
>>> 2 voltages, but that's enough for my laptops and cell phones. Not
>>> really sure what'd ask for 9 or 15 volts ...
>>
>> 9V plugpacks are pretty common for stuff I use, it's typical for
>> devices that reduce that to 5V internally. Similarly 5V devices
>> generally use 3.3V internally. My laptop's power supply is 16V, so
>> 15V might work.
>
> Not sure what a "9v plugpack" is -- maybe something leaning a little
> more "professional grade", like what photographers tend to carry
> about?

I interpreted "plugpack" in this context to be Kev's word for what most
of the rest of us refer to as a "wall-wart".

Dan Purgert <dan@djph.net> wrote:
> Not sure what a "9v plugpack" is -- maybe something leaning a little
> more "professional grade", like what photographers tend to carry about?
> All of my "5v(tm) devices" are certainly running lower voltages inside
> -- batteries are only 3.7 to 4.2 volts (or thereabouts) anyway, and I
> know my phone has a lot of 1.8 volt things inside.
>
> I was more saying that I couldn't really think of anything that'd take
> the middle voltages, given what I'm familiar with.

A number of things which charge at medium speeds - 20-45W use the 9 or 12v
rails.

I have a Dell 130W USB-C charger which doesn't do full PD - it's only 5V or
20V (at 6.5A each). They skip the 9V and 15V modes because their laptops
only really care about 20V (and they provide 5V because that's compulsory).
However that will only slow charge a Pixel phone (which fast charges on a
45W brick).

The reasoning is that you get 3A out of the 5/9/15V rails, so the Dell
charger is only able to provide max 15W, meanwhile the 45W charger can do
3A@9V (=27W) and 3A@15V (45W). The phone is I think selecting the 9V rail
to charge faster, and presumably can't handle the 20V input.

Theo

Dan Purgert <dan@djph.net> wrote:
> On 2024-06-16, Computer Nerd Kev wrote:
>> Dan Purgert <dan@djph.net> wrote:
>>> Mine here are all 5/9/15/20V. I "think" they're missing only 1 or 2
>>> voltages, but that's enough for my laptops and cell phones. Not really
>>> sure what'd ask for 9 or 15 volts ...
>>
>> 9V plugpacks are pretty common for stuff I use, it's typical for
>> devices that reduce that to 5V internally. Similarly 5V devices
>> generally use 3.3V internally. My laptop's power supply is 16V, so
>> 15V might work.
>
> Not sure what a "9v plugpack" is -- maybe something leaning a little
> more "professional grade", like what photographers tend to carry about?

As Rich suggests others call them wall warts, though I thought
plugpack was actually the more universal term for them. Power
supplies with a mains connector built into the enclosure, including
USB ones. Not only supplied with things that charge batteries or
perform computer functions.

>> Yes it's all rather complicated, but in theory a device to allow
>> manual control of the output could be quite cheap because there
>> are chips designed for doing that in relatively dumb USB-C-powered
>> devices. However I found a project online from someone who'd tried
>> making a bench power supply adapter from a wide-range USB-PD PPS
>> power supply and they found the outputs were so far off what was
>> requested that they ended up setting it to a fixed output and used
>> another regulator for the final output. So not using the voltage
>> programming ability of the USB power supply after all. I realised
>> then that I was probably wasting my time - it's a standard for a
>> perfect power supply, which might only be used to make
>> barely-good-enough-to-sell power supplies. I shouldn't really have
>> been surprised.
>
> Happen to have a link to the project? Or was it something you came
> across ages ago?

It was a while ago and if it's the one I found now in my bookmarks
then it's not clear if they were actually using a PPS USB supply
anyway. I've probably been mis-remebering again:
https://tokarski.dev/posts/bench-power-supply-usb-c/

Likely it was just the limited specs of the PPS power supplies
available in Australia put me off the idea, but that was probably
at least six months ago so I should look again.

This article describes charging Li-Ion cells by using a USB-C
development/testing tool to control a PPS one:
https://ripitapart.com/2022/12/31/directly-charging-li-ion-batteries-with-a-usb-c-pd-tester/

That does suggest their current regulation can't be relied on:

"Although the PPS specification allows a device to set a maximum
current level, my own testing revealed that there was too much
variation amongst all my different adapters that I could not rely
on the hardware to perform the constant-current regulation with
enough precision for my liking"

But it seems the voltage regulation from the ones he tested was
acceptable.

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On 2024-06-17, Computer Nerd Kev wrote:
> Dan Purgert <dan@djph.net> wrote:
>> On 2024-06-16, Computer Nerd Kev wrote:
>>> Dan Purgert <dan@djph.net> wrote:
>>>> Mine here are all 5/9/15/20V. I "think" they're missing only 1 or 2
>>>> voltages, but that's enough for my laptops and cell phones. Not really
>>>> sure what'd ask for 9 or 15 volts ...
>>>
>>> 9V plugpacks are pretty common for stuff I use, it's typical for
>>> devices that reduce that to 5V internally. Similarly 5V devices
>>> generally use 3.3V internally. My laptop's power supply is 16V, so
>>> 15V might work.
>>
>> Not sure what a "9v plugpack" is -- maybe something leaning a little
>> more "professional grade", like what photographers tend to carry about?
>
> As Rich suggests others call them wall warts, though I thought
> plugpack was actually the more universal term for them. Power

OHHHH. Yeah, never heard them as "plugpack", but I guess "regional
dialect differences" comes heavily into play with talking online :)

>> Happen to have a link to the project? Or was it something you came
>> across ages ago?
>
> It was a while ago and [...]
>

Thanks for the links :) . Finally got around to reading them --
interesting stuff.

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|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860