5 ms·

> It also supports USB-C Power Delivery, so finding a power supply that’s capable of supplying all that juice to the Pi 5 is a lot easier Isn't this mostly fal

by p1mrx 3y ago

> It also supports USB-C Power Delivery, so finding a power supply that’s capable of supplying all that juice to the Pi 5 is a lot easier Isn't this mostly false? The Pi4 uses 15W at 5V3A. The standard says, to exceed 15W you should increase the voltage, but Pi5 increased the amperage instead. 5V5A USB-PD supplies are almost unheard of. I wonder how much a 9V3A -> 5V5A buck converter dongle would cost.

zarzavat 3y ago
Yeah, ultimately if you want to run a Pi you ought to be buying an approved power supply. Trying to use random USB chargers even with a Pi 4 is a road to unhappiness. It doesn't have a battery, after all.
- comboy 3y ago
  Yes. But also you can try putting some big cap between 5V and GND before it arrives.
- BlueTemplar 3y ago
  Pi 4 does come with a power supply because of being even less standardized.
coder543 3y ago
I don’t agree. I found this straightforward statement: https://www.anandtech.com/show/16712/usbc-power-delivery-hits-240w-with-extended-power-range https://www.anandtech.com/show/16712/usbc-power-delivery-hit... > USB-PD R3.1 supports three charging models: > - Fixed voltage > - Programmable power supply (PPS), and > - Adjustable voltage supply (AVS). > In the fixed voltage scheme, the Standard Power Range (SPR) mode supports 3A and 5A at 5V, 9V, 15V, and 20V. That’s about as clear as it can be, assuming AnandTech is correct. Also keep in mind the existence of PPS as another data point. I have an Anker charger sitting in front of me that offers 3.3V-11V at 5A. 5V at 5A falls squarely in that range, as long as you have an e-marked cable that can support 5A. (I have no idea if the Pi 5 supports negotiating PPS, but it would increase compatibility with chargers if it does.) I agree the Pi 5 should have included a buck converter or something, but I don’t think it’s correct to say they’re not standards compliant. It’s just not a common use of the standard.
- KennyBlanken 3y ago
  It's not hard to find at all. https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Deliver... 5v3A is the limit of USB PD SPR.
  - coder543 3y ago
    No, Wikipedia is looking like it's out of date or wrong. It’s not a definitive source, especially for highly technical topics like this. Here is another industry source which has a table that also says 5V at 5A: https://www.graniteriverlabs.com/en-us/technical-blog/usb-power-delivery-specification-3-1 https://www.graniteriverlabs.com/en-us/technical-blog/usb-po... In fact, using Wikipedia’s sources, I found the actual specs and here is another piece of supporting evidence for these other articles: > The Fixed PDOs Maximum Current field Shall advertise at least 3A, but May advertise up to RoundUp (PDP/Voltage) to the nearest 10mA. Requires a 5A cable if over 3A is advertised.[0] This is a footnote attached to 5V3A, indicating to me that chargers are allowed to offer more than 3A at 5V. At a minimum, the spec seems to be ambiguously written, but I’ve only spent a few minutes skimming it. Multiple industry sources (previously linked) believe that 5V@5A is within the spec, even without using PPS. [0]: “USB_PD_R3_1 V1.8 2023-04”
    - Denvercoder9 3y ago
      You're both correct, but USB Power Delivery, like so many things USB, is a total mess with different revisions, and versions of those revisions, that each extend and deprecate parts of the previous revision. I'm going to ignore the actual protocol used for negotiation here, but there have also been at least three different protocols. The first revision, rev 1.0, had six fixed power profiles: 5V/2A, 12V/1.5A, 12V/3.0A, 12V/5.0A, 20V/3.0A and 20V/5.0A. These were deprecated by rev 2.0, version 1.2, which instead introduced power rules at four fixed voltages, supporting power supplies with different output powers. The maximum supported currents by the specification were 5V/3A, 9V/3A, 15V/3A and 20V/5A. These power rules were retroactively named the Standard Power Range (SPR) in rev 3.1. That revision also added the Extended Power Range (EPR), which raised all the current limits up to 5A, but only when used with electronically marked cables. EPR also added power rules at 28V, 36V and 48V, again requiring (differently) marked cables and up to 5A. So 5V/5A is a valid option, but only when used with a USB PD rev 3.1 compatible power supply and cable. Orthogonally to the fixed power rules, rev 3.0 introduced the Programmable Power Supply, which allows a configurable voltage between 3.3V and 21V in steps of 20 mV. This was extended by rev 3.1 with voltages between 15V and 48V in steps of 100 mV, called the Adjustable Voltage Supply. As far as I'm aware this is not commonly used, and most products advertising Power Delivery support use the predefined power rules.
KennyBlanken 3y ago
[flagged]
- tjoff 3y ago
  It is part of USB C PD, using PPS. Which is kind of new.
- ss48 3y ago
  Regarding the Side Note: probably because of their acquisition by Seimens: https://news.ycombinator.com/item?id=27556552 https://news.ycombinator.com/item?id=27556552
regularfry 3y ago
Probably about the same as the official supply, you'll probably start seeing them pop up. The current price I can see for the 5V5A supply is £11.90. They go into the trade-off in one of the launch videos. Apparently if you've only got a 3A supply then the downstream USB power gets limited but otherwise it works.
geerlingguy 3y ago
From my anecdotal evidence, I've found so far only the Radxa 30W adapter can negotiate 5v5a, most others only go up to 3A, and a few rare ones to 4a, but none I can find in the US. Even if the power adapter supplies it, without a high quality cable there's enough voltage drop to trigger the low voltage warning. I recommend the official supply or eventually the official new PoE+ HAT for now.
BlueTemplar 3y ago
At least better than the Pi3-, which could end up drawing up to 15W on a connector that officially only supports up to 2.5W, therefore resulting in lots and lots of bricked SD cards...
bmicraft 3y ago
The Pi 5 does not require not require more than 5V@3A, except if you plan on pulling significant current from its the USB ports. If you don't get the 5V@5A supply USB ports get limited to 600mA each and you're still good.

by p1mrx 3y ago

zarzavat 3y ago

Yeah, ultimately if you want to run a Pi you ought to be buying an approved power supply. Trying to use random USB chargers even with a Pi 4 is a road to unhappiness. It doesn't have a battery, after all.

comboy 3y ago
Yes. But also you can try putting some big cap between 5V and GND before it arrives.
BlueTemplar 3y ago
Pi 4 does come with a power supply because of being even less standardized.

coder543 3y ago

I don’t agree. I found this straightforward statement: https://www.anandtech.com/show/16712/usbc-power-delivery-hits-240w-with-extended-power-range https://www.anandtech.com/show/16712/usbc-power-delivery-hit... > USB-PD R3.1 supports three charging models: > - Fixed voltage > - Programmable power supply (PPS), and > - Adjustable voltage supply (AVS). > In the fixed voltage scheme, the Standard Power Range (SPR) mode supports 3A and 5A at 5V, 9V, 15V, and 20V. That’s about as clear as it can be, assuming AnandTech is correct. Also keep in mind the existence of PPS as another data point. I have an Anker charger sitting in front of me that offers 3.3V-11V at 5A. 5V at 5A falls squarely in that range, as long as you have an e-marked cable that can support 5A. (I have no idea if the Pi 5 supports negotiating PPS, but it would increase compatibility with chargers if it does.) I agree the Pi 5 should have included a buck converter or something, but I don’t think it’s correct to say they’re not standards compliant. It’s just not a common use of the standard.

KennyBlanken 3y ago
It's not hard to find at all. https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Deliver... 5v3A is the limit of USB PD SPR.
- coder543 3y ago
  No, Wikipedia is looking like it's out of date or wrong. It’s not a definitive source, especially for highly technical topics like this. Here is another industry source which has a table that also says 5V at 5A: https://www.graniteriverlabs.com/en-us/technical-blog/usb-power-delivery-specification-3-1 https://www.graniteriverlabs.com/en-us/technical-blog/usb-po... In fact, using Wikipedia’s sources, I found the actual specs and here is another piece of supporting evidence for these other articles: > The Fixed PDOs Maximum Current field Shall advertise at least 3A, but May advertise up to RoundUp (PDP/Voltage) to the nearest 10mA. Requires a 5A cable if over 3A is advertised.[0] This is a footnote attached to 5V3A, indicating to me that chargers are allowed to offer more than 3A at 5V. At a minimum, the spec seems to be ambiguously written, but I’ve only spent a few minutes skimming it. Multiple industry sources (previously linked) believe that 5V@5A is within the spec, even without using PPS. [0]: “USB_PD_R3_1 V1.8 2023-04”
  - Denvercoder9 3y ago
    You're both correct, but USB Power Delivery, like so many things USB, is a total mess with different revisions, and versions of those revisions, that each extend and deprecate parts of the previous revision. I'm going to ignore the actual protocol used for negotiation here, but there have also been at least three different protocols. The first revision, rev 1.0, had six fixed power profiles: 5V/2A, 12V/1.5A, 12V/3.0A, 12V/5.0A, 20V/3.0A and 20V/5.0A. These were deprecated by rev 2.0, version 1.2, which instead introduced power rules at four fixed voltages, supporting power supplies with different output powers. The maximum supported currents by the specification were 5V/3A, 9V/3A, 15V/3A and 20V/5A. These power rules were retroactively named the Standard Power Range (SPR) in rev 3.1. That revision also added the Extended Power Range (EPR), which raised all the current limits up to 5A, but only when used with electronically marked cables. EPR also added power rules at 28V, 36V and 48V, again requiring (differently) marked cables and up to 5A. So 5V/5A is a valid option, but only when used with a USB PD rev 3.1 compatible power supply and cable. Orthogonally to the fixed power rules, rev 3.0 introduced the Programmable Power Supply, which allows a configurable voltage between 3.3V and 21V in steps of 20 mV. This was extended by rev 3.1 with voltages between 15V and 48V in steps of 100 mV, called the Adjustable Voltage Supply. As far as I'm aware this is not commonly used, and most products advertising Power Delivery support use the predefined power rules.

KennyBlanken 3y ago

[flagged]

tjoff 3y ago
It is part of USB C PD, using PPS. Which is kind of new.
ss48 3y ago
Regarding the Side Note: probably because of their acquisition by Seimens: https://news.ycombinator.com/item?id=27556552 https://news.ycombinator.com/item?id=27556552

regularfry 3y ago

Probably about the same as the official supply, you'll probably start seeing them pop up. The current price I can see for the 5V5A supply is £11.90. They go into the trade-off in one of the launch videos. Apparently if you've only got a 3A supply then the downstream USB power gets limited but otherwise it works.

geerlingguy 3y ago

From my anecdotal evidence, I've found so far only the Radxa 30W adapter can negotiate 5v5a, most others only go up to 3A, and a few rare ones to 4a, but none I can find in the US. Even if the power adapter supplies it, without a high quality cable there's enough voltage drop to trigger the low voltage warning. I recommend the official supply or eventually the official new PoE+ HAT for now.

BlueTemplar 3y ago

At least better than the Pi3-, which could end up drawing up to 15W on a connector that officially only supports up to 2.5W, therefore resulting in lots and lots of bricked SD cards...

bmicraft 3y ago

The Pi 5 does not require not require more than 5V@3A, except if you plan on pulling significant current from its the USB ports. If you don't get the 5V@5A supply USB ports get limited to 600mA each and you're still good.