[LINK] The 'Sea Snake' Phenomenon: 'Please Explain'

[Scott Howard]

On Sat, Sep 25, 2021 at 12:38 AM Karl Auer <kauer at biplane.com.au> wrote:

> The smarts can go in the device just as easily as in the charger. USB-C
> can provide up to 3A right now. The standard will soon be extended to
> allow higher voltages and higher wattages, allowing USB-C to power
> laptops and similar devices. 5A, 240W, 50V.
>

USB-C currently officially supports up to 5A, which at 20 volts gives 100
watts which is more than enough to power most (but not all) laptops. Even
existing Apple laptops use this (the largest USB-C power supply Apple
provides is 96 watts).

3A is the minimum that a USB-C cable must support to be considered
compliant.  5A requires additional circuitry to advertise the fact it
supports the higher power, and the voltage used (5V up to 20V) is
negotiated between the two endpoints.

Some vendors push this even higher with custom hardware - my Dell laptop
runs off a 130 watts USB-C connection, but will only do so when connected
to a specific/supported power supply.

The new standards increase the max voltage up to ~50 volts whilst keeping
the current the same at 5A, getting to 240 watts as you've said.

  Scott