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Comment by Stratoscope | Hacker News Reader

Lenovo has done something interesting in recent generations of laptop power supplies that made them a lot smaller and lighter.

The 170W power supply for my old ThinkPad W520 measures about 17cm x 8cm x 3cm and weighs about 580g.

The 170W supply for my new X1 Extreme measures about 14cm x 8cm x 2cm and weighs about 320g.

Does anyone know what technology let them make the power supply so much smaller and lighter?

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I would suspect that it is simply the subtle art of pushing components closer to their limits... since a laptop is unlikely to be drawing 170W continuously, they may be using PSUs with the same peak ratings but at a lower duty cycle.[1]

(Note that Lenovo itself almost certainly doesn't design nor produce them -- if there's a UL registration number or similar, you may be able to find the actual OEM/ODM.)

[1] You can see something similar in the marketing specs for cars vs. trucks - a performance car may have a 2L engine rated for 300HP, while you can find a truck with a 9L engine also rated at 300HP. The former is unlikely to last for long putting out its rated power.

While possible, high frequency microcontrollers and better capacitor technology (especially extremely low esr hybrid electrolytic capacitors) allow much better efficiency than was previously possible. Component costs have been driven down by wider adoption of inverters too.

Electronic speed controllers for brushless motors are one area you can really see this too - they are amazingly compact, efficient, and high power now.

Probably GaN

Exactly. GaN FETs are slowly taking hold of the market, due to their ridiculous performance capabilities (mainly being able to switch much faster than silicon for the same losses). I think there was a car manufacturer who reckons there would eventually not be any silicon power transistors in their vehicles, they would all be either GaN (for lower voltages) or SiC (for higher voltages).

Oh, thank you. Very interesting, that is exactly what it is:

https://www.google.com/search?q=lenovo+charger+gan

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