On 11/25/2014 11:05 AM, Anton Aylward wrote:
On 11/25/2014 01:39 PM, Lew Wolfgang wrote:
On 11/25/2014 10:35 AM, Anton Aylward wrote:
On 11/25/2014 01:19 PM, Lew Wolfgang wrote:
The laptop will have small DC-to-DC converters and/or regulators to develop the needed voltages. With 19-VDC from the wall-wart they've got plenty of "headroom" to run their regulators. Note that there are other voltages running around in there to power the CPU, which uses something around 2.2-VDC I think. 19V to 2.2V is one hell of a drop!
Yup, that's why it's done with switching power supplies. Resistive regulators would waste a lot of power. Indeed, but it still leaves the question open.
The switcher for laptops is external, the power-brick or wall-wart. I think that steps down with a transformer, then rectifies, then does the capacitive filtering and stabilization so that the 19VDC is delivered to the laptop. There is no switcher in the laptop that I can see when I take mine apart, just regulator chips.
Are we getting confused between the needs of a laptop, specifically for lightness, and the needs of a desktop/tower PC where the switcher is inside the case?
I've been asking about the laptop use-case.
Right. But I don't think the laptop relies on the wall-wart for regulation. They are certainly switching power supplies because they can accept (usually) 120/240-VAC at 50/60-Hz. You might not recognize a small switcher if its components were just connected directly to the motherboard. The transformers can be tiny because of the relatively high (20-KHz?) frequencies. I remember some high-end desktop motherboards where you could select CPU voltages in the Rom BIOS. This would be for gaming over-clocking. Regards, Lew -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org