3 ms·

Short story they measure the output voltage every once in a while, depending on the load, instead of always measuring it. > If no device is drawing current fro

by gens 10y ago

Short story they measure the output voltage every once in a while, depending on the load, instead of always measuring it. > If no device is drawing current from the converter, or if the current is going only to a simple, local circuit, the controllers might release between 1 and a couple hundred packets per second. > .. To accommodate that range of outputs, a typical converter — even a low-power one — will simply perform 1 million voltage measurements a second; on that basis, it will release anywhere from 1 to 1 million packets. ^ Normal switched-mode converter, though a million is not realistic and they don't always work like that Considering that today's computers power supplies work at 70kHz, a megahertz is probably too much. (granted PSUs do PWM so i may be wrong, but it depends on the size of the capacitor at the output; then again chemical capacitors are bad for efficiency and block capacitors are huge compared to their capacity so block capacitors would have to be filled more often meaning more pulses meaning more losses on the FETs but then again transistors now have much lower capacitance and resistance then ever before but .. ramble ramble ramble etc) > Paidimarri and Chandrakasan’s converter thus features a variable clock, which can run the switch controllers at a wide range of rates. Theirs just varies the rate of (in programmers terms) pool()ing. Like clocking down a cpu when there is no load. (note: "packets" means pulses, see switched-mode power supply on wikipedia)

marcosdumay 10y ago
A bit longer story, they add a transistor before the voltage divider that is doing that measurement, and keep the circuit open most of the time: > so in the MIT researchers’ chip, the divider is surrounded by a block of additional circuit elements, which grant access to the divider only for the fraction of a second that a measurement requires That's not something you'd do in any high power PSU. It is really an IoT thing. It will decrease the full-on efficiency, while increasing the sleep efficiency. I also don't think they are using a 1 MHz PWM anywhere. That number probably leaked into the journalist notes from some irrelevant detail.

by gens 10y ago

marcosdumay 10y ago

A bit longer story, they add a transistor before the voltage divider that is doing that measurement, and keep the circuit open most of the time: > so in the MIT researchers’ chip, the divider is surrounded by a block of additional circuit elements, which grant access to the divider only for the fraction of a second that a measurement requires That's not something you'd do in any high power PSU. It is really an IoT thing. It will decrease the full-on efficiency, while increasing the sleep efficiency. I also don't think they are using a 1 MHz PWM anywhere. That number probably leaked into the journalist notes from some irrelevant detail.