3 ms·

Are there processors out there that can handle voltage drops without crashing?

by ghshephard 9y ago

ComputerGuru 9y ago
Pretty much all processors start off that way. The clock speed needs to drop to compensate, though. Unless you actually put some thought into your hardware designs because you're making phones that have a life expectancy of greater than a mere 12 months that will be used around the world for years to come... in which case you can easily reference an electrical engineering textbook and design a circuit that can buffer enough power and supply sufficient voltage/current to meet your expected max sustained power draw with some very simple and cheap components. But simple frequency scaling based off of _dynamically detected_ available power. There's no need to slow down a CPU based off the age of the battery so you can "guess" what the max speed you can safely run at without inducing a brownout is (and even less of a reason to do so in discrete steps instead of linearly scaling the performance, except if you're trying to do it discreetly) - all you have to do is monitor available power and scale the CPU clock rate accordingly in realtime. But if your circuit is poorly designed with no forethought as to what you'd do if the maximum rated power of the battery wasn't available, I suppose that's not so easy to retrofit.
sliverstorm 9y ago
Modern x86 chips have built in support for voltage drops, as part of margin recovery. As the chip changes activity profile increasing current draw (e.g. turning on all cores for multithreaded code) the voltage will drop until the regulators catch up. "Back in the day" you used margin to accommodate this. Today, circuitry detects these events on the fly and slows down the chip for a few microseconds waiting for the voltage to recover. This allows you to remove margin and operate closer to the limit.

3 ms·

Are there processors out there that can handle voltage drops without crashing?

by ghshephard 9y ago

Are there processors out there that can handle voltage drops without crashing?

ComputerGuru 9y ago
Pretty much all processors start off that way. The clock speed needs to drop to compensate, though. Unless you actually put some thought into your hardware designs because you're making phones that have a life expectancy of greater than a mere 12 months that will be used around the world for years to come... in which case you can easily reference an electrical engineering textbook and design a circuit that can buffer enough power and supply sufficient voltage/current to meet your expected max sustained power draw with some very simple and cheap components. But simple frequency scaling based off of _dynamically detected_ available power. There's no need to slow down a CPU based off the age of the battery so you can "guess" what the max speed you can safely run at without inducing a brownout is (and even less of a reason to do so in discrete steps instead of linearly scaling the performance, except if you're trying to do it discreetly) - all you have to do is monitor available power and scale the CPU clock rate accordingly in realtime. But if your circuit is poorly designed with no forethought as to what you'd do if the maximum rated power of the battery wasn't available, I suppose that's not so easy to retrofit.
sliverstorm 9y ago
Modern x86 chips have built in support for voltage drops, as part of margin recovery. As the chip changes activity profile increasing current draw (e.g. turning on all cores for multithreaded code) the voltage will drop until the regulators catch up. "Back in the day" you used margin to accommodate this. Today, circuitry detects these events on the fly and slows down the chip for a few microseconds waiting for the voltage to recover. This allows you to remove margin and operate closer to the limit.