T
Tim Williams
- Jan 1, 1970
- 0
It's always so annoying to invert yourself a new power supply rail to
supply those high-side MOSFETs. And how much does it need? Average?
Peak? Microamperes or amperes?
Well the gate is a capacitor, why not recover some energy from it? Hmm,
could run a boost converter, but running one for sub-microsecond bursts
would be weird... How about just tacking an inductor on it, eh? Well,
then it'll resonate from its initial position to something swinging up and
down around a power supply rail. Let's clamp that flyback with a diode,
dumping the inductor's energy into the supply rail. With some keen drive,
I can see it running pretty low average current. Instead of a lossy
resistor, you have an inductor controlling rise/fall time. With a CMOS
sort of driver, I bet you could get consumption under a miliamp, using a
weedy flying capacitor supply for it.
Tim
supply those high-side MOSFETs. And how much does it need? Average?
Peak? Microamperes or amperes?
Well the gate is a capacitor, why not recover some energy from it? Hmm,
could run a boost converter, but running one for sub-microsecond bursts
would be weird... How about just tacking an inductor on it, eh? Well,
then it'll resonate from its initial position to something swinging up and
down around a power supply rail. Let's clamp that flyback with a diode,
dumping the inductor's energy into the supply rail. With some keen drive,
I can see it running pretty low average current. Instead of a lossy
resistor, you have an inductor controlling rise/fall time. With a CMOS
sort of driver, I bet you could get consumption under a miliamp, using a
weedy flying capacitor supply for it.
Tim