02-08-2015, 10:14 AM
That IC is primarily designed to replace the high-value start-up resistor in switched-mode power supplies that always fails high. And as such, the current it can supply is quite limited - fair enough! It's basically a super-charged LM317 - and most application circuits for the 317 could probably be adapted to this device.
So it would be quite easy to use this to drive a MOS-FET. A single BJT might be pushing your luck, but Darlington would probably be OK. You'd need to pay attention to current limiting and protection, naturally. Essentially, a P-channel MOS-FET is needed, along with a few resistors and a "jellybean" BJT for current limiting. Put the MOS-FET on a heat sink, and I'd add a bi-metallic thermal switch for insurance.
Most voltage regulators use a band-gap reference - these are very stable, and in practice, the two resistors surrounding the IC will dominate the DC precision. Remember, standard 0.25W resistors are only rated for 250V! Metal oxide types are good for high voltage operation. If this is to be variable, then check the rating of the pots or switches.
I'm a little concerned about how you have 450V between 2 legs of a TO92 package!
So it would be quite easy to use this to drive a MOS-FET. A single BJT might be pushing your luck, but Darlington would probably be OK. You'd need to pay attention to current limiting and protection, naturally. Essentially, a P-channel MOS-FET is needed, along with a few resistors and a "jellybean" BJT for current limiting. Put the MOS-FET on a heat sink, and I'd add a bi-metallic thermal switch for insurance.
Most voltage regulators use a band-gap reference - these are very stable, and in practice, the two resistors surrounding the IC will dominate the DC precision. Remember, standard 0.25W resistors are only rated for 250V! Metal oxide types are good for high voltage operation. If this is to be variable, then check the rating of the pots or switches.
I'm a little concerned about how you have 450V between 2 legs of a TO92 package!
