The block diagram shows this as a closed-loop regulator, not just some jfet sort of thing.
The high minimum voltage and unspecified capacitance/speed limits its use, but it is cute.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
onsdag den 30. maj 2018 kl. 17.24.34 UTC+2 skrev John Larkin:
I think we used a similar one to current limit a relay drive, it didn't like that much
AC or DC relay?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
onsdag den 30. maj 2018 kl. 19.29.46 UTC+2 skrev John Larkin:
DC
block diagram is a fiction
What's actually inside?
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Interesting question: it'd be cheaper with a bipolar transistor as pass element. There's no mention of how the bias current of the reference is handled, which means that might be an error current.
But, the 7V minimum dropout does imply that the pass element is MOSFET. Is high voltage bipolar/FET now economic?
It'd be more interesting if it could work at 2V and was available in 1mA; a diode bridge and one of these would make a nice symmetric clamp. The intended LED drive is flawed, because you have high voltage DC going to the lamps (very hard to keep that safe as a shock hazard). Two of 'em back-to-back, if they could work that way, would drive AC into antiparallel LED strings without that problem.
OnSemi has a line of these intended for low wattage LED bulbs powered by the mains. They have a little bit more of a description of the technology they're using.
Just use your diode bridge idea. It'll knock the peaks off the current waveform just fine.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
I've tested the On parts. They act like big jfets and are probably depletion mosfets with substrate diodes. They are ohmic near zero volts and go constant-current at a couple of volts.
The E:I curve of the Diodes parts is nothing like that. They are not ohmic and at room temp, they begin conducting at 4 volts or so.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
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