Electronics > Projects, Designs, and Technical Stuff
High voltage/low current Power supply
Neomys Sapiens:
Ok, 450V are not 600V and 20mA is just a fifth of 100mA, but those might have been exemplary values, so:
There is even a chip for that. Microchip LR84K will take up to 450V and provide you with a 20mA LV supply.
Red_Micro:
--- Quote from: Neomys Sapiens on April 09, 2020, 03:47:22 am ---Ok, 450V are not 600V and 20mA is just a fifth of 100mA, but those might have been exemplary values, so:
There is even a chip for that. Microchip LR84K will take up to 450V and provide you with a 20mA LV supply.
--- End quote ---
This one seems a good idea. I will have a look at it. Thanks!
NiHaoMike:
--- Quote from: Red_Micro on April 08, 2020, 12:15:03 am ---The size. Usually these kind of high voltage/low current supplies are used in small metering accessories.
--- End quote ---
Since the power needed is small, use a capacitor in series with a SIDAC to get fast rise time pulses that can be converted using a much smaller transformer.
jbb:
If looking at capacitive droppers in an industrial setting, beware large spikes passing straight through your dropper cap into the clamp circuitry.
On SiC MOSFET flyback:
- flyback converters work just fine without isolation
- SiC MOSFET is on 0 Volt potential, unlike buck converter
- SiC MOSFETs do cost more money, but may lower total system cost
Zero999:
--- Quote from: Red_Micro on April 08, 2020, 08:16:49 pm ---I was also looking into off-line-switchers like this approach: ti.com/tool/PMP11302
--- End quote ---
The general idea looks fine, as long as it doesn't need to be isolated.
www.ti.com/lit/df/tidrk45/tidrk45.pdf
The schematic I found on TI's website does contain an error. D3 the BY255GP-E3/54, is only rated for 1.3kV, yet it will see double the reverse peak mains voltage across it. This will limit the absolute maximum RMS AC input voltage to 1300/(2√2) = 460V. Another diode could be added, but I'd just run the whole thing off a suitable bridge rectifier and it should be fine up to 600VAC.
http://www.farnell.com/datasheets/2046942.pdf
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