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| Power bipolar transistor die -> parallel??? |
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| Yansi:
Yesterday I have dug through a lot of different small high voltage depletion mode mosfets. Some of the datasheets claimed they are of DMOS type and also free from 2nd breakdown. :-// For example this one: http://ww1.microchip.com/downloads/en/DeviceDoc/LND150%20C041114.pdf Is that really true or not? Those Supertex/Microchip datasheets for these depletion mode trannies are often pisspure junk with incomplete information, sometimes even lacking characteristic plots completely (I am talking you, DN3145!) or having the characteristics incomplete, measured in areas the part will never be likely used at. |O |
| exe:
--- Quote from: Yansi on November 12, 2019, 04:50:31 pm ---For example this one: http://ww1.microchip.com/downloads/en/DeviceDoc/LND150%20C041114.pdf --- End quote --- Ha! Just recently I was looking for a depletion-mode fet. Found none back then. Here you are! Looking at characteristics, it feels it's just a poor jfet. I can imagine it's free from secondary breakdown because maximum current is just 13mA continius, 30mA pulsed, maximum voltages is +-20V. Try kill something with that! Gate leakage current is also not stellar. Afaik, I've seen jfet for large currents, like for 5 or 15 amps. But they are rare. |
| Yansi:
No, it is not a JFET. It is a MOS-FET, it has insulated gate. But sure, both types are depletion mode. There are surprisingly quite many high voltage small signal depletion fets out there, just have a search. (BSS126, LND150, DN3145, BSP135, ...) Sure, LDN150 is very low current one, but its specifically good for small high voltage current sources (as well as a very good analog input protection circuitry). These are not switching high current types. But this is a bit offtopic here. |
| magic:
--- Quote from: exe on November 12, 2019, 06:56:23 pm ---Afaik, I've seen jfet for large currents, like for 5 or 15 amps. But they are rare. --- End quote --- You have probably seen silicon carbide power JFETs. They are relatively new and pricey and AFAIK used mainly for switching high voltage with low RDS(on), although of course some exotic manufacturers are building audio amplifiers with them too ::) |
| exe:
Ah, I confused maximum gate voltage with Vds, sorry :(. I wonder what are the advantages of depletion mode mosfet vs jfet. Seems jfet supposed to have higher gate leakage, better works as a current source, and gate will conduct if reverse biased. Anything else? |
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