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New depletion MOSFET - BSS126

Started by Unknown September 13, 2020
I happened upon this today while looking at other things...

BSS126 - 600V, 500 ohms, Idss = 21mA.

https://www.infineon.com/cms/en/product/power/mosfet/60v-600v-n-channel-depletion-mode-mosfet/

I've not used any depletion MOSFETs but I know some of you guys are fans (and I hope to join the fan club someday too)!

Cheers,
James Arthur
On 2020-09-13 15:27, dagmargoodboat@yahoo.com wrote:
> I happened upon this today while looking at other things... > > BSS126 - 600V, 500 ohms, Idss = 21mA. > > https://www.infineon.com/cms/en/product/power/mosfet/60v-600v-n-channel-depletion-mode-mosfet/ > > I've not used any depletion MOSFETs but I know some of you guys are fans (and I hope to join the fan club someday too)! > > Cheers, > James Arthur >
Weird. The LND150 is 500V, 1.6 mA, and looks like 1k for small signals. 13 of them in parallel would have about the same IDSS but only 1/4 of the zero-bias resistance. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
On Sun, 13 Sep 2020 12:27:42 -0700 (PDT), dagmargoodboat@yahoo.com
wrote:

>I happened upon this today while looking at other things... > >BSS126 - 600V, 500 ohms, Idss = 21mA. > >https://www.infineon.com/cms/en/product/power/mosfet/60v-600v-n-channel-depletion-mode-mosfet/ > >I've not used any depletion MOSFETs but I know some of you guys are fans (and I hope to join the fan club someday too)! > >Cheers, >James Arthur
Nice. But Idss is 7 mA min, 25 typ (from the graphs), no max. And Id is 21 mA abs max! So it can't legally be used at Idss. The Supertex parts are very repeatable in real life. I use a lot of LND250 and DN2530. Depletions are good for all sorts of things. Like to discharge filter caps through an LED. The voltage declines linearly to near zero, where the LED winks out. Nice for current limiters and making high-voltage regulators. -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard
On Sun, 13 Sep 2020 13:58:14 -0700, jlarkin@highlandsniptechnology.com
wrote:

>On Sun, 13 Sep 2020 12:27:42 -0700 (PDT), dagmargoodboat@yahoo.com >wrote: > >>I happened upon this today while looking at other things... >> >>BSS126 - 600V, 500 ohms, Idss = 21mA. >> >>https://www.infineon.com/cms/en/product/power/mosfet/60v-600v-n-channel-depletion-mode-mosfet/ >> >>I've not used any depletion MOSFETs but I know some of you guys are fans (and I hope to join the fan club someday too)! >> >>Cheers, >>James Arthur > >Nice. > >But Idss is 7 mA min, 25 typ (from the graphs), no max. And Id is 21 >mA abs max! So it can't legally be used at Idss. > >The Supertex parts are very repeatable in real life. I use a lot of >LND250 and DN2530. > >Depletions are good for all sorts of things. Like to discharge filter >caps through an LED. The voltage declines linearly to near zero, where >the LED winks out. > >Nice for current limiters and making high-voltage regulators.
We use one DM NFET in a product I think. Normally On I like to call them. We were talking about depeletion mode FETs the other day and I wondered why I could not find a P-Channel depletion mode FET ? I don't think that anyone makes a P-chammel version ? Anybody know ? Not that I need one.... Just wondering
boB wrote:

> We were talking about depeletion mode FETs the other day and I > wondered why I could not find a P-Channel depletion mode FET ? > > I don't think that anyone makes a P-chammel version ? Anybody know ? > Not that I need one.... Just wondering
Nothing fundamental, they can be found in the ICs. Best regards, Piotr
dagmargoodboat@yahoo.com wrote:


 >BSS126 - 600V, 500 ohms, Idss = 21mA.

600V in SOT23, that is interesting.

 >I've not used any depletion MOSFETs but I know some of you guys are 
 >fans (and I hope to join the fan club someday too)!

Yes, they are cool.

Olaf
On 9/14/2020 1:40 AM, Piotr Wyderski wrote:
> boB wrote: > >> We were talking about depeletion mode FETs the other day and I >> wondered why I could not find a P-Channel depletion mode FET ? >> >> I don't think that anyone makes a P-chammel version ?  Anybody know ? >> Not that I need one....  Just wondering > > Nothing fundamental, they can be found in the ICs. > >     Best regards, Piotr
Only thing that's not reasonable to make AFAIK in a BICMOS process is a PNP power BJT, at least not if you want N-type devices on the same die since the substrate layer is usually P material, and not thick enough for both the buried collector p-type section and n-type isolation layer around it you'd need to handle high currents.
On Sunday, September 13, 2020 at 12:27:49 PM UTC-7, dagmarg...@yahoo.com wrote:
> I happened upon this today while looking at other things... > > BSS126 - 600V, 500 ohms, Idss = 21mA. > > https://www.infineon.com/cms/en/product/power/mosfet/60v-600v-n-channel-depletion-mode-mosfet/ > > I've not used any depletion MOSFETs but I know some of you guys are fans (and I hope to join the fan club someday too)!
Cool. Thanks. I used a couple BSS159N recently in a current source/limiter. For that app, any solutions that were not depletion were more complicated. The thing about depletion is that you must do something to "turn it off" (stop it from conducting) whereas for enhancement (MOS) and bipolar, something must be done to "turn it on." So, that "ON till you turn it OFF" is a special characteristic not easily emulated by other devices.
On Wed, 16 Sep 2020 11:12:14 -0700 (PDT), Simon S Aysdie
<gwhite@ti.com> wrote:

>On Sunday, September 13, 2020 at 12:27:49 PM UTC-7, dagmarg...@yahoo.com wrote: >> I happened upon this today while looking at other things... >> >> BSS126 - 600V, 500 ohms, Idss = 21mA. >> >> https://www.infineon.com/cms/en/product/power/mosfet/60v-600v-n-channel-depletion-mode-mosfet/ >> >> I've not used any depletion MOSFETs but I know some of you guys are fans (and I hope to join the fan club someday too)! > >Cool. Thanks. > >I used a couple BSS159N recently in a current source/limiter. For that app, any solutions that were not depletion were more complicated. > >The thing about depletion is that you must do something to "turn it off" (stop it from conducting) whereas for enhancement (MOS) and bipolar, something must be done to "turn it on." So, that "ON till you turn it OFF" is a special characteristic not easily emulated by other devices.
Here are a few depl circuits: https://www.dropbox.com/s/apmj1ldmwcb99o0/Depl_Fet_Regs.JPG?dl=0 https://www.dropbox.com/s/u10nhcxgnw4636e/HV_Reg_4.JPG?dl=0 https://www.dropbox.com/s/h9u4ygl8ci9a13h/HV_Reg_5.JPG?dl=0 https://www.dropbox.com/s/pn6jfucq2vsfw7d/HV_Reg3.asc?dl=0 https://www.dropbox.com/s/fb24bhvsftvoexs/HVPS2.jpg?dl=0 https://www.dropbox.com/s/wad45kkw2c6wpte/LND150_reg_2.asc?dl=0 https://www.dropbox.com/s/7jr6glneepxhuem/250V_reg_1.asc?dl=0 https://www.dropbox.com/s/948oo5g2ndocbsk/Bleeder_1400.JPG?dl=0 https://www.dropbox.com/s/p8j3j7ga545vj24/Classic_Voltage_Regulators.JPG?dl=0 (the last one uses a depletion-mode tube) -- John Larkin Highland Technology, Inc Science teaches us to doubt. Claude Bernard