Post by thread:[EE] Depletion mode MOSFETs

I am not a hardware guru, one schematic I was looking at mentiones the need for a Supertex MOSFET Depletion Mode N-Channel DN3535 to be specific. DigiKey does not carry this product, although Mouser does. However, I would like to find a replacement for the part from other manufacturers as well. Any ideas or suggestions? The datasheet notes that following data are important characteristics, and therefore DN3535 is chosen: FET Type: N-Channel Depletion Mode Idss: 24mA min BVds: 21 V min Vpinchoff: 3.3 V max Power Dissipation: 24mA x 21 V min (504 mW) So I need a replacement for it with above critical data. Any help is appriciated. Regards, Omer ____________________________________________

At 12:59 PM 11/1/2004 +0200, you wrote: >I am not a hardware guru, one schematic I was looking at mentiones the >need for a Supertex MOSFET Depletion Mode N-Channel DN3535 to be >specific. DigiKey does not carry this product, although Mouser >does. However, I would like to find a replacement for the part from other >manufacturers as well. Any ideas or suggestions? The datasheet notes >that following data are important characteristics, and therefore DN3535 is >chosen: > >FET Type: N-Channel Depletion Mode >Idss: 24mA min >BVds: 21 V min >Vpinchoff: 3.3 V max >Power Dissipation: 24mA x 21 V min (504 mW) > > >So I need a replacement for it with above critical data. Any help is >appriciated. Probably overkill, but try Clare/IXYS. There are not many manufacturers of depletion-mode MOSFETs. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" spam_OUTspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com ____________________________________________

>I am not a hardware guru, one schematic I was looking at mentiones the need >for a Supertex MOSFET Depletion Mode N-Channel DN3535 to be specific. >DigiKey does not carry this product, although Mouser does. However, I >would like to find a replacement for the part from other manufacturers as >well. Any ideas or suggestions? The datasheet notes that following data >are important characteristics, and therefore DN3535 is chosen: > > FET Type: N-Channel Depletion Mode > Idss: 24mA min > BVds: 21 V min > Vpinchoff: 3.3 V max > Power Dissipation: 24mA x 21 V min (504 mW) Of the 19 distributors accessed in a single search from http://www.findchips.com only Mouser had the term "depletion" mentioned !!! They sound like a good place to shop in this case! The FET mentioned seems to have a vastly higher spec than what you specify. You can easily judge voltage and current yourself. Pinchoff voltage is probably the only critical voltage. It should have the opposite polarity to the main operating voltage as the FET is normally on when Vgate is zero and is "depleted" to turn it off by applying a negative voltage to the gate. A depletion mode FET with a Vp <= 3.3 volt would probably work OK. Note also that on resistance (10 ohms for the DN3535) may be quite variable between devices. Check this for original and substitutes and see if it matters in the target circuit. RM FindChips: Acroname Brookdale Harry Krantz Mouser Allied Carlton Bates Inland Empire Newark InOne America II Digikey Jameco Rochester Area 51 Future JDR Rydek basicEparts H & R Magnitude Feedback? Contact us. begin 666 no-match.gif M1TE&.#=A/0`,`.<``/______S/__F?__9O__,___`/_,___,S/_,F?_,9O_, M,__,`/^9__^9S/^9F?^99O^9,_^9`/]F__]FS/]FF?]F9O]F,_]F`/\S__\S MS/\SF?\S9O\S,_\S`/\`__\`S/\`F?\`9O\`,_\``,S__\S_S,S_F<S_9LS_ M,\S_`,S,_\S,S,S,F<S,9LS,,\S,`,R9_\R9S,R9F<R99LR9,\R9`,QF_\QF MS,QFF<QF9LQF,\QF`,PS_\PSS,PSF<PS9LPS,\PS`,P`_\P`S,P`F<P`9LP` M,\P``)G__YG_S)G_F9G_9IG_,YG_`)G,_YG,S)G,F9G,9IG,,YG,`)F9_YF9 MS)F9F9F99IF9,YF9`)EF_YEFS)EFF9EF9IEF,YEF`)DS_YDSS)DSF9DS9IDS M,YDS`)D`_YD`S)D`F9D`9ID`,YD``&;__V;_S&;_F6;_9F;_,V;_`&;,_V;, MS&;,F6;,9F;,,V;,`&:9_V:9S&:9F6:99F:9,V:9`&9F_V9FS&9FF69F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F9F M9F9F9F9F9F9F9F9F9F9F9BP`````/0`,```(DP`!"!Q(L*#!@P@3*C08*%!! MAPLC2D0(\6%%@1<G:LS(\*##BQPU1@Q),"3$BB@;F@30$"-(E2Y;LH2)<2;* MFCAERBQY\J3+GRP'ZNP)]&;0HSA+"EW:$>E*ID9],E6:-"5-HP^I@CRZ-6M5 JH%RG4LVI5&K2J5&UBC4;EF=1CEB)SJPJMVO&G2J?.A7:<FA,K$<#`@`[ ` end begin 666 working.gif M1TE&.#EA/0`,`.<``/______S/__F?__9O__,___`/_,___,S/_,F?_,9O_, M,__,`/^9__^9S/^9F?^99O^9,_^9`/]F__]FS/]FF?]F9O]F,_]F`/\S__\S MS/\SF?\S9O\S,_\S`/\`__\`S/\`F?\`9O\`,_\``,S__\S_S,S_F<S_9LS_ M,\S_`,S,_\S,S,S,F<S,9LS,,\S,`,R9_\R9S,R9F<R99LR9,\R9`,QF_\QF MS,QFF<QF9LQF,\QF`,PS_\PSS,PSF<PS9LPS,\PS`,P`_\P`S,P`F<P`9LP` M,\P``)G__YG_S)G_F9G_9IG_,YG_`)G,_YG,S)G,F9G,9IG,,YG,`)F9_YF9 MS)F9F9F99IF9,YF9`)EF_YEFS)EFF9EF9IEF,YEF`)DS_YDSS)DSF9DS9IDS M,YDS`)D`_YD`S)D`F9D`9ID`,YD``&;__V;_S&;_F6;_9F;_,V;_`&;,_V;, MS&;,F6;,9F;,,V;,`&:9_V:9S&:9F6:99F:9,V:9`&9F_V9FS&9FF69F9F9F M,V9F`&8S_V8SS&8SF68S9F8S,V8S`&8`_V8`S&8`F68`9F8`,V8``#/__S/_ MS#/_F3/_9C/_,S/_`#/,_S/,S#/,F3/,9C/,,S/,`#.9_S.9S#.9F3.99C.9 M,S.9`#-F_S-FS#-FF3-F9C-F,S-F`#,S_S,SS#,SF3,S9C,S,S,S`#,`_S,` MS#,`F3,`9C,`,S,```#__P#_S #_F0#_9@#_,P#_``#,_P#,S #,F0#,9@#, M,P#,``"9_P"9S "9F0"99@"9,P"9``!F_P!FS !FF0!F9@!F,P!F```S_P`S MS `SF0`S9@`S,P`S````_P``S ``F0``9@``,P```/__________________ M____________________________________________________________ M____________________________________________________________ M_____________________R'_"TY%5%-#05!%,BXP`P$````A^00)% #_`"P` M````)@`,```(2P`!"!PX\!HK*P03*ES(,.&UAZQ6-)Q(L>!#@Q4S,KSX$*'& MCP(Y8@3Y4>0UD@U-HM3(2N3*C%9<OJS8\N+,BBMJGKQ9T4I+G@H#`@`A^00) M% #_`"P`````)@`,```(60`!"!Q(L*#!@P@-KD"X,*%#A*P"&0S$ZJ%%@E:N M79,X,)!&*Q<OLM*X4:!'C15#/B2I,=!)DBI7LG3)\EI,AR-;FB29\N;!C"4[ M?O29,.+$GD05,DS*E&E `"'Y! D4`/\`+ `````F``P```A+``$('&B%U;6! M"!,J7,APA<%K!QE*G)CP(42*&"5:@<@QH\>*'"]^'!E2Y,B3`TM&1(FQ)"N6 M&4M:@=F2XTN:%&VNP)F3U4R>`@,"`"'Y! $4`/\`+ `````F``P```A4``$( M'&B%U;5KK*P,7,BPH4.&*PP>G,AJQ<.+& 4&FC@Q4,:/#S=V!$FRH4B/)5,. F#(12I4J6+E\>;!DSH\B9-6URQ)G38<2=""WV=%CP8,*A`P,"`#L` ` end ____________________________________________

mer Yalhý wrote: > I am not a hardware guru, one schematic I was looking at mentiones the need for a Supertex MOSFET Depletion Mode N-Channel DN3535 to be specific. DigiKey does not carry this product, although Mouser does. However, I would like to find a replacement for the part from other manufacturers as well. Any ideas or suggestions? The datasheet notes that following data are important characteristics, and therefore DN3535 is chosen: > > FET Type: N-Channel Depletion Mode > Idss: 24mA min > BVds: 21 V min > Vpinchoff: 3.3 V max > Power Dissipation: 24mA x 21 V min (504 mW) > > > So I need a replacement for it with above critical data. Any help is appriciated. Since Siemens/Infineon has canned the BSS135, the Supertex parts are the only high-voltage depletion-mode fets I've been able to locate after several years of looking. (I was never able to find a small-quanity US distributor for the Siemens/Infineon part anyway). I wouldn't know what to suggest for a second source. Is the Vds max low enough to use some kind of JFET? -Dan ___________________________________________

Vds is stated as 21 V min. Maybe all this is an overkill. The depletion mode mosfet is suggested in the AD421 datasheet, and I am trying to find alternatives for it. They suggest one with 350V! Regards, Omer ____________________________________________

Omer YALHI wrote: > Vds is stated as 21 V min. Maybe all this is an overkill. The depletion > mode mosfet is suggested in the AD421 datasheet, and I am trying to find > alternatives for it. They suggest one with 350V! From the datasheet http://www.analog.com/UploadedFiles/Data_Sheets/409317160AD421_c.pdf (pg 6) "The DN25D FET transistor from Supertex meets all the above requirements for the FET. Other suitable transistors include ND2020L and ND2410L, both from Siliconix." I don't know the current production status of the suggested Siliconix parts, but they might be a viable second source. I suspect that a long loop installed in a noisy environment might be subject to some rather high voltage impulse noise, hence the suggestion for a high Vds. -Dan ____________________________________________

Thank you Dan. I did see the alternatives in the datasheet but I could not find them using findchips either. I have found DN3535 though, and one of the datasheets suggests that can also be used, so I will go ahead and use that one. Regards, Omer {Original Message removed}

On Mon, 1 Nov 2004, Dan Kerl wrote: > Since Siemens/Infineon has canned the BSS135, the Supertex parts are the only > high-voltage depletion-mode fets I've been able to locate after several years Argh, you shot my BSS170 proposal down. Peter ____________________________________________

part 1 756 bytes content-type:TEXT/PLAIN; charset=iso-8859-9; format=flowed (decoded quoted-printable) On Mon, 1 Nov 2004, [iso-8859-9] �mer Yalh� wrote: > I am not a hardware guru, one schematic I was looking at mentiones the need for a Supertex MOSFET Depletion Mode N-Channel DN3535 to be specific. DigiKey does not carry this product, although Mouser does. However, I would like to find a replacement for the part from other manufacturers as well. Any ideas or suggestions? The datasheet notes that following data are important characteristics, and therefore DN3535 is chosen: > > FET Type: N-Channel Depletion Mode > Idss: 24mA min > BVds: 21 V min > Vpinchoff: 3.3 V max > Power Dissipation: 24mA x 21 V min (504 mW) Look at BSS170 imho. TO92 and probably smd available. Peter part 2 79 bytes content-type:text/plain; charset="us-ascii" (decoded 7bit) ____________________________________________