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Panasonic schottky......or not ?

Started by legg December 18, 2017
In the Panasonic schottky diode catalog, there are a number of parts
that don't state that the parts are schottky, though the top of the
catalog page still carries the schottky barrier diode heading. They
share similar part numbering structures and descriptions as parts in
the ultrafast rectifier line.

Schottky parts are fabbed using the same 'planar' process, but the
'epitaxial' description seems out of place here.

A possible confusion is aggravated by Panasonic's tendency to describe
the reverse recovery time of schottky parts, when positioned in the
standard Trr test circuit, where performance is basically an RC
effect.

eg:

https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf

Does anyone out there have actual experience in weeding out small
signal and rectifier schottkys from UFRs in the Panasonic line-up? 

I've only ever used a few of their schottky parts. Conventional fast
diodes are easily supplied by more prominent mfrs, so there's never
been an issue. Vendors seem only to have the same ambiguous data
sheets to draw from. They appear to have no trouble correcting
Panasonic's faulty package drawing designations - but descriptions of
'schottky or not' follows the data sheet page catalog section's
header.

RL
On Mon, 18 Dec 2017 11:53:55 -0500, legg <legg@nospam.magma.ca> wrote:

>In the Panasonic schottky diode catalog, there are a number of parts >that don't state that the parts are schottky, though the top of the >catalog page still carries the schottky barrier diode heading. They >share similar part numbering structures and descriptions as parts in >the ultrafast rectifier line. > >Schottky parts are fabbed using the same 'planar' process, but the >'epitaxial' description seems out of place here. > >A possible confusion is aggravated by Panasonic's tendency to describe >the reverse recovery time of schottky parts, when positioned in the >standard Trr test circuit, where performance is basically an RC >effect. > >eg: > >https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf
That data sheet says "schottky" at the top. The forward and reverse curves sure look schottky. I don't think that epitaxial is incompatible with schottky. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Monday, December 18, 2017 at 11:53:26 AM UTC-5, legg wrote:
> In the Panasonic schottky diode catalog, there are a number of parts > that don't state that the parts are schottky, though the top of the > catalog page still carries the schottky barrier diode heading. They > share similar part numbering structures and descriptions as parts in > the ultrafast rectifier line. > > Schottky parts are fabbed using the same 'planar' process, but the > 'epitaxial' description seems out of place here. > > A possible confusion is aggravated by Panasonic's tendency to describe > the reverse recovery time of schottky parts, when positioned in the > standard Trr test circuit, where performance is basically an RC > effect. > > eg: > > https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf > > Does anyone out there have actual experience in weeding out small > signal and rectifier schottkys from UFRs in the Panasonic line-up? > > I've only ever used a few of their schottky parts. Conventional fast > diodes are easily supplied by more prominent mfrs, so there's never > been an issue. Vendors seem only to have the same ambiguous data > sheets to draw from. They appear to have no trouble correcting > Panasonic's faulty package drawing designations - but descriptions of > 'schottky or not' follows the data sheet page catalog section's > header. > > RL
The V_forward graph looks like a Schottky. George h.
On Mon, 18 Dec 2017 09:43:20 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Monday, December 18, 2017 at 11:53:26 AM UTC-5, legg wrote: >> In the Panasonic schottky diode catalog, there are a number of parts >> that don't state that the parts are schottky, though the top of the >> catalog page still carries the schottky barrier diode heading. They >> share similar part numbering structures and descriptions as parts in >> the ultrafast rectifier line. >> >> Schottky parts are fabbed using the same 'planar' process, but the >> 'epitaxial' description seems out of place here. >> >> A possible confusion is aggravated by Panasonic's tendency to describe >> the reverse recovery time of schottky parts, when positioned in the >> standard Trr test circuit, where performance is basically an RC >> effect. >> >> eg: >> >> https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf >> >> Does anyone out there have actual experience in weeding out small >> signal and rectifier schottkys from UFRs in the Panasonic line-up? >> >> I've only ever used a few of their schottky parts. Conventional fast >> diodes are easily supplied by more prominent mfrs, so there's never >> been an issue. Vendors seem only to have the same ambiguous data >> sheets to draw from. They appear to have no trouble correcting >> Panasonic's faulty package drawing designations - but descriptions of >> 'schottky or not' follows the data sheet page catalog section's >> header. >> >> RL > >The V_forward graph looks like a Schottky. > >George h.
So does the reverse curve, both in magnitude and shape. Schottkies can have real reverse recovery, if they have a p-n guard ring that conducts at higher currents. But Panasonic may just be a little weird. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Monday, December 18, 2017 at 1:24:05 PM UTC-5, John Larkin wrote:
> On Mon, 18 Dec 2017 09:43:20 -0800 (PST), George Herold > <gherold@teachspin.com> wrote: > > >On Monday, December 18, 2017 at 11:53:26 AM UTC-5, legg wrote: > >> In the Panasonic schottky diode catalog, there are a number of parts > >> that don't state that the parts are schottky, though the top of the > >> catalog page still carries the schottky barrier diode heading. They > >> share similar part numbering structures and descriptions as parts in > >> the ultrafast rectifier line. > >> > >> Schottky parts are fabbed using the same 'planar' process, but the > >> 'epitaxial' description seems out of place here. > >> > >> A possible confusion is aggravated by Panasonic's tendency to describe > >> the reverse recovery time of schottky parts, when positioned in the > >> standard Trr test circuit, where performance is basically an RC > >> effect. > >> > >> eg: > >> > >> https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf > >> > >> Does anyone out there have actual experience in weeding out small > >> signal and rectifier schottkys from UFRs in the Panasonic line-up? > >> > >> I've only ever used a few of their schottky parts. Conventional fast > >> diodes are easily supplied by more prominent mfrs, so there's never > >> been an issue. Vendors seem only to have the same ambiguous data > >> sheets to draw from. They appear to have no trouble correcting > >> Panasonic's faulty package drawing designations - but descriptions of > >> 'schottky or not' follows the data sheet page catalog section's > >> header. > >> > >> RL > > > >The V_forward graph looks like a Schottky. > > > >George h. > > So does the reverse curve, both in magnitude and shape. > > Schottkies can have real reverse recovery, if they have a p-n guard > ring that conducts at higher currents. But Panasonic may just be a > little weird.
Huh, thanks, I never knew Schottkys were so leaky in reverse. There must be some physics reason for that...? Re: p-n guard ring, well that's doubly beyond my knowledge, though edge effects in photodiodes is something I see all the time. George H.
> > > > > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com
On Mon, 18 Dec 2017 16:25:46 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Monday, December 18, 2017 at 1:24:05 PM UTC-5, John Larkin wrote: >> On Mon, 18 Dec 2017 09:43:20 -0800 (PST), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Monday, December 18, 2017 at 11:53:26 AM UTC-5, legg wrote: >> >> In the Panasonic schottky diode catalog, there are a number of parts >> >> that don't state that the parts are schottky, though the top of the >> >> catalog page still carries the schottky barrier diode heading. They >> >> share similar part numbering structures and descriptions as parts in >> >> the ultrafast rectifier line. >> >> >> >> Schottky parts are fabbed using the same 'planar' process, but the >> >> 'epitaxial' description seems out of place here. >> >> >> >> A possible confusion is aggravated by Panasonic's tendency to describe >> >> the reverse recovery time of schottky parts, when positioned in the >> >> standard Trr test circuit, where performance is basically an RC >> >> effect. >> >> >> >> eg: >> >> >> >> https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf >> >> >> >> Does anyone out there have actual experience in weeding out small >> >> signal and rectifier schottkys from UFRs in the Panasonic line-up? >> >> >> >> I've only ever used a few of their schottky parts. Conventional fast >> >> diodes are easily supplied by more prominent mfrs, so there's never >> >> been an issue. Vendors seem only to have the same ambiguous data >> >> sheets to draw from. They appear to have no trouble correcting >> >> Panasonic's faulty package drawing designations - but descriptions of >> >> 'schottky or not' follows the data sheet page catalog section's >> >> header. >> >> >> >> RL >> > >> >The V_forward graph looks like a Schottky. >> > >> >George h. >> >> So does the reverse curve, both in magnitude and shape. >> >> Schottkies can have real reverse recovery, if they have a p-n guard >> ring that conducts at higher currents. But Panasonic may just be a >> little weird. > >Huh, thanks, I never knew Schottkys were so leaky in reverse. >There must be some physics reason for that...?
Dunno about the physics, but they are very leaky and leakage increases smoothly with voltage. Regular diodes are more constant-current leakage then a steep zener thing. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Tuesday, December 19, 2017 at 11:29:29 AM UTC+11, John Larkin wrote:
> On Mon, 18 Dec 2017 16:25:46 -0800 (PST), George Herold > <gherold@teachspin.com> wrote: > > >On Monday, December 18, 2017 at 1:24:05 PM UTC-5, John Larkin wrote: > >> On Mon, 18 Dec 2017 09:43:20 -0800 (PST), George Herold > >> <gherold@teachspin.com> wrote: > >> > >> >On Monday, December 18, 2017 at 11:53:26 AM UTC-5, legg wrote: > >> >> In the Panasonic schottky diode catalog, there are a number of parts > >> >> that don't state that the parts are schottky, though the top of the > >> >> catalog page still carries the schottky barrier diode heading. They > >> >> share similar part numbering structures and descriptions as parts in > >> >> the ultrafast rectifier line. > >> >> > >> >> Schottky parts are fabbed using the same 'planar' process, but the > >> >> 'epitaxial' description seems out of place here. > >> >> > >> >> A possible confusion is aggravated by Panasonic's tendency to describe > >> >> the reverse recovery time of schottky parts, when positioned in the > >> >> standard Trr test circuit, where performance is basically an RC > >> >> effect. > >> >> > >> >> eg: > >> >> > >> >> https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf > >> >> > >> >> Does anyone out there have actual experience in weeding out small > >> >> signal and rectifier schottkys from UFRs in the Panasonic line-up? > >> >> > >> >> I've only ever used a few of their schottky parts. Conventional fast > >> >> diodes are easily supplied by more prominent mfrs, so there's never > >> >> been an issue. Vendors seem only to have the same ambiguous data > >> >> sheets to draw from. They appear to have no trouble correcting > >> >> Panasonic's faulty package drawing designations - but descriptions of > >> >> 'schottky or not' follows the data sheet page catalog section's > >> >> header. > >> >> > >> >> RL > >> > > >> >The V_forward graph looks like a Schottky. > >> > > >> >George h. > >> > >> So does the reverse curve, both in magnitude and shape. > >> > >> Schottkies can have real reverse recovery, if they have a p-n guard > >> ring that conducts at higher currents. But Panasonic may just be a > >> little weird. > > > >Huh, thanks, I never knew Schottkys were so leaky in reverse. > >There must be some physics reason for that...? > > Dunno about the physics, but they are very leaky and leakage increases > smoothly with voltage. Regular diodes are more constant-current > leakage then a steep zener thing.
It's a steep avalanche thing. Zener breakdown only happens for breakdown voltage less than about five volts. -- Bill Sloman, Sydney
On Mon, 18 Dec 2017 16:25:46 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Monday, December 18, 2017 at 1:24:05 PM UTC-5, John Larkin wrote: >> On Mon, 18 Dec 2017 09:43:20 -0800 (PST), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Monday, December 18, 2017 at 11:53:26 AM UTC-5, legg wrote: >> >> In the Panasonic schottky diode catalog, there are a number of parts >> >> that don't state that the parts are schottky, though the top of the >> >> catalog page still carries the schottky barrier diode heading. They >> >> share similar part numbering structures and descriptions as parts in >> >> the ultrafast rectifier line. >> >> >> >> Schottky parts are fabbed using the same 'planar' process, but the >> >> 'epitaxial' description seems out of place here. >> >> >> >> A possible confusion is aggravated by Panasonic's tendency to describe >> >> the reverse recovery time of schottky parts, when positioned in the >> >> standard Trr test circuit, where performance is basically an RC >> >> effect. >> >> >> >> eg: >> >> >> >> https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf >> >> >> >> Does anyone out there have actual experience in weeding out small >> >> signal and rectifier schottkys from UFRs in the Panasonic line-up? >> >> >> >> I've only ever used a few of their schottky parts. Conventional fast >> >> diodes are easily supplied by more prominent mfrs, so there's never >> >> been an issue. Vendors seem only to have the same ambiguous data >> >> sheets to draw from. They appear to have no trouble correcting >> >> Panasonic's faulty package drawing designations - but descriptions of >> >> 'schottky or not' follows the data sheet page catalog section's >> >> header. >> >> >> >> RL >> > >> >The V_forward graph looks like a Schottky. >> > >> >George h. >> >> So does the reverse curve, both in magnitude and shape. >> >> Schottkies can have real reverse recovery, if they have a p-n guard >> ring that conducts at higher currents. But Panasonic may just be a >> little weird. > >Huh, thanks, I never knew Schottkys were so leaky in reverse. >There must be some physics reason for that...?
Sure, Schottkys are leaky. If they weren't, there will be far less use for silicon diodes.
> >Re: p-n guard ring, well that's doubly beyond my knowledge, >though edge effects in photodiodes is something I see all the >time.
John Larkin wrote...
> > legg <legg@nospam.magma.ca> wrote: > >> In the Panasonic schottky diode catalog, there are a number of parts >> that don't state that the parts are schottky, though the top of the >> catalog page still carries the schottky barrier diode heading. They >> share similar part numbering structures and descriptions as parts in >> the ultrafast rectifier line. >> >> Schottky parts are fabbed using the same 'planar' process, but the >> 'epitaxial' description seems out of place here. >> >> A possible confusion is aggravated by Panasonic's tendency to describe >> the reverse recovery time of schottky parts, when positioned in the >> standard Trr test circuit, where performance is basically an RC >> effect. >> >>eg: >>https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf > > That data sheet says "schottky" at the top. The forward and > reverse curves sure look Schottky. > > I don't think that epitaxial is incompatible with schottky.
Vf = 350mV at 100mA, near the 200mA max, has to be Schottky. -- Thanks, - Win
On Monday, December 18, 2017 at 4:25:54 PM UTC-8, George Herold wrote:
> On Monday, December 18, 2017 at 1:24:05 PM UTC-5, John Larkin wrote:
> > Schottkies can have real reverse recovery, if they have a p-n guard > > ring that conducts at higher currents. But Panasonic may just be a > > little weird. > > Huh, thanks, I never knew Schottkys were so leaky in reverse. > There must be some physics reason for that...? > > Re: p-n guard ring, well that's doubly beyond my knowledge, > though edge effects in photodiodes is something I see all the > time.
A diffused guard ring creates the builtin field of an unbiased PN junction, in the right direction to pull surface dirt away from the (sensitive) edge regions of the Schottky metallization. The same kind of thing helps HV diodes (lessens leakage and aging effects), when simple passivation isn't enough. Half the problem in semiconductors is that you can make resistors, and amplifiers, and switches, easily, but insulators have to be reverse biased PN junctions, and wires have to be mapped onto one surface (if two wires have to cross, there's cost or trickery to do that). The other half, is that the finished item has all the working parts buried, but unburied surfaces ALSO work, usually against your design goals. You can't keep surfaces absolutely clean. Some of those surfaces have to sink heat, through bear grease, too.. Guard rings are a behind-the-scenes necessity, and (from the physics point of view) rather elegant.