Forums

crazy NPN

Started by John Larkin April 10, 2015
http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf

Check the betas!



-- 

John Larkin         Highland Technology, Inc
picosecond timing   laser drivers and controllers

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

John Larkin <jlarkin@highlandtechnology.com> wrote:
> http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf > > Check the betas! > >
hfe = 20. Am I missing something? Where's the bit deserving of the exclamation mark?
John Larkin wrote:

> http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf > > Check the betas!
** High voltage NPN switches are like that - 1500V horizontal output transistors ( like the BU208 ) for colour TV show betas around 20 at 0.5A falling to less than 10 above 3 amps. Simple Hfe testers often show zero readings with one cos the do not supply enough base drive. ... Phil
On Friday, April 10, 2015 at 6:34:02 PM UTC-7, John Larkin wrote:
> http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf > > Check the betas!
Yeah, but when the base circuit is doing 1V, 1 mA and if the collector is doing 1200V, 3 mA the power gain is around 70 dB. It's like the old trick of spec-ing an op amp by its DC gain (20,000 V/V) and output-referenced offset (15 mV times 20,000)... would you believe offset voltage of plus or minus 300 V? Still, the old CA3140 was kinda useful regardless. My main gripe was the quiescent current: so high, I had to heatsink the thing.
On Sat, 11 Apr 2015 01:49:11 GMT, Ralph Barone
<address_is@invalid.invalid> wrote:

>John Larkin <jlarkin@highlandtechnology.com> wrote: >> http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf >> >> Check the betas! >> >> > > >hfe = 20. Am I missing something? Where's the bit deserving of the >exclamation mark?
At the rated peak collector current of 400 mA, the beta isn't specified, but is probably around 2. The data sheet is sort of skimpy. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Pedantically speaking, beta isn't mentioned?  So the answer is, NaN?...

I would be a little more comfortable if they had left off pin 2 on that 
poor SOT-223.  Or same with a DPAK (which usually has a nub there), if it 
were offered in one.

No graphs, no mention of fT or t_r.  I'm sure t_stg is characteristically 
long, but a ballpark would've been nice.

A 6V6GT has much higher hFE, is almost certainly much faster, and is 
capable of dissipating more power, too.  I'm not feeling won over, here. 
;-)

Tim

-- 
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com

"John Larkin" <jlarkin@highlandtechnology.com> wrote in message 
news:5fugia95gsbkt4e0ml5709t7q02p8k2777@4ax.com...
> > http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf > > Check the betas! > > > > -- > > John Larkin Highland Technology, Inc > picosecond timing laser drivers and controllers > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com >
On Fri, 10 Apr 2015 21:08:56 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>Pedantically speaking, beta isn't mentioned? So the answer is, NaN?...
HFE isn't beta? If typ is 3, I wonder what the minimum might be.
> >I would be a little more comfortable if they had left off pin 2 on that >poor SOT-223. Or same with a DPAK (which usually has a nub there), if it >were offered in one. > >No graphs, no mention of fT or t_r. I'm sure t_stg is characteristically >long, but a ballpark would've been nice. > >A 6V6GT has much higher hFE, is almost certainly much faster, and is >capable of dissipating more power, too. I'm not feeling won over, here. >;-)
I might have trouble putting 16 of them in a box the size of a bagel. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 2015-04-11, John Larkin <jlarkin@highlandtechnology.com> wrote:
> > http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf > > Check the betas!
yeah, but this part is all about voltage gain, not current gain. -- umop apisdn
>"The data sheet is sort of skimpy"
Seems for good reason. Phil said something about horizntal (line) outputs for yoke driven TVs ? Those pins are to close together for a kilovolt. What's more, a gain of 3 is not really impressive. The current, are you really going to drive a relay with a 1,200 volt coil ? And this "haptic" - what does that mean ? A qwiki comes up wiht something to do with touch. You want to shock people of they touch your stereo or something ? Well with a wimp like this they are not likely to convict you of murder... But then again, remember the Watchman ? Hell this might even be better than the transistors they used in those.
On 11/04/2015 02:33, John Larkin wrote:
> > http://www.st.com/web/en/resource/technical/document/datasheet/DM00047825.pdf > > Check the betas! > > >
What sort of high voltage can one safely generate on FR4 without the fear of tracking arcing ? Is it enough to have wide enough gaps or will it eventually track through top to bottom ( 1.6 mm) assuming there is a ground plane on the bottom layer ? --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com