PNPs with high BV_EBO

I'll check up and correct the two errors, if so.

There are a number of ways to reverse Veb stress, the most common of which is to simple add input and shunt resistors that do not grossly affect forward operation. Another is to add a diode.

Component limitations are one of the things that make design more interesting than jigsaw puzzles.

You don't just sit arround, waiting for the right parts to become available, but it helps to know what is...

RL

Sure. There are lots of prebiased ('digital') transistors that'll do that in one package. In the present case I just added a BAV99W to the PNP side.

Thanks again

Phil Hobbs

RL

Both also obsolete. :(

Cheers

Phil Hobbs

How about cmpt404a, Vebo = 25 volts.

(Many parts may qualify, but won't spec it.)

Thanks, Win. We talked about that one upthread--it seems to be another of t hose unique parts that are dangerous to design with. :(

Cheers

Phil Hobbs

Maybe not. Like I said, I suspect many BJTs can handle the voltage, without saying so. At any rate, I don't think Central Semi is one of those NXP-like companies that go around axing slow-moving or out-of-favor parts. And it's not likely Mouser would keep so many in stock, if it wasn't moving. Also, at 23 cents ea in reels, a lifetime supply isn't a deal breaker.

For our proprietary stuff, sure. I have about 40,000 BF862s and CPH3910s, p lus 6000 BFT92s in stock. But for customer designs and licensing, that does n't fly so well.

Cheers

Phil Hobbs

Central is where transistors go to die.

I doesn't mean they're dead dead -- more like an expensive legacy zombie state. The price jacks up many times, depending on demand I'm sure.

Make of that what you will. Forever available? Possible; certainly more likely than other sources. Commodity pricing? No way Jose.

Tim

I object to that terminology.

If a manufacturer is not capable of making, or unwilling to make, or too inept to sell, something as good as they used to make, that might make the manufacturer obsolete or incompetent or irrelevant, but in my book it makes the parts become merely unavailable, not obsolete.

If they could make something better then the parts would be obsolete, but then we wouldn't be upset about it.

Hear, hear!

Actually, not very unique at all. These were originally designed as chopper transistors, and used for very low saturation-voltage switches. That's an area that Zetex has put to great use, making a huge line of cheaper BJTs that compete with MOSFET switches for up to 10s of amps. These transistor have high inverting gain, and are designed to be highly symmetrical, so you can exchange the emitter and collector almost without affect. That's why the Veb values are so high. And that's why Vce(sat) is so low, in the forward as well as the inverted modes.

There are many uses for transistors made this way, and with a reliable company like Central Semi, they should be here for the long term.

The 2SD2704K is an NPN version of the same idea, and it sure is useful, I a gree. I wouldn't have a big problem characterizing a low-sat transistor for inverted use at higher voltage, though I'd probably do a lifetime buy once the design was done.

My trouble is that customers who are producing my designs tend to get queas y about exceeding Absolute Maximum limits from the datasheets.

Cheers

Phil Hobbs

agree. I wouldn't have a big problem characterizing a low-sat transistor f or inverted use at higher voltage, though I'd probably do a lifetime buy on ce the design was done.

asy about exceeding Absolute Maximum limits from the datasheets.

is it the only way?

I agree. I wouldn't have a big problem characterizing a low-sat transistor for inverted use at higher voltage, though I'd probably do a lifetime buy once the design was done.

ueasy about exceeding Absolute Maximum limits from the datasheets.

Not at all--it just saves parts. Low-Z circuits have fewer options, but my PNP is the driver stage of a Sziklai pair so I can just use a 10k resistor and a diode from base to emitter to prevent reverse voltage. (For lurkers : a Sziklai is like a Darlington, but with a PNP driving an NPN, so that th e whole thing looks like a single power PNP).

Cheers

Phil Hobbs

Nonsense. Perhaps it's no longer *profitable* to make?

As I stated, I was objecting to the terminology. I was not speculating on the profitability of making the parts and selling them at any particular price.

Price is only tangentially related to profit. If something isn't making a profit, it's not going to get made. That's all there is to it.