Component Pinouts

[BrendanP]

As I mentioned in another post re.inductors Im working on a switch mode battery charger bassed on the MAX713.

I am using the parts Maxim suggests on page 16 figure 19 of the MAX713 data sheet.

Some of the parts are made by several different manufacturers the 2N2907 PNP transistor for example. Im using the part made by ST.

Do the different manufacturers of the same part use the same pin out configuration? Is there an industry standard?

Another question. What are the criteria for deciding to use a NPN as opposed to PNP transistor in a given application?

 

[BCJKiwi]

The data sheet for the part you are using will give you it's pinout. Compare that with the Board design.

While one would expect the same numbered part to be interchangeable, why make such an assumption when the datasheet from the maker of the part you have can be compared to the one specified.

 

[BrendanP]

I ask because the pinout for the ST part is so poorly depicted Im having trouble indentifying which pin is which.

Is it the collector or the emitter that is closest to the tab on the case?

Have a look at the Phillips data sheet for the MPSA06. Is that view from the bottom of the case or the top?

 

[Dippy]

Poorly depicted?
Maybe it depends where you got the Data Sheet from or maybe it was a rubbish scan of a photocopy?

I have stuck together the pinout details of the 2N2907A from 3 different manufs. including ST.
The pinout is perfectly clear as far as I can see. Emitter nearest tab.

NPN/PNP choice? Depends which way you want your current to go

MPSA06: can't find Phillips data sheet and haven't got all day to look. I have looked at the version from Fairchild, Multicomp and ON . The pinouts are the same for all three TO-92 packages.
Just to save you looking; if you hold the device such that the pins are facing you and the package looks like a D, then top-bottom is C , B , E.

 

[moxhamj]

Can you pls post a photo of your board. Maybe it is correct. Maybe not but at least we can answer it quickly.

NPN vs PNP? Just pick one at random. All transistors are the same, right?

No seriously, it helps to get to know a few. A generic small signal NPN is the BC547. You connect the emitter to ground. The collecter goes to the negative side of the load. And you put positive current into the base to turn it on. This is the transistor I use the most.

A PNP is the mirror image. eg a 557. It is generally the high side of a power supply. Current goes into the emitter, out of the collector and you suck current out of the base to turn it on.

Bigger transistors switch bigger currents. Some are specialised for speed etc.

Many small signal transistors are interchangeable. But they are all very cheap, and if a design specifies a certain one, it is just easiest to use the one that is specified.

But if you connect PNP instead of NPN and connect them the wrong way, there are some situations where the circuit sort of works, and you think you have a working circuit but you don't. Your mosfet gate won't be swinging the full voltage range.

BC547 and 557 (NPN/PNP) go together and are good for 100mA.

BC337 and BC327 (NPN/PNP) go together and are good for 800mA.

In the US, it appears the 2N2222 is the popular signal transistor. Good for 1 amp. And the complementary transistor is the 2N2907.

It helps to know the common parts round the world, because often there is a very similar local variant that you know and understand. Use the parts they suggest though in your circuit diagram - there may be a good reason they chose a certain part.

A quick photo of the board and the components will answer all these questions. We won't laugh. Promise.

 

[westaust55]

I ask because the pinout for the ST part is so poorly depicted Im having trouble indentifying which pin is which.

Here is an actual ST datahsheet . . .

Cannot see anything unclear on that.

The MPSA06 datasheet by Philips (there are at lease 17 manufacturers from the datasheets I found) took just 30 seconds to find.
The view is form the bottom of the case. Just a case of knowing how techncial drawings are drawn (which projection is used)

 

[westaust55]

Maybe this (sort of isometric) view from the Motorola datasheet is easier to understand.

 

[westaust55]

To respond to your original question,

Yes, normally all manufacturers of a component use the same pin-out for that device in a particular package.

The rule for metal can type GP small signal transistors is that when looking at the bottom, starting at the tab and going clockwise, the pins/legs are E, B and C.

For plastic pack types of GP small signal transistors looking from the bottom with the flat to the top, going left to right it is still E, B and C.

The same applies for 74xx and 4000 series IC's. Imaging the problems if each manufacturer had a different pinout for a simple 7400.

 

[Dippy]

WA: That ST one is the same as I linked before but thanks for confirming the T092 Package is the same as all the others. I don't know how many more times we can send pictures of the same thing

I thought it all looked clear enough... ?

Do we now have 3 separate theads on Brendan's non-PICAXE-related questions on a non-PICAXE-related project?

 

[Mycroft2152]

WA: That ST one is the same as I linked before but thanks for confirming the T092 Package is the same as all the others. I don't know how many more times we can send pictures of the same thing

I thought it all looked clear enough... ?

Do we now have 3 separate theads on Brendan's non-PICAXE-related questions on a non-PICAXE-related project?

Brendan has found a captive audience and a friendly ear.

Besides, it is a quick way for someone to spoon feed you the answers.

 

[Dippy]

Oh Myc, you devil

I thought it was just delegation when in a state of panic after making a boob.

 

[westaust55]

Brendan has found a captive audience and a friendly ear.

Besides, it is a quick way for someone to spoon feed you the answers.

While I do not "pounce" on all who ask questions. It is clear that some do little homework/research or do not have the skills to research for themselves. Only 4 days ago of another who seemed to be looking for all on a plate I asked:

are you actively looking for yourself?

Have you considered writing the program yourself?

Whiile I did duplicate some of what Dippy have already given, finding two clear and very easily read datsheets took less than a minute.

 

[Mycroft2152]

Westy,

I usually just ignore these type of questions...

But there has be a rash of them lately and I guess I didn"t have enough coffee this morning.

Myc

Remember all the experts have a "y" in their name..

 

[westaust55]

Maybe this recent past response by the "delegation team" to another member who had clearly ready the manuals says it all:

This guy has got too much free time on his hands.

time for that misssed cup of coffee myc
in my case time for an evening phone call

 

[BrendanP]

I think I was the one who told him he had too much free time on his hands! But that was because he was complaining about typos!

Anyway thanks for the input and clarifications.

Honestly I do read the manuals, Dippy. (I can't really complain about Dippys acerbic wit, I've handed out a bit of abuse on this forum myself. What goes around come around.)

The the batteries power a 28X1 so I guess that qualifies as a picaxe related project . Where do you draw the line?

Im ashamed to say I think I know why my pcb isnt functioning correctly. There was track where there wasnt meant to be track, the dremel has taken care of that and now that the pin out of the 2N2907has been more than clarified I'm going to fire it up.

10 minutes latter

Well Delegation members it appears to working. Although Im getting a fair bit of heat comming off the inductor, I can touch it but its pretty warm. Is this normal? The MOSFET is also hottish. The power supply show the circuit drawing 666 milliamps. ( evil number that but thats what it says)
Dr. I will post some pics on tuesday.