New user frustrated - can't find part  :(

Check if the 4514 (4-bit latch 4-16 line DECODER) in the 45xx.lbr is

compatible.

"Steve Klett" <communitymanager@premierfarnell.com> wrote in message

news:820482050.2921314252822852.JavaMail.jive@flcspu-csapp-01.premierfarnell.com...

Hi,

 

I just purchased Eagle CAD to draw a schematic for a project that was

dumped in my lap. Not only am I brand new to eagle but I'm also not

experienced with electronics; I know enough to get basic stuff done, but

oftens not enough to fully understand why it works (or doesn't)!

 

So I've isntalled Eagle, watched tutorials, read the manual (I really did)

and googled for various answers. I STILL cannot figure out where to find a

part to represent a 74HCT4514. I've found parts that seem similar (e.g.

45xx > 4514 > 4514D) but the pin labels don't match what I'm expected

(specifically, where is /E and /LE?) The part in eagle has /ST and /INH

however I'm unfamiliar with these labels.

 

Of the 6 hours I've spent ACTUALLY drawing a schematic I would say that

90% of that time has been spent search for parts. I checked the eagle site

for downloadable libraries but didn't see anything that seemed better than

what is already installed.

 

Can someone please let me know if there is a pin compatible part in eagle

for a 74HC4514? If I DO have the correct part already, what do /ST and

/INH stand for?

 

Thanks for reading,

Steve

 

Am 25.08.2011 08:13, schrieb Steve Klett:

Hi,

 

I just purchased Eagle CAD to draw a schematic for a project that was dumped in my lap.  Not only am I brand new to eagle but I'm also not experienced with electronics; I know enough to get basic stuff done, but oftens not enough to fully understand why it works (or doesn't)!

 

So I've isntalled Eagle, watched tutorials, read the manual (I really did) and googled for various answers.  I STILL cannot figure out where to find a part to represent a 74HCT4514.  I've found parts that seem similar (e.g. 45xx>  4514>  4514D) but the pin labels don't match what I'm expected (specifically, where is /E and /LE?)  The part in eagle has /ST and /INH however I'm unfamiliar with these labels.

 

Of the 6 hours I've spent ACTUALLY drawing a schematic I would say that 90% of that time has been spent search for parts.  I checked the eagle site for downloadable libraries but didn't see anything that seemed better than what is already installed.

 

Can someone please let me know if there is a pin compatible part in eagle for a 74HC4514?  If I DO have the correct part already, what do /ST and /INH stand for?

 

Thanks for reading,

Steve

 

If you don't have a basic knowledge about ic-groups then you certainly

have problems. Usually the groups are pin compatible, but here in my

example I shall LIE a little bit to make things more clear (I hope).

The name of the ic is 4514 but there are a lot of different groups

like cd4514, 74ls4514, 74als4514, 47hc4514 or 74hct4514 etc.

So you better get the datasheet for YOUR ic and check if it is compatible.

The datasheet also tells you what the pins (/ST and /inh in your

question) are doing.

Neither eagle nor any other layout program gives you the garantee that

its libraries are correct. It's allways up to you, so get the datasheets.

And, since we are on it, the download site of cadsoft offers a lot of

libraries and other stuff uploaded by users but no guarantee.

For a beginning in a new sheet perhaps shou should enter in the command

line(at the very top): "use *" without the " which means use ALL libraries.

If you start to ADD devices, in this dialog at the very bottom left

side, you find a search line marked with an "X".

Here you can enter: 4514* to search for ALL parts that beginn with 4514.

I hope you know the use of "?" and "*" and the combination of it.

It is useless to search for EXACT the ic you want to have, because the

libraries would blow up to gigabytes if every variation and character is

listed and for all those still the different packages.

So allways search for the basic number.

Hopefully this helps you to enjoy eagle

--

Mit freundlichen Grüßen / With best regards

Joern Paschedag

Am 25.08.2011 08:13, schrieb Steve Klett:

but the pin labels don't match what I'm expected (specifically, where is /E and /LE?)  The part in eagle has /ST and /INH

A lot of parts are available from MORE than one manufacturer, and,

unfortunately, these sometimes name their component pins differently:

E.g., the pin called LE ('latch enable') might be called /INH ('inhibit

not') by some other manufacturer. Without looking into the data sheets,

it's sometimes tricky to get to know whether things are compatible or

not. This might or might not be the case with your IC, but at least it's

something you should be aware of.

Andreas Weidner

> If you don't have a basic knowledge about ic-groups then you certainly

> have problems.

I agree, it does make things more difficult.

> So you better get the datasheet for YOUR ic and check if it is compatible.

> The datasheet also tells you what the pins (/ST and /inh in your question)

> are doing.

I have all the datasheets for my parts, but Texas Instruments, NXP, etc. do not use the pin references that I'm seeing in Eagle - this is where my confusion comes in.  I don't mind comparing pins from datasheets but I don't even know which part Eagle is using for the 4514.

> For a beginning in a new sheet perhaps shou should enter in the command

> line(at the very top): "use *" without the " which means use ALL libraries.

> If you start to ADD devices, in this dialog at the very bottom left

> side, you find a search line marked with an "X".

> Here you can enter: 4514* to search for ALL parts that beginn with 4514.

> I hope you know the use of "?" and "*" and the combination of it.

Yes, I've been using the wildcard in my searches and have tried to find a 4514 in the HC or HCT group but there doesn't appear to be one.

> Hopefully this helps you to enjoy eagle

It has helped me understand that I may need to create my own parts.  However this is not something I was expecting to need to do so I may consider hiring someone to take on this project for me.  Thanks for taking the time to respond to me in such detail, I appreciate it.

-Steve

Hi, thanks for the reply.  I realize there are multiple manufacturers but wasn't aware they would use different pin identifiers.

Interesting - I just did a digikey search for "HC4514" to get a list of some manufacturers to include in this response.  I noticed fairchild down at the bottom and checked out their datasheet.  And hey! - they use "strobe" for /LE and "Inhibit" for /E (assuming they are pin compatible)

You mention "Inhibit not" which I still need to read up on because the datasheet just says "inhibit"  From reading the datasheet it sounds like the outputs will respond to the inputs when the inhibit is LOW, so maybe this is what "inhibit not" means; "inhibit low"?

Anyway, thanks for the response and information.

Steve Klett schrieb:

Yes, I've been using the wildcard in my searches and have tried to

find a 4514 in the HC or HCT group but there doesn't appear to be

one.

You don't need to find it explicitly as HC or HCT. All those devices are

pin and function compatible between "normal" CD series and 74HC/HCT

series. Simply use any 4514 in the correct package and assign it the

needed VALUE.

It is generally helpful to think more generically about parts. As an

example, I don't use devices for particular operational amplifiers or

comparators - I just have a generic device (i.e. OP2) containing two

opamps in the standard pinout and with all common package variants, and

then I assign the particular values. Same for transistors, thyristors,

triacs etc. - all parts with common standard pinouts can be defined

generically. (Of course you need to take care that the desired part

really uses that standard pinout... But then, when specifying a circuit,

you need to take care anyway.)

Tilmann

Am 26.08.2011 03:40, schrieb Steve Klett:

You mention "Inhibit not" which I still need to read up on because the datasheet just says "inhibit"  From reading the datasheet it sounds like the outputs will respond to the inputs when the inhibit is LOW, so maybe this is what "inhibit not" means; "inhibit low"?

Yes that means low level active Unfortunately, as you have found

out, different manufacturers use different identifiers. So one must

compare the pin numbers. You see for cadsoft it is not so easy to hit

the "correct" identifier, since there is none. It just depends what

datasheet they used.

(The source is sometimes mentioned in the description of a device).

I have more than 4000 datasheets and still have to check a douzen or so

against other manufacturers because those sheets contain insufficient

information.

--

Mit freundlichen Grüßen / With best regards

Joern Paschedag

Am 26.08.2011 03:40, schrieb Steve Klett:

And hey! - they use "strobe" for /LE and "Inhibit" for /E (assuming they are pin compatible)

For digital ICs, one VERY often names a pin after its function, assuming

that this function is activated by a logic '1' signal.

E.g., the input pin 'EN' might mean 'enable' and usually enables some

functionality if connected to a logic '1'. If this function were

activated by a logic '0', the pin would often be called 'EN\' or '/EN'

or something like that (or, even nicer, would contain an overstrike,

which now can be done in EAGLE by using '!EN').

Depending on your view of the world, the same function could therefore

be called either 'EN' (enabled with a logic '1') or '/DIS' (disabled

with a logic '0'),...

In your case, it would be '/E' (enabled with a logic '0') and 'INH'

(inhibited or disabled with a logic '1'), which is essentially the same.

However this may be, you can never fully rely on it, and always should

risk a look into the data sheet.

Andreas Weidner

Guest wrote:

 

...It is generally helpful to think more generically about parts. As an

example, I don't use devices for particular operational amplifiers or

comparators - I just have a generic device (i.e. OP2) containing two

opamps in the standard pinout and with all common package variants, and

then I assign the particular values. Same for transistors, thyristors,

triacs etc. - all parts with common standard pinouts can be defined

generically. (Of course you need to take care that the desired part

really uses that standard pinout... But then, when specifying a circuit,

you need to take care anyway.) ...

 

This is a good strategy and seems tthat it would save time, thanks.

Guest wrote:

 

...(The source is sometimes mentioned in the description of a device). ...

 

I've come across this on a few parts avnd immediately appreciated it.  I have created a few parts (8 resistor SOIC array and Clare CPC1014 SSR) and added links to the parts, manf. info and PN.  If everyone did this (where applicable) it would be nice