Why do people use 74... instead of 4000 series?

[grrr_arrghh]

Hi.

As a victim of a secondary school education, I have been 'brought up' using 4000B series ICs. However, I look in this forum, and on web sites, and they all seem to use some form of 74... series ICs. Then they have all sorts of problems because you need to provide an approx 5v supply, meaning that you can't use a normal 9v battery (which is the simplest for testing projects).

I can't understand why people make it so difficult for them selves. Am I missing something?

Thanks :?

Tim

 

[Sebi]

Maybe the circuits born about '70...'80 and not redesigned for CMOS.
Or many pieces of TTL huddle in drawer...
For battery operating only the CMOS recommended.

 

[samcheetah]

just like u have been brought up using the 4000 series. many of us (including me) have been brought up using the 74 series :lol: :lol:

 

[grrr_arrghh]

just like u have been brought up using the 4000 series. many of us (including me) have been brought up using the 74 series :lol: :lol:

Fair enough.

Have a nice day.

 

[Roff]

Hi.

As a victim of a secondary school education, I have been 'brought up' using 4000B series ICs. However, I look in this forum, and on web sites, and they all seem to use some form of 74... series ICs. Then they have all sorts of problems because you need to provide an approx 5v supply, meaning that you can't use a normal 9v battery (which is the simplest for testing projects).

I can't understand why people make it so difficult for them selves. Am I missing something?

Thanks :?

Tim

There are many families of "74 series" logic. Some (most) of them are also CMOS. All of them are faster than 4000 series.

 

[grrr_arrghh]

really? how much faster?

do the CMOS 74 series still need 4.5-5.5v?

Tim

 

[Klaus]

Only the TTL 74 series chips require a 5V power source. CMOS chips require whatever the datasheet says you can get away with.

TTL chips are also far more rugged than CMOS chips, none of the constant worry about static damage due to carelass handling. This comes at the price of a higher current draw but one gets some speed advantages in turn.
Check the data sheets regarding the exact figures.
You'll find most data sheets right here on the net with Google, just type in the chip number as the search subject.

You can get useful experimenters 5V power supplies from older scrapped computers, sometimes its the only thing in these machines worth recycling.
Klaus

 

[grrr_arrghh]

TTL chips are also far more rugged than CMOS chips, none of the constant worry about static damage due to carelass handling

I know that CMOS are quite sensitive, but I was under the impression that the 4000B series (take not of the 'B' on the end) had static protection built in...?

Tim.

 

[laroche73]

static protection

The 4000B devices do have improved input protection vs. 4000A devices, though they're still susceptible to static damage. The gate input of a CMOS device is equivalent to a very small capacitor (a few pF) in parallel with a very high resistance (10^12 ohms), and a static charge can easily generate enough voltage to break down the gate oxide. The input protection networks help a lot, but you still need to take precautions when handling any kind of CMOS device.

As you've noticed, one of the nicer features of the CD4000 series is the wide operating voltage range (3-18V). The closest thing in a newer CMOS family is probably the 74HCxxx series (2-6V) or the still newer 74VHC series. You can still use a 9V battery, but you'll need to use a 78L05 or 06 regulator to drop the voltage. Power consumption is very low with the HC parts (about 1/10 of the equivalent CD4000 part, and both are far below TTL consumption), so power dissipation in the regulator generally isn't a problem (of course, it depends on what load you're driving as well).

 

[grrr_arrghh]

oh, ok, thanks, that very helpful.

however, I am slightly confused, what is CD4000? is that TTL or CMOS?

Thanks, what you wrote cleared it up a lot!!

Tim

 

[laroche73]

CD

CD (CMOS device?) is just the common prefix for the 4000 series.

 

[grrr_arrghh]

CD (CMOS device?)

lol, it makes so much sense when someone points it out to you!! :shock:

so (for example) a CD4047 could be a 4047A or a 4047B?

Thanks again

Tim

 

[laroche73]

A/B CMOS versions

Yes, but it's hard to find the "A" (unbuffered) versions any more, at least in the states. You're almost always better off going with the "B" (buffered output) series anyway, with a few exceptions (Ex - using unbuffered inverters for crystal oscillators).