CD4050AE vs CD4050BE

[logjam]

I have a project that requires a 4050. I bought around 50 CD4050BE
ICs, but none of them work in place of the old (vintage 1975)
CD4050AE.

I lifted legs 2 and 3 out of the IC socket, attached my scope to leg 2
and connected leg 3 to leg 1. This should have caused pin 2 to go
high according to the data sheet. The input threshold for high is
supposed to be 3.5v. Pin 8 is a good hard ground. The voltage supply
is 5.02v. The CD4050BE (new ones) were pulling the inputs down from
4.5-5v down to 2.5v (there is a 47ohm resistor in front of the
inputs). With the CD4050AE part the inputs are not pulled down.

So either I got an entire tube of bad parts, or the AE / BE indicates
something important? I haven't been able to find a data sheet
specifically for the CD4050AE.

I have tested a vintage 1975 MC14050CP is known to work in place of
the CD4050AE for this application.

I will continue to try to find the data sheet.

Right now I am going crazy. I have tried 8 or so parts from the
tube. I wouldn't imagine the whole tube would be bad. Even in a test
circuit I can't get anything out of them... : ( Even if the voltage
was not high enough to be "high", it was sure loading the inputs a
lot...

Thanks,
Grant

 

[DaveM]

I have a project that requires a 4050. I bought around 50 CD4050BE
ICs, but none of them work in place of the old (vintage 1975)
CD4050AE.

I lifted legs 2 and 3 out of the IC socket, attached my scope to leg 2
and connected leg 3 to leg 1. This should have caused pin 2 to go
high according to the data sheet. The input threshold for high is
supposed to be 3.5v. Pin 8 is a good hard ground. The voltage supply
is 5.02v. The CD4050BE (new ones) were pulling the inputs down from
4.5-5v down to 2.5v (there is a 47ohm resistor in front of the
inputs). With the CD4050AE part the inputs are not pulled down.

So either I got an entire tube of bad parts, or the AE / BE indicates
something important? I haven't been able to find a data sheet
specifically for the CD4050AE.

I have tested a vintage 1975 MC14050CP is known to work in place of
the CD4050AE for this application.

I will continue to try to find the data sheet.

Right now I am going crazy. I have tried 8 or so parts from the
tube. I wouldn't imagine the whole tube would be bad. Even in a test
circuit I can't get anything out of them... : ( Even if the voltage
was not high enough to be "high", it was sure loading the inputs a
lot...

Thanks,
Grant

Download the CD4050A datasheet from
http://www.datasheet4u.com/download.php?id=489323

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Life is like a roll of toilet paper; the closer to the end, the faster it goes.

 

[logjam]

Where did you buy these parts?

Unicorn Electronics. I have never had a problem with anything from
there before... I can't help but think that there might be a
difference between the AE and BE suffix???

If the device were damaged by static, is it possible that the inputs
would have more load?

Grant

 

[Bob]

Unicorn Electronics. I have never had a problem with anything from
there before... I can't help but think that there might be a
difference between the AE and BE suffix???

If the device were damaged by static, is it possible that the inputs
would have more load?

Grant

The 4xxxB family has a has added input diodes for ESD protection. There may
be more differences, but I'm not sure.

I never had any trouble with the B family, but the A parts I used to get
from Radio Shack had a high failure rate. This, however, was a LONG time
ago.

Bob

 

[Spehro Pefhany]

I have a project that requires a 4050. I bought around 50 CD4050BE
ICs, but none of them work in place of the old (vintage 1975)
CD4050AE.

I lifted legs 2 and 3 out of the IC socket, attached my scope to leg 2
and connected leg 3 to leg 1. This should have caused pin 2 to go
high according to the data sheet. The input threshold for high is
supposed to be 3.5v. Pin 8 is a good hard ground. The voltage supply
is 5.02v. The CD4050BE (new ones) were pulling the inputs down from
4.5-5v down to 2.5v (there is a 47ohm resistor in front of the
inputs). With the CD4050AE part the inputs are not pulled down.

So either I got an entire tube of bad parts, or the AE / BE indicates
something important? I haven't been able to find a data sheet
specifically for the CD4050AE.

I have tested a vintage 1975 MC14050CP is known to work in place of
the CD4050AE for this application.

I will continue to try to find the data sheet.

Right now I am going crazy. I have tried 8 or so parts from the
tube. I wouldn't imagine the whole tube would be bad. Even in a test
circuit I can't get anything out of them... : ( Even if the voltage
was not high enough to be "high", it was sure loading the inputs a
lot...

Thanks,
Grant

Where did you buy these parts?


Best regards,
Spehro Pefhany

 

[Al]

There should be virtually no current going into or out of the inputs
for applied voltages of 0..12V, even with the Vcc open or shorted to
Vss. Either they are entirely fried, your pin numbers are wrong, or
they are actually a different kind of part.


Best regards,
Spehro Pefhany

If I remember correctly, the A series had a max. voltage of 10 whereas the
B series has a max. voltage of 20. The high and low logic levels are 90% or
18V when supplied by 20V and 10% or 2 volts for the B series. The high and
low levels for 10 volts series are 9 and 1, respectively. So a logic high
would have to be 9 volts or above or for a logic low 1 volt or below. The
higher values provide more noise immunity. At least that was the thought.
I'm not sure the B series would work well with a supply voltage of 5V. As
this is all from memory, take it with a bit of salt.

I think I have some old databooks lying around and will take a look.

Al

 

[Spehro Pefhany]

Unicorn Electronics. I have never had a problem with anything from
there before... I can't help but think that there might be a
difference between the AE and BE suffix???

If the device were damaged by static, is it possible that the inputs
would have more load?

Grant

There should be virtually no current going into or out of the inputs
for applied voltages of 0..12V, even with the Vcc open or shorted to
Vss. Either they are entirely fried, your pin numbers are wrong, or
they are actually a different kind of part.


Best regards,
Spehro Pefhany

 

[RST Engineering \(jw\)]

My memory is that the 4000 series cmos had a voltage range from 3 to 18 from
the getgo. If I'm not mistaken, the B suffix were buffered and had a hard
time being forced into such things as analog amplifiers and oscillators.

The guaranteed OUTput of the 4000 series is (as a percentage of Vdd) 90%
high and 10% low, while the INput had guaranteed switching rates of 70% and
30% respectively. You always had a guaranteed noise margin of 20%, 3.6
volts at 18 volts Vdd and 1 volt at 5 volts Vdd.



Jim





7

 

[Ross Herbert]

My memory is that the 4000 series cmos had a voltage range from 3 to 18 from
the getgo. If I'm not mistaken, the B suffix were buffered and had a hard
time being forced into such things as analog amplifiers and oscillators.

The guaranteed OUTput of the 4000 series is (as a percentage of Vdd) 90%
high and 10% low, while the INput had guaranteed switching rates of 70% and
30% respectively. You always had a guaranteed noise margin of 20%, 3.6
volts at 18 volts Vdd and 1 volt at 5 volts Vdd.



Jim

My recollections are similar. I know that there were definite areas
where buffered CMOS could not be interchanged for unbuffered devices.

This TI document refers to this fact in the background paragraph.
http://focus.ti.com/lit/an/scha004/scha004.pdf

While this doc specifies unbuffered devices as being marked UB I think
this only applied well after the introduction of the buffered series.
Initially, only the RCA 4000 (unbuffered) series existed and I think
they may have begun to use the A suffix to differentiate from the B
series when the latter started to appear more commonly. My old RCA
literature may have some further info.

 

[Tony Williams]

............... I haven't been able to find a data sheet
specifically for the CD4050AE.

There is little difference except that the -B version
has a higher supply and input voltage range.

Right now I am going crazy. I have tried 8 or so parts from the
tube. I wouldn't imagine the whole tube would be bad. Even in a
test circuit I can't get anything out of them... : ( Even if
the voltage was not high enough to be "high", it was sure loading
the inputs a lot...

The 4050 does have a weakness on the inputs. It is
designed to operate with a logic 1 that can exceed
the Vcc, up to 20V for the 4050B. In order to do
this there is little or no protection against a
positive input overvoltage.

Your apparent high current taken by the inputs does
suggest damaged parts.

 

[whit3rd]

I have a project that requires a 4050. I bought around 50 CD4050BE
ICs, but none of them work in place of the old (vintage 1975)
CD4050AE.

My old RCA CMOS databook has both data sheets; the main difference
is that the 'B' is good for 3-18V power, and the 'A' is good for 3-12V
power. Input limits are 20V for 'B' and 12V for 'A'. Both are
intended
to be driven from higher voltage than the power supply.

(+) power is on pin 1, (-) power is on pin 8.

Other differences are minor (guaranteed sink current at 5V is 3.2 mA
for the 'B' and 3 mA for 'A').

 

[Tim Shoppa]

I have a project that requires a 4050. I bought around 50 CD4050BE
ICs, but none of them work in place of the old (vintage 1975)
CD4050AE.

Right now I am going crazy. I have tried 8 or so parts from the
tube. I wouldn't imagine the whole tube would be bad. Even in a test
circuit I can't get anything out of them... : ( Even if the voltage
was not high enough to be "high", it was sure loading the inputs a
lot...

Are you sure you got real CD4050BE's? Motorola had a part line with
numbers beginning like 40xx but they were Motorola's own version of
TTL and had nothing to do with the similar CD-series CMOS parts.

It's hard to imagine them being counterfeit parts - it'd be like
counterfeiting pennies! - but on the surplus market large batches of
mislabeled or just plain defective parts show up quite regularly. The
older the chips, or the lower in the distribution chain you go, the
more likely what you got were factory rejects or floor sweepings. Are
you sure you didn't get these through a time warp from Poly Paks?

Tim.

 

[Tim Shoppa]

Are you sure you got real CD4050BE's? Motorola had a part line with
numbers beginning like 40xx but they were Motorola's own version of
TTL and had nothing to do with the similar CD-series CMOS parts.

Ahah! Now I remember, the MC4050 was a decade counter and maybe a
display decoder used in lots of 70's/80's vintage frequency counters.
It won't work nothin like a CD4050.

Tim.

 

[Spehro Pefhany]

Ahah! Now I remember, the MC4050 was a decade counter and maybe a
display decoder used in lots of 70's/80's vintage frequency counters.
It won't work nothin like a CD4050.

Tim.

But the OP specifically said "CD4050BE", which is nothin' like
"MC4050". But maybe the parts are marked differently from what s/he
thinks they are.


Best regards,
Spehro Pefhany

 

[RST Engineering \(jw\)]

Precisely.

Jim