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CMOS logic level range

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Robert Harris

Jan 1, 1970
0
I am designing a circuit using all CMOS 4000 series IC's.

It is to be powered by four AA cells, either alkaline or NiCad's.

What is the minimum and maximum voltage that will work as logic level
"1"?

IOW how far off 5V can it go either way?

Thank you,

Rob Harris
 
D

D from BC

Jan 1, 1970
0
I am designing a circuit using all CMOS 4000 series IC's.

It is to be powered by four AA cells, either alkaline or NiCad's.

What is the minimum and maximum voltage that will work as logic level
"1"?

IOW how far off 5V can it go either way?

Thank you,

Rob Harris

Isn't this a datasheet thing?
D from BC
 
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Jim Thompson

Jan 1, 1970
0
level 1 is 4.5V to Vcc 0.5V, okay?

The "official" specification is usually...

"0" <= 0.3*VDD

"1" >= 0.7*VDD

...Jim Thompson
 
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Joerg

Jan 1, 1970
0
Jim said:
The "official" specification is usually...

"0" <= 0.3*VDD

"1" >= 0.7*VDD

The not-so-official specification is usually...

"0" <= 0.3*VDD

"1" >= 0.7*VDD

"linear" = 0.5*VDD

:)))
 
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Jim Thompson

Jan 1, 1970
0
The not-so-official specification is usually...

"0" <= 0.3*VDD

"1" >= 0.7*VDD

"linear" = 0.5*VDD

:)))

Sane people don't do "linear" with off-the-shelf CMOS ;-)

...Jim Thompson
 
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Joerg

Jan 1, 1970
0
Jim said:
Sane people don't do "linear" with off-the-shelf CMOS ;-)

Good. So if someone wants to sue me I could then claim immunity based on
the grounds of insanity ;-)
 
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John Larkin

Jan 1, 1970
0
level 1 is 4.5V to Vcc 0.5V, okay?

That will certainly work, but if any logic level is very far off the
rails (a volt maybe? less?) the chips will draw excess current and run
down your battery.

John
 
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Rich Grise

Jan 1, 1970
0
Sane people don't do "linear" with off-the-shelf CMOS ;-)

So, I guess the HCU04 isn't "off the shelf"? ;-)

and, BTW, I had thought that 0 <= 1/3 Vdd (.33) and 1 >= 2/3 Vdd. (.67)

Thanks,
Rich
 
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Joerg

Jan 1, 1970
0
Rich said:
So, I guess the HCU04 isn't "off the shelf"? ;-)

and, BTW, I had thought that 0 <= 1/3 Vdd (.33) and 1 >= 2/3 Vdd. (.67)

That doesn't include taxes ;-)
 
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jasen

Jan 1, 1970
0
I am designing a circuit using all CMOS 4000 series IC's.

It is to be powered by four AA cells, either alkaline or NiCad's.

What is the minimum and maximum voltage that will work as logic level
"1"?

typically cmos high is 2/3 of VCC and above, read a few datasheets.
IOW how far off 5V can it go either way?

with a 15V supply 5V would be low :)

Bye.
Jasen
 
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Lionel

Jan 1, 1970
0
I am designing a circuit using all CMOS 4000 series IC's.

It is to be powered by four AA cells, either alkaline or NiCad's.

What is the minimum and maximum voltage that will work as logic level
"1"?

IOW how far off 5V can it go either way?

Depends on the logic family. Traditionally (eg the old CD4000 series
chips), you can power them from anywhere from 3V to 15V, & a logic '1'
is anything above 1/2 the supply voltage, '0' is anything below that.
For newer CMOS logic families, they specified for all sorts of weird
voltage ranges. You can find out for sure from the data sheet.

But as a general rule of thumb for any CMOS logic chip powered by 5V,
you can assume that any signal above 2.5V will be treated as a '1', &
that anything below about 1V will be considered a '0'.

Again, if you're doing anything critical, you need to look up the data
sheet.
 
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Anthony Fremont

Jan 1, 1970
0
Lionel said:
Depends on the logic family. Traditionally (eg the old CD4000 series
chips), you can power them from anywhere from 3V to 15V, & a logic '1'
is anything above 1/2 the supply voltage, '0' is anything below that.
For newer CMOS logic families, they specified for all sorts of weird
voltage ranges. You can find out for sure from the data sheet.

But as a general rule of thumb for any CMOS logic chip powered by 5V,
you can assume that any signal above 2.5V will be treated as a '1', &
that anything below about 1V will be considered a '0'.

Again, if you're doing anything critical, you need to look up the data
sheet.

I believe 2.5V is wayyyyy too low for a Vcc of 5V unless you're warming up
the parts. ;-) I'd keep it at .7Vcc (.8 *Vcc for Schmitt trigger inputs)
to be safe. IOW, 3.5V is the minimum.
 
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Lionel

Jan 1, 1970
0
I believe 2.5V is wayyyyy too low for a Vcc of 5V unless you're warming up
the parts. ;-) I'd keep it at .7Vcc (.8 *Vcc for Schmitt trigger inputs)
to be safe. IOW, 3.5V is the minimum.

You've obviously grown up with TTL compatible CMOS parts. ;) Go check
the 4000 series spec's.
 
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Jim Thompson

Jan 1, 1970
0
You've obviously grown up with TTL compatible CMOS parts. ;) Go check
the 4000 series spec's.

Lionel, YOU need to re-read the data sheets.

...Jim Thompson
 
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Anthony Fremont

Jan 1, 1970
0
Lionel said:
You've obviously grown up with TTL compatible CMOS parts. ;) Go check
the 4000 series spec's.

You must think they all are. ;-) I'm not trying to be rude, but maybe you
should look again. Vih is usually at least 3.5V on CMOS, anything below
that and you are gambling. 2.5V is waaaayyyyyyy toooooooo looooooowwww for
CMOS inputs. ;-) PIC chips want 4V minimun on 5V Vcc (.8 * Vcc).
 
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Anthony Fremont

Jan 1, 1970
0
Anthony said:
You must think they all are. ;-) I'm not trying to be rude, but
maybe you should look again. Vih is usually at least 3.5V on CMOS,
anything below that and you are gambling. 2.5V is waaaayyyyyyy
toooooooo looooooowwww for CMOS inputs. ;-) PIC chips want 4V
minimun on 5V Vcc (.8 * Vcc).

I will add that for the PICs, the pins that have TTL input buffers (most of
them) only require 2.0V (4.5V < Vcc < 5.5V). The official formula is (1.25
* Vcc) + .8V, but they make a special case for 5V operation. But I believe
this is a special case and not consistant with normal CMOS specifications.
The Schmitt trigger inputs want .8 * Vcc.
 
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Lionel

Jan 1, 1970
0
Lionel, YOU need to re-read the data sheets.

I do? I'll admit that it's been at least 15 years since I last looked
at a 4000 series data sheet...

<goes & checks>

Well, according to Motorola
(<http://www.onsemi.com/pub/Collateral/MC14001B-D.PDF>),
at a Vcc of 5V, (@25c), a logic '0' = 0-2.25V, & a logic '1' = 2.75V -
5V. That'd make the swicthing point 50% of Vcc, wouldn't it?
Seems to me that I was dead on the money.

Maybe your memory's getting a little rusty too, eh Jim? ;^)
 
A

Anthony Fremont

Jan 1, 1970
0
Lionel said:
I do? I'll admit that it's been at least 15 years since I last looked
at a 4000 series data sheet...

<goes & checks>

Well, according to Motorola
(<http://www.onsemi.com/pub/Collateral/MC14001B-D.PDF>),
at a Vcc of 5V, (@25c), a logic '0' = 0-2.25V, & a logic '1' = 2.75V -
5V. That'd make the swicthing point 50% of Vcc, wouldn't it?
Seems to me that I was dead on the money.

Maybe your memory's getting a little rusty too, eh Jim? ;^)

That's the Typical spec and certainly wouldn't be something to recommend as
a rule of thumb IMO. I'm going to stick with the value in the column next
to that one that says (Min 3.5V).
 
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Lionel

Jan 1, 1970
0
That's the Typical spec and certainly wouldn't be something to recommend as
a rule of thumb IMO. I'm going to stick with the value in the column next
to that one that says (Min 3.5V).

Sure, but they're designed to switch at Vcc/2.
 
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