In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

--
Tekkie

On Monday, January 21, 2019 at 2:36:13 PM UTC-5, Tekkie® wrote:
In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

--
Tekkie

5V was the first standard for digital logic going back to the 60s.
It's still common for designs that are not battery powered and
that need very low power.
How exactly they picked 5, IDK. But transistors can work with just
a couple volts, some logic designs had two transistors stacked one
on top of the other, so you'd need about twice the minimum.
Next consideration, you need enough range in a digital design to
reliably distinguish between
a logic level of one and zero. You'd also need that to be agreed on so
that chips from one supplier would work with chips from other suppliers.
Zero wound up being defined as less than .8V,
you needed some separation between that and whatever voltage would
be a one. One I think was above 2.5V and if the logic wasn't malfunctioning
you couldn't get a voltage in between. So, with a one being above
2.5V and needing some internal headroom, 5V is a logical, convenient
choice. Today with improvements, smaller transistors, and the need
for low ultra low power in mobile devices, logic families at 3V and
1.8 v are being used for those applications. Even desktop CPUs are
running down at 3V and below, I think.

This of course is for digital logic electronics. For analog, all kinds
of voltages have been used.

On Mon, 21 Jan 2019 14:36:31 -0500, Tekkie®
wrote:


In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

The 5 volt standard goes WAY back to TTL logic
As for the origins of 5V/TTL, that was a set of design tradeoffs. If
you find a schematic of a TTL gate, you'll notice that it needs at
least 3 diode drops internally, plus various resistor drops. What that
doesn't tell you is the choice of reference currents (1.6 mA for a low
input) which was in part determined by the current levels required to
produce acceptable switching speeds. These current levels in turn set
limits on the internal resistor values, and the voltages needed to
feed them. You also need to factor in the state of semiconductor fab
capability - the first TTL circuits were at the edge of what could be
reliably produced. Imagine - 20 to 100 gates on a chip! That's (gulp)
hundreds of transistors, with the masks all laid out by hand. All of
this, including power dissipation limits, resulted in the standard TTL
supply voltage spec of 4.75 to 5.25 volts. As it turned out, this was
an adequately wide margin for practical systems, and the speed (10 -
20 MHz) was adequate for a wide range of applications. So TTL became
king. Even then, if you wanted faster speed there were other families
available, like 74S and ECL, but those puppies were even bigger power
hogs than TTL. Go look up the construction techniques for the first
Cray computers

"Clare Snyder" wrote in message
...
On Mon, 21 Jan 2019 14:36:31 -0500, Tekkie®
wrote:


In electronics and automotive electronics 5 volts seems to be the
standard.
I am curious as to how this was made the standard.

The 5 volt standard goes WAY back to TTL logic

To well before that with RTL and DTL in fact.

As for the origins of 5V/TTL, that was a set of design tradeoffs. If
you find a schematic of a TTL gate, you'll notice that it needs at
least 3 diode drops internally, plus various resistor drops. What that
doesn't tell you is the choice of reference currents (1.6 mA for a low
input) which was in part determined by the current levels required to
produce acceptable switching speeds. These current levels in turn set
limits on the internal resistor values, and the voltages needed to
feed them. You also need to factor in the state of semiconductor fab
capability - the first TTL circuits were at the edge of what could be
reliably produced. Imagine - 20 to 100 gates on a chip! That's (gulp)
hundreds of transistors, with the masks all laid out by hand. All of
this, including power dissipation limits, resulted in the standard TTL
supply voltage spec of 4.75 to 5.25 volts. As it turned out, this was
an adequately wide margin for practical systems, and the speed (10 -
20 MHz) was adequate for a wide range of applications. So TTL became
king. Even then, if you wanted faster speed there were other families
available, like 74S and ECL, but those puppies were even bigger power
hogs than TTL. Go look up the construction techniques for the first
Cray computers

On Tue, 22 Jan 2019 09:22:33 +1100, Samsungo, better known as cantankerous
trolling senile geezer Rot Speed, wrote:


In electronics and automotive electronics 5 volts seems to be the
standard.
I am curious as to how this was made the standard.

The 5 volt standard goes WAY back to TTL logic

To well before that with RTL and DTL in fact.

It can't have been before you were born, you 85-year-old senile pest. Or can
it? BG

--
FredXX to Rot Speed:
"You are still an idiot and an embarrassment to your country. No wonder
we shippe the likes of you out of the British Isles. Perhaps stupidity
and criminality is inherited after all?"
Message-ID:

On Mon, 21 Jan 2019 12:24:20 -0800 (PST), trader_4
wrote:

On Monday, January 21, 2019 at 2:36:13 PM UTC-5, Tekkie® wrote:
In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

--
Tekkie

5V was the first standard for digital logic going back to the 60s.
It's still common for designs that are not battery powered and
that need very low power.
How exactly they picked 5, IDK. But transistors can work with just
a couple volts, some logic designs had two transistors stacked one
on top of the other, so you'd need about twice the minimum.
Next consideration, you need enough range in a digital design to
reliably distinguish between
a logic level of one and zero. You'd also need that to be agreed on so
that chips from one supplier would work with chips from other suppliers.
Zero wound up being defined as less than .8V,
you needed some separation between that and whatever voltage would
be a one. One I think was above 2.5V and if the logic wasn't malfunctioning
you couldn't get a voltage in between. So, with a one being above
2.5V and needing some internal headroom, 5V is a logical, convenient
choice. Today with improvements, smaller transistors, and the need
for low ultra low power in mobile devices, logic families at 3V and
1.8 v are being used for those applications. Even desktop CPUs are
running down at 3V and below, I think.

This of course is for digital logic electronics. For analog, all kinds
of voltages have been used.

Yup 5v was what the original TTL ran on and those were the most common
IC chips in the beginning. CMOS is more forgiving and will run on a
pretty wide range of voltages.
These days I suspect 5v was chosen because that is what you get from a
USB port and they are everywhere. Before USB became the "go to"
charging port 12v was getting pretty popular and it still is for a lot
of stuff.
It is pretty much #2 in that coaxial power plug you see on wall warts.

On Mon, 21 Jan 2019 16:23:49 -0500, Clare Snyder
wrote:

On Mon, 21 Jan 2019 14:36:31 -0500, Tekkie®
wrote:


In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

The 5 volt standard goes WAY back to TTL logic
As for the origins of 5V/TTL, that was a set of design tradeoffs. If
you find a schematic of a TTL gate, you'll notice that it needs at
least 3 diode drops internally, plus various resistor drops. What that
doesn't tell you is the choice of reference currents (1.6 mA for a low
input) which was in part determined by the current levels required to
produce acceptable switching speeds. These current levels in turn set
limits on the internal resistor values, and the voltages needed to
feed them. You also need to factor in the state of semiconductor fab
capability - the first TTL circuits were at the edge of what could be
reliably produced. Imagine - 20 to 100 gates on a chip! That's (gulp)
hundreds of transistors, with the masks all laid out by hand. All of
this, including power dissipation limits, resulted in the standard TTL
supply voltage spec of 4.75 to 5.25 volts. As it turned out, this was
an adequately wide margin for practical systems, and the speed (10 -
20 MHz) was adequate for a wide range of applications. So TTL became
king. Even then, if you wanted faster speed there were other families
available, like 74S and ECL, but those puppies were even bigger power
hogs than TTL. Go look up the construction techniques for the first
Cray computers


IBM's high speed logic used +0.9 and +1.9 levels for a "0" and a "1"
in the S/370 days when LSI "transistor logic" ICs were the thing.
The power rails were 1.5v and 3v. Keeping the voltage down made
switching faster and reduced power consumption but they were still
power hogs compared to the CMOS that followed.
You could easily have a 1.5v power supply running close to 100 amps.
The big systems were water cooled.

On Tue, 22 Jan 2019 00:31:51 -0500, wrote:

On Mon, 21 Jan 2019 12:24:20 -0800 (PST), trader_4
wrote:

On Monday, January 21, 2019 at 2:36:13 PM UTC-5, Tekkie® wrote:
In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

--
Tekkie

5V was the first standard for digital logic going back to the 60s.
It's still common for designs that are not battery powered and
that need very low power.
How exactly they picked 5, IDK. But transistors can work with just
a couple volts, some logic designs had two transistors stacked one
on top of the other, so you'd need about twice the minimum.
Next consideration, you need enough range in a digital design to
reliably distinguish between
a logic level of one and zero. You'd also need that to be agreed on so
that chips from one supplier would work with chips from other suppliers.
Zero wound up being defined as less than .8V,
you needed some separation between that and whatever voltage would
be a one. One I think was above 2.5V and if the logic wasn't malfunctioning
you couldn't get a voltage in between. So, with a one being above
2.5V and needing some internal headroom, 5V is a logical, convenient
choice. Today with improvements, smaller transistors, and the need
for low ultra low power in mobile devices, logic families at 3V and
1.8 v are being used for those applications. Even desktop CPUs are
running down at 3V and below, I think.

This of course is for digital logic electronics. For analog, all kinds
of voltages have been used.

Yup 5v was what the original TTL ran on and those were the most common
IC chips in the beginning. CMOS is more forgiving and will run on a
pretty wide range of voltages.
These days I suspect 5v was chosen because that is what you get from a
USB port and they are everywhere. Before USB became the "go to"
charging port 12v was getting pretty popular and it still is for a lot
of stuff.
It is pretty much #2 in that coaxial power plug you see on wall warts.

You notice 6 and 9 volts are pretty well history? 3.7 and 4.5 are
also getting scarce,even with Lithium cells.

On 01/21/2019 10:37 PM, wrote:
IBM's high speed logic used +0.9 and +1.9 levels for a "0" and a "1"
in the S/370 days when LSI "transistor logic" ICs were the thing.
The power rails were 1.5v and 3v. Keeping the voltage down made
switching faster and reduced power consumption but they were still
power hogs compared to the CMOS that followed.

iirc the first gen CMOS parts became hogs if you drove them hard. After
I sent my Osborne 1 back to the factory for the video card and double
sided floppy upgrade I found the video would fail after a few minutes.
Investigating, I found a CMOS part that was running very hot. I replaced
it with the LS equivalent and life was good.

Tekkie® wrote:
In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.


Available chips I think. Previously every company had their own logic and
different voltages, and positive or negative logic. There was DEC logic,
Collins logic, Zerox logic, etc. There was also Dynamic logic. A one was a
pulse, no steady state signals except no pulse a zero. One dandy machine I
worked on had Audio, RF, TTL, MECL, the SRE. We called it Sorry.

Greg