comparators in IC 555

I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order?
Thanks,
DAM

 

[petrus bitbyter]

<macmanus130@btinternet.com> schreef in bericht
news:7367bef3-58ac-4086-a713-4db17bdb61b4@googlegroups.com...

I've looked on the internet but no joy...there are two comapators inside
an IC 555. What are these two comparators? Are they 'standard'? What are
they called? If you wanted a make an IC 555 what comparator would you
order?
Thanks,
DAM

There are tons of stuff about the 555, including detailed descriptions of
the inner workings. If you're only interested in a comparator, get the
datasheet of the LM393.

petrus bitbyter

 

[Tom Biasi]

On 8/12/2012 1:43 PM, macmanus130@btinternet.com wrote:

On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere does it say what the comparators are! Unless you know somewhere where it says...
Thx

The original 555 constructed the comparators on chip. They didn't give

them a name. You can find the characteristics by doing what was
suggested to you. Look at the data sheet.

 

On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:

I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere does it say what the comparators are! Unless you know somewhere where it says...
Thx

 

[Sjouke Burry]

macmanus130@btinternet.com wrote in
news:25f79dba-a9fb-4d03-afdd-5d1e1058ea78@googlegroups.com:

On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators
inside an IC 555. What are these two comparators? Are they
'standard'? What are they called? If you wanted a make an IC 555 what
comparator would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but
nowhere does it say what the comparators are! Unless you know
somewhere where it says... Thx

Comarator A trips when the generated sawtooth reaches 2/3 VCC,
and toggles the internal flipflop,so the sawtooth goes down,
comprator B trips when the saw tooth then reaches 1/3 VCC,
and also toggles the flipflop, so the sawtooth goes up.
All in all a voltage divider, 2 comparators and a flipflop,
charging and draining a capacitor.
Thats all.

 

[Jim Thompson]

On Sun, 12 Aug 2012 15:23:33 -0400, Tom Biasi <tombiasi@optonline.net>
wrote:

On 8/12/2012 1:43 PM, macmanus130@btinternet.com wrote:
On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere does it say what the comparators are! Unless you know somewhere where it says...
Thx

The original 555 constructed the comparators on chip. They didn't give
them a name. You can find the characteristics by doing what was
suggested to you. Look at the data sheet.

Tom is correct. Internal to the 555, the "comparators" are simplistic
diff stages driving latches... because there's no need for driving the
outside world.

If you can find a circuit schematic of the 555 BIPOLAR version, you'll
easily spot the diff pairs making up the "comparators".

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Ian Field]

"Tom Biasi" <tombiasi@optonline.net> wrote in message
news:50280294$0$11518$607ed4bc@cv.net...

On 8/12/2012 1:43 PM, macmanus130@btinternet.com wrote:
On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators inside
an IC 555. What are these two comparators? Are they 'standard'? What are
they called? If you wanted a make an IC 555 what comparator would you
order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere
does it say what the comparators are! Unless you know somewhere where it
says...
Thx

The original 555 constructed the comparators on chip. They didn't give
them a name. You can find the characteristics by doing what was suggested
to you. Look at the data sheet.

Its possible that macmanus has looked at the 555 schematic and failed to see
much similarity between the one's on the chip & typical industry standard
types.

Confusion can arise from the "shorthand" chip manufacturers use - like the
far from standard representations of current mirrors, then there's the fact
that the comparators in a 555 have much simpler structures than industry
standard parts, they each only have to do one simple job - not be an all
things to all circuits like the 393.

 

[krw@att.bizzzzzzzzzzzz]

On Sun, 12 Aug 2012 09:01:47 -0700 (PDT), macmanus130@btinternet.com wrote:

I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order?

Is it homework time already?

 

[John Fields]

On Sun, 12 Aug 2012 14:01:50 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sun, 12 Aug 2012 15:23:33 -0400, Tom Biasi <tombiasi@optonline.net
wrote:

On 8/12/2012 1:43 PM, macmanus130@btinternet.com wrote:
On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere does it say what the comparators are! Unless you know somewhere where it says...
Thx

The original 555 constructed the comparators on chip. They didn't give
them a name. You can find the characteristics by doing what was
suggested to you. Look at the data sheet.

Tom is correct. Internal to the 555, the "comparators" are simplistic
diff stages driving latches... because there's no need for driving the
outside world.

If you can find a circuit schematic of the 555 BIPOLAR version, you'll
easily spot the diff pairs making up the "comparators".

...Jim Thompson

---
The schematic is on page 11-4 of Hans Camenzind's book,
"Designing Analog Chips", which can be downloaded for free at:

www.designinganalogchips.com

--
JF

 

[fungus]

On Sunday, August 12, 2012 6:01:47 PM UTC+2, (unknown) wrote:

I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order?

https://en.wikipedia.org/wiki/555_timer_IC

 

[Jim Thompson]

On Mon, 13 Aug 2012 07:17:39 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Sun, 12 Aug 2012 14:01:50 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Sun, 12 Aug 2012 15:23:33 -0400, Tom Biasi <tombiasi@optonline.net
wrote:

On 8/12/2012 1:43 PM, macmanus130@btinternet.com wrote:
On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere does it say what the comparators are! Unless you know somewhere where it says...
Thx

The original 555 constructed the comparators on chip. They didn't give
them a name. You can find the characteristics by doing what was
suggested to you. Look at the data sheet.

Tom is correct. Internal to the 555, the "comparators" are simplistic
diff stages driving latches... because there's no need for driving the
outside world.

If you can find a circuit schematic of the 555 BIPOLAR version, you'll
easily spot the diff pairs making up the "comparators".

...Jim Thompson

---
The schematic is on page 11-4 of Hans Camenzind's book,
"Designing Analog Chips", which can be downloaded for free at:

www.designinganalogchips.com

Yup.

NPN's, Q1-Q4 make up one comparator

PNP's, Q10-Q13 make up the other

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jamie]

macmanus130@btinternet.com wrote:

I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order?
Thanks,
DAM

Yes, they are standard as far as being supported through out different
venders if that is what you mean?

Also, 555 timers have and are used for comparator with latching
function etc..

The trigger input acts on a sink signal or, any signal that is 1/3
or less in voltage of the rail.

THe threshold input works with souring voltage and that will trigger
when the signal is 2/3 or more of the VCC(rail).

THe trigger will turn on the output when it gets active, which is when
any signal at the trigger is 1/3 or less at that input. THis input is a
PNP input so you actually need a sink related signal that is below 1/3
Vcc to trip it.

The threshold is a NPN input and only acts with source signals..

when Threshold is activated the discharge output pulls to common (open
collector NPN)..

This gives you a number of things you can do with it..

I've used the 555 as a comparator in apps where a latching trigger was
required due to an event and those inputs as comparators work very well
for that.

Jamie

 

[Jamie]

macmanus130@btinternet.com wrote:

On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:

I've looked on the internet but no joy...there are two comapators inside an IC 555. What are these two comparators? Are they 'standard'? What are they called? If you wanted a make an IC 555 what comparator would you order? Thanks, DAM


All the stuff on the internet says there are two comparators but nowhere does it say what the comparators are! Unless you know somewhere where it says...
Thx

Yup, the Trigger and Threshold inputs are the comparators and they are
set internally at 1/3 and 2/3 voltage..

Jamie

 

[Michael Black]

On Sun, 12 Aug 2012, macmanus130@btinternet.com wrote:

On Sunday, 12 August 2012 17:01:47 UTC+1, (unknown) wrote:
I've looked on the internet but no joy...there are two comapators
inside an IC 555. What are these two comparators? Are they 'standard'?
What are they called? If you wanted a make an IC 555 what comparator
would you order? Thanks, DAM

All the stuff on the internet says there are two comparators but nowhere
does it say what the comparators are! Unless you know somewhere where it
says... Thx

Because they aren't. Someone didn't say "we'll take that comparator and

that flip flop and put it into a single package". They figured out what
was needed, and then proceeded to work out the circuit.

You could probably make a 555 from any comparator that worked off a single
supply voltage going up to +12v, and a CMOS flip flop. If that's what you
are trying to do. Might not work perfectly, but the concept is there.

Michael