Opto coupler CTR curve

[Engin Ciftci]

In most of the opto-coupler data sheets min CTR value is given. But
there is no comment on max value and the typical value for the CTR
value. I have measured different parts in different parties for the
same opto-coupler (H11AA1) and saw that they are surprisingly varied.
Also their actual CTR values are far from the min CTR value given in
the data sheet.

So i gave up finding a low cost opto-coupler with a constant or limited
CTR value. My question is:

How can I fix or compensate CTR variations in my circuits. I have
tried many combinations of feedback circuits and they not satisfactory
to fulfill my expectations. One constraint in my design is I can not
add additional component such as capacitor or a series resistor to
cancel pole of the current transfer function.

Any suggestions?

Thanks a lot.

Engin

 

[Jim Thompson]

In most of the opto-coupler data sheets min CTR value is given. But
there is no comment on max value and the typical value for the CTR
value. I have measured different parts in different parties for the
same opto-coupler (H11AA1) and saw that they are surprisingly varied.
Also their actual CTR values are far from the min CTR value given in
the data sheet.

So i gave up finding a low cost opto-coupler with a constant or limited
CTR value. My question is:

How can I fix or compensate CTR variations in my circuits. I have
tried many combinations of feedback circuits and they not satisfactory
to fulfill my expectations. One constraint in my design is I can not
add additional component such as capacitor or a series resistor to
cancel pole of the current transfer function.

Any suggestions?

Thanks a lot.

Engin

Can you afford an HCNR201 (a matched pair)?

...Jim Thompson

 

[Genome]

In most of the opto-coupler data sheets min CTR value is given. But
there is no comment on max value and the typical value for the CTR
value. I have measured different parts in different parties for the
same opto-coupler (H11AA1) and saw that they are surprisingly varied.
Also their actual CTR values are far from the min CTR value given in
the data sheet.

So i gave up finding a low cost opto-coupler with a constant or limited
CTR value. My question is:

How can I fix or compensate CTR variations in my circuits. I have
tried many combinations of feedback circuits and they not satisfactory
to fulfill my expectations. One constraint in my design is I can not
add additional component such as capacitor or a series resistor to
cancel pole of the current transfer function.

Any suggestions?

Thanks a lot.

Engin

You mean

http://www.fairchildsemi.com/ds/H1/H11AA1.pdf

My Landlord and 'friends' went to Turkey for a holiday. Full board in the
Hotel.

Turns out the food was shit and they played seriously loud music all the
time. Result was my Landlord and 'friends' were forced to 'eat out' in
places provided by the hotel owners family.

I guess that means it is payback time.

Your situation on this subject is?

And.... you are using an AC optocoupler in its linear region for why?

'One constraint in my design is I can not add additional component such as
capacitor or a series resistor to cancel pole of the current transfer
function.'

I'll assume you know what you are on about and suggest that 'the management'
needs a good kicking for not allowing you to do that.

DNA

 

[Joe G \(Home\)]

The H11AA1 is designed as a digital opto coupler (not analogue linear) hence
your design should cater for the min CTR (IE the worst case).

If you need to pass a linear signal over the opto - then use something else.

So you have found variations in the CTR.. ALsO the LED age and the CTR may
vary over time.

So use a specific linear opto or something else.

JG


When I mean digital opto , I mean it has 2 states off or on.

 

[Engin Ciftci]

I will contact to check for the prices. Thank you for your suggestion.

Jim Thompson yazdi:

 

[Engin Ciftci]

First of all I'm sorry that your friends have a bad experience on
holiday. Many travel companies are mostly interested with your money
and they forgot that they are wasting your invaluable time.

My situation is: There is a board that was previously designed. I am
trying to lower the cost of board by trowing out some components which
are problem in production.

I am using optocoupler in linear region because I need to extract
mainly a monotone signal which is added on a dc value.

Actually I don't care if the waveform of the sinusoidal signal is
deformed because of nonlinearities. I use a filter to get the
fundamental freq.


Genome yazdi:

 

[John Fields]

First of all I'm sorry that your friends have a bad experience on
holiday. Many travel companies are mostly interested with your money
and they forgot that they are wasting your invaluable time.

My situation is: There is a board that was previously designed. I am
trying to lower the cost of board by trowing out some components which
are problem in production.

I am using optocoupler in linear region because I need to extract
mainly a monotone signal which is added on a dc value.

Actually I don't care if the waveform of the sinusoidal signal is
deformed because of nonlinearities. I use a filter to get the
fundamental freq.