help on optocoupler circuit .

[michael nikolaou]

Hi to newsgroup

I want to use one optocoupler type LTV-8x6 from LITE-ON as a simple switch .
Output transistor drives one 4.7 K load @ 3,3V and directly to a mcu pin.
Input led is biased from 12 or 24 volts. As i see i can use a resistor to
bias the led at 12 volt and have double current at 24 volts . I imagine 6 ma
for 12 volt is ok . This calculates to 12 ma for 24 volts with the same
resistor.My question is after 10 years of operation if the led deteriorates
is the current sufficient ?. Do i need absolutely a reverse polarity diode
for the led?. Finally what is the simplest configuration in the input led
circuit so it can be driven with active low or active high signals . The
thing is i need an array of 4 optocouplers and only one common input per
opto for both types of logic .
Any help would be appreciated .

 

[John Fields]

On Fri, 30 Jan 2009 18:02:55 +0200, "michael nikolaou"
<michaelnikolaou_remove_me_@yahoo.com> wrote:

Hi to newsgroup

I want to use one optocoupler type LTV-8x6 from LITE-ON as a simple switch .
Output transistor drives one 4.7 K load @ 3,3V and directly to a mcu pin.
Input led is biased from 12 or 24 volts. As i see i can use a resistor to
bias the led at 12 volt and have double current at 24 volts . I imagine 6 ma
for 12 volt is ok . This calculates to 12 ma for 24 volts with the same
resistor.My question is after 10 years of operation if the led deteriorates
is the current sufficient ?. Do i need absolutely a reverse polarity diode
for the led?. Finally what is the simplest configuration in the input led
circuit so it can be driven with active low or active high signals . The
thing is i need an array of 4 optocouplers and only one common input per
opto for both types of logic .
Any help would be appreciated .

---
How do you plan on driving the LEDs?

JF

 

[michael Nikolaou]

John Fields wrote:

On Fri, 30 Jan 2009 18:02:55 +0200, "michael nikolaou"
michaelnikolaou_remove_me_@yahoo.com> wrote:

Hi to newsgroup

I want to use one optocoupler type LTV-8x6 from LITE-ON as a simple switch
. Output transistor drives one 4.7 K load @ 3,3V and directly to a mcu
pin. Input led is biased from 12 or 24 volts. As i see i can use a
resistor to bias the led at 12 volt and have double current at 24 volts .
I imagine 6 ma for 12 volt is ok . This calculates to 12 ma for 24 volts
with the same resistor.My question is after 10 years of operation if the
led deteriorates is the current sufficient ?. Do i need absolutely a
reverse polarity diode for the led?. Finally what is the simplest
configuration in the input led circuit so it can be driven with active low
or active high signals . The thing is i need an array of 4 optocouplers
and only one common input per opto for both types of logic .
Any help would be appreciated .

---
How do you plan on driving the LEDs?

JF
DC Voltage 12V or 24Volts with a series resistor

 

[John Fields]

On Fri, 30 Jan 2009 20:04:27 +0200, michael Nikolaou
<michaelnikolaou_remove@yahoo.com> wrote:

John Fields wrote:

On Fri, 30 Jan 2009 18:02:55 +0200, "michael nikolaou"
michaelnikolaou_remove_me_@yahoo.com> wrote:

Hi to newsgroup

I want to use one optocoupler type LTV-8x6 from LITE-ON as a simple switch
. Output transistor drives one 4.7 K load @ 3,3V and directly to a mcu
pin. Input led is biased from 12 or 24 volts. As i see i can use a
resistor to bias the led at 12 volt and have double current at 24 volts .
I imagine 6 ma for 12 volt is ok . This calculates to 12 ma for 24 volts
with the same resistor.My question is after 10 years of operation if the
led deteriorates is the current sufficient ?. Do i need absolutely a
reverse polarity diode for the led?. Finally what is the simplest
configuration in the input led circuit so it can be driven with active low
or active high signals . The thing is i need an array of 4 optocouplers
and only one common input per opto for both types of logic .
Any help would be appreciated .

---
How do you plan on driving the LEDs?

JF
DC Voltage 12V or 24Volts with a series resistor

---
Yes, I assumed that from your post.

What I meant was what are you going to be driving them with?
Transistors, MOSFETs...

Also, when you say that you only have one common input per opto, does
that mean that you'll have, say, all four anodes connected together and
you'll only have the cathodes available to drive?


JF