Re: ISOLATING 4-20mA INPUT SIGNAL USING IL300 Linear Optocoupler

On Mon, 30 May 2005 18:15:50 GMT, the renowned Rich Grise
<richgrise@xxxxxxxxxxx> wrote:

>On Mon, 30 May 2005 08:22:51 -0700, alcuemar wrote:
>
>> Thanks Dan for your feedback.
>>
>> I will test this figure 19 schematic in a new prototype, just i have the
>> doubt of how to calculate the Vo voltage depending the I input. I have see
>> the equation:
>>
>> Vo/IL=(R3/R4)*R5*K3
>>
>> But I have not clear the value of K3.
>>
>> Thanks in advance.
>
>From:
>http://crio.mib.infn.it/wig/electronics/Componenti/Siemens%20e%20Infinenon/Accoppiatori%20Ottici/IL300%20per%20industria.pdf
>>From the paragraph fragment at the top of page 11-202, between equations (15) and (16), it
>says:
>
>Where: IP1 = feedback photocurrent
>K1 = feedback gain
>IP2 = output photocurrent
>K2 = output gain
>K3 = transfer gain.
>
>The value of K3 will be determined by the implementation of your circuit.
>
>In other words, let the math mumbo-jumbo go to the bit bucket, where
>all mumbo-jumbo belongs, and lash up the circuit in figure 19, page
>11-204, and calibrate it by putting a known 4 mA through "line", and
>measure the voltage at "output", and put a known 20 mA through "line",
>and measure the voltage at "output".
>
>In short, K3 = K2/K1.
>
>Hope This Helps!
>Rich

"The remaining variable is the IL300?s transfer gain, K3. The part to
part variation of the transfer gain offers (sic) a range of 0.56 to
1.53"

K3 is a data*** parameter. Nominally it's 1.0 (the ratio of the
small currents you get out of the two photodiodes) but it could be
anywhere between 0.56 and 1.65, according to the data *** (0.56 and
1.53 sez the AN, but that's suspect).


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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