Problem With TLP250, PWM to isolated analog output

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dhruv_electro

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Hi,

I want to design an isolated 0-5v analog output from PWM(0-5 volt for 0-100% duty cycle). For that I have two isolated 5V supply (A and B as seen in attached image). I just tested TLP250 as shown in Fig. 1 of attached image. I got 4.75V output on Pin 6 of TLP250. My idea of making analog output is shown in Fig.2, but as I mentioned I can not get full (5V) output on pin 6 when I have 100% duty cycle(or if i connect 5V directly to R1). Pardon me if my basic electronics knowledge is poor.



Please suggest me if I am missing something. Thanks in advance.
 

What are you talking about LED Side?

But I have tried for Output side, here is result

for Rpullup = 10k Vout (Vin=5V) = 4.79, Vout(vin =0V) = 0.12V
Rpullup = 1k Vout (Vin=5V) = 4.86, Vout(vin =0V) = 0.13V
for Rpullup = 100E Vout (Vin=5V) = 4.93, Vout(vin =0V) = 0.14V but now ckt is taking high current when Vin=0V
 

i thought that you are using micro controller to trigger input.. sorry for that...
 
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