Hi, anyone could help me review the optocoupler circuit, i wonder if it is right, on the left is digital signal, there is a current limlited resistor, and on the roght is vcc signal, there is a pull up resistor

 

What is the amplitude of the input signal at J1 ? What are the values of R1 and R7 ? What is the purpose of R7 between the supply and the Vcc terminal ? What is the volyage of the Vcc powersupply ? What is the nature of the load on the output ? (You refer to R7 as a pullup resistor. This makes me think that you are considering the output side as a simple phototransistor which would require a pullup resistor. Looking at the datasheet this device has a pushpull output so it can source and sink a reasonable current.) Why do you not have the decoupling capacitor between Vcc and ground as suggested in the datasheet ?

Les

 

What is the amplitude of the input signal at J1 ? What are the values of R1 and R7 ? What is the purpose of R7 between the supply and the Vcc terminal ? What is the volyage of the Vcc powersupply ? What is the nature of the load on the output ? (You refer to R7 as a pullup resistor. This makes me think that you are considering the output side as a simple phototransistor which would require a pullup resistor. Looking at the datasheet this device has a pushpull output so it can source and sink a reasonable current.) Why do you not have the decoupling capacitor between Vcc and ground as suggested in the datasheet ?

Les

Hi, thanks, for replying, the digital signal voltage is 3.3V, i calculated the R1 which is 120ohm, by using formula (3.3v-VF)/I_forword, so i have to use a resistor to get the I_forword, and for this pull up res just to keep a signal line at defined high logucal level when no active device is pulling it low, the value is 1K, VCC is 15V, i have the bypass cap at my driver circuit, so there is no problem, and the load on output is input of my gate driver.

 

What is the amplitude of the input signal at J1 ? What are the values of R1 and R7 ? What is the purpose of R7 between the supply and the Vcc terminal ? What is the volyage of the Vcc powersupply ? What is the nature of the load on the output ? (You refer to R7 as a pullup resistor. This makes me think that you are considering the output side as a simple phototransistor which would require a pullup resistor. Looking at the datasheet this device has a pushpull output so it can source and sink a reasonable current.) Why do you not have the decoupling capacitor between Vcc and ground as suggested in the datasheet ?

Les

So output of opto directly connnect to the input of gate driver ic