UCC23313: Are there any risk by supplying 3.3v at the input?

Howard, 

Howard Zou said:

Since Vf is as high as 2.4V, they are not confident that 3.3V supply at the input stage is enough to turn on the device.

Howard Zou said:

Are there any risk of using 3.3V supply at the input?

2.4V is the peak forward voltage for ON-state. And to answer your question, yes UCC23313 can be used with a 3.3V supply, there are essentially no risks with a 3.3V supply as long as resistor is chosen correctly. The only other consideration they need to make is if the 3.3V supply has a very low tolerance and weak and might end up being, for example, 3.0V or maybe a little higher. Then I would consider the 3.3V supply range and tune the resistor value a bit.

The 90Ohm current limiting resistor the customer have selected is a fine choice for their design, but they could actually target a lower current than 10mA in the worst-case, and instead target 7mA (128ohm). So 90-120 ohm range is honestly fine.

Howard Zou said:

Is it true that as long as If is within 7-16mA, the device is on and the output will be high?

Is it true that as long as If is within 7-16mA, the device is on and the output will be high?

Yes, this is correct. 

Please let me know of any other questions, and if this answers your question fully could you please press the green button?

Best

DImitri