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THVD1505: Optical Isolation

Part Number: THVD1505

Hi ,

  I'm planning to use the below circuit for optically isolated RS-485 interface.  Can anyone confirm if the below design is valid? My primary concern is receiver pin of XCVR where the IOL limit is 8mA. Whereas I have designed for 10mA. SInce 10mA is needed for opto coupler to switch reliably. Please confirm of this will cause any problem.  

  • Hello,

    We will review this and get back to you early next week.

    Max

  • Hi Diwakar,

    The recommended receiver output current for this device is specified in relation to the the low-level output voltage for the pin. More current may flow through this pin to drive something such as an LED as long as it does not exceed the Absolute Max Receiver Output Current. With a larger current draw, you can also expect a higher low-level output voltage than what is specified in the Electrical Characteristics. 

    Let me know if this helps with your design.

    Regards,
    Eric