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ISO7240C: Confusion on launchxl-f28069m isolator connection

Part Number: ISO7240C
Other Parts Discussed in Thread: LAUNCHXL-F28069M, ISO7731, ISO7740

The LaunchXL-F28069M board has two isolation ISO7240 and ISO7231. Here the power is driving from USB. I am designing a custom board, can I use the same connection for driving the debugger from a different source? Here Different means a separate power supply other than USB. 

  • Hi Shahrukh,

    I am not very familiar with the LauchXL-F28069M board but from the schematic I see that ISO72xx devices are used to isolate the FTDI chip from the MCU F28069. Yes, you can use a different power source to power VCC1 or VCC2 of the isolators provided the isolator shares the same GND with FTDI on VCC1 side and also shares same GND with F28069 on VCC2 side. It is also important to make sure the value of VCC for FTDI & ISO72xx VCC1 are at same level even if they are from different sources but referenced to the same GND. Similarly, the value of VCC for F28069 & ISO72xx VCC2 should be at the same level even if they are from two different sources and refer to the same GND point.

    ISO72xx is one of older generation devices and use older device architecture. I would recommend you to use ISO7740 and ISO7731 in place of ISO7240 and ISO7231, respectively. ISO77xx is our latest family that offers the best performance without much of an impact on the cost. Please let me know if you have any questions, thank you.

    Regards,
    Koteshwar Rao

  • Hello Koteshwar,

    I am in the designing stage of the circuit. Just before the first design, I am having this doubt. 

    Thank you for the clarification, I will order both ISO72xx and your suggested IC.