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ISO1644: I would like to know the advantages of isolating devices.

Part Number: ISO1644

Hi TI engineer,

As the title suggests, I would like to know the benefits of isolation products.

I designed ISO1644 for board-to-board communication.

Any questions you may have are as follows:

1. Is there any problem even if the I/O interface power level between the primary and secondary is different?

 ex) VCC_1 : 5V Vs VCC_2 : 3.3V or VCC_1 : 3.3V Vs VCC_2 : 5.0V

2. Is it possible that the signal level of the target board causes reverse voltage to enter the primary side?

3. Should I add an ESD protection device to the secondary pin?

 ex) 10, 11, 12, 13, 14 and 16 Pin

4. What are the advantages of isolation products over level shift products?

5. Does the insulation product have a protection function if a short circuit occurs on the target board?

If you have information on the benefits of isolation products, please share them.

I am very sorry for asking so many questions.

Thank you.

  • Hello,

    Thanks for reaching out.

    As the title suggests, I would like to know the benefits of isolation products.

    Using an isolator in a design can have the following benefits:

    -Protects low voltage circuits and humans from high voltage circuits/systems

    -Reduces and eliminates ground potential differences that can be harmful in systems where devices are communicating over large distances

    -Provides reliable communication to high side components in motor drive systems

    -Protects low voltage circuit and humans from high voltage EMI transients/Improves EMC capabilities of a system

    1. Is there any problem even if the I/O interface power level between the primary and secondary is different?

     ex) VCC_1 : 5V Vs VCC_2 : 3.3V or VCC_1 : 3.3V Vs VCC_2 : 5.0V

    There is no problem with having a difference in the voltage levels of VCC1 and VCC2. The device is fully capable of supporting a configuration where VCC1 and VCC2 are not equal to each other. The two power supplies for this device are independent from each other, and are each used to independently power each side of the device.

    2. Is it possible that the signal level of the target board causes reverse voltage to enter the primary side?

    This is not something that we expect to happen. As previously mentioned, the device supports using different voltage levels for each side of the device, provided that the voltage levels used are within the recommended operating ranges specified by the datasheet.

    3. Should I add an ESD protection device to the secondary pin?

     ex) 10, 11, 12, 13, 14 and 16 Pin

    The device has built-in same side ESD protection, and the isolation barrier is also capable of providing ESD protection. For more information on this, you can refer to the first page of the datasheet and Section 6.2. If your application requires more ESD protection that what the device already has, then you can look into connecting additional ESD protection devices to the pins of the device.

    What are the advantages of isolation products over level shift products?

    In many cases, isolation devices are capable of voltage level shifting over a much wider range than what a typical level shifter device supports. This is because the isolation barrier enables there to be a large ground potential difference between the voltage domains on either side of the device. As a result, you can level shift over a range that is much larger than what is supported by a typical voltage level shifter. 

    Does the insulation product have a protection function if a short circuit occurs on the target board?

    The ISO1644 does not have a specific protection function for short circuit events, but if there is a short circuit from one of the SDA2/SCL2 pins to GND2, we don't expect this to damage the device because the output pins are only capable of driving the output to GND2, and not to VCC2 (output pins are open-drain).

    Regards,

    Kenneth

  • Hi Kenneth,

    Thanks for your quick reply.

    Thank you for attention and support.

    I understood thanks to the detailed explanation.

    Thank you for your support.

  • Hello,

    Thanks for the update.

    If you have any further questions, please let me know. 

    Regards,

    Kenneth