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ISO1540 Hot Swappable

Steve Orosz
Prodigy 10 points
Other Parts Discussed in Thread: ISO1540

Is the ISO1540 hot swappable?  At the bottom of page 5 there is a VCC Undervoltage Lockout Threshold parameter.  The datasheet does not provide a description of the state of the signals.  I need to isolate an I2C device from the main I2C bus because this device can be switched on and off from a separate power source.


My configuration is as follows:

Side 1:  I2C Compatible Device.  This device is powered from VCC1.

Side 2:  I2C bus with a single Master and multiple I2C devices.  Both devices are powered from VCC2.


Theory of operation:

Side 2 of the I2C bus will normally be active with both the master and slave device powered from VCC2.  The device on side 1 will initially be off.  At some point in time, the device on side 1 will be switched on.  I want to ensure the following:

1) When the device on side 1 is off, side 2 is unaffected. 

2) When the device is switched on, the state of the I2C bus will not be affected by the transition.

Thanks!

  • 0
    TI__Intellectual 2200 points

    Hi Steve,

    Sorry for the very delayed response.

    1) When the device on side 1 is off, side 2 is unaffected. 

    >> ISO1540 will meet this requirement. If side 2 of ISO1540 is stable, not having side 1 supply is not a problem.

    2) When the device is switched on, the state of the I2C bus will not be affected by the transition.

    >> This condition is difficult to analyze and we cannot say for sure what the impact will be. If side 1 wakes up at the same time when there's a transition on the bus, that particular transition could be impacted.

    Rgds,

    Anant