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ISO7760: alternative with 28V support in the inputs without supply voltage

Art Mecina
Genius 16505 points
Part Number: ISO7760
Other Parts Discussed in Thread: ISO1212, ISO1211

Hello Guys,

Good day.

Our customer is having troubles with the isolator ISO7760DBQR in the isolation test. They have a loop when the supply is off and there is a high level in any input pins. The device does not support  28V in the inputs without voltage in the supply. When they apply 28V in the input, the internal diode (datasheet figure 23) provoke the loop with GND and VCC.

Do we have an alternative which can support 28V in the inputs without voltage in the supply?

Thanks and regards,

Art

  • 0
    TI__Mastermind 49445 points

    Hi Art,

    Thanks for reaching out.

    ISO7760 is a digital isolator that isolates digital logic CMOS signals that come from various digital devices like MCUs, MPUs, Data Converters, FPGA, transceivers and others. Most of these digital logic signals are 5V, 3.3V, 2.5V or 1.8V and ISO7760 is a suitable device to isolate these signals.

    The absolute maximum input voltage that can be applied to the inputs pins of digital isolators is "VCCx + 0.5V", as stated in absolute maximum ratings in the datasheet. This means that if VCCx is 0V, then INx should be <0.5V. Violating this spec turns on the ESD bypass diode and can damage the device. Hence, input signals should't be applied without powering up the device.

    For isolating industrial digital inputs that come from field and are higher in voltage, we have a dedicated device family for this purpose, ISO1211 and ISO1212. These devices accept inputs upto 60V and do not require any external power on the field side. Please go through the below links to understand more about the devices. Thanks.

    https://www.ti.com/product/ISO1212

    https://www.ti.com/lit/slla370

    https://www.ti.com/lit/slla379

    https://www.ti.com/lit/slla382



    Regards,
    Koteshwar Rao