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LMT87: Maximum voltage on the plastic cover

Frank Song
Expert 4035 points
Part Number: LMT87
Other Parts Discussed in Thread: ISOTMP35

Tool/software:

Hi team,

Below is an question from customer. Could you help to take a look?

What is the maximum voltage applied on the plastic cover of LMT87, or what is the isolation voltage of the plastic cover?

We are using the LPM package, and below diagram is our testing system. The sensor head is directly in contact with the metal heat sink, and there may be ~1200V voltage between the heat sink & GND.

Is it safe to operate in this configuration?

Thanks,

Frank

  • 0
    TI__Genius 12935 points

    Frank,

    I would not use the LMT87 for this, there is no special insulation inside of the LMT87 package. I would not apply more than 6V to the package of LMT87, which is the absolute max voltage that can applied to LMT87.

    Instead, I would look at our ISOTMP35. This temperature sensor is a basic level isolated temperature sensor. It is designed to be directly connected to high voltage heat sources, so in other words it is designed to be placed directly on heat sinks like this that may have high voltages. The ISOTMP35 has a working DC voltage 707V. Please take a look at the datasheet to see if the voltage ratings would make sense for your application.

    Assuming the voltage ratings are acceptable, the main drawback I see with using the ISOTMP35 here is that it is not in a TO-92 package, but instead sits on the PCB. so you would have to move the PCB around to accommodate that. Let me know if you think the ISOTMP35 would be helpful.

    Regards

    -Alex Thompson