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ISO7141CC Does SLLA197 Document Also Cover the ISO7141CC

Other Parts Discussed in Thread: ISO7141CC, ISO7741

Does the SLLA197 document (High-Voltage Lifetime of the ISO72x Family of Digital Isolators) also apply to the ISO7141CC isolator? If not, do we have a similar document that could be used to calculate the lifetime of this series?

I have a question about the SLLA197 document:

The calculations in figure 3 and the results in Table 2 do not seem to match. Do you have something that would explain the differences that seem to be present between the two? The calculation (at least my calculations) appear to produce different number than are present in Table 2.

Thanks for your help with this!

Richard Elmquist

  • Hi Richard,

    ISO72xx is one of our older family of devices and SLLA197 is primarily applicable for ISO72xx alone and does not apply to ISO7141CC. The lifetime of ISO71xx family should be better than ISO72xx. Both ISO71xx & ISO72xx have maximum working voltage of 400Vrms (or 566Vpk of VIORM) and are not recommended for applications requiring continuous operation at voltages higher than working voltage of the device.

    Regarding the calculations in SLLA197 you are referring to, please note that X-axis in the chart is Working voltage in Vrms whereas VIORM in Table 2. is given in Vpeak. This could be the reason you may have noticed difference in values. I just recalculated the values, from the chart 400Vrms yields a life of ~28 years and similarly 560Vpk (=400Vrms) in Table 2. indicates a life of 28 years.
    Please do note that Working Voltage (VIOWM by UL) is generally stated in Vrms whereas Repetitive Voltage (VIORM by VDE) is given in Vpk, these parameters mean the same thing but belong to two different Standards (UL vs VDE).

    ISO7141 is a device with 3.7mm Creepage and this Creepage can only provide a working voltage of about 400Vrms. Working voltage of 1000Vpk is only achievable with a minimum Creepage of 7mm and hence the need for bigger package otherwise air will break with smaller packages and isolation is no longer maintained.

    ISO7741 is one of our newer devices with reinforced isolation of 1kVrms working voltage available in WB SOIC16 package with a Creepage of ~8mm. The same device is also available in SSOP16 package with a Creepage of 3.7mm leading lower working voltage of 400Vrms, hence working voltage in this case is limited by package and not by the device.

    I hope that answers your questions, thank you.

    Koteshwar Rao
  • Koteshwar,

    Thanks for your response!

    I will let you know if the customer has any further questions.

    Thanks again.

    Richard Elmquist