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Creepage distance of AMC1100DUBR

BRANDON SMITH1
Prodigy 240 points
Other Parts Discussed in Thread: AMC1100

Hello,

I am looking to use the AMC1100 in one of my designs and have started looking into the creepage distance on the chip. In the datasheet the creepage distance is defined as 7.0mm as the shortest terminal to terminal distance. In the datasheet creepage distance is defined as "Creepage Distance: The shortest path between two conductive input-to-output leads measured along the surface of the insulation. The shortest distance path is found around the end of the package body." I guess I am having trouble with this definition because in standard 60664 they do not define input and output they only define conductive materials. In the 60664 definition then the creepage distance would be, for instance, the distance between pin 1 and 2 or 2 and 3, which certainly isn't 7.0mm. I must be interpreting the standard incorrectly and would appreciate any light you could shed on my understanding on the definition of creepage distance.

In the datasheet Figure 40 also shows proper layout and the use of an 0603 resistor in series with VINP pin. Certainly the use of a 0603 resistor will also limit the input voltage level because the creepage distance between the pads on the 0603 is very small. Again i am not sure i am fully understanding the definition of creepage and perhaps you can provide me with a link to a TI app note that will help me with this board design.

Thanks,

Brandon 

  • 0
    TI__Genius 9975 points

    Hello Brandon,

    The “input-to-output” terminology refers to the fact that creepage and clearance distances apply to points that will be spread apart by high voltages (for example, up to 6000 V in the case of a surge for the AMC1100).

    Pins 1, 2, 3 and 4 should not see voltage differences greater than the VDD1 supply voltage level used. Similarly, pins 5, 6, 7 and 8 should not see voltage differences greater than the VDD2 supply voltage level used. There is no explicit or implied isolation between pin 1 and pin 2, or pin 1 and pin 3 or pin 2 and pin 3, etc. However, there IS a certified galvanic isolation between any pin in the group (1, 2, 3, 4) and any pin in the group (5, 6, 7, 8); therefore creepage and clearance distances apply between these groups and not between individual members of each group.

    The following link provides additional information about creepage and clearance and some intuitive ways of understanding these terms.

    http://www.edn.com/design/sensors/4423415/Isolation-navigation-frustration-cessation-education-Part-2-Creepage-and-clearance-

    Please note that there is a mistake in the DUB land pattern data currently published in the AMC1100 datasheet. The image below shows the correct dimensions.

    Hope this helps.

    Best,

    Jose

  • 0 in reply to Jose Duenas
    Prodigy 240 points

    Jose,

    Thank you for the link, the explanation was very helpful! On the above layout change screenshot do you have one that shows the size of the body of the chip? I want to make the appropriate changes to my 3D model in my footprint as well.

    Thanks,

    Brandon

  • 0 in reply to BRANDON SMITH1
    TI__Genius 9975 points
    Hello Brandon,
    The size of the body of the chip indicated in the AMC1100 datasheet are correct.
    Best regards,
    Jose