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UCC2813-4-Q1: VCC ABS Max Voltage Rating vs. Turn-On Threshold Voltage Specification

Marc1
Expert 4585 points
Part Number: UCC2813-4-Q1
Other Parts Discussed in Thread: UCC1804

The datasheet for the UCC2813-x-Q1 family shows that the VCC ABS MAX rating is 12V.  There is a footnote that states "

In normal operation VCC is powered through a current limiting resistor. Absolute maximum of 12 V applies when VCC is driven from a low

impedance source such that ICC does not exceed 30 mA (which includes gate drive current requirement).

".  So does this mean that if a design has VCC higher than 12V they must include a series resistor that limits the current for the maximum expected voltage to less than 30mA.  For example, if VCC(max) is 100V the resistor must be ~ 3.33k?

Also, is there some level that even with a series resistor would not be OK to exceed on VCC?  Where we might need to provide additional protection to the VCC node?

This is especially relevant for the variants that have a UVLO Turn-On Threshold typical of 12.5V (can be as high as 13.5V) since at first glance it looks like the 2 specs conflict....but I'm sure this is a misinterpretation on my part.

Please clarify for me.

-Marc

  • 0
    TI__Genius 9130 points
    Marc

    This same question was previously asked with regard to UC1804 - the same specs for startup voltage and VCC abs max apply. Please check that post for the details:

    e2e.ti.com/.../542539


    The bottom line answer from that post also applies here:
    "... data sheet was written to cover a wide range of devices in that family so it does get confusing when it comes to the ABS MAX ratings. For the devices that have a turn on threshold greater than the 12.0V maximum given in the table, VCC must be powered through a current limiting resistor so that ICC is less than 30mA. The VCC of the UCC1804 obviously needs to be at least as high as the UVLO start threshold of 13.5V but the current on VCC needs to be limited to less than 30mA so that the internal 13.5V clamp does not sink excessive current and cause device heating resulting in reliability issues."


    I hope this answers your question, if so please click the "verify answer" button.

    Thanks,
    Bernard
  • 0 in reply to Bernard Keogh
    TI__Expert 4585 points
    Bernard,
    So with a properly chosen series current limiting resistor what is the allowed VCC voltage allowed to be (Maximum). Only 13.5V or can it be higher? If higher, what is allowed? Is the clamp really at 13.5V internally?
    Kind Regards,
    -Marc
  • 0 in reply to Marc1
    TI__Prodigy 50 points

    Marc,

    To add on to what Bernard has explained above, please see attached presentation for all the details behind the explanation on UCC2813-x VCC abs. max rating and UVLO turn on threshold.

    Explain on UCC2813-X VCC Abs.pptx

  • 0 in reply to Brandon Sbert
    TI__Expert 4585 points

    Thank you.  The presentation clarifies all open items.

    -Marc