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UCC2802: VCC Rating

Brian Wang0928
Genius 14000 points
Part Number: UCC2802

In the UCC2802 D/S, it says the absolute max. VCC rating is 12V. However, the turn-on threshold of the UCC2802 is 12.5V,typ. It looks it's not making sensing, right?

and When supply voltage is higher than 12.5V, what happened? Being Clamping to 13.5V or other behavior?

Regards,

Brian 

  • TI__Intellectual 880 points

    Hey Brian,

    Yes, the information in the datasheets have the correct information. I've attached a powerpoint slide that can explain the UCC2802 VCC abs max question.

    Section 9.3.1.7 of the UCC2802 datasheet has some more information about the VCC pin that may clear things up. This section mentions that applications that require a higher VCC voltage, a resistor must be placed in series with VCC to increase the source impedance.

    There is an internal Zener clamping diode that regulates the VCC voltage to 13.5V.

    If the external voltage source is above the Zener breakdown voltage without a current limiting resistor then the Zener diode will be damaged. Therefore, the VCC rating is based on the minimum Zener breakdown voltage. Equation 7 in the datasheet is used to calculate the series resistor value to be used as a current limit to ensure that the Zener diode will break down safely.

    Regards,

     Davit

    Explain on UCC2802 VCC Abs.pptx