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UCC2808A-1: Specification differences vs UCC2808-1

Kurt Schmidt
Genius 11125 points
Part Number: UCC2808A-1
Other Parts Discussed in Thread: UCC2808-1

Can you comment on the following questions:

1) OUTA/OUTB Source Current: The UCC2808 lists -0.5A as a minimum whereas the UCC2808A lists -0.5A as a maximum. Is this an error? Should they both be listed as minimum?

2) HBM ESD Rating is 1000V less for the UCC2808A. Is this correct? Why?

3) There is a slight variation in the COMP pin source current. Is this a typo or is there really 50uA less in the minimum current sourcing?

Thank you in advance, Kurt

  • 0
    TI__Guru 74015 points

    Hi,

    1) These need to clarify. Source current max 0.5A. 

    2) These are correct.

    3) These are also need to clarify. The meaning is COMP source current typical 0.5A, min 0.25A for UCC2808, and min 0.2A for UCC2808A at said conditions.

  • 0 in reply to Hong Huang
    TI__Genius 11125 points

    Thank you for the rapid response Hong! We await your confirmation. I strongly suspect the OUTA/OUTB source current listed as a maximum has to be a typo since at least a minimum is the only thing that makes sense. Worse, a maximum without a minimum for source current is an unusable spec.

  • 0 in reply to Kurt Schmidt
    TI__Guru 74015 points

    Hi,

    My reply to you is good and no other clarification is needed, i.e., the max source current at peak is 0.5A.

    In a sense, the min would be 0A when the pins are open.

  • 0 in reply to Hong Huang
    TI__Genius 11125 points

    Going to have to disagree with you on this and ask for more clarification as a max without a minimum is not how a gate drive is normally speced and makes no sense. Without a minimum you can't do a gate drive design. In other words, as stated you can get up to 500mA out; But you might also not be able to get anything out. So there is no gaurantee you can drive anything.

    With a minimum I can know that I will always be able to get at least that much out so that's what I design my gate drive to. Anything more is a bonus. I submit that is why the original non-A device has it as a minimum.

    Maybe what you are saying is that I can count on always being able to get 500mA out? But if so, then that is the definition of a minimum, not the definition of a maximum.

    Please advise. Respecfully, Kurt

  • 0 in reply to Kurt Schmidt
    TI__Guru 74015 points

    Hi,

    I suggest you do design with 0.5A for source current peak. It is maximum, and if exceed then the IC becomes violating the abs max.

    The designs associated to this device have been made in this way.

  • 0 in reply to Hong Huang
    TI__Genius 11125 points

    I'm pretty sure we are in agreement on how to design. What I am arguing for is that what you describe is actually a minimum (as in, don't design a gate drive that requires more than 500mA to work because there is no gaurantee of getting any more.) What you re calling a max is what every other gate drive output in the world calls a minimum. In other words, you should design assuming that this is the maximum you will get because there is no gaurantee of getting more; But in a gate driver this is the very definition of a minimum. It is the minimum maximum.

    So I don't argue that you are thinking about it right and know how to design with it. I argue that your definition of max and min are wrong. I'll likely concede the point if:

    1) You can tell me how then I would possibly do the same design with the UCC2808-1 where there is no maximum? What current would I use?

    2) You can show me a single gate drive, other than this one, where there is a maximum in the data sheet but no minimum? Or, show me a written definition that conforms to yours?

    Again, respectfully, Kurt

    PS - let me know if you want to jump on a call to discuss?

  • 0 in reply to Kurt Schmidt
    TI__Guru 74015 points

    Hi,

    The existing datasheet does not have this parameter as an electrical characterization parameter and only shows in the abs max table. So it is not a tested parameter at production. Your inquiring can be discussed to see how to adapt or change in the future but now it looks like what can be followed is like what described from the design history so far.