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UCC21222-Q1: Why does it have different sink/source maximum current capability?

Yoshiki Ochi
Genius 9435 points
Part Number: UCC21222-Q1
Other Parts Discussed in Thread: UCC21222

Hi team, 

Could you tell me why does UCC21222-Q1 have different current sink/source capability, 6A/4A?
There are a lot of same characteristics in this aspect.

Could you tell me the purpose to use different current sink value and current source value?
(For example, why engineer tends to use 6Amax sink current and 4Amax source current in their design?)

Regards,
Ochi

  • 0
    TI__Prodigy 460 points

    Hi Ochi-San,

    Thank you for your question.

    The current sink/source differences in capability for the UCC21222 are a result of the switching methods used to turn the FETs on or off. You’ll find that a high sink current helps keep FETs off when they should be off.

    In the case of a half-bridge topology, avoiding shoot through (both FETs on at the same time) is an absolute must, and a higher sink current capability helps achieve this. The internal circuitry for the pull-up and pull-down features found in Section 8.3.4 of the datasheet is designed asymmetrically to increase the sink current so that during turn off, switching losses and shoot through can be prevented.

    Calculations for the parameters that influence the peak currents can be found in Section 9.2.2.5 of the datasheet.

     

    Let us know if you have any clarifying questions. If this helped, please press the green button below.

     

    Best regards,

     

    Liban Hussein