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TPS74901: Dropout in electrical characteristics and typical characteristics graph

Aaron Jones
Intellectual 760 points
Part Number: TPS74901

Hi TI,

In the electrical characteristics graph, I see VDO for 3A specified to a typical of 120mV and a max of 280mV.

Figure 6 in the datasheet shows typical performance where DO at 3A at 125C is ~180mV and at 25C is roughly 120mV.

Does this tell me that figure 6 at 125C does not give worst case dropout, and that figure could be shifted up a full 100mV (roughly 30% off) worst case?

Thanks in advance!

  • 0
    TI__Genius 13485 points
    Hi Aaron,

    The EC table min and max are statistically calculated from the final test variation and device variation to ensure no shipped device will exceed the limits. Your summary is correct - Figure 6 gives a typical of 180 mV, whereas the max. is 280 mV. However, some devices will be higher than 180 and others lower. The max. spec. guarantees no device shipped will be higher than 280 mV.

    Regards,
    Mike
  • 0 in reply to Michael Hartshorne
    TI__Intellectual 760 points
    Hi Michael,

    For my application where the temp will not exceed 80 degrees C what would be the worst case Vdo with Vbias = 5v, Vin = 1.2v, Vout = 1v, and current 2.5A?
  • 0 in reply to Aaron Jones
    TI__Genius 13485 points
    Aaron,
    You can scale the 3A dropout back by 16% (from 3A to 2.5A), so, 0.233 V, then, if the JUNCTION temp (temp. of the die on the part, not the ambient temp) is lowered by 45 deg. C, you can approximate a 3000 ppm/deg. C drop, so that would be another 13.5% lower, giving approximately 0.202 V.
    Regards,
    Mike