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LMV431

Other Parts Discussed in Thread: LMV431, TL431

Can I use LMV431 as single supply comparator like fig.18 of TL431 datasheet ?

I would realize a POWERGOOD signal with very low current consumption : TL431 needs 1mA of bias current, while LMV431 needs only 100uA . 

Thanks to everyone in advance.

Simone

  • Hi Simone,
    I assume you are referring to figure 25 from the latest TL431 datasheet, in section 10.2.1? If so, then yes, you can make a comparator by driving the feedback pin with some input signal. The LMV431 will work similarly to the TL431, with the main difference being the minimum Iq as you noted, and the low output value will be closer to 1.25V with the LMV431 as opposed to 2.5V (min output reference voltage).

    Chris
  • Hi Chris,

    first of all, thaks for your cooperation !

    Actually I refer to an old datasheet of TL431 (SLVS543J − AUGUST 2004 − REVISED DECEMBER 2005) fig. 18. pag.25.

    In the new datasheet on the web (SLVS543O –AUGUST 2004–REVISED JANUARY 2015) I don't find this feature: this make me think it is not possible.

  • Oh I see, that must have been part of the conversion to the new format.  The figure seems to be replaced by Figure 25 in section 10.2, which describes in detail the process of using the TL431 as a comparator.  I can assure you the feature has not been lost.   The figure you show here shows all the same information as the new section, just without the detailed description.    

    As noted in the image or the new section, the output, Vo  (Vka in the figure below), will be low when Input is above 2.5V (Vit, V input threshold), and high (pulled to supply voltage) when the Input signal is low.  Shown by Figure  26 in the latest datasheet.

    You should not have problems using the LMV431 in place of the TL431.  The input threshold and low value will be closer to 1.25V instead of 2.5V.