LM25037: UVLO circuit design

Part Number: LM25037

Tool/software:

Hi,

I’m designing the UVLO circuit for the LM25037 and I don’t understand the 20×10⁻³ term (20mV?) in Equation (7) used to calculate R1. Is this perhaps the comparator’s internal hysteresis that isn’t explicitly mentioned in the datasheet, or did I overlook it? Could you please help clarify this?

  • Hi,

    In theory, this below circuit should give R1 = VHYS / 22uA so that   -20×10⁻³VPWR/1.25 should not be there. It is there is most likely the circuit below is approximated so some small corrections need to add in.

    Note when you check the calculation based on the circuit the that "-", you cannot get the VHYS - back calculated value is always smaller than VHYS.