L6920 Low voltage indicator LED does not work

[aetosa]

I 've made a boost converter with L6920

As you can see in the image, at LBO pin I've put the cathode of the LED.
LBO is an open drain output, which goes low (does that mean it gets grounded???) when the battery voltage goes below the treshold we have defined at LBI pin. (I have a treshold of 1.8V).
But when the voltage of the batteries goes below the treshold, the LED does not get lit.



- - - Updated - - -

I read at page 3, LBO logic LOW : sink < 250µA.
Does that mean it can sink only 250µA, and that's why the LED does not lit?

 

[kam1787]

as LBO can only sink < 250uA it won't work!

going low means just that, the voltage goes 'low' - not the same as grounded

 

[aetosa]

So, what can I do? Use a mosfet as a switch for the LED?
Is there any mosfet (small, smd) that when it's positive (V G-S) it's off?
And when zero (grounded, V G-S=0) it's on?

 

[kam1787]

mosfet or bi-polar in CE configuration.

 

[aetosa]

Yes, but which mosfet?
Can you propose me some concrete?
I 'm not quite relevant, as you understand...