How does the quiescent current of STLQ020 change when operating in dropout?

[JHobb.2]

Hi,

I'm interested in the STLQ020 in a very low load current application and am keen to minimise quiescent current consumption.

Looking at the data and graphs in the datasheet, I can see that the quiescent current use is maximum 1000nA at no load, and typically ~300-400nA at a low load current (for example 1uA).

However, I spotted that in Figure 18 (attached) there is a large step increase in Iq as Vin falls below 2.5V. Is that 2.5V "fixed", or is it the case that this step in current is caused by the regulator running in dropout? Here, where Vin is below the target Vout of 2.5V.

In my design, I would like to support a range of input voltages, say 2 to 4V, with a target output voltage of 3.5V, so I expect to often be running in dropout; will this approach cost me extra quiescent current consumption?

I'm referring to datasheet revision 4.

Thanks very much.

Jonathan