xl97:
p.s. what does it mean when a v regulator is 'oscillating'?
It means that the regulator's automatic control system that is ideally meant to allow the output to stay relatively constant (fixed) ------ no longer does the desired (wanted) thing. The behaviour (ie. whether it oscillates or not --- or how close it is to being pushed over the edge into unstable territory) depends on components internal to the regulator and also external to it .... like capacitors or whatever else is connected. To properly understand this sort of thing.....it requires a bit of electronics theory and maybe some automatic control theory ....that will basically explain how oscillators are formed. In this case, it's about conditions that prevent an oscillator from being formed. Some maths would be involved.
When they say that LDO regulators require suitable choice of capacitor ... with some value of capacitance and some value of effective/equiv series resistance....... this just means that the capacitor (and practical values associated with it... like its 'ESR') can be used to set-up or configure the regulator's behaviour so that it doesn't do want we don't want - under the conditions that we want to operate at.