
Power supplies 249
protection, can be gathered up into a single power supply supervisory circuit, and
several ICs are on the market for this purpose. Examples are the MC3423, ICL7665 and
7673, TL7705 and MAX690 series. These chips are basically a collection of
comparators and delay circuits, integrated into one package for ease of use.
Unfortunately, there are a multiplicity of types and few second sources, and the parts
cost may be greater than you would suffer when using standard comparators such as the
LM339. In many cases you may still prefer to design your own supervisory circuit from
such standard components.
A typical application will require ...