Method and circuit for switchover between a primary and a secondary power source

An integrated circuit for providing a switchover from a primary power source to a secondary power source, the integrated circuit comprising:

• a power source switchover circuit for receiving a supply level of the primary power source and generating (i) a reference signal based on the supply level of the primary power source and (ii) an indication signal representative of the supply level of the primary power source, the power source switchover circuit having a plurality of input terminals, a first input terminal electrically coupled to the primary power source and a second input terminal electrically coupled to a substrate of the integrated circuit, the power source switchover circuit further having a plurality of output terminals;
• a comparator, electrically coupled to the power source switchover circuit, for indicating that the indication signal has decreased below the reference signal, the comparator having a first and a second input terminal connected to a first and a second output terminal of the power source switchover circuit, respectively, the comparator further having an output terminal;
• a forced power source switchover circuit for detecting that the supply level of the primary power source drops below a predefined threshold level, the forced power source switchover circuit having at least one input terminal and at least one output terminal, one input terminal being electrically connected to the primary power source;
• and
• a switchover circuit for initiating a switchover operation based upon the indication from the comparator or upon an indication that the forced power source switchover circuit detects that the supply level of the primary power drops below the predefined threshold level, the switchover circuit having a first input terminal connected to the output terminal of the comparator and a second input terminal connected to one output terminal of the forced power source switchover circuit.