Detecting power supply sag in an integrated circuit

A packaged integrated circuit, comprising:

• (a) a semiconductor substrate carrying circuitry, a voltage lead and a ground lead;
• (b) encapsulating material encapsulating the semiconductor substrate;
• (c) an array of connectors on only one side of the encapsulating material that are coupled to the circuitry, the voltage lead, and the ground lead;
• and
• (d) the circuitry including a voltage sag detector that includes:
• i. a voltage reference having a reference voltage output;
• ii. a comparator having an input connected to the reference voltage output, an input coupled to the internal power bus, and a comparator output;
• iii. a latch having an input coupled to the comparator output and a latch output;
• and
• iv. a sticky register having an input coupled to the latch output and having a sticky register output, the sticky register retaining an output of the latch in the event of a reset of the circuitry.