Apparatus for sub-regulating and sensing an input voltage with minimum connections

An electronic circuit produces a measurement signal and a regulated power supply from a single common connection to a raw power supply signal. The electronic circuit can be used as a module in a power control circuit, such as a circuit for charging a battery cell. In an integrated circuit (IC), the electronic circuit has a single pin connection for accepting signals or connecting to elements external to the IC. The electronic circuit sub-regulates the potential at the common connection or node using a voltage regulator. The electronic circuit produces a measurement signal that corresponds to a potential of the unregulated power supply. A sense circuit measures a potential drop from the common connection to an internal node of the electronic circuit. The measurement signal corresponds to the drop in potential. The raw power supply signal can be calculated from examining the measurement signal. The measurement signal can be used by another circuit to generate one or more control signals. The control signals can then be used for applications in other circuits. One example of the application of the electronic circuit is in the charging circuit for a battery cell. The control signals can be used to regulate the rate and amount of charge delivered to the battery cell during charging.