*2.2. Operation*

Before the SC converter starts a normal operation, its main controller is pre-programmed with the sequence of the operating states of the load. Figure 2b shows an example of such a program for operation states. The program stores a sequence of Operating State Indexes (OSI), which contains the target Voltage Conversion Ratio (VCR) and Frequency Code (FC). The VCR indicates the ratio of the target output voltage to the input voltage. The FC in each entry in the OSI table is programmed to match the target load current for the corresponding operating state. To configure the proper voltage ratio, the main controller stores a VCR table, which is shown in Figure 2c. Each entry of the VCR table

provides control signals for the two states of the capacitor banks, e.g., state0 (charging) and state1 (delivery).

When the power managemen<sup>t</sup> software in the load CPU of sensor nodes is about to change its operating state, it sends its operating state index (OSI) to the controller of the converter. The main controller looks up the OSI table and retrieves VCR and the FC for the corresponding OSI. The VCR is passed to the VCR table to retrieve the control signals for each state of the capacitor bank. The FC is provided to the oscillator to generate the frequency that allows the converter to supply the required current. The main controller maintains its current frequency and VCR, until a new OSI is received from the power managemen<sup>t</sup> software.
