Drive and startup for a switched capacitor divider

A power supply for an integrated circuit comprising:

• an input to receive system power;
• a linear regulated voltage supply to receive the system power and supply a regulated voltage;
• a switched capacitor drive circuit having a switch network including a plurality of switches connected in series across a voltage and a capacitor network including a plurality of capacitors connected in series across the voltage to divide the voltage into a plurality of different voltage outputs, each capacitor of the plurality of capacitors being coupled across a source and a drain of two series-connected switches of the plurality of switches, a first of the two switches of each of the two series-connected switches constituting a top switch path and the second of the two switches of each of the two series-connected switches constituting a bottom switch path;
• a plurality of level shifters each coupled to a gate of each switch of the switched capacitor drive circuit to couple alternating current into the respective gate;
• a positive phase, non-inverted low side driver coupled to each level shifter to receive the regulated voltage from the linear regulated voltage supply and drive the gates of the top switch path through the respective level shifters;
• a negative phase, inverted low side driver coupled to each level shifter to receive the regulated voltage from the linear regulated voltage supply and drive gates of the bottom switch path through the respective level shifters;
• a pulse width modulated input coupled to the positive and negative phase low side drivers to activate corresponding switches with a duty cycle according to the input;
• and
• a plurality of voltage output nodes coupled to the switched capacitor circuit to provide the plurality of different voltage outputs at each output node.

A method comprising:

• driving the gates of a top switch path of a switched capacitor drive circuit with an alternating current through respective level shifters using a positive phase, non-inverted low side driver coupled to each respective level shifter;
• and
• driving the gates of a bottom switch path of a switched capacitor drive circuit with an alternating current through respective level shifters using a negative phase, inverted low side driver coupled to each respective level shifter,
• wherein the switched capacitor drive circuit comprises a plurality of capacitors connected in series across a voltage to divide the voltage into a plurality of different voltage outputs, the top switch path having switches, each with a source coupled to one side of a respective capacitor of the capacitor network, the bottom switch path having switches, each with a drain coupled to an opposite side of a respective capacitor of the capacitor network, each switch of the top switch path being coupled in series to a respective switch of the bottom switch path.