Adaptive boost driver charging circuit

A method of operating a power converter, comprising:

• providing a series capacitor buck converter including a first half-bridge circuit having a first high side power switch (HSA) and a first low side power switch (LSA) connected in series, a second half-bridge circuit including a second HS power switch (HSB) and second LS power switch (LSB) connected in series, and a transfer capacitor (Ct) connected in series with said HSA and said LSA and between said first half-bridge circuit and said second half-bridge circuit;
• providing an adaptive HS driver circuit having an output coupled to a gate of said HSA, said adaptive HS driver circuit including a power supply including summing circuitry configured for dynamically outputting a variable power supply level (VGX) based on a fixed voltage and changeable voltage across said Ct, a buffer driver, and a boost capacitor (CA) across power supply terminals of said buffer driver, said VGX coupled to a positive terminal of said CA;
• dynamically generating said VGX from a fixed voltage level and a voltage across said Ct, and
• responsive to a change in said voltage across said Ct, controlling a voltage across said CA using said VGX so that said voltage across said CA is changed by a magnitude that is less than a magnitude of said change in said voltage across said Ct.

A power circuit combination, comprising:

• a series capacitor buck converter including:
• a first half-bridge circuit including a first high side power switch (HSA) and a first low side power switch (LSA) connected in series having a first switching node (SWA) therebetween which drives a first output inductor;
• a second half-bridge circuit including a second HS power switch (HSB) and a second LS power switch (LSB) connected in series having a second switching node (SWB) therebetween which drives a second output inductor;
• a transfer capacitor (Ct) connected in series with said HSA and said LSA and between said first half-bridge circuit and said second half-bridge circuit;
• and
• an adaptive HS driver circuit having an output coupled to a gate of said HSA, said HS driver circuit including:
• a power supply circuit including summing circuitry configured for dynamically outputting a variable power supply level (VGX) based on a received fixed voltage and a voltage across said Ct;
• a buffer driver, and
• a boost capacitor (CA) connected across power supply terminals of said buffer driver;
• wherein said VGX is coupled to a positive terminal of said CA, and wherein said power supply circuit is configured so that as said voltage across said Ct varies, said VGX adjusts so that a voltage across said CA changes less than a change in said voltage across said Ct, and
• wherein said summing circuitry is configured so that said voltage across said CA is forced to a fixed voltage level independent of said voltage across said Ct.