Gate driver

A circuit, comprising:

• a supply voltage terminal;
• a bootstrap terminal connected to the supply voltage terminal;
• a bootstrap capacitor connected to the bootstrap terminal;
• a high side transistor;
• a low side transistor;
• a high side gate driver connected to the high side transistor and having a power input terminal connected to the bootstrap terminal;
• a low side gate driver connected to the low side transistor;
• a controller configured to generate a start-up pulse using the low side gate driver to charge the bootstrap capacitor;
• a clamp driver;
• a clamp transistor connected between a gate of the high side transistor and a reference voltage terminal and having a gate connected to the clamp driver;
• and
• an energy harvesting circuit connected between the gate of the high side transistor and the gate of the clamp transistor and configured to harvest energy from the gate of the high side transistor responsive to the start-up pulse and activate the clamp transistor using the harvested energy.

A method, comprising:

• generating a start-up pulse;
• harvesting energy injected on a clamp signal input terminal responsive to the start-up pulse;
• and
• activating a clamp transistor connected between the clamp signal input terminal and a reference voltage terminal using the harvested energy to provide a low impedance path from the clamp signal input terminal to the reference voltage terminal.