Patent ID: 7372240

Claim:
An apparatus for selecting a gate drive voltage, as used in a DC to DC converter, from a plurality of gate drive voltages, responsive to the load current at the output of the converter, comprising: a current sense resistor in series with the path of output current flow, across which is generated a voltage proportional to output current an amplifier coupled to said sense resistor, whereby said voltage proportional to output current is amplified; a plurality of comparators, each having as a first input the amplified voltage indicative of output current, each having as a second input one of a plurality of reference voltages corresponding to a plurality of current threshold levels, whereby the logical outputs from the plurality of comparators are indicative of which of the plurality of current ranges the output current falls within; a multiplexer having select inputs coupled to said outputs from said plurality of comparators, having inputs coupled to a plurality of gate drive voltages, and having an output which is coupled to one of the plurality of said inputs responsive to the plurality of select inputs, said output also being coupled to the gate drive input of a known DC to DC converter; whereby the multiplexer output is a gate drive voltage dependent on output current, and whereby each of the plurality of voltages is chosen to optimize efficiency in the corresponding current range.