HIGH EFFICIENCY DC-DC CONVERTER WITH ACTIVE SHUNT TO ACCOMMODATE HIGH INPUT VOLTAGE TRANSIENTS

摘要

Switch mode power supplies and integrated circuits are presented to provide a DC output voltage signal using high and low side switches, with a switching control circuit to turn off the high side switch and engage an active shunt circuit to provide a reduced voltage to continue converter operation to accommodate high input voltage transients when the DC input voltage exceeds a threshold voltage without requiring an oversized low side switch for improved efficiency through reduced switching and conduction losses in normal operation.

主权项

1. An integrated circuit, comprising:
a DC-DC converter circuit to control an output voltage signal, the DC-DC converter circuit including:
a first switching device coupled between a DC input node and a switching node, the first switching device operative according to a first switching control signal, anda second switching device coupled between the switching node and a constant voltage node, the second switching device operative according to a second switching control signal; an active shunt circuit including a shunt circuit input coupled to the DC input node, and a shunt circuit output, the active shunt circuit operative according to a shunt circuit switching control signal to provide a shunt circuit output voltage signal to the shunt circuit output at a shunt circuit voltage level less than the input voltage; and a detector circuit including an input coupled to the DC input node, and an output to provide a mode control signal in a first state when an input voltage of the DC input node is less than a threshold voltage, the output operative to provide the mode control signal in a different second state when the input voltage of the DC input node is greater than the threshold voltage; a switching control circuit operative in a first mode when the mode control signal is in the first state to provide the first and second switching control signals to operate the first and second switching devices to regulate the output voltage signal according to a feedback signal, the switching control circuit operative in a second mode when the mode control signal is in the second state to provide the first switching control signal to turn off the first switching device, and to provide the second switching control signal and the shunt circuit switching control signal to operate the active shunt circuit and the second switching device to control the output voltage signal.