Scheme to reduce static power consumption in analog controller based power converters requiring an external high voltage startup circuit

Circuitry for supplying a DC supply voltage to an integrated circuit chip having a power supply input terminal, comprising:

• a first circuit coupled to receive an input voltage and selectively generate the DC supply voltage at the power supply input terminal;
• and
• a second circuit that controls the selective generation by the first circuit, said second circuit coupled to receive the input voltage and the DC supply voltage and configured to compare the DC supply voltage to a threshold and cause the first circuit to terminate selective generation if the DC supply voltage exceeds the threshold;
• wherein the first circuit comprises:
• a first resistor;
• and
• a transistor switch;
• wherein the first resistor and transistor switch are coupled in series between an input node receiving the input voltage and the power supply input terminal.

Circuitry for supplying a DC supply voltage to an integrated circuit chip, wherein the integrated circuit chip controls operation of a switched mode power conversion circuit, comprising:

• a first circuit including a first transistor switch, wherein said first circuit is coupled to receive an input voltage and configured to generate the DC supply voltage for the integrated circuit chip when the first transistor is turned ON;
• and
• a second circuit that controls turning ON and turning OFF of the first transistor switch, said second circuit configured to bias the first transistor switch to turn ON by default in response to the input voltage and further configured to switch the first transistor switch to turn OFF in response to the DC supply voltage exceeding a threshold;
• and
• wherein the threshold is higher than a minimum operating voltage threshold of the integrated circuit chip for controlling operation of the switched mode power conversion circuit.

Circuitry, comprising:

• a power conversion circuit including a first transistor switch having a control terminal configured to receive a switching control signal, said power conversion circuit receiving an input voltage and generating an output voltage in response to said switching control signal;
• an integrated circuit chip having a power supply input configured to receive a DC supply voltage, said integrated circuit configured to generate said switching control signal if said DC supply voltage exceeds a first threshold;
• a second transistor switch with a conduction path coupled between the input voltage and the power supply input;
• a first biasing circuit configured to bias the second transistor switch in an on state as a default operation;
• and
• a second biasing circuit configured to bias the second transistor switch in an off state if said DC supply voltage exceeds a second threshold that is greater than the first threshold.