Sensing resistor short determiner, switch control circuit including the same and power supply including the switch control circuit

A short-circuit detection circuit, comprising:

• an input voltage detector circuit configured to detect an input voltage coupled to a power switch and to generate an input sense voltage according to the input voltage;
• a sense voltage comparator circuit configured to compare a sense voltage and a reference voltage to generate a comparison signal, the sense voltage being generated by a current that flows from the input voltage through the power switch and a sense resistor when the power switch is turned;
• and
• a blanking period setting circuit configured to assert a blanking signal when the power switch is on, wherein the blanking period setting circuit determines a duration of the blanking signal according to the input sense voltage,
• wherein the short-circuit detection circuit is configured to:
• not detect a short-circuit of the sense resistor when the blanking signal is asserted, and
• detect the short-circuit of the sense resistor according to the comparison signal when the blanking signal is not asserted and the power switch is on.

A short-circuit detection circuit, comprising:

• a blanking period setting circuit configured to receive an input sense voltage and produce a blanking signal having an asserted duration determined using the input sense voltage;
• a first comparator circuit configured to compare a sense voltage to a reference voltage and assert a comparison signal when the sense voltage is less than the reference voltage;
• and
• an AND gate configured to receive the blanking signal, the comparison signal, and a gate control signal and to assert a shut-down signal when the blanking signal is asserted, the comparison signal is asserted, and the gate control signal is asserted,
• wherein the gate control signal being asserted indicates a power switch is turned on.

A method for detecting a short circuit, the method comprising:

• determining, using an input voltage detector circuit, an input sense voltage corresponding to an input voltage coupled to a power switch;
• generating, using a blanking period setting circuit, a blanking signal having an asserted duration determined using the input sense voltage;
• determining, using a sense voltage comparator circuit, whether a sense voltage is less than a reference voltage;
• determining whether the power switch is turned on;
• and
• asserting a shut-down signal in response to the sense voltage being less than the reference voltage when the blanking signal is not asserted and the power switch is turned on,
• wherein the sense voltage is generated using a sense resistor coupled in series with the power switch.