Sensing resistor short determiner, switch control circuit including the same and power supply including the switch control circuit
AssigneeSemiconductor Components Industries, LLC
InventorsIn-Ki Park, Hyun-Chul Eum, Yong-Sang Shin
Life of this patent
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Abstract
According to the exemplary embodiments, a short-circuit of a sense resistor is detected according to a result of comparison between a sense voltage and a reference voltage at a time based on at least one of a period set based on an input sense voltage and a turn-on time of a power switch. A blanking period is set based on the input sense voltage in a current mode, and a short-circuited resistor detection period is set based on the input sense voltage.
Claims24
A sense resistor short-circuit determiner, comprising:
- an input voltage detector configured to detect an input voltage coupled to a power switch and to generate an input sense voltage;
- a sense voltage comparator 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 power switch to a sense resistor when the power switch is turned on to couple the input voltage to the sense resistor;
- and
- a blanking period setting unit that is configured to set a blanking period during which the sense resistor short-circuit determiner does not determine a short-circuit of the sense resistor, a beginning of the blanking period being synchronized to a turn-on time of the power switch,
- wherein the sense resistor short-circuit determiner is configured to detect the short-circuit of the sense resistor within a sensing time and according to the comparison signal,
- wherein the sensing time starts after expiration of the blanking period, and a length of the sensing time is changed according to the input voltage.
A switch control circuit for controlling a switching operation of a power switch that is electrically coupled to an input voltage, comprising:
- a sense resistor;
- a PWM controller configured to control the switching operation of the power switch using a sense voltage generated by a current of the power switch flowing to the sense resistor;
- and
- a sense resistor short-circuit determiner configured to generate an input sense voltage by detecting the input voltage, to set a blanking period during which the sense resistor short-circuit determiner does not determine a short-circuit of the sense resistor, and to detect the short-circuit of the sense resistor within a sensing time and according to a result of a comparison between the sense voltage and a reference voltage,
- wherein a beginning of the blanking period is synchronized to a turn-on time of the power switch, and
- wherein the sensing time starts after expiration of the blanking period, and a length of the sensing time is adjusted according to the input voltage.
A power supply comprising:
- a power switch electrically coupled to an input voltage;
- a sense resistor coupled to the power switch to sense a current flowing through the power switch when the power switch couples the input voltage to the sense resistor;
- and
- a sense resistor short-circuit determiner configured to generate an input sense voltage by detecting the input voltage, to set a blanking period during which the sense resistor short-circuit determiner does not determine a short-circuit of the sense resistor, and to detect a short-circuit of the sense resistor within a sensing time and according to a result of comparison between a sense voltage of the sense resistor and a reference voltage sensed,
- wherein a beginning of the blanking period is synchronized to a turn-on time of the power switch, and
- wherein the sensing time starts after expiration of the blanking period, and a length of the sensing time is changed according to the input voltage.
Dependencies are inferred from the claim text.