Overcurrent protection circuit
View Patent ↗The semiconductor device includes: a first transistor controlled by a control signal; a sense voltage generating circuit for sensing current flowing through the first transistor, mirroring current flowing through a reference current circuit, and summing the currents to generate voltage based on the summed currents; a reference voltage circuit for mirroring current flowing through the reference current circuit and generating reference voltage; an amplifier for comparing the voltage generated by the sense voltage generating circuit and the reference voltage; and a second transistor which has a gate connected to an output terminal of the amplifier and which can turn off the first transistor.
1. A semiconductor device, comprising:
a first transistor controlled by a control signal;
a reference current circuit for generating reference current;
a sense voltage generating circuit for generating sense voltage based on current which is a sum of current in accordance with current flowing through the first transistor and the reference current;
a reference voltage circuit for generating reference voltage based on the reference current;
an amplifier for comparing the sense voltage and the reference voltage; and
a second transistor which has a gate connected to an output terminal of the amplifier and which turns off the first transistor when the sense voltage becomes higher than the reference voltage.
2. A semiconductor device according to claim 1 , wherein the sense voltage generating circuit comprises:
a third transistor for sensing the current flowing through the first transistor;
a fourth transistor for mirroring the reference current; and
a first resistor through which current that flows through the third transistor and current that flows through the fourth transistor flow.
3. A semiconductor device according to claim 1 , wherein the reference voltage circuit comprises:
a fifth transistor for mirroring the reference current; and
a first PN junction element and a second resistor through which current that flows through the fifth transistor flows and which are connected in parallel with each other.
4. A semiconductor device according to claim 1 , wherein the reference current circuit comprises a plurality of PN junction elements and generates current based on a forward voltage difference among the plurality of PN junction elements.