Drive protection circuit, semiconductor module, and automobile
It is an object of the present invention to provide a technology capable of reliably suppressing a surge voltage even in a case where noise having a small pulse width is generated. A drive protection circuit that drives and protects a switching element includes a gate driving circuit that drives the switching element in response to a gate driving signal and an overcurrent protection circuit that operates a soft cutoff circuit upon an overcurrent of the switching element, the soft cutoff circuit causing the switching element to transition from ON to OFF at a switching speed slower than that of the gate driving circuit. In the drive protection circuit, in a case where a pulse width of ON of the gate driving signal is less than or equal to a response time of the overcurrent protection circuit, the drive protection circuit operates the soft cutoff circuit to cause the switching element to transition from ON to OFF, regardless of the overcurrent.
1. A drive protection circuit that drives and protects a switching element, comprising:
a drive circuit that drives said switching element in response to an input signal; and
an overcurrent protection circuit that operates a soft cutoff circuit upon an overcurrent of said switching element, said soft cutoff circuit causing said switching element to transition from ON to OFF at a switching speed slower than that of said drive circuit,
wherein in a case where a pulse width of ON of said input signal is less than or equal to a response time of said overcurrent protection circuit, said drive protection circuit operates said soft cutoff circuit to cause said switching element to transition from ON to OFF, regardless of said overcurrent.
2. The drive protection circuit according to claim 1 , further comprising a timer circuit that outputs a predetermined signal, from a timing of said input signal brought into ON, for a fixed period of time equal to the response time of said overcurrent protection circuit,
wherein in a case where said predetermined signal is output from said timer circuit and said input signal is OFF, said drive protection circuit operates said soft cutoff circuit to cause said switching element to transition from ON to OFF, regardless of said overcurrent.
3. The drive protection circuit according to claim 1 , wherein a mirror period of said switching element is used instead of said response time.
4. The drive protection circuit according to claim 1 , wherein a period of time from rising of a gate voltage of said switching element to turning OFF said input signal is used instead of the pulse width of ON of said input signal.
5. The drive protection circuit according to claim 1 , further comprising a comparator that compares a gate threshold of said switching element with a gate voltage of said switching element,
wherein in the transition of said switching element to OFF by said soft cutoff circuit, said drive protection circuit operates said drive circuit instead of said soft cutoff circuit to cause said switching element to transition to OFF, in accordance with a comparison result of said comparator.
6. The drive protection circuit according to claim 1 , wherein said switching element is included in an inverter device that drives a motor installed in an automobile.
7. A semiconductor module, comprising:
the drive protection circuit according to claim 1 ; and
said switching element.
8. An automobile, comprising:
the drive protection circuit according to claim 1 ; and
said switching element included in an inverter device that drives a motor.