A level shift circuit for transmitting a control signal from a low voltage side circuit having a low-voltage direct-current power source as a power source to a high voltage side circuit having a high-voltage direct-current power source as a power source, comprising:
- a one-shot pulse generator for generating a set signal pulse and a reset signal pulse at a rise of and at a fall of an input signal, respectively, with the low-voltage direct-current power source as the power source;
- a first semiconductor switching element wherein the first terminal is connected to a low voltage terminal of the high-voltage direct-current power source and the set signal pulse is inputted;
- a second semiconductor switching element wherein the first terminal is connected to the low voltage terminal of the high-voltage direct-current power source and the reset signal pulse is inputted;
- a first resistance one end of which is connected to a high voltage terminal of the high-voltage direct-current power source;
- a second resistance one end of which is connected to a high voltage terminal of the high-voltage direct-current power source;
- a third resistance connected between other end of the first resistance and a second terminal of the first semiconductor switching element;
- a fourth resistance connected between other end of the second resistance and a second terminal of the second semiconductor switching element;
- a first time-constant generation circuit wherein a connection point of the first resistance and the third resistance is connected to an input terminal;
- a second time-constant generation circuit wherein a connection point of the second terminal of the second semiconductor switching element and the fourth resistance is connected to an input terminal;
- a third time-constant generation circuit wherein a connection point of the second resistance and the fourth resistance is connected to an input terminal;
- a fourth time-constant generation circuit wherein a connection point of the second terminal of the first semiconductor switching element and the third resistance is connected to an input terminal;
- a first logic circuit wherein an output terminal of the first time-constant generation circuit and an output terminal of the second time-constant generation circuit are connected to a first input terminal and a second input terminal, respectively, using the high-voltage direct-current power source as a power source, and a set signal is output;
- a second logic circuit wherein an output terminal of the third time-constant generation circuit and an output terminal of the fourth time-constant generation circuit are connected to a first input terminal and a second input terminal, respectively, using the high-voltage direct-current power source as a power source, and a reset signal is output;
- and
- a flip-flop circuit wherein the set signal from an output terminal of the first logic circuit and the reset signal from an output terminal of the second logic circuit are inputted, respectively, using the high-voltage direct-current power source as the power source, and a drive signal is output.