Abstract: A solenoid valve driving circuit for a solenoid valve includes a current detector for detecting a current that flows in a solenoid coil, a rate of change over time calculating unit for calculating a rate of change over time of the detected current, and a maintaining state transition determining unit for determining a timing at which transition from a first period to a second period occurs based on the calculated rate of change over time.

Abstract: A solenoid valve driving circuit for a solenoid valve includes a current detector for detecting a current that flows in a solenoid coil, a rate of change over time calculating unit for calculating a rate of change over time of the detected current, and a maintaining state transition determining unit for determining a timing at which transition from a first period to a second period occurs based on the calculated rate of change over time.

Abstract: A current detection circuit generates a pulse signal Sd based on a voltage Vd corresponding to a current I flowing through a solenoid coil, and feeds the pulse signal Sd back to a PWM circuit of a switch controller. The PWM circuit generates a pulse signal Sr having a predetermined duty ratio, based on a comparison between the fed back pulse signal Sd and a voltage value corresponding to a first current value or a second current value, and supplies the pulse signal Sr to a pulse supplying unit. The pulse supplying unit supplies the pulse signal Sr as a first pulse signal S1 and/or a second pulse signal S2 to a gate terminal G of a MOSFET.

Abstract: When a power source voltage is applied to a switch control section, a control signal is supplied from the switch control section to a transistor. The transistor is placed in an ON state during a period of time corresponding to a pulse width of the control signal. The power source voltage is applied as a first voltage to a solenoid coil. On the other hand, when supply of the control signal to the transistor is stopped, the transistor is placed in an OFF state. A voltage-generating section generates a DC voltage, which is lower than the power source voltage. The transistor applies the generated DC voltage as a second voltage to the solenoid coil.

Abstract: A current detection circuit generates a pulse signal Sd based on a voltage Vd corresponding to a current I flowing through a solenoid coil, and feeds the pulse signal Sd back to a PWM circuit of a switch controller. The PWM circuit generates a pulse signal Sr having a predetermined duty ratio, based on a comparison between the fed back pulse signal Sd and a voltage value corresponding to a first current value or a second current value, and supplies the pulse signal Sr to a pulse supplying unit. The pulse supplying unit supplies the pulse signal Sr as a first pulse signal S1 and/or a second pulse signal S2 to a gate terminal G of a MOSFET.

Abstract: A current detection circuit generates a pulse signal Sd based on a voltage Vd corresponding to a current I flowing through a solenoid coil, and feeds the pulse signal Sd back to a PWM circuit of a switch controller. The PWM circuit generates a pulse signal Sr having a predetermined duty ratio, based on a comparison between the fed back pulse signal Sd and a voltage value corresponding to a first current value or a second current value, and supplies the pulse signal Sr to a pulse supplying unit. The pulse supplying unit supplies the pulse signal Sr as a first pulse signal S1 and/or a second pulse signal S2 to a gate terminal G of a MOSFET.

Abstract: An input circuit has a first current-limiting resistor, a second current-limiting resistor, and an AC-input photocoupler. The photocoupler has an input terminal connected to a first external terminal and another input terminal connected to a positive electrode through the first current-limiting resistor and also to a ground electrode through the second current-limiting resistor. The first external terminal is connected to a PNP transistor and NPN transistors.

Abstract: When a power source voltage is applied to a switch control section, a control signal is supplied from the switch control section to a transistor. The transistor is placed in an ON state during a period of time corresponding to a pulse width of the control signal. The power source voltage is applied as a first voltage to a solenoid coil. On the other hand, when supply of the control signal to the transistor is stopped, the transistor is placed in an OFF state. A voltage-generating section generates a DC voltage, which is lower than the power source voltage. The transistor applies the generated DC voltage as a second voltage to the solenoid coil.

Abstract: An input circuit has a first current-limiting resistor, a second current-limiting resistor, and an AC-input photocoupler. The photocoupler has an input terminal connected to a first external terminal and another input terminal connected to a positive electrode through the first current-limiting resistor and also to a ground electrode through the second current-limiting resistor. The first external terminal is connected to a PNP transistor and NPN transistors.