Power Supply Controller

A power supply controller disposed between a power source and a load for controlling power supply from said power source to said load, said power supply controller comprising:

• a semiconductor switching element disposed on a current supply line connected between said power source and said load;
• and
• a PWM signal generator including an oscillator circuit for outputting an oscillator signal, and further including a comparator circuit for receiving said oscillator signal and a reference signal and outputting an output signal that is level-inverted according to a magnitude relation between a level of said oscillator signal and a level of said reference signal, said PWM signal generator being configured to provide an output signal of a pulse train from said comparator circuit, as a PWM signal for pulse width modulation control, to said semiconductor switching element in order to cause ON/OFF operation, wherein said oscillator circuit includes:
• a parallel circuit having a first resistive element and a capacitor which are arranged parallel to each other;
• a first switching element disposed on a path of a charging current for charging said capacitor;
• a charge/discharge control circuit for turning said first switching element from ON to OFF when a charging voltage for said capacitor reaches a first voltage that changes depending on a power supply voltage of said power source, and for turning said first switching element from OFF to ON when said charging voltage is the same as a second voltage that changes depending on said power supply voltage;
• and
• a current changing circuit for changing said charging current depending on said power supply voltage.

A power supply controller disposed between a power source and a load for controlling power supply from said power source to said load, said power supply controller comprising:

• a semiconductor switching element disposed on a current supply line connected between said power source and said load;
• and
• a PWM signal generator including an oscillator circuit for outputting an oscillator signal, and further including a comparator circuit for receiving said oscillator signal and a reference signal and outputting an output signal that is level-inverted according to a magnitude relation between a level of said oscillator signal and a level of said reference signal, said PWM signal generator being configured to provide an output signal of a pulse train from said comparator circuit, as a PWM signal for pulse width modulation control, to said semiconductor switching element in order to cause an ON/OFF operation, wherein:
• said oscillator circuit includes a parallel circuit having a first resistive element and a capacitor which are arranged parallel to each other;
• a first switching element disposed on a path of a charging current for charging said capacitor;
• and
• a charge/discharge control circuit for turning said first switching element from ON to OFF when a charging voltage for said capacitor reaches a first voltage, and for turning said first switching element from OFF to ON when said charging voltage is the same as a second voltage, said oscillator circuit being configured to output an oscillator signal based on said charging voltage;
• circuits of said PWM signal generator except for said parallel circuit are configured onto at least one of a single chip or a plurality of chips housed in a package so as to form a semiconductor device, and said parallel circuit is disposed outside of said semiconductor device and connected to the circuits other than said parallel circuit via a first external terminal of said semiconductor device;
• and
• a discharging time for said capacitor based on turn-off of said first switching element is set to be longer than a charging time for said capacitor which is based on turn-on of said first switching element.