Abstract: Provided is an LED drive circuit capable of controlling a current caused to flow through an LED at a proper value even when a power supply voltage is higher than a sum of a forward voltage of the LED to be driven and a voltage of a current sense element. In a configuration where an inductor and a rectifying element are connected in series to each other, at each one terminal thereof and the LED and a current sense element, which are connected in series to each other, are a smoothing capacity are respectively connected to the other terminals of the inductor and the rectifying device, in parallel with each other, the LED and these elements are separated from a power supply or a ground by a switching element.

Abstract: Provided is a DC-DC converter circuit which is stably operated without being affected by a size of an output capacitor (111) and a cost thereof. When a switching element is turned on so that a charge current that was flowing into an output capacitor flows into the switching element, the current is converted into a voltage to be added to an output voltage, and a resultant voltage is fed back to a control system.

Abstract: Provided is an LED drive circuit capable of controlling a current caused to flow through an LED at a proper value even when a power supply voltage is higher than a sum of a forward voltage of the LED to be driven and a voltage of a current sense element. In a configuration where an inductor and a rectifying element are connected in series to each other, at each one terminal thereof and the LED and a current sense element, which are connected in series to each other, are a smoothing capacity are respectively connected to the other terminals of the inductor and the rectifying device, in parallel with each other, the LED and these elements are separated from a power supply or a ground by a switching element.

Abstract: To provide a battery protecting circuit in which a delay circuit for generating delay times for a plurality of abnormality detecting functions is realized without increasing a circuit scale. A control circuit of a battery protecting circuit is provided with a function of, when an abnormality requiring a short delay time is detected while a delay time is counted, resetting count of the delay time for the detected abnormality.

Abstract: Provided is a DC-DC converter circuit which is stably operated without being affected by a size of an output capacitor (111) and a cost thereof. When a switching element is turned on so that a charge current that was flowing into an output capacitor flows into the switching element, the current is converted into a voltage to be added to an output voltage, and a resultant voltage is fed back to a control system.

Abstract: To eliminate in structure a parasitic capacity formed between a polycrystalline silicon film resistor and a semiconductor substrate, and to provide a battery voltage detecting circuit capable of surely detecting a battery voltage. A layer such as a well which is insulated from a semiconductor substrate is disposed on the semiconductor substrate just below a polycrystalline silicon film resistor, and a potential of the layer is set to be a stable potential which is not influenced by a potential of the polycrystalline silicon film resistor or a detecting operation of a battery. With this structure, no parasitic capacity is eliminated in structure, thereby being capable of surely detecting the battery voltage.

Abstract: The present invention provides a rechargeable power source apparatus capable of performing the detection of a charge current with the overdischarge protection state being held and the detection of a discharge current with the overcharge protection state being held. For the detection of the charge current, the voltage developed across a resistance component of a charging switch of a switching circuit is utilized. Also, for the detection of the discharge current, the voltage developed across a resistance component of a discharging switch of the switching circuit is utilized. As a result, it is possible to perform the detection of the overcharge current in the overdischarge protection state and the detection of the overdischarge current in the overcharge protection state.

Abstract: To eliminate in structure a parasitic capacity formed between a polycrystalline silicon film resistor and a semiconductor substrate, and to provide a battery voltage detecting circuit capable of surely detecting a battery voltage. A layer such as a well which is insulated from a semiconductor substrate is disposed on the semiconductor substrate just below a polycrystalline silicon film resistor, and a potential of the layer is set to be a stable potential which is not influenced by a potential of the polycrystalline silicon film resistor or a detecting operation of a battery. With this structure, no parasitic capacity is eliminated in structure, thereby being capable of surely detecting the battery voltage.

Abstract: A switching regulator includes an input power supply connected to an input of the switching regulator; at least one input/output disconnection switch disposed between the input power supply and a device connected to an output of the switching regulator, for interrupting the supply of an energy to the device from the input power supply; and a device for limiting a rush current that flows into an output capacitor from the input power supply when the input/output disconnection switch turns on to start step-up operation.

Abstract: The present invention provides a rechargeable power source apparatus capable of performing the detection of a charge current with the overdischarge protection state being held and the detection of a discharge current with the overcharge protection state being held. For the detection of the charge current, the voltage developed across a resistance component of a charging switch of a switching circuit is utilized. Also, for the detection of the discharge current, the voltage developed across a resistance component of a discharging switch of the switching circuit is utilized. As a result, it is possible to perform the detection of the overcharge current in the overdischarge protection state and the detection of the overdischarge current in the overcharge protection state.

Abstract: Instability and oscillation are avoided in an overcharge/overdischarge control circuit by providing comparators with sufficient gain to minimize leakage current penetration into control circuitry when an output of a comparator used for comparing the output voltage of a secondary cell with a reference voltage is at an intermediate level. An overcharging/overdischarging detection circuit with two secondary cells connected in series has voltage dividing resistors connected in parallel therewith for producing a divided output voltage for each secondary cell, the divided output voltages each being supplied to a respective comparator. A first comparator has an input stage comprising N-channel MOS devices. A second comparator has an input stage comprising P-channel MOS devices.