Abstract: In a switching power supply apparatus for performing a switching control of a power MOS transistor that flows current to a coil and converting input voltage into output voltage, even if there occurs offset voltage in a current sensing operational amplifier, source potential of a current sensing MOS transistor is precisely kept at source potential of a low side power MOS transistor. For example, an offset cancel capacitor is arranged at an inverting input terminal of the current sensing operational amplifier, and voltage in the direction to offset the offset voltage occurring in the operational amplifier is charged to this capacitor.

Abstract: In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor, and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Abstract: A capacitor is disposed between the output side and the ground potential of an inductor which creates an output voltage. A first switch element supplies a current from an input voltage to an input side of the inductor, and a second switch element which is turned on when the first switch element is off sets the input side of the inductor to a prescribed potential. A control circuit detects the arrival of the voltage on the input side of the inductor at a high voltage corresponding to the input voltage when the load circuit is in a light load state and the second switch element is off, and turns on the first switch element. It invalidates the detection output of the voltage detecting circuit when the load circuit is in a heavy load state and, after the second switch element is turned off, turns on the first switch element.

Abstract: In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor, and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Abstract: A capacitor is disposed between the output side and the ground potential of an inductor which creates an output voltage. A first switch element supplies a current from an input voltage to an input side of the inductor, and a second switch element which is turned on when the first switch element is off sets the input side of the inductor to a prescribed potential. A control circuit detects the arrival of the voltage on the input side of the inductor at a high voltage corresponding to the input voltage when the load circuit is in a light load state and the second switch element is off, and turns on the first switch element. It invalidates the detection output of the voltage detecting circuit when the load circuit is in a heavy load state and, after the second switch element is turned off, turns on the first switch element.

Abstract: In a switching power supply apparatus for performing a switching control of a power MOS transistor that flows current to a coil and converting input voltage into output voltage, even if there occurs offset voltage in a current sensing operational amplifier, source potential of a current sensing MOS transistor is precisely kept at source potential of a low side power MOS transistor. For example, an offset cancel capacitor is arranged at an inverting input terminal of the current sensing operational amplifier, and voltage in the direction to offset the offset voltage occurring in the operational amplifier is charged to this capacitor.

Abstract: In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor, and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Abstract: Disclosed is a semiconductor device which makes it easy to design a wiring pattern for a wiring substrate on which the semiconductor device is to be mounted. In manufacturing plural semiconductor devices for providing different amounts of output current, arrangements and numbers of leads to which semiconductor chips for power transistors of the semiconductor devices are to be electrically connected are changed according to output current requirements for the semiconductor devices, whereas arrangements and numbers of leads to which semiconductor chips for control circuits of the semiconductor devices are to be electrically connected are fixed to be common to the semiconductor devices. In this way, the probability of malfunction of control circuits (PWM circuits) of the semiconductor devices can be reduced, so that a semiconductor device which makes it easy to design a wiring pattern for a wiring substrate on which the semiconductor device is to be mounted can be provided.

Abstract: In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Abstract: The present invention provides a switching power source and a semiconductor integrated circuit which realize an acquisition a sufficient driving voltage of a high-potential side switching element M1 even when a power source voltage VDD is low.

Abstract: There are provided a switching power supply device performing a stable operation with fast response, a semiconductor integrated circuit device, and a power supply device. A capacitor is provided between the output side of an inductor and a ground potential. A first power MOSFET supplies an electric current from an input voltage to the input side of the inductor. A second power MOSFET turned on when the first power MOSFET is off allows the input side of the inductor to be of a predetermined potential. A first feedback signal corresponding to an output voltage obtained from the output side of the inductor and a second feedback signal corresponding to an electric current flowed to the first power MOSFET are used to form a PWM signal. The first power MOSFET has plural cells of a vertical type MOS-construction. The number of cells is 1/N. A detection MOSFET in which the gains and the drains are shared over the same semiconductor substrate with the first power MOSFET is provided to form a second feedback signal.

Abstract: A capacitor is disposed between the output side and the ground potential of an inductor which creates an output voltage. A first switch element supplies a current from an input voltage to an input side of the inductor, and a second switch element which is turned on when the first switch element is off sets the input side of the inductor to a prescribed potential. A control circuit detects the arrival of the voltage on the input side of the inductor at a high voltage corresponding to the input voltage when the load circuit is in a light load state and the second switch element is off, and turns on the first switch element. It invalidates the detection output of the voltage detecting circuit when the load circuit is in a heavy load state and, after the second switch element is turned off, turns on the first switch element.

Abstract: This invention provides a semiconductor integrated circuit for drive and a module for building a synchronous rectifier type switching regulator that is able to correctly detect and prevent a reverse current flowing through a coil (inductance element) during light load using a comparator and has a good power efficiency. In a synchronous rectifier type switching regulator including a reverse current detection circuit that is able to detect a state in which a reverse current flows through the inductance element (coil) and a reverse current prevention function, a switching element for synchronous rectification is formed by a plurality of parallel transistors and the transistors are controlled so that a part of them are not driven during light load.

Abstract: It is aimed at decreasing losses not only in a synchronous rectifier circuit provided at a secondary side of a DC-DC converter, but also in a full-bridge switching circuit provided at a primary side thereof. The DC-DC converter comprises a transformer for voltage conversion, a synchronous rectifier circuit at the secondary side, and a full-bridge switching circuit at the primary side. The DC-DC converter performs synchronous rectifier control which uses switch transistors to change paths of currents flowing through the secondary coil in synchronization with switching operations at the primary side. The DC-DC converter detects currents flowing through a load at the secondary side, primary-side currents varying with the load currents, or primary-side input voltages to dynamically control off-timings of a synchronous rectification transistor at the secondary side.

Abstract: A power supply driver circuit with low power losses and desired response characteristics with respect to changes in output and its miniaturization is provided. In a driver IC constituting a switched-mode power supply equipment controlling the switching, by pulse width modulation, of first and second power transistors passing a current in a coil, and outputting a voltage bucked or boosted from an input voltage, current sensing with desired responsiveness is enabled by providing a switching transistor between an inverted input terminal and a non-inverted input terminal of an operational amplifier, preventing, while the second power transistor is ON, the generation of a potential which is undefined when first power transistor is ON, i.e. when the second power transistor is OFF, and maintaining a node potential in a state in which the potential is well defined.

Abstract: This invention provides a semiconductor integrated circuit for drive and a module for building a synchronous rectifier type switching regulator that is able to correctly detect and prevent a reverse current flowing through a coil (inductance element) during light load using a comparator and has a good power efficiency. In a synchronous rectifier type switching regulator including a reverse current detection circuit that is able to detect a state in which a reverse current flows through the inductance element (coil) and a reverse current prevention function, a switching element for synchronous rectification is formed by a plurality of parallel transistors and the transistors are controlled so that a part of them are not driven during light load.

Abstract: A power supply driver circuit with low power losses and desired response characteristics with respect to changes in output and its miniaturization is provided. In a driver IC constituting a switched-mode power supply equipment controlling the switching, by pulse width modulation, of first and second power transistors passing a current in a coil, and outputting a voltage bucked or boosted from an input voltage, current sensing with desired responsiveness is enabled by providing a switching transistor between an inverted input terminal and a non-inverted input terminal of an operational amplifier, preventing, while the second power transistor is ON, the generation of a potential which is undefined when first power transistor is ON, i.e. when the second power transistor is OFF, and maintaining a node potential in a state in which the potential is well defined.

Abstract: In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Abstract: It is aimed at decreasing losses not only in a synchronous rectifier circuit provided at a secondary side of a DC-DC converter, but also in a full-bridge switching circuit provided at a primary side thereof. The DC-DC converter comprises a transformer for voltage conversion, a synchronous rectifier circuit at the secondary side, and a full-bridge switching circuit at the primary side. The DC-DC converter performs synchronous rectifier control which uses switch transistors to change paths of currents flowing through the secondary coil in synchronization with switching operations at the primary side. The DC-DC converter detects currents flowing through a load at the secondary side, primary-side currents varying with the load currents, or primary-side input voltages to dynamically control off-timings of a synchronous rectification transistor at the secondary side.

Abstract: In order to decrease a change in the offset caused by high-frequency noise, filter circuits for cutting high-frequency noise are inserted between the input terminals of a differential amplifier circuit and input nodes of a differential amplifier stage, the filter circuits having a cut-off frequency which is higher than a cut-off frequency of the differential amplifier circuit but is lower than a cut-off frequency of a parasitic filter circuit constituted by a parasitic capacity and a parasitic resistance in the input unit.