Abstract: To provide a digital control switching power-supply device capable of suitably achieving fast transient response at the time of a sudden load change. In parallel with normal digital signal processing means that outputs a PWM pulse signal having a desired duty, transient variation detection means composed of a CR filter provided across an output inductor and a window comparator is provided in preparation for a sudden load change. If a sudden decrease in load is detected, a PWM pulse signal having a duty of 0% is forcedly output, and if a sudden increase in load is detected, a PWM pulse signal having a duty of 100% is forcedly output.

Abstract: A power-supply device including a marginal check voltage setting circuit that is easily adaptable to downsizing of the device and to configuration using ICs. The power-supply device of this invention includes a marginal check voltage setting circuit that sets a desired marginal check voltage, an error amplifier that delivers output of an error signal, a pulse width modulation oscillator that modulates the pulse width of the output from the error amplifier, a driver circuit that generates driving signal from the pulse signal originating from the pulse width modulation oscillator, and a pair of power semiconductor switching devices that work to step down the input voltage and generate an output voltage based on the driving signal. Furthermore, the power-supply device is also provided with an over-voltage detection circuit and a power-good circuit both circuits being positioned at the output terminal of the marginal check voltage setting circuit.

Abstract: The power supply device of the present invention supplies power highly reliably by suppressing an increase in costs even when a multiplicity of load groups are present. When operating normally, each of the normal power supply units supplies power via a normal path to each of the load groups. One redundant power supply unit is provided for a plurality of normal power supply units. When any of the normal power supply units fail, the redundant power supply unit continues to supply power to the load group via the redundant path. A diode for connecting the redundant path to the normal path is provided in each normal power supply unit and the redundant paths that are routed through the respective normal power supply units are connected so as to intersect one another between the normal power supply units.

Abstract: An electric current flowing to an upper side power MOSFET during soft-start is detected according to an on-voltage of the MOSFET and an on-pulse width of a PWM pulse for driving the upper side power MOSFET is forced to be reset in the idle and decided according to a signal generated when the voltage falls below a predetermined specified voltage.

Abstract: To provide a digital control switching power-supply device capable of suitably achieving fast transient response at the time of a sudden load change. In parallel with normal digital signal processing means that outputs a PWM pulse signal having a desired duty, transient variation detection means composed of a CR filter provided across an output inductor and a window comparator is provided in preparation for a sudden load change. If a sudden decrease in load is detected, a PWM pulse signal having a duty of 0% is forcedly output, and if a sudden increase in load is detected, a PWM pulse signal having a duty of 100% is forcedly output.

Abstract: An over-current detection circuit using the ON-voltage of a main MOSFET is provided, which is resistant to process variations of a main MOSFET and is not easily influenced by switching noise. Separately from a main MOSFET (Q1), a sense MOSFET (Q3) whose size is 1/m of the main MOSFET is provided and it is caused to be normally on. A DC ON-voltage generated when a current that is 1/m of an over-current value is caused to flow through the sense MOSFET is obtained as a reference voltage for over-current setting. The ON-voltage when the main MOSFET is on is sampled and held, and it is obtained as a DC voltage. These DC voltages are compared in a comparator (COMP).

Abstract: The power supply device of the present invention supplies power highly reliably by suppressing an increase in costs even when a multiplicity of load groups are present. When operating normally, each of the normal power supply units supplies power via a normal path to each of the load groups. One redundant power supply unit is provided for a plurality of normal power supply units. When any of the normal power supply units fail, the redundant power supply unit continues to supply power to the load group via the redundant path. A diode for connecting the redundant path to the normal path is provided in each normal power supply unit and the redundant paths that are routed through the respective normal power supply units are connected so as to intersect one another between the normal power supply units.

Abstract: An over-current detection circuit using the ON-voltage of a main MOSFET is provided, which is resistant to process variations of a main MOSFET and is not easily influenced by switching noise. Separately from a main MOSFET (Q1), a sense MOSFET (Q3) whose size is 1/m of the main MOSFET is provided and it is caused to be normally on. A DC ON-voltage generated when a current that is 1/m of an over-current value is caused to flow through the sense MOSFET is obtained as a reference voltage for over-current setting. The ON-voltage when the main MOSFET is on is sampled and held, and it is obtained as a DC voltage. These DC voltages are compared in a comparator (COMP).

Abstract: A power-supply device comprising such marginal check voltage setting circuit that is easily adaptable to downsizing of the device and to configuration using ICs. The power-supply device of this invention comprises a marginal check voltage setting circuit that accepts input of a reference voltage and sets a desired marginal check voltage, an error amplifier that accepts input of the marginal check voltage and also the output voltage of the power-supply device and delivers output of an error signal, that is, the difference between the two inputs, a pulse width modulation oscillator that modulates the pulse width of the output from the error amplifier, a driver circuit that generates driving signal from the pulse signal originating from the pulse width modulation oscillator, and a pair of power semiconductor switching devices that work to step down the input voltage and generate an output voltage based on the driving signal.

Abstract: A feeding technique for a storage unit is provided, in which power can be supplied from an optimum power source depending on an operation mode of a cache memory, the stable switching of feeding paths can be performed, and the feeding with high voltage accuracy and small voltage variation can be achieved. For its achievement, the feeding system in the RAID system including a hard disk drive, a disk adaptor, a channel adaptor, and a cache memory is provided. The feeding system includes a DC-DC power source to supply, to the cache memory, the voltage for a normal operation mode in which the data is written/read to/from the cache memory, and a DC-DC power source to supply, to the cache memory, the voltage for a backup operation mode in which the data stored in the cache memory is retained, and the power sources are switched during the feeding depending on the operation mode of the cache memory.

Abstract: A feeding technique for a storage unit is provided, in which power can be supplied from an optimum power source depending on an operation mode of a cache memory, the stable switching of feeding paths can be performed, and the feeding with high voltage accuracy and small voltage variation can be achieved. For its achievement, the feeding system in the RAID system including a hard disk drive, a disk adaptor, a channel adaptor, and a cache memory is provided. The feeding system includes a DC-DC power source to supply, to the cache memory, the voltage for a normal operation mode in which the data is written/read to/from the cache memory, and a DC-DC power source to supply, to the cache memory, the voltage for a backup operation mode in which the data stored in the cache memory is retained, and the power sources are switched during the feeding depending on the operation mode of the cache memory.

Abstract: To provide a A digital control switching power-supply device is provided which is capable of suitably achieving fast transient response at the time of a sudden load change. In parallel with normal digital signal processing means that outputs a PWM pulse signal having a desired duty, transient variation detection means composed of a CR filter provided across an output inductor and a window comparator is provided in preparation for a sudden load change. If a sudden decrease in load is detected, a PWM pulse signal having a duty of 0% is forcedly output, and if a sudden increase in load is detected, a PWM pulse signal having a duty of 100% is forcedly output.