Mitsumi Electric Company Ltd.

Satoshi Arima

Hiroki Matsuda

Yukio Murata

Takeshi Sato

Minoru Kado

Daisuke Imade

Kenji Nakata

Takashi Inoue

A resonance voltage attenuation detection circuit detects attenuation of a resonance voltage of a winding of a transformer. The resonance voltage attenuation detection circuit includes a first voltage comparator circuit and a time-out circuit. The first voltage comparator circuit compares a voltage of the winding with a predetermined first voltage. The time-out circuit performs clocking operation in accordance with an output of the first voltage comparator circuit. The time-out circuit outputs an attenuation detection signal when the time-out circuit has clocked a preset period which is shorter than a time required for a peak voltage of the winding to be attenuated from the first voltage to a predetermined second voltage lower than the first voltage.

Resonance voltage attenuation detection circuit, semiconductor device for switching power, and switching power supply

A switching power supply device includes a voltage conversion transformer, a primary-side control semiconductor device, a rectification and smoothing circuit, an output voltage detection circuit, a failure detection circuit, and a switch. The primary-side control semiconductor device generates a driving signal which controls a switching element connected to a primary winding of the transformer. The rectification and smoothing circuit is connected to a secondary winding of the transformer. The output voltage detection circuit detects a secondary-side output voltage of the transformer and transmits a feedback signal corresponding to the output voltage to the primary-side control semiconductor device through an insulated signal transmitter. The failure detection circuit detects a failure on a secondary side of the transformer. The switch cuts off a current flowing to the insulated signal transmitter if the failure detection circuit detects a failure.

Switching power supply device having failure protection function, and method for controlling the same

A power supply apparatus includes a voltage conversion circuit, a reference voltage generating circuit, a constant current control circuit which includes a current controller and a differential circuit which controls the current controller based on the reference voltage and current detection voltage showing a size of the output current, and wherein an electric current on the current path is controlled by the current controller a reference voltage adjustment circuit which adjusts a first reference voltage generated by the reference voltage generating circuit to converge a ripple occurring in the output current to a predetermined ripple rate or less, based on a voltage of a first potential point set on the current path from an output portion on a high potential side of the voltage conversion circuit to the current controller and a control voltage of the current controller.

Power supply apparatus, semiconductor integrated circuit, and ripple suppressing method

Disclosed is a semiconductor device for switching power supply control including: a power supply terminal; a current inflow terminal; a starting circuit; and a brownout detection circuit, wherein a control signal of a switching element is generated, the starting circuit includes: a first comparator; a starting control circuit which controls on and off of the switch; and an operation start circuit which detects that the voltage of the power supply terminal becomes equal to or more than a predetermined voltage, and generates a signal for operating an internal circuit, and the brownout detection circuit includes: a voltage divider; a second comparator which has a hysteresis characteristic for detecting generation of a brownout state; a timer circuit which measures a predetermined time during which the generation of the brownout state continues; and an output stop circuit which stops outputting of a switching control signal.

Semiconductor device for switching power supply control and AC-DC converter

Disclosed is a semiconductor device for switching power supply control including: a high voltage input starting terminal; a discharger; and an input state detection circuit that includes: a voltage divider; a peak hold circuit; a first comparator which detects generation of a plug removal state; a second comparator which detects generation of a brownout state; a timer circuit; and a control signal generation circuit which generates a signal to turn on the discharger or a signal to stop outputting of a switching control signal, Td, Tdand Tdare set to have a relationship of Td&#x3c;Td&#x3c;Td, Tdbeing a delay time until the capacitor is discharged, Tdbeing a delay time for determining the plug removal state, and Tdbeing a delay time for determining the brownout state, and at least the delay time Tdand the delay time Tdare measured by a common timer circuit.

A semiconductor device for a switching power supply includes first and second external terminals, ON and OFF timing generation circuits, and a drive pulse generation circuit. To the first and second external terminals, a feedback voltage and a voltage induced in an auxiliary winding are input, respectively. The ON and OFF timing generation circuits respectively generate timing signals turning on and off a switching element based on the voltages. The drive pulse generation circuit generates a pulse signal based on these signals. The ON timing generation circuit includes: a bottom detection circuit detecting a lowest point of the voltage of the second external terminal; and a timer circuit, and operates in a PWM mode and a quasi-resonant mode in response to a timing of an output of the timer circuit being before a timing of an output of the bottom detection circuit and the reverse case, respectively.

Semiconductor device for switching power supply and AC-DC convertor

A power controlling semiconductor device generates a drive pulse to turn on or off a switching device which applies an intermittent current to a primary side winding of a transformer in response to a voltage proportional to a present current flowing through the primary side winding of the transformer and to an output voltage detection signal from a secondary side of the transformer. The device includes a current detecting terminal and an overcurrent detecting circuit. The voltage proportional to the present current flowing through the primary side winding is applied to the current detecting terminal. The overcurrent detecting circuit compares a voltage corresponding to the voltage applied to the current detecting terminal with an upper limit current detecting voltage to detect an overcurrent. A correction current is applied to a correction resistor connected to the current detecting terminal for a shift in the voltage.

Power controlling semiconductor device, switched-mode power supply, and method of designing the device and power-supply

An insulated DC power supply includes a voltage transformer, a switching device and a primary-side regulating circuit. The voltage transformer includes primary and secondary windings and an auxiliary winding. The switching device causes current to flow intermittently through the primary winding. The primary-side regulating circuit receives a voltage proportional to a current flowing through the primary winding of the transformer, and a voltage proportional to a voltage induced in the auxiliary winding of the transformer to generate and output a drive pulse for turning on or off the switching device. The primary-side regulating circuit includes an ON/OFF signal generator circuit and first and second timer circuits. The switching device is turned off upon expiration of the first timer circuit, and the ON/OFF signal generator circuit does not generate a signal for turn-on of the switching device when the second timer circuit expires.

Insulated DC power supply and a method of controlling same

An insulated power supply device includes: an electric power conversion unit, a rectifier, a filter, a detection unit, a control circuit, and a signal transmission unit. The control circuit generates and outputs a control signal for a switching element that controls a current to be flown through a primary side of the electric power conversion unit. The signal transmission unit transmits, to the control circuit, a detection signal by the detection unit for detecting an output current or an output voltage. An output control pulse signal having control information in a duty ratio can be supplied as an outputted control signal individually to both of the control circuit and a secondary side of the electric power conversion unit. The output current or the output voltage can be thereby controlled.

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Isehara, Japan

Satoshi Arima