Patent application number | Description | Published |
20080309303 | SWITCHING POWER SUPPLY AND REGULATION CIRCUIT - The present invention provides a switching power supply that enables a reduction in noise without the need for an anti-noise component such as a filter circuit. A secondary current on period detecting circuit detects a first period during which a secondary current flows, the secondary current starting to flow through a secondary winding after a switching element is turned off. A secondary current on duty control circuit oscillates a clock signal set turning on the switching element so as to maintain, at a constant value, an on duty ratio of the first period to a third period made up of the first period and a second period during which the secondary current does not flow. A secondary current on duty modulating circuit applies a modulation component to the on duty ratio to periodically modulate the on duty ratio and thus the oscillation frequency of the switching element. | 12-18-2008 |
20090001954 | SWITCHING POWER SUPPLY - A switching power supply is provided which keeps constant, even when the oscillation frequency of a switching element increases, the on duty of secondary current passing through a secondary winding, thereby achieving a constant current drooping characteristic with high accuracy. To be specific, a secondary current on-period detection circuit generates a signal indicating the off timing of the secondary current, based on a flyback voltage generated on an auxiliary winding. A secondary-current detection delay time correction circuit generates a signal indicating a time when a predetermined period has elapsed since the switching element is turned off. A secondary current on-duty control circuit generates a clock signal for turning on the switching element so as to keep constant the on duty of the secondary current, based on the signal generated by the secondary current on-period detection circuit and the signal generated by the secondary-current detection delay time correction circuit. | 01-01-2009 |
20090201705 | ENERGY CONVERTING APPARATUS, AND SEMICONDUCTOR DEVICE AND SWITCHING CONTROL METHOD USED THEREIN - The present invention reliably reduces output power during an overload, due to overload protection in which an on-time of a switching element | 08-13-2009 |
20100008106 | SWITCHING CONTROL CIRCUIT, SEMICONDUCTOR DEVICE AND SWITCHING POWER SOURCE APPARATUS - At the starting time and an overload time in which the output voltage of the switching power source apparatus is low, if an overcurrent state, in which the ON period of the switching device becomes short and a current not less than the current limit value of the switching device flows through the switching device, occurs, this overcurrent state is detected. The blanking period of a blanking pulse signal is made shorter than the blanking period that is obtained during steady operation, and the ON period of the switching device is made shorter. Hence, the device current flowing through the switching device can be made small in each pulse for the switching operation, and, at the same time, the device current is suppressed from increasing each time a pulse for the switching operation is generated. | 01-14-2010 |
20100008109 | SWITCHING POWER SUPPLY AND SEMICONDUCTOR DEVICE FOR SWITCHING POWER SUPPLY - A switching power supply of the present invention includes: an oscillator circuit for oscillating a signal for turning on a switching element; an error signal generating circuit for generating an error signal having a signal level corresponding to a difference between the signal level of a feedback signal and a reference level; a switching control circuit for turning on the switching element at a time in response to the signal oscillated by the oscillator circuit and turning off the switching element at a time in response to the signal level of the error signal; and a reference level control circuit for controlling the reference level according to a time period during which the switching operation of the switching element is stopped. | 01-14-2010 |
20100124081 | SWITCHING POWER SUPPLY - According to the present invention, when a secondary current on period T | 05-20-2010 |
20100309690 | SWITCHING POWER SUPPLY APPARATUS AND SEMICONDUCTOR DEVICE - The switching power supply apparatus according to the present invention includes: a transformer including a primary winding, a secondary winding, and an auxiliary winding; a switching device connected to the primary winding; an output voltage generation circuit which is connected to the secondary winding and generates an output voltage; an auxiliary power voltage generation circuit which is connected to the auxiliary winding and generates an auxiliary power voltage; and a control circuit which operates using the auxiliary power voltage and controls a driver circuit so that an intermittent oscillation is performed when the output voltage is higher than a first output voltage and controls a peak of a current flowing through a switching device is lower than a peak in a normal mode, when the auxiliary power voltage is lower than a first auxiliary power voltage in the intermittent oscillation. | 12-09-2010 |
20110085356 | SWITCHING ELEMENT DRIVING CONTROL CIRCUIT AND SWITCHING POWER SUPPLY DEVICE - A switching element driving control circuit includes: a regulator circuit which generates a power supply voltage having an amplitude; a capacitor which smoothes the power supply voltage generated by the regulator circuit to remove a high frequency component; a circuit power supply line to which the smoothed power supply voltage is supplied; an oscillation circuit which generates a periodic signal according to an oscillation of the power supply voltage supplied from the circuit power supply line; a control circuit which generates a control signal for controlling the switching operation of the switching element, based on the periodic signal; and a driver circuit which supplies the switching element with the control signal. | 04-14-2011 |
20110090718 | SWITCHING POWER SUPPLY DEVICE - The present invention has as an object to introduce a switching power supply device having a simple circuit structure and controlling a secondary-side output voltage in a highly-accurate and stable manner. The switching power supply device includes: an auxiliary winding resetting detecting circuit which is connected to the auxiliary winding, monitors an auxiliary winding voltage pulse signal generated on the auxiliary winding, and generates an auxiliary winding reset signal indicating timing of which a secondary-side current finishes flowing into the secondary winding and the auxiliary winding voltage signal drops; and an auxiliary winding voltage sample hold circuit which holds the auxiliary winding voltage signal. The auxiliary winding voltage sample hold circuit includes a delaying circuit which delays the auxiliary winding voltage signal, and holds the auxiliary winding voltage pulse signal delayed by the delaying circuit with the timing indicated by the auxiliary winding reset signal. | 04-21-2011 |
20110194314 | SWITCHING POWER SUPPLY DEVICE - A switching power supply device including: a power transformer including a primary winding, a secondary winding, and an auxiliary winding; a switching element which is connected to the primary winding; an output voltage generation circuit which converts, into a direct-current voltage, a voltage induced in the secondary winding; a secondary-side on-time signal generation circuit which generates a secondary-side on-time signal indicating a secondary-side on-time; and a switching control circuit which controls a switching operation of the switching element so that the second direct-current voltage falls within a specified range, wherein the switching control circuit controls the switching operation so that the direct-current voltage becomes equal to or below an overvoltage specified value when the secondary-side on-time becomes smaller than a set value. | 08-11-2011 |
20110194316 | SWITCHING POWER SUPPLY DEVICE - A switching power supply device including: a switching element which performs a switching operation; an output voltage generation circuit; a transformer reset detection circuit which generates a transformer reset signal; a secondary-side on-time signal generation circuit; a feedback control circuit which generates a feedback signal; a switching element drive circuit which controls the switching operation of the switching element according to the feedback signal; and an output voltage correcting signal generation circuit which generates an output voltage correcting signal from the feedback signal and a secondary-side on-time signal, and supplies the output voltage correcting signal to the feedback control circuit. | 08-11-2011 |
20120044724 | SWITCHING POWER SUPPLY APPARATUS - A switching power supply apparatus that can precisely control the overload protection voltage is provided. The apparatus includes a secondary current on-period detection circuit for detecting the time between turn-off of the switching device and off-timing of the secondary current; and an output power limiting circuit for comparing the output signal of the secondary current on-period detection circuit with a signal indicating a predetermined maximum secondary current on-period, and for outputting an output power limiting signal for reducing or stopping power supply to a load to a switching signal control circuit when the former signal is higher than the latter signal, wherein the maximum secondary current on-period is arranged to correspond to the secondary current on-period when the device current flowing through the switching device reaches the maximum current defined by the switching signal control circuit, or the oscillation frequency of the device current reaches the maximum oscillation frequency defined by the oscillator, and the second DC voltage from the output voltage generation circuit is released from constant-voltage control and reduced. | 02-23-2012 |