Abstract: A switching power supply is provided in which the efficiency is improved and the regulation and cross-regulation of an output voltage is also improved. Terminals (A) and (B) of a primary winding N1 and secondary winding N2 at which the same polarity is set are interconnected via a first capacitor C4. A tap provided at a given winding position (C) of the primary winding N1 and the other terminal (D) of the secondary winding N2 are interconnected via a second capacitor. Herein, assuming that areas of the primary winding N1 divided by the tap are N.sub.11 and N.sub.12, the number of turns in the area N.sub.11 between the terminal (A) and winding position (C) is nearly the same with the number of turns existing between the one terminal (B) of the secondary winding N2 and the other terminal (C) thereof. Owing to the configuration, an equivalent coupling coefficient observed between the primary winding N1 and secondary winding N2 approaches 1.0.

Abstract: A power supply control device, by which a plurality of switching power supply circuits of different properties are operated under switching conditions respectively fitted therefor simultaneously with the prevention of an occurrence of what is called a low-frequency switching beat phenomenon, thereby achieving the miniaturization and the increasing of the efficiency of a power supply unit. To synchronize the timing of switching operations among control systems or units of the power supply control device, the control device of the multi-channel type or the control device having a master-slave function is used. Further, a frequency divider circuit or a frequency multiplier circuit is connected to a comparator of such a control device. Thereby, although synchronizing the timing among the switching operations, a plurality of pulse output signals of different frequencies are outputted from the control systems or the control units.

Abstract: A radio-frequency tuning circuit includes an input tuning transformer, and an output tuning transformer. The input tuning transformer comprises a primary coil adapted to serve as input coil, and a secondary coil to which a pair of variable-capacitance diodes having cathodes thereof connected together are connected in parallel therewith to form a first tuning circuit. The output tuning transformer comprises a primary coil to which a variable-capacitance element is connected to form a second tuning circuit, and a secondary coil adapted to serve as output coil. The input and output tuning transformers are connected in such a manner as to form a double-tuning circuit. Q-factor of the output tuning transformer is made to be twice as high as that of the input tuning transformer, and resonant impedance of the first tuning circuit and that of the second tuning circuit are made to be substantially equal to each other.

Abstract: A low-cost and highly reliable flyback isolation-type switching power supply comprises a main transformer and an auxiliary transformer. A secondary winding of the main transformer is connected in parallel with an input winding of the auxiliary transformer. A series network of a diode and a capacitor is connected between the terminals of an output winding of the auxiliary transformer, and a voltage corresponding to the output voltage of the power supply is obtained across the capacitor. The main transformer and the auxiliary transformer preferably share a core having a plurality of bobbin sections, with the windings of each transformer wound around respective different bobbin sections. The equivalent degree of coupling between the secondary winding and the output winding is thus sufficiently larger than the degree of coupling between the primary winding and the output winding.

Abstract: In an inverter transformer comprising a primary winding and secondary winding which are wound on a first and a second spool respectively and disposed in juxtaposing relationship.with each other with the axes of the first and second spools being substantially parallel to each other, and a pair of cores which are disposed in abutting relationship to each other so as to define a closed magnetic path, the primary and secondary windings being electromagnetically coupled to each other through the pair of cores, at least one of said cores being provided with a protuberance which is disposed in opposing relationship to the other core, with a small distance maintained therebetween, the protuberance being interposed between the primary winding and the secondary winding, the arrangement is made such that secondary-side minimum sectional area of that portion of the cores through which magnetic flux is permitted to pass, is given substantially by S.sub.1 K, where S.sub.

Abstract: A self-excited oscillation type power supply device comprises an auxiliary transistor Q4. When the device is started, a voltage signal providing forward biasis applied to the base of the auxiliary transistor; and when the device is operated, besides the forward bias, at least one of a voltage signal derived from alternate voltage which occurs at a choke coil L1 and a voltage signal corresponding to output voltage, is applied thereto. More specifically, the voltage signal providing forward bias is provided by a resistor R9 connected between the base of the auxiliary transistor Q4 and input terminal 1; the voltage signal derived from the alternate voltage is provided by a capacitor C4 connected between the base of the auxiliary transistor Q4 and one end of a choke coil L1; and the voltage signal corresponding to output voltage is provided by a constant-voltage diode DZ2 connected between the base of the auxiliary transistor Q4 and output terminal 2.

Abstract: A power factor improving circuit capable of obtaining a high power factor for a power supply circuit and at the same time of achieving a smaller size and lower cost of the power supply apparatus by a simple construction. To accomplish this object, a choke coil L1 is connected between the higher potential side output terminal of a rectifier 1 and the primary winding N1 of a transformer T of a converter circuit 2, and one end of a smoothing capacitor C1 is connected to a connecting point between the choke coil L1 and the primary winding N1 of the transformer T. The other end of the smoothing capacitor C1 is connected to the cathode of a first diode D1, to the anode of a second diode D2 and to the anode of a third diode D3.

Abstract: A switching power supply in which high efficiency is obtained by further reducing a loss occurring in a PNP type transistor as a rectifying element, particularly in case of making a switching frequency higher. Further, the switching power supply is a boost/buck converter in which an application range of an input voltage is broadened by causing a circuit not to perform intermittent operation when the voltage V.sub.IN is higher than an output voltage V.sub.o. One end of a choke coil L1 is connected to an input terminal 1 and another end thereof is connected to an emitter of a PNP type transistor Q2 as a rectifying element. A base of transistor Q2 is connected to a collector of a driving transistor Q3 via a resistor R4. The base of the driving transistor Q3 is connected to another end of the choke coil L1 via a series circuit of a capacitor C3 and a resistor R3.

Abstract: The present invention provides a self-oscillation type DC-DC converter that can perform self-oscillating operation without disposing a feedback winding in a choke coil and realizes the high efficiency, small size and low cost by using a MOSFET as a switching element. The self-oscillation type DC-DC converter comprises a switching transistor Q12 being a P-MOSFET; a first PNP type driving transistor Q2, the collector and emitter of which are connected to the gate and source of the switching transistor Q12, respectively and the base of which is connected to the switching transistor Q12 through a feedback circuit 3; and a second NPN type driving transistor Q3, the gate of the switching transistor Q12 being connected to the ground through the collector and emitter of the second driving transistor Q3 and the base of the second driving transistor Q3 being connected to the feedback circuit 3 through a capacitor C4.

Abstract: A pulse width modulated controller controls a zero-voltage switching resonant power converter or inverter. The on time of the power switch (110) of the converter or inverter is varied by an error amplifier (280) such that the output voltage of the converter or inverter maintains proportionality to a reference voltage (290). The off time is terminated by a switch-voltage detector (320) when the voltage across the power switch (110) drops below a threshold voltage (330) due to the natural resonance of the external resonating capacitor (120) and inductors (130 and 150). In the first two embodiments of the invention, a single timing capacitor (260) is employed both for determining the on time and the off time. In two other embodiments, two timing capacitors (262 and 264) are employed for separately determining the maximum allowed off time and the variable on time.

Abstract: A video receiver including an interface to which compressed and encoded video-audio data is supplied from a transmission line and stored in the receiver, a decoder for decoding the video-audio data retrieved from storage, a monitor for connecting to the decoder and a CPU for controlling data processing. A common buffer memory for temporarily storing the video-audio data is provided between the interface and the decoder and between the interface and the storage device and, while the video-audio data is being received, access to the buffer memory is subjected to time-shared, exclusive control by the CPU in synchronism with the clock frequency of the transmission line, whereby video data is read out of the buffer memory by the decoder in parallel with the storage of the video-audio data, and is thereby decoded so that a picture is viewed on the monitor.

Abstract: A MOSFET driven integrated circuit or other peripheral circuit interfaced to a controller that operates on the primary side of a DC to DC converter having a high input voltage relative to the supply voltage powering both the controller and the MOSFET driver or other peripheral circuit is controlled by an under-voltage lockout circuit to transition from a standby mode to a normal operating mode of the MOSFET driver or other peripheral circuit only when the supply voltage is sufficient to sustain normal operation and the driver or other peripheral circuit senses activity at an input that indicates that the controller has previously transitioned from a standby mode to a normal operating mode.

Abstract: In a video transmitter including a first data processing system wherein compressed and encoded video-audio data are read out of a first store under control of a CPU, and then decoded to be reproduced, there is provided a second data processing system for after-recording, data processing operation of which is controlled by a CPU. The second processing system comprises a audio data compressor, a first buffer memory, a second store, a second buffer memory, and a audio data decoder. Reproducing operations of the first and second data processing systems are performed in synchronism with each other. Thus, with a video transmitter equipped with a codec apparatus, it is possible to achieve after-recording.

Abstract: A switching power supply with a high power-conversion-efficiency is obtained by further reducing a loss occurring in a transistor rectifying element. A driving transistor Q3 is arranged between a base of a transistor Q2 as the rectifying element and the ground. A driving signal is inputted from a connection point of the transistor Q2 and a choke coil L1 generating a flyback voltage to the base of the driving transistor Q3, and an ON ad OFF operation of the transistor Q2 is caused to synchronize with an ON ad OFF operation of the switching transistor Q1, thereby preventing a leakage of the current in direction of the base from the collector of the transistor Q2 when it turns off, reducing the loss of the transistor rectifying element and then, improving the power conversion efficiency of the switching power supply.

Abstract: A synchronous rectifying circuit for a switching power supply is disclosed which is arranged such that the necessity to provide a diode element in parallel with a rectifying transistor is eliminated so that a highly efficient and stable operation can be achieved. "On" drive signal of a switching transistor (Q1) is detected by a first limiter circuit (6), and a flip-flop circuit (5) causes a rectifying transistor (Q2) to be turned off in response to output of the first limiter circuit (6); turning-off operation of the switching transistor (Q1) is detected by a second limiter circuit (7), and the flip-flop circuit (5) causes the rectifying transistor (Q2) to be turned on in response to output of the second limiter circuit (7). The necessity to provide a diode element in parallel with the rectifying transistor is eliminated. Stable operation can be performed even if the switching element has an indefinite operation delay time. An enhanced efficiency can be achieved.

Abstract: The present invention provides an AC-DC converter in which a voltage at a light load is kept from rising, and an application range of an AC input voltage can be made broader. In the AC-DC converter having a rectifier 3, a boost chopper 4 and a DC--DC converter, a PWM circuit 6, a frequency divider 7 and a peak value detector 8 are further arranged. A first pulse signal V.sub.pa which the PWM circuit 6 outputs is inputted to a first switching transistor Q1 in the DC--DC converter 5 and the frequency divider 7. The frequency divider 7 divides a frequency of the first pulse signal V.sub.pa according to a frequency dividing control signal which the peak value detector 8 outputs, for monitoring a rectified output voltage in the rectifier 3 and outputs a second pulse signal V.sub.pb generated by the frequency divider 7 to the second switching transistor Q2 in the boost chopper 4.

Abstract: An object of the present invention is to reduce a cost and a power consumption, eliminating a voltage source for generating a reference voltage in an isolated switching power source achieving a feedback from an output side of the power source to a control circuit in an input side of the power source through a photo-coupler. A voltage V.sub.1 obtained by dividing an output voltage V.sub.0 by a voltage dividing resistors 8, 9 is applied to a base of a transistor 11-1 for an error amplifier, and a photo-coupler light emitting element 10-1 is connected between an emitter of the transistor 11-1 and a negative side of an power source output. A forward dropping voltage of the photo-coupler light emitting element becomes approximately constant (approximately 1.1 v) over a variation range of a current flowing to the photo-coupler light emitting element at actually using time.

Abstract: An AC-DC converter is disclosed which is so designed as to realize an improved power factor and thereby minimize generation of voltage distortion and higher harmonies in power supply line, without making the circuit arrangement complex and bulky. A step-down DC-DC converter is connected to an output side rectifier, and the arrangement is made such that the output current of the rectifier is permitted to flow only during a time period when the output voltage of the rectifier is higher than the voltage at an output capacitor of the DC-DC converter.

Abstract: An AC-DC converter of a type having an improved power factor having an arrangement that enlargements of loads to be borne by circuit components due to AC input voltage is prevented so that the size and cost of the AC-DC converter are reduced. A constant-current circuit is, in parallel, connected to a voltage dividing point of charge voltage of an output capacitor to be connected to an input terminal of an error amplifier of a booster converter circuit and realized by a plurality of resistors so that control of a constant-current value of the constant-current circuit is performed with the rectified output from the rectifying circuit. As a result, the loads to be borne by the circuit components of the AC-DC converter can be made constant regardless of the supplied AC voltage level so that the size and cost of the AC-DC converter are reduced.

Abstract: A complete type integrator is disclosed which is designed such that the time-constant thereof can be controlled; wide input and output dynamic ranges can be achieved; operation with low power supply voltage is possible; and no offset voltage is generated. More specifically, the integrator comprises an amplifier circuit having a combination of a first and a second differential amplifier circuit (A1, A2) and connected to the input side of an integrator circuit; and an offset eliminating circuit connected to that portion of the amplifier circuit where the input signal (9) is applied. The offset eliminating circuit comprises a combination of a first, a second and a third current-mirror circuit (B1, B2, B3).