Toko, Inc.

Toko Kabushiki Kaisha

Tetsushi Otake

Noriyuki Yoshizawa

Disclosed is a switching constant-current power supply system, comprising a feedback circuitprovided between a detector circuitfor generating a first feedback signal in proportion to a current flowing in a load, and a control circuitfor driving a first power converter circuitwhich is provided on the input side of a second power converter circuitto stabilize the load current. The feedback circuitincludes a signal hold sectionfor generating a second feedback signal. The feedback circuitis operable to supply the first feedback signal to the control circuitin a current supply period, and to supply the second feedback signal to the control circuitin a current cutoff period. The second feedback signal has a signal value approximately equal to that of the first feedback signal appearing in the current supply period. The switching constant-current power supply system can stabilize the load current even under the condition that the load is repeatedly turned on/off.

Switching constant-current power supply system

A boost-type switching power device which obtains a dc output by connecting a rectifying diode to the output side of an inductance element, connected in series to a main switching element, the device including: a control circuit which controls the operation of the main switching element by using a feedback signal in accordance with the dc output; and a constant-current circuit comprising a plurality of active elements, which are provided between the the rectifying diode and the output terminal; and wherein, when there is an overload on the output side, the operation of the active elements comprising the constant-current circuit controls the control circuit, switching the main switching element off and thereby stopping the boost function, and, in addition, the output is controlled by the constant-current circuit.

Boost-type switching power device

A switching constant-current power device can stabilize current flowing to a load (e.g. a display device comprising an LED, or the like) even when the current is repeatedly interrupted. A voltage current detector is connected to the output side of a power converter and creates a voltage signal in accordance with the output voltage thereof; and a feedback circuit is provided between a controller for driving the power converter and a current detector, which generates a first feedback signal in accordance with the load current. The feedback circuit comprises a signal holding unit, which outputs a second feedback signal that was created by consulting the voltage signal at a given time, the feedback circuit supplying the first feedback signal, output by the current detector, to the controller when load current is flowing, and supplying the second feedback signal, output by the signal holding unit, to the controller when load current is not flowing.

Switching constant-current power device

Disclosed herein is a switching constant-current power supply which comprises: a switching-system power converter for supplying a predetermined current to a load; a current detector for generating a feedback signal in correspondence with the load current; a controller for driving the power converter in correspondence with the feedback signal; and a feedback circuit, which is provided between the current detector and the controller, and comprises a signal holding unit, the feedback circuit supplying either a first feedback signal, output from the current detector, or a second feedback signal, output from the signal holding unit, to the controller; the size of the second feedback signal being approximately equal to the first feedback signal at a given time.

Switching constant-current power supply

A switching power supply circuit arranged such that stability of each output voltage is enhanced and the device is kept from being large-sized. Secondary winding N2 of transformer T1 is grounded at one end through diode D1: the other end of the secondary winding N2 is connected to first output terminal 2; and tap CT thereof is coupled to second output terminal 3 through diode D2; and capacitors C2 and C3 are connected between the first output terminal 2 and ground and between the second output terminal and ground respectively. In addition to being arranged as above, the present switching power supply circuit is further arranged such that first output voltage V.sub.01L is obtained from feedback voltage generated at the whole of the secondary winding N2, while second output voltage V.sub.02H is obtained from combination of induced voltage generated at winding section n21 defined through division by the tap CT of the secondary winding N2 and the first output voltage V.sub.01L.

Switching power supply circuit

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.

Self-oscillation type DC-DC converter having a driving transistor

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.

Switching power supply

A switching power supply circuit comprising a main switching element, and a second switching element which is on-off driven by the output of the main switching element. The design is made such that when the main switching element is turned on, the second switching element is turned off, while when the main switching element is turned off, the second switching element is turned on, and unwanted charges stored at the main switching element can be discharged through the second switching element when the main switching element is turned off.

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Tsurugashima, Japan

Tetsushi Otake