JPH02261016A - Switching power source device - Google Patents

Abstract

PURPOSE:To simplify a circuit construction by providing a power supply circuit for a driving IC connected to a snubber circuit and by using it as a control power source to the IC of a switching element base circuit. CONSTITUTION:A snubber circuit is composed of a resistance R1, a capacitor C1 and a diode D1 and connected in parallel between the source and drain of a switching element Q. A series circuit of a diode D2, a resistance R2 and a capacitor C2 is connected to the capacitor C1 of the snubber circuit and to the capacitor C2 a constant voltage diode ZD is connected in series and this constant voltage diode ZD is connected to a switching element driving IC. The circuit of the diode D2, resistance R2, capacitor C2, constant voltage diode ZD connected to the capacitor C1 in parallel constitutes a power supply circuit to use the energy charged up to the capacitor C1 as a control power source of an IC for a switching element base circuit.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a switching power supply device.

[Prior Art] In conventional switching power supplies, a separate winding is provided on the transformer to ensure control power for the switching element drive IC connected to the primary winding of the transformer.
The circuit was configured to provide power for the drive.

In addition, a snubber circuit (Q, R1, C
1, DI) to reduce the switching loss of the switching element by blunting the rise of the voltage at 08 o'clock in the switching element.

[Problems to be Solved by the Invention] In the conventional device as described above, a separate winding must be installed in the transformer in order to secure the control power for the IC, which makes the winding configuration of the transformer complicated. There was a point.

Furthermore, even if an attempt is made to reduce the switching loss, the energy charged up in the capacitor C1 of the snubber circuit at the time of 08 of the switching element flows through the resistor R1 to the switching element.
There was a problem in that the switching loss during operation increased.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a switching power supply device with a simplified circuit configuration and reduced switching loss.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the switching power supply device of the present invention provides a switching power supply device for a drive connected to a base circuit of a switching element Q connected to a primary winding of a transformer T. IC
A switching power supply device is constituted by a snubber circuit connected in parallel to the switching element Q, and a power supply circuit for a drive IC connected in parallel to the capacitor C1 of the snubber circuit.

[Operation] The snubber circuit parallel to the switching element Q reduces switching loss by blunting the rise of the voltage at 08 o'clock in the switching element.

Further, the power supply circuit for the drive IC connected in parallel to the capacitor C1 of the snubber circuit uses the energy charged up in the capacitor C1 of the snubber circuit at 08:00 of the switching element as a power supply for controlling the IC drive. do.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

T is the transformer, N1 is the primary winding, N2 is the secondary winding, RO
lCO is a resistor and capacitor connected in parallel to the primary winding N1, Q is a switching element connected to the primary winding N1, and a switching transistor such as an FET is used, and an IC for driving the switching element is connected to its base circuit. Ru.

A resistor R1, a capacitor C1, and a diode D1 are a snubber circuit connected in parallel between the source and train of a switching element Q such as an FET.

A series circuit of a diode D2, a resistor R2, and a capacitor C2 is connected in parallel to the capacitor C1 of the snubber circuit, and a constant voltage diode ZD is connected in parallel to the capacitor C2, and this constant voltage diode ID drives the switching element. Connect to the IC for use. A circuit including a diode D2, a resistor R2, a capacitor C2, and a constant voltage diode ID connected in parallel to the capacitor C1 of the snubber circuit within a dotted line frame transfers the energy charged up to the capacitor C1 of the snubber circuit to the switching element. A power supply circuit is configured to be used as a control power source for the base circuit IC.

In the above circuit, the switching loss is reduced by blunting the rise of the voltage of the switching element at 08 o'clock with the snubber circuit.

Further, the energy charged up in the capacitor C1 of the snubber circuit at 8 o'clock of the switching element is supplied by the power supply circuit within the dotted line frame as a power source for controlling the drive IC of the switching element base circuit.

By using the IC control power supply simplified as described above, it is possible to configure a switching power supply device with reduced switching loss.

[Effects of the Invention] As described above, the present invention includes a drive IC in a snubber circuit that is parallel to a switching element connected to a transformer primary winding.
A power supply circuit is connected and used as a power supply for controlling the IC of the switching element-based circuit, which simplifies the circuit configuration of the power supply for controlling the drive IC, and also It is possible to reduce loss.

[Brief explanation of drawings]

The figure is a circuit diagram of one embodiment of the present invention. T Nidor Lance N1: Primary winding Q Niswitching element C1, R1, Dl: Snubber circuit

Claims (1)

[Claims] A control IC connected to a base circuit of a switching element on the transformer primary winding side, a snubber circuit connected in parallel to the switching element, and an IC power supply circuit connected in parallel to a capacitor of the snubber circuit. A switching power supply device characterized by: