JPH11285242A - Switching regulator equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of an apparatus by reducing switching losses and preventing heat generation of a power source and temperature rise of the apparatus in which the power source is built. SOLUTION: This switching regulator equipment is provided with a switching control IC IC1 and a switching element Q1 which are controlled by the switching control IC, connects a diode D1 and a choke coil L1 with the switching element, and outputs a voltage V1 to a load 1 after smoothing with a capacitor C1 via the choke coil. A transistor TR1 which turns ON and OFF when the switching element turns OFF and ON, respectively, a diode D2 which holds the transistor in the states of ON and OFF when the switching element turns OFF and ON, respectively, and a capacitor C2 for rapidly discharging the charges of a capacitor existing equivalently in the switching element by turning the transistor ON by increasing the potential by the effect of charges stored, when the switching element is in the state of ON are installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching regulator device, and more particularly to a switching regulator device capable of preventing heat generation of a power supply and a temperature rise of a device incorporating the same by reducing switching loss and improving reliability of the device. It relates to a possible switching regulator device.

[0002]

2. Description of the Related Art Conventionally, a DC-DC converter shown in FIG. 3 has been proposed as this type of switching regulator device. The DC-DC converter shown in FIG.
Switching control ICIC51 and switching control IC
A switching element Q51 whose ON / OFF control is performed by the IC51;
A resistor R51 connected between C51 and the base of the switching element Q51, a resistor R52 connected between the base and the emitter of the switching element Q51, and a switching speed of the switching element Q51, which is connected between both ends of the resistor R51. A capacitor C52, a capacitor C51 for smoothing a current (collector current) via a choke coil L51 described later, and one end connected to the collector of the switching element Q51, and the other end connected to a reference potential point (GND) via the capacitor C51. The connected choke coil L51 and the switching element Q51
Only in the case of the FF, the energy (current) accumulated as a magnetic flux in the coil L51 is released, and the anode is connected to the reference potential point (GN).
D), a diode D51 whose cathode is connected to the collector of the switching element Q51, and a capacitor C51.
And a load 51 connected between both ends of the load.

In the DC-DC converter as a switching regulator device configured as described above, the switching control ICIC51 turns ON / OFF the switching element Q51 according to the potential difference between input and output (input voltage VIN ', output voltage V51). The constant voltage control of the output voltage V51 is performed by changing the OFF ratio. Here, as shown in the explanatory diagram of the switching loss in FIG. 4, when the switching element Q51 is turned on under the control of the switching control ICIC51, the collector current Ic ′ due to the input voltage VIN ′ is changed by the emitter of the switching element Q51, Collector and choke coil L
The capacitor C51 is charged via the capacitor 51 to supply power to the load 51, and energy corresponding to the input / output voltage difference is accumulated as magnetic flux in the choke coil L51.

When the switching element Q51 is turned off, the energy (current) stored as a magnetic flux in the choke coil L51 is released, and the energy (current) is charged to the capacitor C51 through a path of the capacitor C51 and the diode D51. The power is continuously supplied to the load 51. Further, the capacitor C52 is connected to the switching element Q
At the moment when 51 is turned on, the base current IB 'shown in FIG. 4 is bypassed, and the resistor R52 is connected to the switching element Q51 shown in FIG.
The charge accumulated in the capacitor Cs' equivalently present between the collector and the emitter of the
At the moment of F, it was discharging.

[0005]

However, since the DC-DC converter as a conventional switching regulator device is configured as described above, the transient state at the moment when the switching element Q51 turns from ON to OFF and from OFF to ON. In FIG. 4, as shown in FIG. 4, the switching element Q51 has a collector current Ic 'caused by the input voltage VIN'.
Flows, and a voltage VCE 'is applied between the collector and the emitter, so that a switching loss (Pc') occurs and is released as heat. This switching loss occurs in each switching cycle and increases as the switching frequency increases. Therefore, in order to reduce the switching loss and suppress heat generation, the turn-off time tf ′ from ON to OFF, and OFF to ON In this case, the turn-on time tr 'until the operation must be shortened.

Further, in order to solve the above-mentioned difficulties and to shorten the turn-off time tf ', a capacitor C equivalently present between the emitter and the collector of the switching element Q51 is required.
It is necessary to quickly discharge the electric charge accumulated in s ', and in order to shorten the turn-on time tr', the base current I
B 'had to be increased. Further, the capacitor C52
Has the effect of increasing the base current IB 'at the moment of turn-on, and the resistor R52 has the role of discharging the charge of the capacitor Cs'. To enhance the discharging effect of the capacitor Cs', the resistance of the resistor R52 must be increased. Must be made sufficiently small, but if it is set too small, the switching element Q51
Becomes short, and at the same time, the switching operation range with respect to the fluctuation of the input voltage VIN 'becomes narrow. Therefore, the resistance value of the resistor R52 cannot be set so small. There is a disadvantage that the switching loss of the switching element Q51 cannot be effectively reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned difficulties. By effectively reducing the switching loss, it is possible to prevent the heat generation of the power supply and the temperature rise of the equipment incorporating the power supply, and to improve the reliability of the equipment. It is an object of the present invention to provide a switching regulator device capable of improving performance.

[0008]

In order to achieve the above object, a switching regulator device according to the present invention comprises:
A switching regulator device comprising a switching control IC and a switching element controlled by the switching control IC, connecting a diode and a choke coil to the switching element, smoothing with a capacitor via the choke coil, and outputting an output voltage to a load. When the switching element is ON and OFF,
N transistor, switching element is ON, OF
A diode for holding the transistor in the OFF or ON state at the time of F, and a capacitor for rapidly discharging the charge of the capacitor equivalent to the switching element by raising the potential by the electric charge stored when the switching element is ON to turn on the transistor; Are provided.

According to such a switching regulator device, by effectively reducing the switching loss, it is possible to prevent the heat generation of the power supply and the temperature rise of the device incorporating the power supply.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a switching regulator device according to the present invention will be described below as an embodiment with reference to the drawings. A DC-DC converter as a switching regulator device shown in FIG. 1 includes a switching control ICIC1, a switching element Q1 that is ON / OFF controlled by the switching control ICIC1,
A switching loss reducing circuit a for reducing the switching loss of the switching element Q1, a base current is limited, and a resistor R1 connected between the switching control ICIC1 and the base of the switching element Q1 and a current (hereinafter referred to as a choke coil L1) through a choke coil L1. A capacitor C1 for smoothing the collector current) and one end connected to the collector of the switching element Q1, and the other end connected to the reference potential point (GND) via the capacitor C1.
The energy (current) accumulated as a magnetic flux in the coil L1 is released only when the switching element Q1 is OFF, and the anode is connected to the reference potential point (GND) and the cathode is connected to the switching element Q1. It comprises a diode D1 connected to the collector and a load 1 connected between both ends of the capacitor C1.

The switching loss reduction circuit a is OFF and ON when the switching element Q1 is ON and OFF, respectively.
Transistor TR1 and the switching element Q1
N, a diode D2 for holding the transistor TR1 in the OFF / ON state when the transistor TR1 is OFF;
Is turned on, and a capacitor Cs equivalently present in the switching element Q1 shown in FIG.
And a resistor R2 for minimizing the heat generation of the switching element Q1 when the switching reduction circuit a does not operate normally, for example, when the diode D2 is damaged in the short mode. ,
R3 for limiting the base current to the transistor TR1. The ON period of the transistor TR1 is determined by the time constant of the capacitor C2 and the resistor R3, and is set to a constant so that the transistor TR1 is turned on until the electric charge of the equivalent capacitor CS is sufficiently discharged.

The (+) terminal of the input voltage VIN whose (-) terminal is connected to the reference potential point (GND) is connected between the collector of the transistor TR1 of the switching reduction circuit a and the other end between the base and the emitter of the transistor TR1. One end of the resistor R2 connected to the anode of the connected diode D2 and the emitter of the switching element Q1 are connected. The switching control ICIC1 is connected to the base of the transistor TR1 via a resistor R3, and a capacitor C2 is connected to both ends of the resistor R3.

The operation of the switching loss of the switching element Q1 in the DC-DC converter as the switching diode device thus configured will be described below with reference to the explanatory diagram of FIG. The switching control ICIC1 turns ON / O the switching element Q1 according to the potential difference between the input and output (input voltage VIN, output voltage V1).
The constant voltage control of the output voltage V1 is performed by changing the FF ratio,
In the transient state at the moment when the switching element Q1 turns from ON to OFF and from OFF to ON, the collector loss Ic due to the input voltage VIN shown in FIG. 4 flows, and the collector-emitter voltage VCE is applied. Occurs and is released as heat. Since this switching loss occurs in each switching cycle, it becomes larger as the switching frequency becomes higher. Therefore, in order to reduce the switching loss and suppress heat generation, the turn-off time tf from ON to OFF, and from OFF to ON. And the turn-on time tr before the operation must be shortened.

Therefore, at the moment when the switching element Q1 turns from OFF to ON, the base current IB due to the input voltage VIN is bypassed through the diode D2 and the capacitor C2 of the switching loss reduction circuit a, so that the base current IB transiently changes. As a result, the turn-on time tr can be shortened, and the switching loss can be reduced. At this time, if electric charge is sufficiently accumulated in the capacitor C2, no current flows through the capacitor C2. Therefore, the supply of the base current IB is limited by the resistor R1, so that unnecessary base current IB is suppressed. It is also possible.

Further, at the moment when the switching element Q1 turns from ON to OFF, the base potential of the transistor TR1 of the switching loss reduction circuit a is raised by the electric charge accumulated in the capacitor C2, and the transistor TR1 is turned on. Switching element Q1 base
Since the emitter is short-circuited and the charge of the capacitor Cs equivalently present between the emitter and the collector is rapidly discharged, the turn-off time tf can be shortened, and the switching loss can be reduced. Therefore, the collector current Ic sent through the emitter-collector of the switching element Q1 shown in FIG. 4 is smoothed and charged by the capacitor C1 via the choke coil L1, and the switching loss is reduced in the load 1 and the power ( Since the output voltage V1) is supplied, a rise in temperature due to heat generation can be prevented.

In the above embodiment, the emitter of the transistor TR1 is connected to the anode of the diode D2 constituting the switching loss reducing circuit a. However, as shown in FIG. 2, the anode of the diode D2 is connected to the collector of the transistor TR1. The switching loss can be reduced by using the switching loss reducing circuit b having the above-described configuration, and the same effect as in the above-described embodiment can be obtained.

[0017]

As is apparent from the above description, according to the switching regulator device of the present invention, the switching loss generated when the switching element controlled by the switching control IC turns on and off is more efficiently reduced. It is possible to reduce the heat generation of the power supply and the temperature rise of the equipment incorporating it,
The reliability of the device is improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a DC-DC converter as one embodiment of a switching regulator device according to the present invention.

FIG. 2 is a circuit diagram showing a configuration as another embodiment of the switching loss reduction circuit shown in FIG. 1;

FIG. 3 is a circuit diagram showing a configuration of a DC-DC converter as a conventional switching regulator device.

FIG. 4 is an explanatory diagram of switching loss of the DC-DC converter shown in FIGS. 1 and 3;

[Explanation of symbols]

 IC1 ... Switching control IC Q1 ... Switching element D1, D2 ... Diode L1 ... Choke coil C1, C2 ... Capacitor Cs ... Switching Capacitor in element TR1 ... Transistor V1 ... Output voltage 1 ... Load

Claims (1)

[Claims] 1. A switching control IC (IC1), comprising: a switching element (Q1) controlled by the switching control IC; a diode (D1) and a choke coil (L1) connected to the switching element; Smoothing with a capacitor (C1) through a coil,
A switching regulator device for outputting an output voltage (V1) to a load (1), wherein each of said switching elements is turned on and off when said switching element is turned on and off.
F, a transistor (TR1) to be turned on, and the transistor is turned off when the switching element is turned on and off.
F, a diode (D2) that is held in an ON state, and a charge that is stored when the switching element is turned on raises a potential to turn on the transistor, thereby rapidly discharging a charge of a capacitor (Cs) equivalently present in the switching element. A switching regulator device comprising a capacitor (C2) for discharging.