JPH08149804A - Switching regulator power supply circuit - Google Patents

Abstract

PURPOSE: To provide a switching regulator power supply circuit for efficiently improving output load current over a wide range. CONSTITUTION: A power supply is provided with a first switching element for small current and a second switching element for large current and switches the first and second switching elements according to the output current value detected from a voltage at both terminals of a resistor 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching regulator type power supply circuit which stabilizes an output voltage by switching.

[0002]

2. Description of the Related Art Generally, a power supply circuit is designed in accordance with a large output load current value, and the efficiency tends to be poor when the output load current value is small. In addition, in recent years, it is known that a switching regulator type power supply circuit improves efficiency even when the output current is small by controlling the switching cycle according to the output load current value.

[0003]

However, in the above-mentioned conventional example, even when the output current load of the power supply circuit becomes small, the power required for one-time (one cycle) switching is generated when operating at the maximum output current load. There is a limit to the improvement in efficiency because it is the same as. This is because the same switching element is used for operation even if the output load current value changes, and there is no change in the power for driving the switching element.

The present invention has been made in view of this point, and an object thereof is to provide a switching regulator type power supply circuit capable of improving the efficiency over a wide range of the output load current.

[0005]

In order to achieve the above object, the present invention provides a plurality of switching means, a current detecting means for detecting an output load current value, and a plurality of the plurality of switching means according to the detected output load current value. The present invention provides a switching regulator type power supply circuit characterized in that switching means for switching the switching means is provided.

[0006]

The output negative overcurrent is detected, and the plurality of switching means are switched according to the detected output load current value.

[0007]

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

FIG. 1 is a step-down type D according to an embodiment of the present invention.
FIG. 3 is a circuit diagram showing a configuration of a C / DC converter.
The C / DC converter operates when the output load current is small (the rated output current is small) and operates when the output load current is large (the rated output current is smaller than that of the first switching element). (Large) second switching element 2, resistor 3 for detecting the output load current value, amplifier 4 for amplifying the voltage generated across resistor 3 and converting the output load current into voltage, and this power supply circuit The operation time of the switching elements 1 and 2 is determined on the basis of the output voltage value of the amplifier 4 and the voltage of the output terminal 7 for generating a reference signal which is a reference for the operation of the above, and these operations are controlled. The control circuit 6 is the main component.

An input terminal 8 to which DC power is supplied from a battery (not shown) is connected to the input sides of the switching elements 1 and 2, and a capacitor 9 is connected between the input terminal 8 and ground. There is. Switching element 1,
A diode 10 and a filter including a coil 11 and a capacitor 12 are connected to the output side of 2, the output side of the filter is connected to one end of the resistor 3, and the other end of the resistor 3 is connected to the output terminal 7. There is. Both ends of the resistor 3 are connected to the input of the amplifier 4, and the output terminal 7 and the output of the amplifier 4 are connected to the control circuit 6. A reference signal is supplied from the oscillation circuit 5 to the control circuit 6, and the output of the control circuit 6 is connected to the switching elements 1 and 2.

In the power supply circuit configured as described above, this circuit is activated and operates at the rated output load current (at this time, the switching elements 1 and 2 are both operating), and the detected output voltage The operation when the output load current flowing through the resistor 3 decreases from the state where the value and the output current value are stable will be described.

First, when the value of the current flowing through the resistor 3 decreases,
The voltage of the output terminal 7 rises. For this reason, the control circuit 6 reduces the time during which the switching elements 1 and 2 are on, and performs feedback control so that the output voltage (voltage of the output terminal 7) becomes an appropriate value. As a result, the output voltage is controlled to have a constant value even if the output current value decreases.

Here, when the output current value, that is, the value of the current flowing through the resistor 3 further decreases and becomes smaller than the first predetermined value, the control circuit 6 stops the operation of the second switching element 2. , So that only the first switching element 1 operates.

From this state, when the output current value increases, the control circuit 6 which monitors the voltage of the output terminal 7 detects the decrease in the voltage of the output terminal 7 and the first switching element 1 is turned on. The period during which the output voltage is increasing is controlled so that the output voltage becomes constant. At this time, when the output current value further increases and the output of the amplifier 4 indicating the current value flowing through the resistor 3 exceeds the second predetermined value, the control circuit 6 restarts the operation of the second switching element 2. Let

When the output current value decreases as described above, the power for driving the switching element can be reduced by operating only the first switching element 1 having a small rated output current, and the fluctuation of the output load. The conversion efficiency can be improved.

In the above embodiment, when the output current value is large (when operating at the rated output load current).
In the above, the first and second switching elements are operated together, but the present invention is not limited to this, and only the second switching element may be operated. Also,
The number of switching elements may be three or more and they may be switched.

Further, the above-mentioned embodiment is a step-down type D according to the present invention.
Although the present invention is applied to the C / DC converter, the present invention is not limited to this and can be applied to all switching regulators. However, it is particularly effective in a DC / DC converter driven by a battery and can be applied not only to the step-down type but also to the step-up type and the inverting type.

[0017]

As described above in detail, according to the present invention, an output negative overcurrent is detected, and the plurality of switching means are switched according to the detected output load current value, which is suitable for the output current value. Using switching elements
The conversion efficiency can be improved with respect to changes in the output current load.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a power supply circuit according to an embodiment of the present invention.

[Explanation of symbols]

 1 1st switching element (switching means) 2 2nd switching element (switching means) 3 resistance (current detection means) 4 amplifier (current detection means) 6 control circuit (switching means)

Claims (1)

[Claims] 1. A plurality of switching means, a current detection means for detecting an output load current value, and a switching means for switching the plurality of switching means in accordance with the detected output load current value. Switching regulator type power supply circuit.