JPH06189527A - Dc-dc converter - Google Patents

Abstract

PURPOSE:To provide a DC-DC converter that almost completely save power in standby condition. CONSTITUTION:In a DC-DC converter, which generates the output voltage VL by switching a transistor Q3, according to the timing control signal T from the controller 2 under power source voltage Vcc on input side, for the transistors Q1 and Q2, which receive the timing control signals T with its base, the emitters receive the supply voltage Vcc in an input circuit which receives the base current of the transistor Q3, according to the timing control signal T. Hereby, the consumption of a battery in standby condition can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter, and more particularly to a DC-D of low power consumption suitable for battery-driven equipment such as portable headphone stereos.
Regarding the C converter.

[0002]

2. Description of the Related Art FIG. 2 shows a circuit configuration of a conventional DC-DC converter. Where 1 is a 1.8V battery,
Reference numeral 2 is a controller for generating a timing control signal T indicating switching timing, 3 is a transformer for generating a voltage on the output side, and Q3 is a transistor for switching a line of the input side power supply voltage Vcc through the transformer 3.

At the time of voltage conversion, the timing control signal T alternately takes the values of "L" and "H". When the timing control signal T is "L", the base current is supplied to the transistor Q3 via the transistor Q1 of the input stage circuit which is turned on in response to this. As a result, the transistor Q3 is turned on and a current flows through the transformer 3. On the other hand, when the timing control signal T becomes "H", in response to this, the transistor Q1 turns off and the transistor Q2 turns on in the input stage circuit. As a result, the base accumulated charge of the transistor Q3 is rapidly released, and the transistor Q3 is quickly turned off.
Therefore, the current passing through the transformer 3 is cut off at its destination, boosted, rectified by the transistor Q4, and supplied to the smoothing capacitor C and the load RL. By repeating such a switching operation at high speed, for example, the audio circuit power supply voltage VL of 3.3V is generated from the battery voltage Vcc of 1.8V and is supplied to the load RL.

[0004]

As described above, the conventional DC is used.
In the DC converter, in order to turn on and off the transistor Q3 that interrupts a large current at high speed, in addition to the transistor Q1 that supplies the base current of the transistor Q3 to the input stage circuit, the transistor Q2 that releases the base accumulated charge of the transistor Q3. Also equipped with. By the way, there are cases where an audio device or the like does not require sound output such as a mute state, and in such a state, the output side power supply voltage is unnecessary. Therefore, in order to prevent the battery power consumption due to the switching of the transistor Q3, the timing control signal T is fixed to a constant value, so that the transistor Q3 is maintained in the off state and put in the standby state.

However, in the standby state, as described above, the transistor Q2 for discharging the base accumulated charge of the transistor Q3.
Is on. Therefore, the base current of the transistor Q2 supplied from the line of the timing control signal T flows to the emitter side. This base current is the battery voltage V
Supplied from controller 2 operating under cc. Therefore, even in the standby state where the converter does not operate,
This DC-DC converter consumes the electric power of the battery 1, which is a problem. This current is 2-3
Although it is on the order of mA, the current demand for low power consumption is becoming more severe, and this value cannot be ignored. An object of the present invention is to solve the above-mentioned problems of the conventional technique, and to realize a DC-DC converter having a configuration that consumes almost no power in a standby state.

[0006]

The first structure of the DC-DC converter of the present invention which achieves the above object receives a timing control signal generated by a controller operating under an input side power supply voltage and receives the timing control signal. In a DC-DC converter that generates an output side power supply voltage by switching a supply line of an input side power supply voltage according to a control signal, a first bipolar transistor that performs the switching according to a received base current, and the timing. And an input stage circuit that controls the base current according to a control signal, the input stage circuit having a second bipolar transistor that receives the timing control signal at its base, and the second bipolar transistor, All of the emitters are supplied with the input side power supply voltage.

The DC of the present invention which achieves such an object
In the second configuration of the DC converter, in addition to the first configuration, the input stage circuit has a third bipolar transistor that does not receive the timing control signal at its base, and the third bipolar transistor is It operates by receiving the supply of the output side power supply voltage or by receiving the supply of the input side power supply voltage via the second transistor.

The DC of the present invention which achieves such an object
-The third configuration of the DC converter is the first configuration or the second configuration.
In addition to the above configuration, the line of the timing control signal is pulled up to the input side power supply voltage via a resistor.

[0009]

The DC-DC of the present invention having such a first structure
In the converter, when the value of the timing control signal is held at "H" and the DC-DC converter is in the standby state, the emitters of all the second bipolar transistors receive the input side power supply voltage, that is, the value "H". . Since the voltages of the base and the emitter are the same, all the second bipolar transistors receiving the timing control signal at the base are turned off. Therefore, the base current that has received the timing control signal does not flow in these transistors.
Therefore, when in the standby state, D
It is possible to prevent the battery power from being consumed by the current flowing through the C-DC converter.

The DC-of the present invention having such a second configuration
The DC converter has, in the input stage circuit, a third bipolar transistor which does not directly receive the timing control signal, in addition to the second bipolar transistor which directly receives the timing control signal. Therefore, it is easy to configure a circuit responsible for logic conversion and the like. Moreover, the third bipolar transistor operates by being supplied with the output side power supply voltage or by being supplied with the input side power supply voltage via the second bipolar transistor. Therefore, in the standby state in which the second bipolar transistor is off, the input side power supply, that is, the battery power is not consumed by the third bipolar transistor.

The DC-of the present invention having such a third structure
In the DC converter, the line of the timing control signal is pulled up. Therefore, not only when the value of the timing control signal is held at “H” when the DC-DC converter is in the standby state but also when the line of the timing control signal is held at the high impedance state, The line is brought to the "H" state. Therefore, the DC-DC converter of the present invention having the third configuration can also be applied to a controller that outputs a tri-state timing control signal.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit configuration using an embodiment of the DC-DC converter of the present invention. Here, 1 is a 1.8V battery, 2 is a controller that generates a timing control signal T that indicates the timing of switching, 3 is an external transformer that generates a voltage VL on the output side, and Q3 is a primary side of the transformer 3. A transistor capable of driving a large current for switching the line of the supplied power voltage Vcc on the input side, a transistor Q4 for rectifying the current on the output side, a smoothing capacitor C, and a load RL for a microcomputer, a servo amplifier, a laser amplifier and the like.

In addition, the timing control signal T generated by the controller 2 which operates under the voltage Vcc of the battery 1 is received, and the transistor Q3 is operated in accordance with the timing control signal T.
The input stage circuit for controlling the base current of the transistors is a transistor Q1, Q2, Q21, Q22 described later and resistors R1, R2, R3, R21, R22, R23, R2 connected thereto.
4, R25, R30. The main part of the DC-DC converter is integrated as a DC-DC converter IC 40 except for some components such as the transformer 3. The transistor Q3 corresponds to the first transistor, the transistors Q1 and Q22 correspond to the second transistor, the transistors Q2 and Q21 correspond to the third transistor, and the resistor R30 is a pull-up resistor.

Transistor Q1 is for supplying its base current to transistor Q3. this is,
The base receives the timing control signal T via the resistors R23 and R1, the emitter receives the voltage Vcc of the battery 1,
The collector is connected to the base of the transistor Q3. When the timing control signal T is "L", the transistor Q is turned on, and the collector current via the resistor R3 is sent to the base of the transistor Q3, so that the transistor Q3 is turned on.
Turn on 3. On the other hand, the timing control signal T is "H"
At the time of, it is turned off and the base current of the transistor Q3 is cut off. As a result, the transistor Q3 is not turned on, and neither the base current from the line of the timing control signal T nor the emitter current from the line of the voltage Vcc of the battery 1 flows.

Transistor Q2 uses transistor Q3 in order to rapidly discharge the base accumulated charge of transistor Q3.
It is inserted and connected between the base and the ground GND. However, the base of the transistor Q2 is the timing control signal T
Are not directly received by the transistors Q22, Q21
Is indirectly controlled by the timing control signal T. That is, the transistor Q22 has the resistors R23 and R
The base receives the timing control signal T via the emitter 22, the emitter receives the voltage Vcc of the battery 1, and the collector is connected to the base of the transistor Q21. further,
The transistor Q21 has a collector connected to the base of the transistor Q2 and an emitter grounded. Also,
The base of the transistor Q2 is also connected to the connection point of the resistors R25 and R24 that divide the output power supply voltage VL.

As a result, when the timing control signal T is "L", the transistor Q22 turns on, the transistor Q21 also turns on, and in response to this, the transistor Q2 turns off. Therefore, the supply of the base current from the transistor Q1 to the transistor Q3 is not hindered. On the other hand, when the timing control signal T becomes "H", the transistor Q22 turns off, the transistor Q21 also turns off, and in response thereto, the transistor Q2 turns on. Therefore, as described above, the base accumulated charge of the transistor Q3 whose supply of the base current from the transistor Q1 is cut off is rapidly released to the ground GND.

That is, the transistor Q22 preceding the transistor Q2 receives the timing control signal T in place of the transistor Q2, and the transistor Q2
1 is for converting the on / off logic state of the transistor Q22 to match with the transistor Q2. By doing so, when the timing control signal T is "H", the transistor Q3 is turned off. At that time, not only the transistor Q22 but also the transistors Q21 and Q2, and the current from the line of the timing control signal T is supplied to the battery. No current flows from the line with the voltage Vcc of 1.

Under such a structure, the DC-
In the DC converter, the transistor Q3 repeats ON / OFF switching during voltage conversion in which the timing control signal T alternately takes the values of "L" and "H". Moreover,
Since the transistor Q3 rapidly releases the base accumulated charge and turns off quickly, the transistor Q3 can normally perform a high-speed switching operation at about 100 kHz in accordance with the timing control signal T. Therefore, the current through the transformer 3 is boosted and rectified by the transistor Q4 and supplied to the smoothing capacitor C and the load RL each time the power supply is cut off. By repeating such a switching operation at high speed, for example, from the battery voltage Vcc of 1.8V to 3.3.
The V audio circuit power supply voltage VL is generated and supplied to the load.

Further, when the DC-DC converter is placed in the standby state, the timing control signal T is applied to the controller 2
Is held in the "H" state. In such a state, as described above, the transistors Q1 and Q22 are cut off and neither the current from the line of the timing control signal T nor the current from the line of the voltage Vcc of the battery 1 flows toward the DC-DC converter. Therefore, DC-D
When the C converter is in the standby state, the electric power of the battery 1 is not consumed by the DC-DC converter. Since the line of the timing control signal T is pulled up by the resistor 30, the controller 2 puts this line in a high impedance state, and DC-D
Even if the C converter is placed in the standby state, the same effect is maintained.

It should be noted that the output side power supply voltage VL is "0" V immediately after the power is turned on after the standby state continues for a long time, and it seems that the supply source of the base voltage of the transistor Q2 is seemingly absent. However, when transitioning from this state to the operating state, the timing control signal T first changes from "H" to "L". As a result, the first supply to the output side is completed, and the output side power supply voltage VL rises to some extent at the timing when the transistor Q2 should be turned on. Therefore, the transistor that operates by receiving the output power supply voltage VL can also operate normally.

[0021]

As can be understood from the above description, the first
According to the invention, the output side power supply voltage is generated by receiving the timing control signal generated by the controller that operates under the input side power supply voltage and switching the receiving line of the input side power supply voltage according to the timing control signal. The DC-DC converter includes a first bipolar transistor that performs the switching according to the received base current, and an input stage circuit that controls the base current according to the timing control signal. All of the second bipolar transistors in the input stage circuit receiving at the base thereof are supplied with the input side power supply voltage at their emitters. Accordingly, it is possible to almost completely prevent the battery power from being consumed by the current flowing through the DC-DC converter via the controller in the standby state.

In the second invention, the DC of the first invention is used.
-A DC converter, wherein the third bipolar transistor in the input stage circuit which does not receive the timing control signal as a base receives the input side power supply voltage via the second transistor or the output side power supply. It operates by receiving supply. As a result, it becomes easy to configure a circuit responsible for logic conversion and the like.

A third aspect of the invention is the DC-DC converter of the first or second aspect of the invention, wherein the line of the timing control signal is pulled up to the input side power supply voltage via a resistor. . Accordingly, there is an effect that it can be applied to a controller that outputs a tri-state timing control signal.

[Brief description of drawings]

FIG. 1 shows a circuit configuration using an embodiment of a DC-DC converter of the present invention.

FIG. 2 is an example of a conventional DC-DC converter.

[Explanation of symbols]

 1 Battery 2 Controller 3 Transformer 40 DC-DC Converter IC

Claims (3)

[Claims] 1. A DC which receives a timing control signal generated by a controller operating under an input side power supply voltage and switches an input side power supply voltage receiving line according to the timing control signal to generate an output side power supply voltage. −
In a DC converter, the first switching is performed according to the received base current.
A bipolar transistor and an input stage circuit that controls the base current according to the timing control signal, the input stage circuit having a second bipolar transistor that receives the timing control signal at its base, All of the second bipolar transistors have the emitters supplied with the input side power supply voltage.
-DC converter. 2. The DC-DC converter according to claim 1, wherein the input stage circuit has a third bipolar transistor that does not receive the timing control signal at its base,
The DC-DC converter, wherein the third bipolar transistor operates by receiving the supply of the output side power supply voltage or by receiving the supply of the input side power supply voltage via the second transistor. 3. The DC-DC converter according to claim 1, wherein the line of the timing control signal is pulled up to the input side power supply voltage via a resistor. -DC converter.