JPS6016174A - Switching type constant-voltage device - Google Patents

Abstract

PURPOSE:To obtain positive and negative constant voltage outputs of different polarities with equal absolute value by supplying the first output voltage to a polarity inversion type DC/DC converter and controlling the output voltage. CONSTITUTION:When the voltage of a battery BT is +V1 or lower, the first and second output voltages obtained at the first and second output terminals t3, t4 are respectively substantially equal to +E and -E. When the voltage E of the battery BT exceeds +V1, the first constant-voltage circuit 1 operates differentially, and the first output voltage is suppressed to the constant value of +V1. On the other hand, since the control voltage supplied to the control terminal T2 of a converter 3 is also suppressed to +V1, the voltage obtained at the output terminal T3 of the converter 3 is suppressed to the prescribed value. Then, the second constant-voltage circuit 2 operates differentially, and the second output voltage -V is suppressed to -V1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a constant voltage device suitable for application to electronic audio equipment mounted on a vehicle, and more particularly to a constant voltage device using a battery as a power source.

BACKGROUND ART AND PROBLEMS The present applicant has previously developed a complete set of batteries and polarity reversible DC-DCC.
We proposed a power supply circuit that can obtain positive and negative voltages by combining voltages.

By the way, when making the positive and negative voltages of such a power supply circuit constant voltage, it is sufficient to provide a pair of symmetrical series type voltage regulator circuits, but the collector loss of the transistors used in each series type voltage regulator circuit is large. Therefore, a large heat sink is required.

Purpose of the Invention In view of the above, the present invention provides positive and negative constant voltage outputs having the same absolute value and different polarities, as well as reducing the collector loss of the transistor of the series type constant voltage circuit used. The purpose of this paper is to propose a switching type constant voltage device that can perform the following functions.

Summary of the Invention A switching type constant voltage device according to the present invention includes a first series type constant voltage circuit inserted between a first electrode of a battery and a first output terminal, the second electrode of which is grounded; A polarity inversion type DC-DC converter connected between the first electrode and ground, and a second series type connected between the output terminal of this polarity inversion type DC, -DC converter and the second output terminal. a constant voltage circuit, the first output voltage from the first output terminal is supplied to the polarity inversion type DC-DCC set, the output voltage is controlled, and the first output voltage is supplied to the first and second output terminals. First and second output voltages having the same absolute value and very different polarities can be obtained.

According to the present invention, there is provided a switching method that can obtain constant voltage outputs having the same absolute value and different polarities, negative and negative, and can reduce the collector loss of the transistor of the series type constant voltage circuit used. A constant voltage device can be obtained.

Embodiment An embodiment of the present invention will now be described with reference to FIG. BT is a battery, in this case a car battery. Its rated voltage is, for example, 12 volts.

However, since the battery BT is a car battery, its voltage fluctuates significantly around 12 volts. The IE pole of the battery BT is connected to the terminal t1, and its negative pole is connected to the terminal t1.
Connected to 2. L3+L4 are first and second output terminals, and the first and second output voltages from these output terminals j3+14 are supplied to, for example, a preamplifier (4). In this case box 1 and the second output terminal t3. The voltages applied before t4 are positive and negative output voltages +v and -v corresponding to the voltage E when the voltage E of the battery BT is low, but
Even if the voltage E becomes considerably high, the output voltages +V and -V can be suppressed to below, for example, +8.5V and -8.5V, respectively.

'(1) and (2) are symmetrical first and second series type constant voltage circuits, each of which includes an NPN transistor Q1. Q2, field effect transistors Q3 and C4 for constant current sources, and Zener diodes D1 and D2 as constant voltage elements, respectively.

(3) is a polarity reversal DC-DC converter.

Then, the terminal t1 is connected to the terminal T1 of the ζ converter (3) through the choke coil l,1.
3) common terminal T4 is grounded. An output terminal T3 of the converter (3) is connected to the input side of the second constant voltage circuit (2) through a choke coil L2.

The first constant voltage circuit +11 is inserted between the terminals tt+L3. The second constant voltage circuit (2) is inserted between the output terminal T3 and the terminal t4 of the converter (3). Then, the output voltage +V from the capacitor t2 is supplied to the control terminal T2 of the converter (3) through the negative feedback resistor R1, and the output voltage is controlled.

In the first and second constant voltage circuits (11, (21),
The collectors of the transistors Ql and Q2 are respectively connected to the terminal L1 and the terminal T3, and the emitters of each transistor are connected to the terminal t3+.
Connected to t4. Field effect transistor Q3 with gate and source directly connected. The drain and source of Q4 are transistors Q□, respectively.

Connected to the collector and base of C2, respectively. Diode D1. The anode and cathode of D2 are grounded, the cathode of diode D1 is connected to the base of transistor Q1, and the anode of diode D2 is connected to the base of transistor Q2.

Note that C1 and C2 are smoothing capacitors connected between terminals t3+t4 and ground, respectively.

Next, referring to FIG. 2, the polarity reversal type DC-DC of FIG.
The specific configuration of the C set-ta (3) will be explained. TR is a transformer having a primary coil a, a secondary coil b, and a detection coil C. C12 is an oscillating NPN transistor, the collector of which is connected to one end of the primary coil a, and the emitter connected to the common terminal T4. The terminal T1 is connected to the other end of the primary coil a through a filter F1 consisting of a coil Lrt and capacitors C1'11 and C12. Note that the cold end side of the filter F1 is connected to the common terminal T4.
It is connected to the. The midpoint of the connection between Koizuki 111 and a is connected to the transistor C1 through a series circuit of resistors Rt3+Ru.
Connected to 2 bases. Furthermore, the base of transistor Q12 is connected to common terminal T4 through a series circuit of resistor R55, capacitor C16, and coil C.

Furthermore, a PNP type transistor Q1'1 is provided,
The terminal T2, whose emitter is connected to the base of the transistor Q12 and whose collector is connected to the common terminal T4, is connected to the transistor Q through a series circuit of resistors RxIR12.
Connected to the base of 1'1.

One end of the secondary coil b of the transformer TR is connected to the cathode of the rectifying diode D1'1, and the other end is connected to the resistor R1t.
It is connected to the common terminal T4 through R18.

Note that C1a is a smoothing capacitor connected between the anode of the diode D11 and one end of the secondary coil b. The anode of the diode D11 is connected to the terminal T3 through the filter F2 consisting of the coil L12 and the capacitor C14.The cold end side of the capacitor C14 is connected to the common terminal T3.
Connected to 4. Terminal T3 is connected to the base of transistor Q l'i through a resistor R1s.

A PNP type transistor Q14 and an NPN type transistor Q13 are provided and connected to form an SCR. That is, the base of transistor Q1+ is connected to the collector of transistor Q13, and the base of transistor Q43 is connected to the collector of transistor Q14. A midpoint between the capacitor C13 and the resistor R1t is connected to the collector of the transistor Q14 through the resistor Ru. The collector of transistor C14 is connected to common terminal T4 through capacitor Cte. The emitter of transistor CLta is also connected to common terminal T4. The collector of transistor Q13 is connected to the midpoint of connection of resistors R13 and R14, and the emitter of transistor Q14 is connected to the midpoint of connection of resistors R1 and R12.

First, the operation of the r) C-DC converter (3) in FIG. 2 will be explained. This converter (3) has terminal T2
The voltage available at the output terminal T3 is controlled by the reference voltage supplied to the output terminal T3. First, when the transistor Q12 is off, when current is supplied to the base of the transistor Q12 through the resistor supplies R13 and R14, this turns on and a pulse voltage is generated in the primary coil a of the transformer TR.
As a result, a pulse voltage is also generated in the detection coil C, and based on the pulse voltage, the capacitor C1B and the resistor supply R
A current flows to the base of transistor Q12 through a time constant circuit consisting of Become polar. Thereafter, transistor Q12 is turned on again and the above-described operation is repeated.

On the other hand, transistor Q11 turns off when its base voltage becomes greater than 0 volts, and turns on when it becomes smaller. When this transistor Q1'1 is turned on, the current that was flowing into the base of the transistor Q1.2 from the coil C through the time constant circuit flows to the common terminal T4 through the emitter-collector of the transistor Q11, and the transistor Q12 is turned on. It will turn off immediately. As a result, the on-period and frequency of the pulse obtained in the secondary coil b of the transformer TR are controlled according to the reference voltage supplied to the terminal T2, and the output voltage obtained at the terminal T3 is controlled.

Note that when the voltage at the midpoint of the connection between the resistors R13 and R14 is higher than the voltage at the midpoint of the connection between the resistors R11 and R12, the device operates in a compressive manner.

Further, when the current flowing through the secondary coil b of the transformer TR exceeds a predetermined value, or when the voltage at the midpoint between the resistors R11 and R12 becomes higher than the voltage at the midpoint between the resistors Ri3 and R14, the transistor Q13 is on, so transistor Q14 is also on, resistors R11 and R
The voltages at the midpoint of the connection of T12 and the voltages at resistors R13 and R14 are both made substantially equal to the voltage at the common terminal T4, ie, the ground voltage. Therefore, the oscillation operation of the converter (3) is stopped.

Note that in order to restart the oscillation operation, the voltage supplied to the terminal T2 may be set to the ground voltage.

Next, the operation of the constant voltage device shown in FIG. 1 will be explained with reference to 3.1. The voltage E of the battery BT is +V1 (= +8.
5V) or less, the first and second output terminals t3. t4
The first and second output voltages obtained are approximately +E and -, respectively.
Equal to E. Electricity Pi and E of battery BT are +Vx (=+8
．． 5V), the first constant voltage circuit (1) operates differentially, and the first output voltage (2) is suppressed to a constant value of +1 (+1). On the other hand, the control voltage supplied to the control terminal T2 of the converter (3) is also suppressed to +v1, so the voltage obtained at the output terminal T3 of the converter (3) is -VIIM (=-10,5V). . L7, the second constant voltage circuit (2) is also differentially operated, and the second output voltage -V is suppressed to -v1.

In this case, the transistor Q1 of the first constant voltage circuit (1)
The collector loss is large as shown in the shaded area A in FIG. However, the collector loss of transistor Q2 of the second constant voltage circuit (2) is such that when its input voltage is −VBH
Therefore, it becomes small as shown in the shaded area B. That is, the collector loss is significantly smaller than the collector loss in region C corresponding to region A. Therefore, the heat sink for transistor Q2 may be smaller than the heat sink for transistor Q1.

Effects of the Invention According to the present invention described in section 1, positive and negative constant voltage outputs having the same absolute value and different polarities can be obtained, and the collector loss of the transistor of the series type constant voltage circuit used can be reduced. It is possible to obtain a switching type constant voltage device that can perform the following steps.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of a switching type constant voltage device according to the present invention, Fig. 2 is a circuit diagram showing a specific configuration of the DC-DC converter shown in Fig. 1, and Fig. 3 is an explanation of the present invention. FIG. BT is a battery, (1) and (2) are first and second constant voltage circuits, (3) is a DC-DC converter, t3. t4 are the first and second output terminals.

Claims (1)

[Claims] a first series type constant voltage circuit inserted between a first electrode of a battery whose second electrode is grounded and the first output terminal; and a polarity reversal circuit connected between the first electrode and the ground. Model DC-D
a second series type voltage circuit connected between the output terminal of the polarity inversion type DC-DCC set-ter and a second output terminal; A first output voltage is supplied to the polarity inversion type DC-DCC set to control its output voltage, and first and second output terminals having equal absolute values and different polarities are supplied to the first and second output terminals. A switching type constant voltage device characterized in that two output voltages can be obtained.