JPS61166221A - Power switch - Google Patents

Abstract

PURPOSE:To suppress a rush current by inserting an error and a collector of the 1st and 2nd transistors (Trs) to a power supply line in series and providing further the 3rd Tr, a capacitor and a constant voltage diode. CONSTITUTION:When a switch SW 5 is turned on, a voltage across a capacitor C1 is increased gradually, a collector-emitter voltage VCE of the Tr3 is decreased gradually and a collector current IC is increased gradually. The voltage VCE of the Tr1 approaches '0' attended therewith, a voltage VO(+) applied to an electronic circuit 2 approaches gradually +5V from '0'. A constant voltage diode D1 during this time is conducted when the voltage exceeds the breakdown voltage, a voltage increasing gradually is fed to a base of the Tr2 and its volt age VCE approaches gradually '0'. Thus, the voltage VO(-) fed to the electronic circuit 2 approaches gradually -5V.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides the following features:
This invention relates to an improvement in a power switch that prevents inrush currents when loads that generate multiple inrush currents are connected.

When a plurality of loads are connected as described above, a power switch that prevents inrush current is required to be able to completely prevent inrush current.

[Conventional technology]

FIG. 5 is a block diagram of an example of a power supply system in which a conventional power switch is used.

In the figure, 1 is a DC power supply that supplies +5V and -5V, 2 to 4 are electronic circuits for the capacitor input power supply circuit, and 5 to 7
is the power switch, SWI~SW4 is the switch, RIO,
R11 represents resistance.

Since the power supply circuits of electronic circuits 2 to 4 in FIG. 5 are capacitor inputs, when the power is turned on, a large current, that is, a rush current flows temporarily.

For example, if the electronic circuit 2.3 has already been powered on and is in operation, and the electronic circuit 4 is powered on, the normal power switch will not output the DC power supply 1 due to the inrush current. The voltage drops, adversely affecting the electronic circuits 2 and 3.

For this reason, as shown in FIG. 5, a power switch for preventing rush current is provided on the power input side of each electronic circuit 2-4.

Here, FIG. 5 shows a conventional power switch, which shows that when trying to supply power, the switch SWI
, SV/3 is turned on first, and then switch SW2 is turned on.
．． Switch SW4 is turned on.
When I and SW3 are turned on, resistors R1 and R2 are inserted in series between the DC power supply l and the power input of the electronic circuit 2, respectively, to reduce the rush current, and then the resistor RIO1R1
Switch SW2.1 to short-circuit SW2.1. ．． ．． This turns on S and W4.

[Problem that the invention seeks to solve]

However, switch SW1. When SW3 is turned on, the inrush current cannot be prevented unless the values of resistors RIO and R11 are to a certain extent. When SW4 is turned on, resistors R10 and R11 are suddenly short-circuited, so
Another problem is that the current increases suddenly and the rush current cannot be completely suppressed.

[Means for solving problems]

The above problem is solved by inserting the emitter and collector of the first transistor in series on one voltage side of the power supply line and the emitter and collector of the second transistor in series on the other voltage side. The emitter and collector of a third transistor are inserted in series between the base of the first transistor and the ground, and a capacitor is connected between the base of the third transistor and the ground, and the base and the voltage side of the one transistor are connected in series. This problem is solved by the power switch of the present invention, in which a power on/off switch is provided between the second transistor and the load side of the first transistor, and a constant voltage diode is inserted between the base of the second transistor and the load side of the first transistor. Ru.

[Effect]

According to the present invention, when the switch is turned on, the voltage across the capacitor gradually increases, the collector current of the third transistor gradually increases, and the voltage between the emitter and the collector of the first transistor gradually increases. The voltage gradually approaches O and, along with this, exceeds the breakdown voltage of the voltage regulator diode, so the voltage regulator diode becomes conductive, voltage is applied to the base of the second transistor, and the emitter of the second transistor , the voltage between the collectors gradually approaches 0, and the voltages applied to the load, both positive and negative, gradually increase from 0 to a predetermined voltage.

In this way, since the voltage applied to the load is gradually increased from 0, rush current can be completely eliminated.

〔Example〕

1 and 3 are circuit diagrams of a power switch according to an embodiment of the present invention, and FIG. 2 is a time chart showing the state of current and voltage at each part of FIG. 1.

In the figure, 8.9 is the power switch, Tri and Tr4 are PNP)
transistor, Tr2. Tr, 3 is NPN) transistor, Dl is Zener diode, R1-R4 is resistor, C1
indicates a capacitor, SW5 indicates a switch, and the same reference numerals indicate the same functions throughout the drawings.

Here, we used a PNP transistor on the positive voltage side and an NPN transistor on the negative voltage side, because both transistors operate because the base potential is lower than the potential applied to the emitter, which simplifies the circuit. It is for this purpose.

In addition, the Zener diode D1 has a negative voltage (-5V) in FIG.
In FIG. 3, those having a breakdown voltage slightly larger in absolute value than the positive voltage (+5V) are selected.

In FIG. 1, when the switch SW5 is turned on, the voltage across the capacitor CI gradually increases as shown in FIG. 2(A).

Accordingly, the collector-emitter voltage V CE of the transistor Tr3 gradually decreases as shown in FIG. 2(B), and the collector current becomes {circle around (2)}. gradually increases as shown in FIG. 2(C).

Along with this, the base current of the transistor Tri increases, and the collector-emitter voltage Vc increases as shown in FIG. 2(D).
As shown in Fig. 2(E), the voltage VO(+) applied to the positive voltage side power supply of the electronic circuit 2 gradually decreases and approaches 0, as shown in Fig. 2(E).
As shown in , it gradually increases from 0 and approaches +5■.

During this period, the Zener diode D1 becomes conductive at point A in FIG. 2(E), which exceeds the breakdown voltage of the Zener diode D1, and the base of the transistor Tr2 is
), a gradually larger voltage is applied, and the voltage ν between the collector and emitter of the transistor Tr2 becomes
As shown in G), it gradually approaches O.

Therefore, the voltage V applied to the negative voltage side power supply of the electronic circuit 2.

As shown in FIG. 2 (H), (-) gradually increases from 0 and approaches -5V.

In this way, since a voltage gradually higher than 0 is applied to the power supply circuit of the electronic circuit 2, rush current can be completely eliminated.

In the case of the power supply system shown in FIG. 5, this power switch of the present invention can of course be used in place of the power switches 5 to 7.

In FIG. 3, a transistor Tr4 is provided on the base side of the transistor Tr2 on the negative voltage side in place of the transistor Tr3 provided on the base side of the transistor Tri in FIG.
In addition, the circuit related to the switch SW5 is provided on the negative voltage side, and the Zener diode D1 is provided on the base side of the transistor Tri instead of on the base side of the transistor Tr2, so that the on/off of the switch SW5 is processed on the negative voltage side. This is a circuit diagram, and the operation is the same as that in FIG. 1.

FIG. 4 is a circuit diagram of a power switch in an application example of the present invention in which the voltage supplied to the load is equal to the number of positive and negative voltages.

In the figure, Tr5 is a PNP l-transistor, and Tr6 is an NPN
) transistor, D2. D3 is a Zener diode whose breakdown voltage is a little higher than +12V and a little lower than -12V. Also, 10 is a power switch, 20
30 indicates a DC power supply and 30 indicates an electronic circuit.

In Fig. 4, after turning on switch SW5, +5V,
The process until -5V is supplied to the electronic circuit 30 is the same as the case shown in FIG. 1, but as the voltage between the collector and emitter of the transistor Tri gradually decreases, the Zener diode D3 is The transistor Tr6 becomes conductive, and a gradually larger voltage is applied to the base of the transistor Tr6, and the voltage between the collector and emitter of the transistor Tr6 gradually decreases until the voltage of -12■ becomes O.
is gradually added to the electronic circuit 30.

Also, while -5V is being applied to the electronic circuit 30, the voltage across the Zener diode D2 exceeds the breakdown voltage and becomes conductive, and the voltage between the collector and emitter of the transistor Tr5 gradually decreases until +12■ becomes 0. is gradually added to the electronic circuit 30.

Therefore, in this way, no matter how many types of positive voltages and negative voltages there are, voltage can be supplied without inrush current by turning on one switch.

〔Effect of the invention〕

As explained in detail above, according to the present invention, there is an effect that voltage can be supplied to a load that generates an inrush current from a DC power supply without an inrush current.

[Brief explanation of drawings]

Figures 1 and 3 are circuit diagrams of a power switch according to an embodiment of the present invention, Figure 2 is a time chart showing the state of current and voltage at each part of Figure 1, and Figure 4 is an application example of the present invention with a load. Figure 5 is a block diagram of an example of a power supply system in which a conventional power switch is used. In the figure, 1.20 is a DC power supply, 2-4.30 are electronic circuits, 5-1O are power switches, Tri-Tr6 are transistors, D1-D3 are Zener diodes, R1-R6, RIO, R11 are resistors, C1 is a capacitor, and SWI to SW5 are switches. 1.Q. u... G (1, JQ (To S ¥1

Claims (1)

[Claims] When applying positive and negative voltages from a DC power supply through a power supply line to a load that generates an inrush current, the emitter and collector of the first transistor are connected in series to one voltage side of the power supply line, and the other side is connected in series. The emitter and collector of a second transistor are inserted in series on the voltage side of the transistor, and the emitter and collector of a third transistor are inserted in series between the base of the first transistor and the ground. A capacitor is connected between the base of the transistor and the ground, a power supply on/off switch is provided between the base and the one voltage side, and a capacitor is connected between the base of the second transistor and the load side of the first transistor. A power switch characterized in that a constant voltage diode is inserted between the power switches.