JPH0888485A - Hot-line insertion circuit - Google Patents

Abstract

PURPOSE: To restrict the feeding to a printed board and increase the feeding to the printed board with the passage of time and finally maximize the feeding to the printed board by inserting a saturable inductance in a line to connect a power input terminal and the printed board. CONSTITUTION: When a printed wiring board 3 is connected to a positive terminal 2a and a negative terminal 2b of a connector 2, a positive input terminal 2c is connected to the terminal 2a and a negative input terminal 2d is connected to the terminal 2b and then the printed wiring board is electrically connected. When the printed wiring board is inserted into the line, the output current of a DC power supply 1 flows in a loop of a positive output bus 1a → the terminal 2a → the terminal 2c → a saturable inductance → a logic circuit 4 → the terminal 2b → a negtive output bus 1b. Therefore, the feeding can be restricted by means of a high impedance at the time of rising of current of the saturable inductance 5. After inserting a hot line, the impedance of the saturable inductance 5 becomes small with the passage of time and thereby the feeding to the printed wiring board 3 can be increased and finally maximized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board which is supplied with power from an external power source and a hot-plug circuit for the printed wiring board.

[0002]

2. Description of the Related Art A conventional circuit is shown in a known example of JP-A-62-76800.

The operation of this circuit will be described with reference to FIG.

In this circuit, when the printed wiring board 3 is inserted into the positive side output terminal 2a and the negative side output terminal 2b of the connector 2, the positive side input terminal 2c of the connector 2 on the side of the printed wiring board 3 becomes the terminal 2.
The negative input terminals 2d of the connector 2 are connected to the terminals a and are electrically connected to the terminals 2b.

Immediately after the printed wiring board is inserted, the output current of the DC power supply 1 passes through a loop of the positive side output busbar 1a → terminal 2a → terminal 2c → resistor R → capacitor C → terminal 2d → terminal 2b → negative side output busbar 1b. Since it flows, the base current of the transistor Q is absorbed by the capacitor C, and the transistor Q
Remains cut off.

Therefore, power is not supplied from the DC power supply 1 to the logic circuit 4.

Next, the capacitor C is charged by the current supplied from the DC power source 1 along a time constant determined by the values of the resistor R and the capacitor C.

Then, the voltage across the capacitor C gradually rises, and accordingly, the collector current of the transistor Q begins to flow, and the collector current gradually increases.

As a result, the output current of the DC power supply 1 is positive side output bus bar 1a → terminal 2a → terminal 2c → transistor Q.
Collector, emitter → logic circuit 4 → terminal 2d → terminal 2
Flowing through the loop of b → negative side output bus 1b, power supply to the logic circuit 4 is started.

Further, when the charging of the capacitor C is completed, the transistor Q is in a steady ON state, and the logic circuit 4 is supplied with rated power.

After that, the normal operation state is entered and the transistor Q is maintained in the ON state, so that power is continuously supplied to the logic circuit 4. As described above, when the printed wiring board 3 is hot-plugged, power is gradually supplied to the logic circuit 4 along the time constant determined by the resistor R and the capacitor C.
Since the output voltage of 1 is drastically decreased and the current is not drastically changed, the generation of noise due to electromagnetic induction can be avoided. Therefore, it is possible to continuously supply stable power to other printed wiring boards (not shown) connected to the output buses 1a and 1b of the DC power supply 1.

[0012]

Since the above-mentioned conventional hot-line insertion circuit for a printed wiring board is composed of a circuit using a transistor, the circuit becomes complicated and hinders miniaturization, and there is a problem in reliability. there were.

[0013]

In order to achieve the above object, in the present invention, a saturable inductance having a characteristic of exhibiting a high impedance only for a moment when a current rises is inserted in a circuit connecting a power input terminal and a printed circuit. Therefore, when the printed wiring board is hot-plugged into the external power source, the amount of power supply to the printed circuit is limited by the impedance of the saturable inductance, and the impedance becomes smaller with the passage of time to reduce the amount of power supply to the printed circuit. It is intended to avoid the generation of noise due to electromagnetic induction because the output voltage of direct current sharply drops when the printed wiring board is hot-plugged and there is no rapid change in current. .

[0014]

In FIG. 1, when the printed wiring board 3 is hot-inserted into the connector 2, power is supplied to the logic circuit 4 through the saturable inductance 5, so that the amount of power supply is limited by the high impedance only for a moment when the current rises.

As a result, when the printed wiring board 3 is hot-plugged, the output voltage of the DC power supply 1 is drastically reduced, and since there is no abrupt change in the current, the generation of noise due to electromagnetic induction can be avoided.

After the hot wire is inserted, the impedance of the saturable inductance becomes smaller with the lapse of time, and the power supply amount to the printed wiring board 3 is increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the printed wiring board 3 is connected to the connector 2
When the positive side input terminal 2c of the connector 2 on the printed wiring board 3 side is inserted into the positive side terminal 2a and the negative side terminal 2b of the terminal 2a.
Then, the negative side input terminals 2d of the connector 2 are connected to the terminals 2b, respectively, and are electrically connected.

When the printed wiring board 3 is inserted, the output current of the DC power supply 1 passes through a loop of positive side output busbar 1a → terminal 2a → terminal 2c → saturable inductance 5 → logic circuit 4 → terminal 2b → negative side output busbar 1b. Since the current flows, the amount of power supply is limited by the high impedance of the saturable inductance 5 when the current rises.

As a result, even if the printed wiring board 3 is hot-inserted, the output voltage of the DC power supply 1 is drastically reduced, and since the current is not abruptly changed, noise due to electromagnetic induction is not generated.

After the hot wire is inserted, the impedance of the saturable inductance 5 becomes smaller with the lapse of time, and the amount of electric power supplied to the printed wiring board 3 is increased and maximized.

For this reason, the output buses 1a, 1 of the DC power supply 1 are
Stable electric power can be continuously supplied also to another printed wiring board (not shown) connected to b.

[0023]

According to the present invention, a hot-line insertion circuit of a printed wiring board can be constructed without using a transistor, so that the circuit can be simplified and downsized and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is an example of the present invention.

FIG. 2 shows a conventional circuit example.

FIG. 3 shows the current and inductance characteristics of saturable inductance.

FIG. 4 is a characteristic example of time and impedance of saturable inductance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... Connector for printed wiring board, 3 ... Printed wiring board, 4 ... Logic circuit, 5 ... Saturable inductance, 6 ... Control circuit, R ... Resistor, C ... Capacitor, Q ... Transistor.

Claims (2)

[Claims] 1. A printed wiring board provided with a printed circuit which is operated by power supply from an external power source, wherein a saturable inductance is inserted in a circuit connecting the power input terminal and the printed wiring board. circuit. 2. A hot-line insertion circuit of a printed wiring board for hot-inserting a printed wiring board, which is provided with a printed circuit that operates by external power supply, into an external power supply, wherein the printed wiring board is hot-inserted into an external power supply. In this case, due to the characteristic of the saturable inductance, the initial current rise is limited, and the impedance becomes smaller with the lapse of time to maximize the amount of power supply to the printed circuit. Line insertion circuit.