JPH06282357A - Power supply switching circuit - Google Patents

Abstract

PURPOSE:To allow an expanded board to alternately switch internal power supply and external power supply by driving an external feed detecting circuit, by the internal power supply only when the internal power supply of a computer is fed to a normally fed terminal part. CONSTITUTION:On a expanded board 1 for the computer, the internal power supply of the computer is fed to normally-closed contacts (normally fed terminal parts) 5a, 5b and the external power supply is applied to normally-opened contacts 6a, 6b. A switch 4 connects power supply lines 13a, 13b on the board 1 to the contacts 5a, 5b with priority. An external feed detecting circuit 9 is driven by the power supply through the contact 5a, and only during the ON period of power supply for the computer, judges whether the external power supply is fed to the contacts 6a, 6b or not. In addition, the circuit 9 switches the switch 4 only when the external power supply is fed to connect the lines 13a, 13b to the contacts 6a, 6b. Only when the internal power supply of the computer is fed to the contacts 5a, 5b, the circuit 9 is driven by the internal power supply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-board power supply switching circuit for switching the power supply of an expansion board of a computer such as a personal computer.

[0002]

2. Description of the Related Art Conventionally, an expansion board such as an expansion memory board of a personal computer is used by mounting it in an expansion slot or an expansion box of the personal computer. In addition, this type of expansion board has been conventionally dedicated to internal power supply in which the internal power supply of the personal computer is supplied to the power supply line, or to the power supply line which is separate from the personal computer.
It is formed exclusively for external power feeding to which an external power source from a C adapter or the like is fed.

[0003]

In the case of the conventional expansion board for a computer such as a personal computer, since it is formed exclusively for internal power supply or external power supply, there is a problem described below. First, in the case of internal power supply only, when the number of boards mounted in the computer increases, the capacity of the internal power supply of the computer becomes insufficient and the board malfunctions or malfunctions, which limits the number of boards that can be mounted. is there.

Next, in the case of exclusive use for external power supply, since power supply to the expansion board is continued even when the computer is powered off, there is a problem that the computer malfunctions when it is powered on again. According to the present invention, the power supply of the expansion board of the computer is automatically switched by the board itself to the internal power supply of the computer or the external power supply separate from the computer, according to the power supply condition. An object of the present invention is to provide an expansion board power supply switching circuit for turning on / off the power supply of the expansion board in synchronization with turning on / off of the internal power supply of the computer.

[0005]

In order to achieve the above object, in the power supply switching circuit of the present invention, the internal power supply of the computer is supplied to the expansion board of the computer and is supplied separately from the computer. External power source is supplied to the switching power supply terminal, and the switchboard that preferentially connects the power line of the expansion board to the normal power supply terminal and the internal power supply of the normal power supply terminal operates to switch only while the computer is powered on. An external power supply detection circuit is provided, which determines whether the external power supply of the power supply terminal is supplied or not, and switches the switcher only when the external power supply is supplied to connect the power supply line to the switch power supply terminal.

[0006]

In the power supply switching circuit of the present invention configured as described above, this internal power supply is used only when the computer is powered on and the internal power supply of the computer is supplied to the normal power supply terminal of the switch. The external power supply detection circuit operates.

Therefore, when the power supply of the computer is off, the external power supply detection circuit does not operate, and at this time, the expansion board is irrespective of whether power is supplied to the switching power supply terminal of the switch of the external power supply. The power supply line is connected to the normal power supply terminal of the switch, and the power supply is turned off.

Next, when the internal power supply of the computer is supplied to the normal power supply terminal portion of the switching device when the power supply of the computer is turned on, at this time, unless the external power supply is supplied, the switching device is not switched and the normal power supply is performed. The internal power supply of the terminal is supplied to the power supply line of the expansion board to turn on the power supply.

On the other hand, when an external power supply is supplied to the switching power supply terminal of the switch and the computer is turned on, the external power is detected by the internal power supply of the computer which is supplied to the normal power supply terminal of the switch. The circuit operates to switch the switching device, and the external power supply of the switching power supply terminal portion is supplied to the power supply line of the expansion board to turn on the power supply.

Therefore, when the external power is not supplied, the internal power of the computer is supplied to the expansion board,
The power of this board turns on and off in synchronization with the power of the computer. Also, when external power is supplied, the power of the expansion board is automatically switched to the external power, and the power of the expansion board is synchronized with the power on / off of the computer in the same way as when the internal power is supplied. On,
Turn off.

[0011]

EXAMPLE One example will be described with reference to FIG. This figure shows the case where power of + 12V, + 5V is supplied to the expansion board 1 mounted on a computer such as a personal computer, and 2 is the internal power supply side power receiving unit, + 12V, + 5V,
Each terminal 2a, 2b, 2c of ground is automatically + 12V, + of the expansion board power supply line of the personal computer by mounting the board.
It is connected to each terminal of 5V and ground.

Reference numeral 3 denotes an external power supply receiving unit, which is an expansion board 1.
+ 12V, + 5V, only when the external power is supplied to
To the ground terminals 3a, 3b and 3c are connected the + 12V and + 5V and ground terminals of an external power source such as an AC adapter which is separate from the computer.

Reference numeral 4 is a switching device composed of a relay having four circuits and four contacts, and two normally closed contacts 5a, 5 forming a normally feeding terminal portion.
b is connected to the terminals 2a and 2b of the power receiving unit 2, respectively, and the two normally open contacts 6a and 6b forming the switching power supply terminal unit are connected to the terminals 3a and 3b of the power receiving unit 3, respectively.

A switch 7 has one end connected to the contact 6b.
Relay coil of each contact 5a, 5b,
The movable pieces 6a and 6b are moved in conjunction with each other to move the respective contact points 5a and 5b.
Invert b, 6a, 6b to open or closed. Reference numeral 8 is a protective diode provided in parallel with the relay coil 7.

Reference numeral 9 denotes an external power supply detection circuit formed by the relay coil and the FET 10. The FET 10 has resistors 11 and 1 whose gate G is provided in series between the contact 5b and the ground.
It is biased by the partial pressure of 2, the drain D is connected to the other end of the relay coil 7, and the source S is grounded.

Reference numeral 13a is a + 12V power source line of the expansion board 1, and its terminal terminal 13a 'is connected to the movable piece terminals 5a', 6a 'of the contacts 5a, 6a of the switch 4. Reference numeral 13b is a + 5V power line of the expansion board 1, and its terminal terminal 13b 'is a contact 5 of the switch 4.
It is connected to the movable piece terminals 5b 'and 6b' of b and 6b. Reference numerals 14 and 15 are smoothing capacitors provided between the terminals 13a 'and 13b' and the ground.

The expansion board 1 mounted on the computer is +12 when the power of the computer 1 is turned on.
Internal power supplies of V and +5 V are supplied to the contacts 5 a and 5 b of the switch 4 via the power receiving unit 2.

Further, the + 5V internal power source of the contact 5b is divided by the resistors 11 and 12 of the detection circuit 9 to be FET10.
Is supplied to the gate G of the
0 is held on, and the detection circuit 10 operates. When the power source of the expansion board 1 is set to the internal power source of the computer 1, the power receiving unit 3 is not supplied with the external power source.
The external power of + 5V is not supplied to the contact 6b of the switch 4,
The relay coil 7 is kept de-energized.

Therefore, the switching device 4 is kept in the initial state in which the contacts 5a and 5b are closed and the contacts 6a and 6b are opened, and the + 12V and + 5V internal power supplies of the contacts 5a and 5b are the power lines of the expansion board 1. Power is supplied to 13a and 13b.
On the other hand, when using the external board as the power source for the expansion board 1,
An external power source of 5V, + 12V is supplied to the switching unit 4 via the power receiving unit 3.
Are supplied to the contacts 6a and 6b.

At this time, if the power of the computer is turned on and the FET 10 of the detection circuit 9 is turned on, the contact 6b
+ 5V external power supply for relay coil 7 and FET 10
Current flows through the drain D and the source S of the relay coil 7
Is energized. The switching device 4 is switched by driving the relay coil 7, the contacts 5a and 5b are opened, and the contacts 6a and 6b are closed, and the contact 6 is closed.
External power supply of + 12V and + 5V for a and 6b is expansion board 1
Power is supplied to the power supply lines 13a and 13b.

Next, when the power of the computer 1 is turned off, the + 12V and + 5V internal power supplied to the contacts 5a and 5b of the switch 4 via the power receiving unit 2 disappears. Also, due to the disappearance of the + 5V internal power supply of the contact 5b, the FET
10 is turned off and the operation of the detection circuit 9 is stopped.

At this time, if the external power supply is not supplied and the expansion board 1 is set to the internal power supply, the contact 5
With the disappearance of the internal power supply of a and 5b, the power supply line 13a,
The power of 13b is lost, and the power of the expansion board is also turned off.
On the other hand, when the external power is supplied and the power of the expansion board 1 is set to the external power, the relay coil 7 is de-energized due to the stop of the operation of the detection circuit 9.

The switch 4 is returned to the initial state by the non-energization, and the contacts 5a and 5b are closed to make the contacts 6a and 6b.
b is opened, and the power supply to the power supply lines 13a and 13b of the expansion board 1 from the external power supply of the contacts 6a and 6b is cut off.
Therefore, even if the power source of the extension board 1 is set to the external power source, the power source of the extension board 1 is turned off in synchronization with the turning off of the power source of the computer 1.

Therefore, the power supply of the expansion board 1 can be automatically switched to the internal power supply of the computer or the external power supply depending on the presence or absence of the supply of the external power supply to the power receiving unit 3, and the internal power supply of the computer can be set. The limitation on the number of mounted boards based on capacity is eliminated. Moreover, even when the power of the expansion board 1 becomes an external power source, the power of the expansion board 1 is turned on and off in synchronization with the turning on and off of the computer. Therefore, malfunction may occur when the power of the computer is turned on again. There is no.

In the above embodiment, + 12V, + 5V
Although the present invention is applied to the expansion board 1 requiring the power supply of, the same can be applied to an expansion board having a power supply rating different from that of the embodiment. Further, the configurations of the switching device, the external power supply detection circuit and the like are not limited to the embodiments.

[0026]

Since the present invention is configured as described above, it has the following effects. Since the expansion board 1 is provided with the switch 4 and the external power supply detection circuit 9, when the external power is not supplied, the internal power of the computer is supplied to the expansion board 1, and the power of the board 1 turns on and off the power of the computer. On and off in synchronization with
When the external power is supplied, the power of the expansion board 1 is automatically switched to the external power. Moreover, the power of the expansion board 1 is synchronized with the power on / off of the computer as in the case of supplying the internal power. To turn it on and off.

Therefore, the expansion board 1 automatically switches the power source of the board 1 to the internal power source or the external power source of the computer in accordance with the power feeding condition, and further, the internal power of the computer is supplied during the power feeding of the external power source. The power of the expansion board 1 can be turned on and off in synchronization with the turning on and off of the power.

[Brief description of drawings]

FIG. 1 is a connection diagram of an embodiment of a power supply switching circuit of the present invention.

[Explanation of symbols]

 1 expansion board 4 switcher 5a, 5b normally closed contact forming a normal power supply terminal section 6a, 6b normally open contact forming a switching power supply terminal section 9 external power supply detection circuit 13a, 13b expansion board power supply line

Claims (1)

[Claims] 1. An expansion board of a computer is supplied with an internal power supply of the computer to a normal power supply terminal section and an external power supply separate from the computer is supplied to a switching power supply terminal section, giving priority to a power supply line of the expansion board. And a power supply of the external power source of the switching power supply terminal unit only while the computer is powered on by operating with the internal power supply of the normal power supply terminal unit. An external power supply detection circuit that makes a determination and switches the switcher only when power is supplied from the external power supply to connect the power supply line to the switched power supply terminal.