JPH04145828A - Preventing system for malfunction of power supply protective circuit - Google Patents

Abstract

PURPOSE:To prevent malfunctions of a power supply protective circuit by protecting the power supply protective circuit from receiving an abnormality detecting signal in a transient period of time even when the signal is issued before a DC power supply voltage applied from an external power supply apparatus reaches a predetermined value. CONSTITUTION:An apparatus 5 uses the power supplied from an external power supply apparatus 1 and received once by an internal power supply 2. A protective means 6, when it is supplied with power from the external power supply 1, starts operation and monitors the output of the internal power supply 2, and when the protective means 6 judges the output to be abnormal, the protective means 6 stops the internal power supply 2 to receive power. A reset means 7, when power supply from the external power supply 1 starts, starts operation and keeps stopping the internal power supply 2 of the protective means 6 to receive power until a predetermined period of time passes to protect the internal power supply 2 from erroneously stopping receiving power supply.

Description

[Detailed Description of the Invention] [Summary] Regarding a malfunction prevention method for a power supply protection circuit that prevents a malfunction of a protection circuit of an internal power supply device provided inside a device, the present invention aims to prevent the protection circuit from malfunctioning. After the internal power supply receives power from an external power supply, the device starts operating when power is supplied from the external power supply, monitors the output of the internal power supply, and detects abnormalities. and a reset means that starts operation when power is supplied from the external power supply and prohibits the operation of the protection means for a predetermined period of time. The protection device is configured to prevent the protection unit from stopping power reception from the internal power supply device until the predetermined time period elapses from the time when power supply from the external power supply device is started.

[Industrial application field]

The present invention relates to a device that operates by being supplied with power from an external power supply device, and more particularly to a malfunction prevention method for a power supply protection circuit that prevents a malfunction of a protection circuit of an internal power supply device provided inside the device.

In computer systems and the like, an external power supply device collectively receives commercial power, and generates and supplies the DC power required by each device. In each device, this DC power is received by an internal power supply device, and is used after being made into a constant voltage.

By the way, this internal power supply usually has a protection circuit that monitors the voltage on the output side of the internal power supply and shuts off the power when the voltage falls below a predetermined level, in order to prevent circuit components from being destroyed by overcurrent. However, it is necessary to prevent malfunction of this protection circuit.

[Conventional technology]

FIG. 4 is a block diagram illustrating an example of the prior art.
The figure is a time chart explaining the operation of FIG. 4.

When a switch (not shown) of the external power supply device 1 is turned on, the voltage of the DC power supply generated by the external power supply device 1 rises, as shown in (■) of the external power supply in FIG. Supplied.

When the internal power supply device 2 is supplied with DC power, it controls the voltage of the supplied DC power to a constant value and supplies it to each circuit inside the device, as shown in the internal power supply in FIG. .

The power supply abnormality detection circuit 3 starts operating with the direct current power sent from the external power supply 1 and monitors the voltage on the output side of the internal power supply 2. When this voltage drops below the predetermined voltage shown in (■) of the internal power supply in FIG. A protection signal is sent to the internal power supply device 2, as shown in (■) of the protection signal in FIG.

The internal power supply device 2 that has received the protection signal operates a circuit breaker, for example, to stop receiving the DC power sent out by the external power supply device 1. This prevents damage to circuit components inside the device that are supplied with excessive current due to continued flow.

[Problem to be solved by the invention]

As described above, the conventional power supply abnormality detection circuit 3 starts monitoring the voltage sent out by the internal power supply 2 using the DC power supplied by the external power supply 1. If the power supply abnormality detection circuit 3 starts voltage monitoring before reaching the predetermined voltage shown in ■ of the internal power supply in Figure 5, it sends a power supply abnormality signal to the protection circuit 4 as shown in ■ of the abnormality detection signal in Figure 5. However, the protection circuit 4 sends out a protection signal to the internal power supply device 2, as shown in (■) of the protection signal in FIG.

Therefore, the problem with the internal power supply device 2 is that the circuit breaker operates and stops power supply even though no fault has occurred and no excessive current is flowing.

In view of these problems, the present invention has been designed to prevent abnormality detection signals from being sent to the protection circuit 4 during the transition period until the voltage of the DC power source sent by the external power supply device 1 reaches the specified voltage.
The purpose of this is to prevent the protection circuit 4 from malfunctioning by preventing it from being received.

[Means to solve the problem]

FIG. 1 is a block diagram illustrating the invention in detail.

The device 5 uses the power supplied from the external power supply 1 once received by the internal power supply 2. The protection means 6 starts operating when power is supplied from the external power supply device 1, and when it monitors the output of the internal power supply device 2 and determines that it is abnormal, stops receiving power from the internal power supply device 2. That is, as explained in FIG. 4, the circuit breaker of the internal power supply device 2 is operated.

However, the reset means 7 starts operating when the external power supply device 1 starts supplying power, and prevents the protection means 6 from stopping power reception to the internal power supply device 2 until a predetermined period of time has elapsed. That is, the operation of operating the circuit breaker of this internal power supply device 2 is prevented.

[Function] By configuring as described above, the reset means 7 prevents the protection means 6 from erroneously recognizing an output abnormality and receiving power at the initial stage when the internal power supply device 2 starts receiving power supply from the external power supply device 1. Since the stopping operation is prevented, it is possible to prevent the internal power supply device 2 from accidentally stopping the power supply.

〔Example〕

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a time chart explaining the operation of FIG. 2.

The same reference numerals as in FIG. 4 indicate the same functions. When the switch (not shown) of the external power supply device 1 is turned on, the voltage of the DC power supply generated by the external power supply device 1 rises, as shown in (■) of the external power supply in FIG. 2.

When DC power is supplied, the internal power supply device 2 controls the voltage of the supplied DC power to a constant value and supplies it to each circuit inside the device, as shown in the internal power supply in FIG. .

The power supply abnormality detection circuit 3 starts operating with the direct current power sent from the external power supply 1 and monitors the voltage on the output side of the internal power supply 2. At this time, if the output voltage of the internal power supply device 2 rises slowly and this voltage is below the predetermined voltage shown in ■ of the internal power supply in Figure 3, a power supply abnormality will occur as shown in ■ of the abnormality detection symbol in Figure 3. A logic "1" is sent to the AND circuit 9 as a signal.

At this time, the reset circuit 8 starts operating with the direct current supplied from the external power supply 1, but it can operate at a lower voltage than the power supply abnormality detection circuit 3, and operates faster than the power supply abnormality detection circuit 3. As shown in the reset signal (■) in FIG. 3, a logic "0" is sent to the AND circuit 9.

Therefore, the AND circuit 9 continues to send the logic "0" to the protection circuit 4, and the protection circuit 4 sends out the logic "1" which operates the circuit breaker of the internal power supply 2, as shown in the protection signal in FIG. do not.

When the voltage on the output side of the internal power supply device 2 reaches a predetermined voltage of 0 or more, the power supply abnormality detection circuit 3 detects the abnormality detection symbol [ in Fig. 3].
As shown in the phase], a logic "0" is sent to the AND circuit 9. Further, the reset circuit 8 sends a logic "1" to the AND circuit 9 when a predetermined time period shown in (■) of the reset signal in FIG. 3 has elapsed.

A failure occurs in the power receiving circuit of internal power supply device 2 or device 5,
When the voltage sent out by the internal power supply device 2 decreases and becomes below the predetermined voltage shown in ■ of the internal power supply in FIG. “
1'' to the AND circuit 9.

At this time, the reset circuit 8 is sending a logic "1" to the AND circuit 9 as shown in the reset signal in FIG.
The ND circuit 9 sends the protection signal to the protection circuit 4 as shown in the protection signal in FIG.
Sends logic “1”.

Therefore, since the protection circuit 4 operates the circuit breaker of the internal power supply device 2, the internal power supply bag W2 stops receiving the DC power transmitted from the external power supply device 1. Therefore, it is possible to prevent the circuit components of the internal power supply device 2 and the circuit components inside the device 5 to which power is supplied from the internal power supply device 2 from being destroyed due to continued flow of excessive current.

〔Effect of the invention〕

As explained above, since the present invention prevents the protection circuit from malfunctioning due to the power supply sequence, the reception of power from the external power supply does not stop even if there is no abnormality in the internal power supply or the power receiving circuit inside the device. .

Therefore, the reliability of the protection circuit can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a time chart explaining the operation of FIG. 2, and FIG.
The figure is a block diagram explaining an example of the prior art, and FIG. 5 is a time chart explaining the operation of FIG. 4. In the figure, 1 is an external power supply device, 3 is a power supply abnormality detection circuit, 5 is a device, 7 is a reset means, and 9 is an AND circuit. 2 is an internal power supply device, 4 is a protection circuit, 6 is a protection means, 8 is a reset circuit,

Claims (1)

[Claims] A device (5) that uses power supplied from an external power supply device (1) once received by an internal power supply device (2),
It starts operating when power is supplied from the external power supply device (1), and stops receiving power from the internal power supply device (2) when it monitors the output of the internal power supply device (2) and determines that it is abnormal. A protection means (6) and a reset means (7) that starts operating when power is supplied from the external power supply device (1) and prohibits operation of the protection means (6) for a predetermined period of time, The protection means (
6) A method for preventing malfunction of a power supply protection circuit, characterized in that the operation of stopping power reception to the internal power supply device (2) is prevented.