JPH11178193A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit with a safety circuit for interrupting a power switch surely when the voltage or current is abnormal and being restored automatically after interrupting a switch temporarily in case of a temporary abnormality due to noise, for example. SOLUTION: Upon occurrence of an abnormal voltage or current, an abnormality detection circuit 4 detects the abnormality and delivers a signal for interrupting a line switch 2 to a latch circuit 5. Upon elapsing a predetermined time, a reset circuit 6 delivers an unlatch signal to the latch circuit 5 and the line switch 2 is connected. A number of trial limiting circuit 7 sets the number of times for trying interruption and connection of the line switch 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit.

[0002]

2. Description of the Related Art A power supply device used in an information processing apparatus such as a notebook personal computer is provided with a converter for supplying rated power to devices such as a CPU and a memory, and a safety circuit for protecting the device. .

[0003] When a voltage higher than a predetermined value or a current is applied to a CPU, a memory, or the like, an expensive device may be destroyed, and the information processing apparatus may be in a dangerous state such as smoking or ignition. There is. Therefore, an abnormality detection circuit is provided to provide a safety circuit that shuts off a switch at the root of a power supply line such as an AC adapter or a battery when an overvoltage or an overcurrent occurs.

FIG. 4 shows the operation of the power supply device in a conventional notebook personal computer or the like when the voltage is abnormal.

In FIG. 1, reference numeral 51 denotes an AC adapter, a power supply such as a battery, 52 denotes a line switch at the root of the power supply, 53 denotes a DC / DC converter, 54 denotes an abnormality detection circuit, and 55 denotes a processing circuit.

[0006] The DC / DC converter 53 converts a DC voltage supplied from the power supply 51 and supplies power suitable for devices such as a CPU and a memory in the processing circuit 55. The abnormality detection circuit 54 includes the DC / DC converter 5
3 is detected. When the abnormality detection circuit 54 detects an abnormality, it shuts off the line switch 52 to protect the processing circuit 55.

[0007]

However, the conventional safety circuit has a problem that when an abnormality such as an overvoltage or an overcurrent is detected, the connection and disconnection of the line switch are repeated until the abnormality is removed.

FIG. 4 illustrates this phenomenon. FIG. 4A shows that the voltage is a normal value and the line switch 52 is in a connected state. FIG. 4B shows a state at the time of abnormality, in which the abnormality detection circuit 54 detects an abnormality in voltage, sends a signal to the line switch 52, and the line switch 52 is shut off. FIG. 4 (b)
In this case, since the power supply from the power supply 51 is stopped, the voltage detected by the abnormality detection circuit 54 is within the normal range for a moment. The voltage apparently returns to a normal value, the abnormality detection circuit 54 is released, and the line switch 52 is reconnected. However, since the cause of the abnormality has not been removed, the abnormality detection circuit 54
Detects an abnormality and shuts off the line switch 52. Therefore, the line switch 52 repeats the connection and disconnection operations until the abnormal voltage is removed.

The present invention prevents such repetition of connection / disconnection of a line switch, and further includes a power supply having a safety circuit for automatically resetting the line switch after a certain period of time when an abnormality is detected due to a malfunction such as noise. It is intended to provide a device.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a power supply device according to the present invention is provided with a latch circuit for shutting off a line switch until an abnormality is removed when a safety circuit is activated due to overvoltage or overcurrent. And the repetition of connection / disconnection of the line switch can be eliminated by the latch circuit.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a power supply, a cutoff circuit for cutting off the supply of power from the power supply, a converter for converting a voltage supplied from the power supply, An abnormality detection circuit that detects an abnormality such as a current, and a latch circuit that latches an abnormal state detected by the abnormality detection circuit, wherein when the abnormality detection circuit detects an abnormality, It has the function of reliably preventing repetition of connection / disconnection of the line switch.

According to a second aspect of the present invention, there is provided the first aspect of the present invention, comprising a reset circuit having a timer function for resetting the latch circuit, and a trial number limiting circuit for limiting the number of resets. This has the function of automatically returning the line switch when the abnormality detection circuit detects an abnormality due to a malfunction such as noise.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention, and FIG. 2 is an operation explanatory diagram.

In FIG. 1, 1 is a power supply such as an AC adapter and a battery, 2 is a line switch at the root of the power supply 1, 3 is a DC / DC converter for converting a voltage from the power supply 1 to a voltage corresponding to each device, 4 is a detection circuit for detecting an overvoltage or overcurrent abnormality, 5 is a latch circuit for receiving a detection signal at the time of abnormality, and latching the cutoff of the line switch 2, 6 is a reset & timer circuit, 7 is a circuit for limiting the number of trials, 8 is C
This is a processing circuit including devices such as a PU and a memory.

In FIG. 1, when an overvoltage or overcurrent abnormality occurs due to, for example, a failure of the DC / DC converter 3, an abnormality detection circuit 4 detects the abnormality and sends a signal to a latch circuit 5, and the latch circuit 5 Block 2
By disconnecting the line switch 2 via the latch circuit 5, the line switch 2 is not connected again even if the abnormality detection circuit 4 detects the instantaneous normal voltage and current after the line switch 2 is disconnected.

Therefore, it is possible to solve the conventional repeated connection / disconnection of the line switch 2.

Since the malfunction detection circuit 4 may malfunction due to temporary factors such as noise, the addition of the latch circuit 5 may not be sufficient in some cases. For this reason,
A reset & timer circuit 6 and a trial number limiting circuit 7 are connected to the latch circuit 5 of the embodiment.

The operations of the reset & timer circuit 6 and the trial number limiting circuit 7 will be described with reference to FIGS. FIG. 2 shows a case where the cause of the abnormality is an essential abnormality due to a failure of the DC / DC converter 3 or the like, and FIG. 3 shows a case where the cause of the abnormality is a temporary abnormality such as noise, the line switch 2, the abnormality detection circuit 4, and the latch circuit 5. FIG. 4 is a diagram for explaining operations of a reset & timer circuit 6 and a trial number limiting circuit 7.

In FIG. 2, when the abnormality detecting circuit 4 detects the first abnormality 10, the latch circuit 5 sets the line switch 2 to the cutoff state 11. Reset & timer circuit 6
At the same time as the first detection of the abnormal signal 10, for example, the clock counter operates to start measuring the elapsed time from the abnormal signal 10. After a certain period of time, the reset & timer circuit 6 sends the first reset signal 12 to the latch circuit 5, and the latch circuit 5 sets the line switch 2 to the connection state 13. The above operation is repeated as many times as the number of times set in the trial number limiting circuit 7.
After the third time, the cutoff state 14 of the line switch 2 is maintained.

In the case of FIG. 3, a first reset signal 16 is transmitted a predetermined time after the abnormality detection circuit 4 detects the first abnormality 15, and the line switch 2 is brought into the connection state 17. The reset & timer circuit 6 issues a reset signal so as to shut off the latch circuit 5 up to the set number of times 5, but since the latch circuit 5 is already in the cutoff state 18, the signal is ignored and the power switch 2 changes the connection state 17 to the connection state 17. Keep holding.

[0021]

As described in the above embodiment, according to the present invention, when an abnormality such as an overvoltage or an overcurrent occurs, the line switch is cut off until the abnormality is removed, thereby preventing the line switch from being repeatedly connected / cut off. . In addition, the line switch automatically recovers from temporary abnormality detection due to factors other than overvoltage and overcurrent.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the power supply device according to the embodiment of the present invention;

FIG. 3 is an operation explanatory diagram of the power supply device according to the embodiment of the present invention;

FIG. 4 is a block diagram of a conventional safety circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply device 2 Line switch 3 DC / DC converter 4 Abnormality detection circuit 5 Latch circuit 6 Reset & timer circuit 7 Trial number limiting circuit 8 Processing circuit

Claims (2)

[Claims] 1. A power supply, an interruption circuit for interrupting supply of electric power from the power supply, a converter for converting a voltage supplied from the power supply, an abnormality detection circuit for detecting an abnormality in voltage, current, and the like, and an abnormality detection And a latch circuit for latching an abnormal state detected by the circuit. 2. The power supply device according to claim 1, further comprising a reset circuit having a timer function for resetting the latch circuit, and a trial number limiting circuit for limiting the number of resets.