JPH05224785A - Device provided with overcurrent detection circuit - Google Patents

Abstract

PURPOSE:To prevent the malfunction of a signal interface circuit or the vanishing of stored data even when an overcurrent state is generated. CONSTITUTION:This device equipped with current detection circuit is provided with overcurrent detection circuits 1 and 2 connected to a power supply line 5, circuits 3 and 4, which are supplied power, connected these circuits 1 and 2, and signal interface circuit 8 to exchange interface signals between an external circuit and the circuits 3 and 4 to be supplied power. When the circuits 3 and 4 to which the power is supplied are in the overcurrent state, the overcurrent detection circuits 1 and 2 respectively generate overcurrent detection signals and while these overcurrent detection signals are received, an interface signal cut-off circuit 14 turns off only the exchange circuit of interface signals corresponding to the circuit to which the power is supplied in the overcurrent state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is responsible for a current-supplied circuit that performs the main function of an apparatus, an overcurrent detection circuit that detects an overcurrent state of this circuit, and a signal interface between the current-supplied circuit and an external circuit. The present invention relates to a device with an overcurrent detection circuit including a signal interface circuit, and particularly to a device with an overcurrent detection circuit having a function of stopping power supply to the signal interface circuit in the overcurrent state.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of an example of a conventional device with an overcurrent detection circuit of this type. This device supplies a current from the power supply line 5 and detects an overcurrent state in which the output current value to each of the output lines 6 and 7 exceeds a predetermined current value. And current detection circuit 1A for stopping the power supply to 7 and 7, respectively
And 2A, the power-supplied circuits 3 and 4 connected to the output lines 6 and 7 and supplied with current to perform the main function of this device, and the current supplied from the output lines 6 and 7 and the external circuit ( An interface signal line 9 is connected between the external interface line 11 connected to the power supply circuits 3 and 4 corresponding to the external interface line 11 (not shown).
And a signal interface circuit 8 for transmitting and receiving interface signals via

When the overcurrent detection circuits 1A and 2A detect an overcurrent state in which a current of a predetermined value or more, which is set in each of the power-supplied circuits 3 and 4, flows, the power supply line 5 to the output line 6 or 7 is detected. Stop the power supply of. As a result, in each of the power-supplied circuits 3 and 4, the adverse effect due to the occurrence of the overcurrent state can be prevented.

FIG. 5 is a block diagram of another example of a conventional device with an overcurrent detection circuit. In addition to the functions of the overcurrent detection circuits 6 and 7 described above, the overcurrent detection circuits 1 and 2 in this device generate overcurrent detection signals on the overcurrent detection signal lines 12 and 13 when detecting the overcurrent state. .. These signals 12 and 13 are added to the circuit of FIG. 4 and are supplied to the power supply disconnection switch circuit 15 which relays the current from the power supply line 5 to the signal interface circuit 8.

In the device of FIG. 5, when either of the overcurrent detection circuits 1 and 2 detects an overcurrent state, the power supply disconnection switch circuit 15 which receives the overcurrent detection signal from the overcurrent detection signal line 12 or 13 Signal interface circuit 8
Also stop the power supply to. As a result, this device prevents an adverse effect due to the occurrence of an overcurrent state in the power-supplied circuit 3 or 4 and also causes the power on the interface signal lines 9 and 10 to exceed the power supply voltage supplied from the output lines 6 and 7 when the power is turned on again. It is possible to prevent an adverse effect due to the high voltage.

In the device with an overcurrent detection circuit of FIGS. 4 and 5, when the overcurrent phenomenon is recovered by temporarily stopping the power supply as in the cause of the overcurrent due to the latch-up phenomenon or the like, the overcurrent detection is performed. The circuits 1 and 2 (1A and 2A) perform overcurrent detection according to the characteristics of the respective power-supplied circuits 3 or 4 by providing overcurrent detection levels of the same or different overcurrent detection values.
Further, in the conventional example, overcurrent detection circuits 1 and 2 (1A, 2A)
Also, an example having two circuits of the power-supplied circuits 3 and 4 is shown, but these circuits are respectively realized by one circuit or three or more circuits.

[0007]

The above-mentioned conventional device with an overcurrent detection circuit has the following problems.

First, when an overcurrent state occurs in any of the power-supplied circuits, the overcurrent detection circuit corresponding to this power-supplied circuit detects the overcurrent state to correspond to the power supply line. Disconnect the output line. However, if the cause of overcurrent is a latch-up phenomenon,
Once the power supply is stopped, the overcurrent condition is removed,
At the same time, there is a problem that the data stored in the RAM, the register, the buffer and the like having the built-in signal interface circuit are simultaneously lost.

Further, when one of the power-supplied circuits is in a power-supply-stopped state, some input interface signals to the signal interface circuit are in an open state, which causes problems such as malfunction and reliability deterioration. In some cases, the power-supplied circuit becomes unstable for a short time when the power is reapplied to the power-supplied circuit, and an abnormal signal is output to the signal interface circuit, so that data of the signal interface circuit and There were also problems such as changing the state.

[0010]

A device with an overcurrent detection circuit according to the present invention comprises at least one power-supplied supply circuit that fulfills the main function of the device, and a current from a power supply line to one of the power-supplied supply circuits. And an external circuit and the power source to be supplied with current from the power supply line, and the number of overcurrent detection circuits corresponding to the power source circuit to supply the current when the overcurrent state of the current is detected. In a device with an overcurrent detection circuit having a signal interface circuit that transmits and receives an interface signal to and from each of the supply circuits,
The overcurrent detection circuit generates an overcurrent detection signal by detecting the overcurrent state, and the device with the overcurrent detection circuit further includes the interface between the signal interface circuit and each of the current-supplied circuits. A face signal transmitting / receiving circuit is formed, and when the overcurrent detection signal is received from the overcurrent detection circuit, the overcurrent detection circuit corresponding to the overcurrent detection circuit that has generated this overcurrent detection signal is received during the period in which the signal is received. An interface signal disconnecting circuit for disconnecting the interface signal transmitting / receiving circuit between the current supply circuit and the signal interface circuit is provided.

[0011]

The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.

In addition to the conventional device with an overcurrent detection circuit shown in FIG. 4, this device with an overcurrent detection circuit is provided between the signal interface circuit 8 and the overcurrent supply circuits 3 and 4, respectively. During a period in which an interface signal transmission / reception circuit is formed and an overcurrent detection signal is received from any one of the overcurrent detection signal lines 12 and 13 of the overcurrent detection circuits 1 and 2, the received overcurrent detection signal is received. An interface signal disconnecting circuit 14 for disconnecting an interface signal transmitting / receiving circuit between one of the current-supplied circuits 1 and 2 corresponding to a signal and the signal interface circuit 8 is provided.

In this device, when the overcurrent detection circuit 1 detects an overcurrent state due to the occurrence of an overcurrent state in the power-supplied circuit 3, the overcurrent detection circuit 1 outputs the power supply line 5 and the output line 6. The connection with is disconnected and an overcurrent detection signal is generated on the overcurrent detection signal line 12. Then, the interface signal disconnection circuit 14 determines that the power-supplied circuit 1 is in the overcurrent state, and stops the output of the interface signal from the signal interface circuit 8 to the interface signal line 9. Then, the interface signal disconnecting circuit 14 keeps the interface for a certain time t until the overcurrent detection signal line 12 instructs the power supply circuit 3 to supply power, that is, until the overcurrent detection signal is stopped. Keep the signal off.

A power supply circuit 3 which is determined to be in an overcurrent state
No signal is output from the signal interface circuit 8 to the power-supplied circuit 3 until the power is turned on again by the overcurrent detection circuit 1 after a predetermined time t. Therefore,
In this device, when the power to the power-supplied circuit 3 is turned on again, the output signal voltage Vo1 of the signal interface circuit 8 is the input power supply voltage of the power-supplied circuit 3, that is, the output line of the overcurrent detection circuit 1. A state in which the voltage is larger than the voltage Vi of 6 Vo1> Vi
Can be prevented.

At this time, the signal interface circuit 8
Since the power is being supplied, the volatile data such as the RAM and flag register built in the signal interface circuit 8 can be correctly held. further,
Since the interface signal output from the power-supplied circuit 3 is also electrically disconnected from the signal interface circuit 8, even in an unstable state immediately after the power-supply voltage is reapplied to the power-supplied circuit 3, this It is possible to prevent the data in the signal interface circuit 8 from being adversely affected without sending the data in the unstable period to the signal interface circuit 8.

Needless to say, the above-described operation is similarly performed when an overcurrent state occurs in the power-supplied circuit 4 and the overcurrent detection circuit 2 detects this overcurrent state.

Here, the interface signal disconnection circuit 14
Then, one of the overcurrent detection signal lines 12 and 13 supplies the overcurrent detection signal, that is, the power supply circuit 1
Even if any of the signals 1 and 2 is in an overcurrent state, only the corresponding interface signal line 9 or 10 can be disconnected.

The interface signal disconnection circuit 1
4 is a period during which at least one of the overcurrent detection signals is received from the overcurrent detection signal lines 12 and 13,
All of the interface signal transmission / reception circuits connected to the respective current supply circuits 3 and 4 may be disconnected.

FIG. 2 is a block diagram of the overcurrent detection circuit 1 shown in FIG. Output line 6 supplied from power supply line 5
The level of the current output to the voltage comparator circuit 1 is checked by the voltage generated across the load element 1a.
is supplied to c. This voltage is compared with a predetermined reference voltage to determine whether the output current to the output line 6 is in the overcurrent state. When the output current is in the overcurrent state, the voltage comparison circuit 1c produces an overcurrent detection signal on the overcurrent detection signal line 12. The power switch 1b is automatically disconnected by this signal, and the power supply line 5 and the output line 6 are disconnected. The overcurrent detection signal line 12, for example, produces a certain voltage value Vok when not in the overcurrent state, and shows another voltage value Vover when the overcurrent state is detected. In the power switch 1b, the overcurrent detection signal line 12 is Vo
Only the state k is set to the connection state, and the overcurrent detection signal line 12 is set to the disconnection state when it is in the state of Vover. Therefore,
When the overcurrent state is detected, the voltage comparison circuit 1c sets the voltage value of the overcurrent detection signal line 12 to Vover for a certain time t.
Then, during this time t, the power switch 1b is turned off. On the other hand, after the elapse of this time t, the voltage comparison circuit 1
b returns the voltage on the current detection signal line 12 to Vok, sets the power switch 1b to the connected state, and the power supply line 5 and the output line 6 are automatically reconnected.

The voltage V on the overcurrent detection signal line 12 is
Switching from over to Vok can also be switched by a command from an external circuit.

FIG. 3 is a block diagram of the interface signal cutting circuit 14 shown in FIG. The interface signal disconnecting circuit 14 includes an interface signal line 9 (9) connected to each of the current-supplied circuit 3 and the current-supplied circuit 4.
a, 9b) and 10 (10a, 10b) based on the overcurrent detection signal on the overcurrent detection signal lines 12 and 13, an interface for the current supply circuit 3 for electrically connecting and disconnecting the interface signal. The signal cutting circuit 14A and the interface signal cutting circuit 14B for the current-supplied circuit 4 are provided. These interface signal cutting circuits 14
A and 14B have the same configuration.

The interface signal disconnecting circuit 14A receives the signal interface circuit from the output buffer control line 8a which is one of the output lines of the signal interface circuit 8 and the overcurrent detection signal on the overcurrent detection signal line 12. The output interface line 8b, which is another one of the eight output lines, is provided to the interface signal output line 9a connected to the current supply circuit 3 and has a logic circuit 14a for determining whether or not to output the signal. It controls whether or not to output an interface signal from the face circuit 8 to the current-supplied circuit 3.

The interface signal disconnecting circuit 14 is also provided.
A is for further controlling connection / disconnection of the interface signal line 9b connected to the current-supplied circuit 3 as well as the output line of the signal interface circuit 8 and the overcurrent detection signal on the overcurrent detection signal line 12. One input buffer control line 8c
It has a logic circuit 14c that makes a logical determination as to whether or not the interface signal input line 9b, which is the output line of the current-supplied circuit 3, is input to the signal interface circuit 8.

In the description with reference to FIGS. 1 and 3, the interface signal lines 9 and 10 have been described as unidirectional signal lines, but it goes without saying that bidirectional signal lines can be similarly realized. The same applies to the case where the signal lines 9 and 10 are blocked by a plurality of signal lines.

[0026]

As described above, according to the present invention, the interface signal disconnecting circuit for connecting and controlling the interface signal line for transmitting the interface signal between the signal interface circuit and the current-supplied circuit is added, In the overcurrent state, by cutting only the interface signal line of the signal interface circuit, the following effects are produced.

1. It is possible to prevent malfunction and deterioration of reliability of the signal interface circuit due to the voltage of the interface signal line becoming higher than the power supply voltage of the current supply circuit when the power supply to the current supply circuit is turned on again.

2. When the power to the current-supplied circuit is turned on again, the abnormal signal from the current-supplied circuit is not input to the signal interface circuit, so that the data and state of the signal interface circuit can be kept stable.

3. Even if an overcurrent occurs in the current supply circuit, it is possible to prevent the loss of data in the RAM, flag register, etc. built in the signal interface circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of a device with an overcurrent detection circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of an overcurrent detection circuit 1 shown in FIG.

FIG. 3 is an interface signal disconnection circuit 14 shown in FIG.
It is a block diagram of.

FIG. 4 is a block diagram of an example of a conventional device with an overcurrent detection circuit.

FIG. 5 is a block diagram of another example of a conventional device with an overcurrent detection circuit.

[Explanation of symbols]

 1,1A, 2,2A Overcurrent detection circuit 3,4 Power supply circuit 5 Power supply line 6,7 Output line 8 Signal interface circuit 9,10 Interface signal line 11 External interface line 12,13 Overcurrent detection Signal line 14 Interface signal disconnection circuit 15 Power supply disconnection switch circuit 1a Load element 1b Power supply switch 1c Voltage comparison circuit 8a Output buffer control line 8b Output interface line 8c Input buffer control line 8d Input interface line 8e Output buffer control line 8f Output Interface line 8g Input buffer control line 8h Input interface line 9a Interface signal input line 9b Interface signal output line 10a Interface signal input line 10b Interface signal output line 14A, 14B Interface signal disconnection circuit 14a Logic circuit 4b the output buffer 14c logic circuit 14d input buffer 14e logic circuit 14f output buffer 14g logic circuit 14h input buffer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H02H 3/08 A 9061-5G

Claims (3)

[Claims] 1. At least one power-supplied circuit that fulfills the main function of the apparatus, and a current is supplied from a power supply line to one of the power-supplied circuits while the current is detected when an overcurrent state of the current is detected. A number of overcurrent detection circuits corresponding to the power-supplied circuits for which supply is stopped, and a signal interface for transmitting and receiving an interface signal between the external circuit and each of the power-supplied circuits supplied with current from the power supply line. In a device with an overcurrent detection circuit having a face circuit, the overcurrent detection circuit generates an overcurrent detection signal by detecting the overcurrent state, and further, the device with an overcurrent detection circuit, the signal interface circuit and A transmitting / receiving circuit for the interface signal is formed between each of the current-supplied circuits, and the overcurrent detection signal is sent from the overcurrent detection circuit. Then, while receiving this signal, the interface signal transmission / reception circuit between the current supplied circuit and the signal interface circuit corresponding to the overcurrent detection circuit that has generated this overcurrent detection signal is disconnected. An apparatus with an overcurrent detection circuit, comprising: 2. A current detection circuit that generates the overcurrent detection signal for a predetermined time when the overcurrent detection circuit detects the overcurrent state, and the power supply line during a period in which the overcurrent detection signal is received. 2. A device with an overcurrent detection circuit according to claim 1, further comprising a power supply switch circuit for stopping current supply from the power supply circuit to the power supplied circuit. 3. The interface signal disconnection circuit disconnects all the interface signal transmission / reception circuits during a period in which the interface signal disconnection circuit receives at least one of the overcurrent detection signals. Equipment with current detection circuit.