JPH0454819A - Voltage supply circuit - Google Patents

Abstract

PURPOSE:To prevent overdetection of abnormality in an internal voltage supply by blocking an abnormality detection signal from being inputted to a protective circuit if the abnormality detection signal is provided from a voltage supply abnormality detection circuit before a predetermined time elapses after provision of a voltage supply start command to the voltage supply. CONSTITUTION:An abnormality detection signal blocking circuit 14 comprises a timer circuit 14a for measuring the time to be elapsed after provision of a voltage supply start command to an internal voltage supply 11 and outputting a transient signal, and a switching circuit 14b. A voltage to be applied on the base of a transistor T3 141 rises logarithmically with a time constant to be determined by a capacitor 144 and a resistor 145. Since the transient signal is not provided from the timer circuit 14a so long as the T3 141 is turned ON, the T2 143 remains in ON state thus blocking the abnormality detection signal from being inputted to a protective circuit 12 even if it is outputted from a voltage supply abnormality detection circuit 13.

Description

[Detailed Description of the Invention] (Summary) A voltage source that supplies voltage according to instructions, and a voltage source that detects a voltage abnormality in which the power supply voltage value of the voltage source falls below an abnormality detection voltage value and outputs an abnormality detection signal. Regarding voltage source circuits that have an abnormality detection circuit and a protection circuit that instructs the voltage source to stop supplying voltage when an abnormality detection signal is input, it prevents over-detection of voltage abnormalities of the internal voltage source and reduces malfunctions. In order to provide a voltage source circuit that is easy to handle and reliable, the voltage source abnormality detection circuit detects the abnormality from the time when the voltage source is instructed to start supplying voltage until a predetermined period of time has elapsed. The configuration includes an abnormality detection signal blocking circuit that blocks input of the abnormality detection signal to the protection circuit when a signal is input.

[Industrial application field]

The present invention relates to a voltage source circuit such as an internal circuit, and particularly relates to a voltage source that supplies voltage according to an instruction, and an abnormality detection signal that is generated by detecting a voltage abnormality in which the power supply voltage value of the voltage source falls below an abnormality detection voltage value. The present invention relates to a voltage source circuit that includes a voltage source abnormality detection circuit that outputs a voltage source, and a protection circuit that instructs the voltage source to stop supplying voltage when an abnormality detection signal is input.

[Conventional technology]

Conventionally, there has been a circuit as shown in FIG.

As shown in the figure, this circuit has an external power source 1 in the external circuit.
5 and an internal circuit 50.
includes an internal voltage source 11 that supplies voltage according to instructions, a voltage source abnormality detection circuit 53 that detects an abnormality in the power supply voltage value of the voltage source 11 and outputs an abnormality detection signal, and when there is an abnormality detection signal. and a protection circuit 12 that instructs the internal voltage source 11 to stop supplying voltage.

The operation of this example will be explained based on FIG.

When the voltage of the external power supply 15 is raised (■), the internal voltage source 11 of the internal circuit 50 starts operating accordingly (■). The output signal of the internal voltage source 11 is input to the voltage source abnormality detection circuit 53.

The voltage source abnormality detection circuit 53 compares the voltage value of the output signal with an abnormality detection voltage predetermined for the voltage source abnormality detection circuit 53, and determines that the voltage of the output signal is lower than the abnormality detection voltage value. In this case, an abnormality detection signal will be sent to the protection circuit 12. This is the internal voltage source 1
There is a high possibility that the output voltage of the internal voltage source 1 becomes abnormal due to contact between the internal voltage source 11 and GND, which is the reference voltage (=0).
This is because it is common that 1 is a voltage value closer to GND than the voltage value to be output, 1 internal constant voltage 1>1 abnormality detection voltage 1.

When there is an abnormality detection signal, the protection circuit 12 instructs the internal voltage source 11 to stop supplying voltage.

[Problem to be solved by the invention]

By the way, in the voltage source circuit according to the conventional example, as shown in FIG. The value will rise with a certain time lag.

At that time, the output signal is taken into the voltage source abnormality detection circuit 53, and since the voltage value passes through a state where it does not reach the abnormality detection voltage, as shown in (■) in FIG. 6(c), the voltage source The abnormality detection circuit 53 sends an abnormality detection signal to the protection circuit 12. After that, Fig. 6(b)
), when the voltage value of the internal voltage source 11 exceeds the abnormality detection voltage value, the output of the abnormality detection signal is stopped as shown in (c) of the figure.

When there is an abnormality detection signal, the protection circuit 12 operates as shown in FIG.
), a protection circuit control signal is sent to the protection circuit 12, instructing to stop the voltage supply from the voltage source 11.

That is, in the voltage source circuit according to the conventional example, after the external power source 15 is turned on, but before the internal voltage source is completely turned on, the voltage source abnormality detection circuit 53 does not operate.
), as a result, there is a problem in that an abnormality in the voltage source is over-detected, the protection circuit is activated, and the internal voltage source circuit latches up (stops the voltage supply).

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent over-detection of voltage source abnormalities in an internal voltage source and provide a reliable voltage source circuit.

[Means to solve the problem]

In order to solve the above technical problems, the present invention, as shown in FIG. Voltage source abnormality detection circuit 3 detects an abnormality and outputs an abnormality detection signal, and voltage source 1 detects an abnormality and outputs an abnormality detection signal.
In a voltage source circuit having a protection circuit 2 that instructs the voltage supply to stop, the voltage source abnormality detection circuit 3 detects the When an abnormality detection signal is input,
An abnormality detection signal blocking circuit 4 for blocking input of an abnormality detection signal to the protection circuit 2 is provided.

(effect) The voltage source circuit according to the present invention operates as follows.

As shown in the action explanatory diagram of FIG. 2, for example, when the voltage source 1 is instructed to supply voltage by starting up the external power supply (■), the output voltage of the voltage source 1 is as shown in FIG. 2 (b). As shown in , it starts up at certain time intervals (■).

The output signal from the voltage source 1 is input to the voltage source abnormality detection circuit 3. Then, the voltage source abnormality detection circuit 3 compares the voltage value of the output signal with the abnormality detection voltage.

At this time, the voltage value of the voltage source 1 necessarily passes through a stage where it does not reach the abnormality detection voltage value and reaches a voltage exceeding the abnormality detection voltage. Therefore, the voltage source abnormality detection circuit 3 detects the voltage abnormality of the voltage source 1 and, for example, as shown in FIG. 2(C), until the voltage of the voltage source 1 reaches the abnormality detection voltage, An abnormality detection signal (■, ■) indicating that the voltage of the voltage source 1 is abnormal is sent to the abnormality detection blocking circuit 4.

On the other hand, the abnormality detection signal blocking circuit 4 measures time from the time when the instruction to start voltage supply is received, and the abnormality detection signal from the voltage source abnormality detection circuit 3 is detected before a predetermined time elapses (■). Even if the signal is input, the passage of the signal to the protection circuit 2 will be blocked.

Here, the term "predetermined time" refers to a time interval that includes the time period until the voltage of the voltage source 1 reaches the abnormality detection voltage.

Therefore, when the voltage source 1 rises, the input of the abnormality detection signal of the voltage value of the voltage source 1 to the protection circuit 2 is blocked, and thereafter, as shown in FIG. True voltage abnormality caused by contact with another power source (GND) (
■) is detected as a voltage abnormality by the voltage source abnormality detection circuit 3 as shown in FIG. 2(C) (■), and (e
), an abnormality detection signal (■) is sent to the protection circuit 2.
will be sent.

(Example) Next, a voltage source circuit according to an example of the present invention will be described.

FIG. 3 shows a voltage source circuit according to this embodiment.

This voltage source circuit has an external power supply 15 located in an external circuit and an internal circuit 10.

The internal circuit IO has a voltage source 1 that supplies voltage according to instructions.
1, a voltage source abnormality detection circuit 13 that detects a voltage abnormality in which the power supply voltage value of the voltage s11 is lower than the abnormality detection voltage value and outputs an abnormality detection signal; A protection circuit 12 instructs the voltage supply to stop, and a voltage source abnormality detection circuit 1 for a predetermined period of time after the voltage source 11 is instructed to start voltage supply.
An abnormality detection signal blocking circuit 14 that blocks the input of the signal to the protection circuit 12 when there is an abnormality detection signal from 3.
It has been established that

Further, as shown in FIG. 3, the voltage source abnormality detection circuit 13 includes a transistor T, 134, a Schottky diode D135, and current value adjusting resistors 131, 132, 1.
33.

Further, the abnormality detection signal blocking circuit 14 includes a timer circuit 14a that measures the time from when the internal voltage source 11 is instructed to start supplying voltage until a predetermined period of time has elapsed and outputs a elapsed signal, and a timer circuit 14a. Even if an abnormality detection signal is input from the voltage source abnormality detection circuit 13 before the progress signal from the voltage source is input, the passage of the abnormality detection signal is blocked, and if the abnormality detection signal is input after the progress signal is input, the abnormality is detected. It has a switching circuit 14b that allows passage of the detection signal.

The timer circuit 14a has a resistor of 145°146.147
, 148, 149, and 150, transistors 141 and 142 forming a working pair, and a capacitor 144 that is involved in the time constant of the "predetermined time".

Further, the switching circuit 14b includes a transistor 7.
2143.

Next, the operation of the voltage source circuit according to this embodiment will be explained based on FIG. 4.

As shown in (a) of the figure, when the external power supply 15 is turned on and the voltage (■) begins to rise, the internal voltage source 11 is instructed to start supplying voltage, as shown in (b) of the figure. As shown in , the voltage of the internal voltage source 11 (■)
starts rising after a certain period of time has elapsed after the start instruction, and reaches a predetermined constant voltage value vi.

Here, the power supply voltage y cc is divided in advance by the resistor 131 and the resistor 132 so that the voltage value of Vb8 (for example, 0.7 V) is reached at which the transistor T134 is turned on. The Schottky diode D135 has a voltage value Vr smaller than the voltage value of the vb8 (for example,
0.4V) is assumed to be in the cutoff state or conduction state.

Then, as shown in FIG. 4(C), the transistor 'r
, 134 is higher than the voltage value of ■ as long as the voltage ■i of the internal voltage source 11 is Ov) 7
l 134 (') Vbe (> V t ) (')
is higher, the Schottky diode 135 becomes conductive, the base voltage of the transistor 7.134 decreases and turns off, and the voltage source abnormality detection circuit 13 outputs an abnormality detection signal (voltage vcc). When the voltage value Vi of the internal voltage source 11 reaches a certain voltage value, the vbe of the transistor T1134 becomes smaller than the voltage value v, +V, the Schottky diode 135 becomes cut off, and the transistor T134 is turned on, a signal having a voltage value lower than the voltage value vcc is output, and the abnormality detection signal is not output.

Therefore, the "abnormality detection voltage" is the internal voltage source 1.
The voltage value v5 of the
(V)-0,4(V)-0,3(V) is the abnormality detection voltage.

On the other hand, when the voltage of the external power supply 15 begins to rise,
V of the internal circuit 10 having a value equal to the external voltage.

Since the value of C also starts to rise, the corresponding ycc is connected to the resistor 146.
, 147, 148 is applied with a waveform as shown in FIG. 4(d). On the other hand, the waveform of the voltage applied to the base of the transistor T, 141 has a time constant CR obtained by the capacitance C of the capacitor 144 and the resistance value R6 of the resistor 145, as shown in FIG.

It shows a logarithmic rise determined by .

Therefore, as long as the transistor T3141 is in the on state, the elapsed signal is not output from the timer circuit 14a, the transistor T143 is in the on state, and the abnormality detection signal is connected to the base of the transistor T143. Even if the output is output from the circuit 13, the protection circuit 12
Input of the abnormality detection signal (which is at voltage level Vcc and corresponds to the protection circuit control signal) is blocked.

On the other hand, as shown in FIG. 4(d), after the intersection of both waveforms (ttow), the elapsed signal is input from the timer circuit 14a to the base, so the transistor T, 141 is in an OFF state, and the transistor T, 142 is in an ON state. state, and the fourth
As shown in Figure (e), the transistor T 143 is turned off, the internal voltage source 11 comes into contact with GND, a drop in the voltage value is detected, and the abnormality detection signal is sent from the voltage source abnormality detection circuit 13. When the abnormality detection signal is output, the abnormality detection signal is inputted to the protection circuit 12.

Therefore, even if the voltage source abnormality detection circuit 13 detects an abnormality due to a drop in voltage and the transistor T 134 turns off, from the time the external power source is turned on until the time tl)2, no progress will be made. The signal is not input to the base of the transistor T2143, and the transistor T2143 is turned on, and the protection circuit control signal ("1'"), which is an abnormality detection signal, is output to the protection circuit 12, as shown in FIG. 4(f). Sending will be blocked.

Here, the time tD2 (while the voltage of ■ is lower than the voltage of ■) corresponds to the above-mentioned "predetermined time" and is
As is clear from a) and (e), time to2 must be greater than time tD□.

On the other hand, as shown in FIG. 4(d), after the intersection of both waveforms (t), the elapsed signal from the timer circuit 14a is input to the base, so the transistor T3141 is turned off, and as shown in FIG. 4(e). As shown in , when the transistor 7.143 is turned off, the internal voltage source 11 comes into contact with GND, a drop in the voltage value is detected, and the abnormality detection signal is output from the voltage source abnormality detection circuit 13. The abnormality detection signal is input to the protection circuit 12,
The internal voltage source 11 is instructed to stop supplying voltage.

Note that the timer circuit and the voltage source abnormality detection circuit are not limited to those described above, and other known circuits may of course be used.

(Effects of the Invention) As explained above, the present invention provides an abnormality detection signal blocking circuit in the voltage source circuit, so that the voltage source abnormality can be detected for an initial certain period of time when the internal voltage source is instructed to start supplying voltage. Even if the detection circuit detects a voltage abnormality because the voltage value of the voltage source is low, the signal to the protection circuit is blocked.

Therefore, it is possible to prevent over-detection of voltage source abnormalities in the internal voltage source, and to obtain a voltage source circuit that is reliable and easy to handle with few malfunctions.

[Brief explanation of the drawing]

Fig. 1 is a principle block diagram of the present invention, Fig. 2 is an explanatory diagram of the operation of the invention, Fig. 3 is a circuit diagram according to the embodiment, Fig. 4 is an explanatory diagram of the operation according to the embodiment, and Fig. 5 is a conventional example. A block diagram related to
and Is6 are action explanatory diagrams according to the conventional example. 1 (11)... Voltage source (internal voltage source) 2.12...
Protection circuit 3.13...Voltage source abnormality detection circuit 4.14-...Abnormality detection signal blocking circuit Agent

Claims (2)

[Claims] (1) A voltage source (1) that supplies voltage according to instructions, and a voltage source that detects a voltage abnormality in which the power supply voltage value of the voltage source (1) drops below the abnormality detection voltage value and outputs an abnormality detection signal. In a voltage source circuit having a detection circuit (3) and a protection circuit (2) that instructs the voltage source (1) to stop supplying voltage when an abnormality detection signal is input, supplying voltage to the voltage source (1). If the abnormality detection signal is input from the voltage source abnormality detection circuit (3) before a predetermined period of time elapses after the start instruction is given, the protection circuit (2
) A voltage source circuit characterized in that it is provided with an abnormality detection signal blocking circuit (4) that blocks input of an abnormality detection signal to the voltage source circuit. (2) In the abnormality detection signal blocking circuit according to claim 1, the elapsed signal indicates that the predetermined time has elapsed by measuring the time from the time when the voltage source is instructed to start supplying voltage to the elapse of the predetermined time. Even if an abnormality detection signal is input before the elapsed signal is input,
A voltage source circuit comprising: a switching circuit that blocks passage of the abnormality detection signal and allows passage of the abnormality detection signal when the abnormality detection signal is input after the elapsed signal is input.