KR19980056367U - Abnormal voltage instantaneous detection device in microcontroller - Google Patents

Abstract

An apparatus for instantaneously detecting an abnormal voltage in a microcontroller is disclosed. The apparatus includes a detection circuit for setting a voltage value to be detected and a latch circuit. The detection circuit includes a power supply connection terminal connected to a reset voltage terminal of the internal circuit of the microcontroller, an input terminal connected to the power supply terminal of the internal circuit of the microcontroller, and an output terminal connected to the input terminal of the latch circuit. One is NOT gate. The output terminal of the latch circuit may output a flag signal indicating an abnormal voltage in the microcontroller. Accordingly, whenever the microcontroller voltage changes to a non-rated value, such a voltage change is momentarily detected and latched by a signal such that the flag signal output from the output terminal of the latch circuit indicates an abnormal voltage signal. Causes the controller to be interrupted or reset momentarily.

Description

Abnormal voltage instantaneous detection device in microcontroller

The present invention relates to an apparatus for detecting an abnormal voltage instantaneous in a microcontroller, and more particularly, an abnormal voltage indicating that an instantaneous voltage change to a non-rated value is detected by detecting an instantaneous voltage of a microcontroller and indicating that the change has occurred. It relates to a digital circuit that outputs a signal so that the microcontroller is immediately interrupted or reset based on it.

Conventional microcontrollers can operate normally only within a certain supply voltage range. Once the supply voltage exceeds the normal range, the microcontroller will behave abnormally. Therefore, when an abnormal supply voltage is applied to the microcontroller, the microcontroller must be reset until the supply voltage is normal again using a recent design technique for protecting the microcontroller from the abnormal supply voltage causing the microcontroller to malfunction. do. The microcontroller then restarts and operates. To meet these conditions, a voltage detection device for checking the supply voltage is needed near the microcontroller.

In the voltage detection device generally designed as shown in Fig. 1A, a voltage detector including an analog circuit is employed. However, typical microcontrollers do not use such voltage detectors because the analog circuit architecture is not very satisfactory for systems requiring reduced power consumption. 1B and 1C show another conventional voltage detection device for use in a microcontroller. As shown, the microcontroller is equipped with an external reset pin for the user. The external reset pin requires an external circuit that includes an RC low pass filter structure. International application published on 11 July 1996 (application number: PCT / WO 96/21158) discloses this structure. In this design, the voltage at the reset pin changes with the supply voltage only when the supply voltage drops for a fairly long time to generate an appropriate reset signal. Nevertheless, even if the supply voltage suddenly drops from a stable state and then recovers within a short time, such a momentary change can cause abnormal operation of the microcontroller and, in extreme cases, can cause a failure. That is, the conventional voltage detection apparatus shown in FIGS. 1B and 1C cannot detect an abnormal abnormal voltage, and can detect a voltage change and generate a reset signal only when the voltage change continues for a predetermined maximum time interval.

Therefore, the present inventors have tried to develop a device for instantaneously detecting an abnormal voltage in a microcontroller, eliminating the disadvantage of the conventional device to achieve a similar purpose.

The main object of the present invention is to provide an apparatus for instantaneously detecting an abnormal voltage in a microcontroller.

1A illustrates a conventional voltage detector including an analog circuit.

1B is a diagram illustrating an apparatus for detecting an abnormal voltage in a conventional microcontroller.

1C is a view showing another example of an abnormal voltage detection device in a conventional microcontroller.

2 is a logic circuit diagram of a device according to the present invention.

3 is a graph showing that an abnormal voltage is detected in the device of the present invention.

Abnormal voltage instantaneous detection device of the present invention for achieving the above object is that when the power supply voltage suddenly drops, the comparison time in the internal logic circuit changes as the power supply voltage changes so that an incorrect instantaneous detection result is not obtained. Instead of using the microcontroller's power supply voltage, the voltage at the reset pin is used, which has the same characteristics as low pass filtering the power supply voltage.

Furthermore, since the present invention uses a digital circuit instead of a conventional analog circuit, it reduces power consumption at the reset voltage setting pin and shortens the voltage drop time interval required for detection.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that the specific structure, applied principles, functions, and performances of the present invention can be understood.

2 is a logic circuit diagram of a device according to the present invention. As shown in Fig. 2, the apparatus includes a detection circuit 1 for setting a voltage value to be detected and a latch circuit 2.

The detection circuit 1 includes a NOT gate 10, which preferably is a CMOS. The NOT gate 10 is an input for connecting to a power supply connection terminal P1 for connecting to a reset voltage terminal Vres of an internal circuit of a microcontroller to be detected and a power supply terminal VDD for an internal circuit of a microcontroller. The terminal P2 is provided. The NOT gate 10 also has an output terminal PFDO connected to the input terminal P3 of the latch circuit 2.

The latch circuit 2 may be composed of a flip flop or a latch functionally equivalent to the flip flop. As shown, when the flip-flop 11 is used in the latch circuit 2, the clock input terminal CB of the flip-flop 11 is connected to the output terminal PFDO of the NOT gate 10, and data input is performed. The terminal D and the power supply connection terminal P4 are connected to the reset voltage terminal Vres of the internal circuit of the microcontroller to be detected. The output terminals Q and R of the latch circuit 2 may output flag signals PFF indicating the detected abnormal voltage. These flag signals PFF may be connected to a reset circuit (or a reset terminal of a microcontroller), may cause an unconditional interrupt to be initiated, and the user may use it only to determine whether an abnormal state is present. May be provided to the user. Thus, whenever the microcontroller voltage changes instantaneously to the non-rated value, this change is detected and latched by the signal, causing the flag signal PFF to generate an abnormal voltage signal at the output terminals of the latch circuit 2 so that the micro Causes the controller to be interrupted or reset.

Since the detection potential of the detection circuit 1 can be set by selectively varying during fabrication of the mask to satisfy the needs of the entire system to which the device of the present invention is applied, various needs in the application of the device of the present invention (Needs) can be satisfied.

3 is a graph showing how the device of the present invention operates when an abnormal voltage is applied to the microcontroller.

In FIG. 3, a broken line L1 is a line showing voltage variation with respect to time obtained from the above-described power supply terminal VDD. Curve L2 is a time-varying voltage variation curve obtained from the reset voltage terminal Vres. The cutting line L3 is a line showing the voltage variation with respect to time obtained from the reset output terminal RESET. The cut line L4 is a line showing the voltage variation with respect to time obtained from the power failure detector output terminal (PFDO) of the NOT gate 10. In addition, the cutting line L5 is a line showing voltage variation with respect to time obtained from the flag signal output terminal PFF.

As shown, for both the power supply terminal VDD and the reset voltage terminal Vres, there are instantaneous voltage drops and long voltage drops in the time intervals T1 and T2, respectively. Unlike the conventional abnormal voltage detection device, the present invention can detect even the smallest voltage drop present at a very short time interval T1 at both the power supply abnormality detector output terminal PFDO and the flag signal output terminal PFF.

In Figure 3, the number 1 represents the high potential, which is a message indicating an abnormal state as a basis for interrupting or resetting the microcontroller.

From the above description, the device of the present invention has the ability to detect an abnormal voltage in the microcontroller instantaneously through a digital circuit and cause the microcontroller to be interrupted or reset instantaneously. This characteristic is performed in a conventional abnormal voltage detection device. It is difficult.

In addition, the present invention uses a digital circuit instead of a conventional analog circuit, thereby reducing power consumption.

Although the present invention has been described using the preferred embodiments of the invention, it should be noted that the invention is not limited to such embodiments and may be variously modified without departing from the spirit or later claims of the invention. .

Claims (6)

A detection circuit for setting a voltage value to be detected; A latch circuit connected to the detection circuit; The detection circuit includes a power supply connection terminal connected to a reset voltage terminal of the internal circuit of the microcontroller, an input terminal connected to the power supply terminal of the internal circuit of the microcontroller, and an output terminal connected to the input terminal of the latch circuit. To; The latch circuit has an output terminal for outputting a flag signal representing an abnormal voltage in the microcontroller; Whenever the microcontroller voltage changes to a non-rated value, the voltage change is momentarily detected and latched by a signal such that the flag signal output at the output terminal of the latch circuit indicates an abnormal voltage signal, thereby causing the microcontroller to instantaneously. And an abnormal voltage instantaneous detection device in a microcontroller, characterized in that it is interrupted or reset. 2. The apparatus of claim 1, wherein the detection circuit is a NOT gate in CMOS. 3. An apparatus for detecting an abnormal voltage instant in a microcontroller according to claim 1 or 2, wherein said latch circuit is a flip-flop. 3. The apparatus of claim 1 or 2, wherein the latch circuit is a latch that is functionally equivalent to a flip-flop. The method of claim 3, wherein the flip-flop A clock input terminal connected to an output terminal of the NOT gate; A data input terminal and a power connection terminal connected together to a reset voltage terminal of the microcontroller; And And an Q output terminal and an R output terminal for outputting flag signals indicating the abnormal voltage. The method of claim 3, wherein the detection circuit An apparatus for detecting an abnormal voltage instantaneous in a microcontroller, characterized in that the detection apparatus and the microcontroller have a detection potential that can be set by selection at the time of manufacture of a mask so as to satisfy the overall requirements of a system in which the microcontroller is used.