KR19990009451A - Power-on reset device using voltage detector - Google Patents

Abstract

The present invention relates to a power-on reset device using a voltage detector for outputting a reset signal by detecting that the power supply voltage falls below the minimum operating voltage. The reference voltage generator 10 receives the power supply voltage and receives a predetermined reference voltage. (Vref) is generated, and the divided voltage generator 30 receives the power supply voltage Vref and generates a corresponding divided voltage Vdiv. The comparator 20 compares the reference voltage signal Vref with the divided contact signal Vdiv and outputs a comparison voltage signal DET, which is input to the edge detector 50 through the inverter 40. In this case, when the input power supply voltage Vdd is lowered below a predetermined minimum operating voltage, a reset pulse is generated, thereby preventing malfunction of the corresponding device.

Description

Power-on reset device using voltage detector

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power on reset device, and more particularly, to a power on reset device using a voltage detector that detects that a power supply voltage drops below a minimum operating voltage and outputs a reset signal.

In general, MICOM has a simple power-on reset circuit or a power-on reset circuit using a resistor and a capacitor externally. In such a power-on reset circuit, the condition of power-on reset is usually when the power is full swing. However, when mounted inside the microcomputer, the power may not rise to 0V and rise again to the original power voltage value.

For example, in the case of a remote controller (Remocon), when a shock is applied to the remote control when the mounted battery and its contact is not good, a situation in which power supply is temporarily stopped and then supplied again may occur. At this time, since there is a capacitance due to power, the power supplied to the microcomputer takes a certain time to fall to 0V. In this case, when the power comes back while falling only to about 0.5V ~ 0.7Vdd, the power is not full swing, but it needs to be reset at that time. In other words, if the product is operated at 3V, assuming that the minimum operating voltage is 2.5V, it means that if the power swings below 2.5V, it will malfunction. Therefore, in this case, a reset operation should be performed to stop the malfunction state.

However, since the conventional power-on reset circuit does not use a predetermined fixed voltage, the reset operation is not performed when the above situation occurs.

Accordingly, it is an object of the present invention to provide a power-on reset apparatus for performing a reset operation by generating a reset signal by detecting a minimum voltage using a voltage detector.

1 is a block diagram of a power-on reset device using a voltage detector according to a preferred embodiment of the present invention;

2 is a view showing a state of a critical signal during a power swing,

3 is a detailed circuit diagram of a power-on reset device using a voltage detector according to a preferred embodiment of the present invention.

Explanation of symbols for the main parts of the drawings

10: reference voltage generation unit 20: comparison unit

30: divided voltage generator 40: inverter

50: edge detector

According to a feature of the present invention for achieving the object of the present invention as described above, the reference voltage generator for receiving a power supply voltage and generating a predetermined reference voltage signal; A division voltage generation unit configured to receive a power supply voltage and generate a predetermined division voltage signal; A comparator configured to receive the reference voltage signal and the divided voltage signal and compare the same to output a comparison voltage signal; The edge detection unit detects an edge of which the voltage changes by inputting the comparison voltage signal and outputs a corresponding reset signal.

In this embodiment, the comparator comprises a differential amplifier.

In this embodiment, the operation is disabled by a predetermined standby signal input from the reference voltage generator and the divided voltage generator.

In this embodiment, an inverting unit inverting a comparison voltage signal and providing the edge detection unit to the edge detection unit, wherein the edge detection unit receives an output of the inverting unit, detects a rising edge, and outputs a reset signal.

According to the present invention as described above, if the power supply voltage is lowered below the minimum operating voltage detects this and outputs a reset signal.

EXAMPLE

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a power-on reset device using a voltage detector according to a preferred embodiment of the present invention, Figure 2 is a view showing the state of a critical signal during power swing. 3 is a detailed circuit diagram of a power-on reset device using a voltage detector according to a preferred embodiment of the present invention.

Referring to FIG. 1, a power-on reset device according to an exemplary embodiment of the present invention includes a reference voltage generator 10, a comparator 20, an edge detector 50, and an inverter 40. . The comparator 20 may generally be configured using a differential amplifier, and the inverter 40 may be configured as a general inverter circuit. The edge detector 50 is constructed using a rising edge detector for detecting a rising edge in this embodiment.

The overall operation of the power-on reset circuit using the voltage detector having such a configuration will be described with reference to FIGS. 1 and 2 as follows.

Referring to FIG. 1, the reference voltage generator 10 generates a predetermined reference voltage signal Vref and inputs it to the comparator 20, and the divided voltage generator 30 sets the power supply voltage Vdd at a predetermined ratio. The split voltage signal Vdiv is input to the comparator 20 by dividing by. The comparison unit 20 outputs a comparison voltage signal DET by comparing two input voltage signals, the reference voltage signal Vref and the divided voltage signal Vdiv, which are inverted through the inversion unit 40. (DET #) is provided to the edge detection unit 50. At this time, the edge detector 50 outputs a predetermined reset pulse when an edge is detected.

On the other hand, since the reference voltage generator 10 and the divided voltage generator 30 are formed with a DC path, a predetermined amount of current always flows. This DC path does not cause a problem during normal operation, but when the corresponding device is idle or stopped, the current generated in this block may be a problem. Therefore, in this case, the reference voltage generator 10 and the divided voltage generator 30 are configured to be disabled by receiving a predetermined standby signal. Therefore, when the operation mode is not in the operation mode, the reference voltage generator 10 and the divided voltage generator 30 are disabled so that the DC path is blocked. The state of important signals during power swing of the power-on reset device using the voltage detector as described above is shown in FIG. 2, and a circuit diagram of an example of the implementation circuit thereof is shown in FIG. 3.

On the other hand, in general, the memory embedded in the microcomputer, for example, if the characteristic of the EPROM is less than 1.8V, invalid data may be read from the EPROM and an unexpected operation may occur. Therefore, when the power-on reset device according to the embodiment of the present invention is incorporated as described above, the reset signal is generated when the power supply voltage is less than 1.8V, and the microcomputer is reset. That is, a reset signal is generated when the voltage drops below a predetermined minimum operating voltage. Therefore, the malfunction of the microcomputer is prevented.

According to the present invention as described above, when the input power supply voltage is lowered below the minimum operating voltage, the reset signal is generated, thereby preventing the malfunction of the device.

Claims (4)

In the power-on reset device for outputting a predetermined reset signal when the power supply voltage (Vdd) is input: A reference voltage generator 10 which receives the power supply voltage Vdd and generates a predetermined reference voltage signal Vref; A divided voltage generator 30 receiving a power supply voltage Vdd and generating a predetermined divided voltage signal Vdiv; A comparator 20 which receives the reference voltage signal Vref and the divided voltage signal Vdiv and compares them to output a comparison voltage signal DET; And an edge detector (50) for inputting the comparison voltage signal (DET) to detect an edge at which the voltage changes and output a corresponding reset signal. The method of claim 1, The comparison unit 20 is a power-on reset device using a voltage detector, characterized in that consisting of a differential amplifier. The method of claim 1, The reference voltage generator (10) and the divided voltage generator (30) is a power-on reset device using a voltage detector, characterized in that the operation is disabled by a predetermined standby signal (standby) input from the outside. The method of claim 1, And an inverting unit 40 which inverts the comparison voltage signal DET and provides the edge detecting unit 50 to the edge detecting unit 50. The edge detecting unit 50 receives an output of the inverting unit 40 as an input and detects a rising edge. And a reset signal outputting the reset signal.