Low-voltage reset circuit

Abstract

The invention provides a low-voltage reset circuit. The low-voltage reset circuit comprises a current source, a first resistor, a second resistor, a third resistor, a fourth resistor, a comparator and a voltage-controlled resistor; the current source, the first resistor, the voltage-controlled resistor and the second resistor are sequentially connected in series and are connected between a supply voltage and the ground; the third resistor and the fourth resistor are connected with each other in series and are connected between the current source and the ground; the negative input end of the comparator is connected with sampling voltages extracted from the third resistor and the fourth resistor; the positive input end of the comparator is connected with sampling voltages extracted from the current source and the first resistor, and the current source generates a current with a zero-temperature coefficient or a current with a positive-temperature coefficient and then is used for generating a stable reference voltage. According to the low-voltage reset circuit, a high-level pulse reset signal is generated correctly; in addition, when a system power source powers down to an ultra-low voltage, the reset signal cannot be released wrongly.

Description

technical field [0001] The present invention relates to the technical field of analog integrated circuits or digital-analog hybrid integrated circuits, in particular, the present invention relates to a low-voltage reset circuit. Background technique [0002] The main function of the low-voltage reset (LVR: Low Voltage Reset) circuit is to generate a reset of a high-level pulse (high pulse) of appropriate width when the power supply voltage is lower than the set voltage value during the power-on or power-off process of the system. (reset) signal to reset the system to ensure the stability of all internal digital logic. The LVR circuit is an essential and important circuit module of the microcontroller (MCU) system, and is widely used in the fields of analog integrated circuits and digital-analog hybrid integrated circuits. [0003] Figure 1A It is a schematic structural diagram of a low-voltage reset circuit in the prior art. Traditional high-precision LVR circuits general...

AI Technical Summary

Problems solved by technology

Since the bandgap reference source circuit takes a long time to set up, when the system is quickly powered on, the sampling voltage VSAMP drawn from between the first resistor R1 and the second resistor R2 rises faster than the reference voltage VREF, resulting in the sampling voltage The voltage of VSAMP is always greater than the voltage of the reference voltage VREF, and the LVR circuit cannot generate a high-level pulse reset signal, such as Figure 1B shown

Most systems need to add other circuit modules to make up for the problem of fast power-on, but the newly added circuit not only needs to increase power consumption and area, but also has more or less other defects

[0005] 2. Figure 1C for Figure 1A A schematic diagram of the failure of a low-voltage reset circuit in the prior art when the system power is turned off

When the system power supply VDD continues to drop to a certain low voltage, the bandgap reference source circuit cannot work normally under low voltage, causing the curve of the reference voltage VREF to drop rapidly, and a second "intersection" occurs with the curve of the sampling voltage VSAMP, resulting in a high-level pulse Error release of the reset signal, such as Figure 1C shown

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