CN202550986U - Novel power-on reset circuit - Google Patents

Abstract

The utility model discloses a novel power-on reset circuit. The power-on reset circuit generates a reset signal inside the chip, which is crucial to the normal operation of the chip. The utility model can accurately detect various power supply voltages on the premise of not needing an external voltage reference or generating an internal band gap reference. It overcomes the disadvantage that the traditional power-on reset circuit needs to provide an accurate reference voltage from the outside. Compared with the traditional power-on reset circuit, this circuit has greater performance improvement, lower power consumption and temperature coefficient, and smaller process changes.

Description

A New Power-On Reset Circuit

technical field

The utility model relates to a power-on reset circuit.

Background technique

The power-on reset circuit generates a reset signal inside the chip, which is crucial to the normal operation of the chip. In 2004, W.C.Yen et al. introduced their research in an academic paper titled "A precision CMOS power-on reset circuit with power noiseimmunity for low-voltage technology" published in "IEICE Trans. Electron" The power-on reset circuit based on the Kuijk bandgap reference is shown in Figure 1. Its principle is to detect whether the difference between the power supply voltage VDD and the voltage Vb at point b is higher than the bandgap reference voltage. Since Vb is grounded, it can be regarded as Vb=0, That is, it is detected whether the power supply voltage VDD is higher than the bandgap reference voltage. Since the voltage difference between the emitter and the base of the triode and the voltage drop of the diode have the same negative temperature coefficient, the diode can be replaced by a triode whose base is connected to the collector to detect whether VDD-Vb is greater than the bandgap reference. Voltage, the modified circuit is shown in Figure 2, from Figure 2 we can see that Vb is zero, so the detection effect of this circuit is consistent with that of the circuit shown in Figure 1.

The above two circuits based on the Kuijk bandgap reference voltage have the advantages of simple circuit structure and small deviation with temperature and process. The disadvantage is that the detected power level is fixed at the bandgap reference voltage. However, in general applications, the level of the power supply level is determined according to other circuit requirements, so the above circuit cannot meet this requirement.

Utility model content

In view of this, the purpose of the utility model is to provide a new power-on reset circuit to realize accurate detection of different power levels. In order to solve the above problems, the following technical solutions are adopted:

A new type of power-on reset circuit, including a comparator, transistor Q1, transistor Q2, resistor R1, resistor R2, resistor R3, resistor R4, and resistor R5; one end of resistor R4 is connected to the same input end of the comparator, and resistor R5 One end is connected to the inverting input end of the comparator, the other end of the resistor R4 and the resistor R5 are both connected to the power supply, the resistance value of the resistor R4 is equal to the resistance value of R5, the transistor Q1 is connected to the base of Q2, and the collector of the transistor Q1 and Q2 The emitters are all grounded, the emitter of Q1 is connected to the same input terminal of the comparator, the emitter of Q2 is connected to the inverting input terminal of the comparator through the resistor R3, the resistor R1 is connected between the power supply and the base of the transistor Q1, and the resistor R2 is connected between the base of the transistor Q1 and the ground, and different detection threshold voltages can be obtained by adjusting the ratio of the resistors R1 and R2.

The area of the transistor Q1 is proportional to the area of Q2, wherein the area of Q2 is larger than the area of Q1.

A new type of power-on reset circuit, including a comparator, transistor Q1, transistor Q2, resistor R1, resistor R2, resistor R3, resistor R4, and resistor R5; one end of resistor R4 is connected to the inverting input end of the comparator, and resistor R5 One end is connected to the same input end of the comparator, the other end of the resistor R4 and the resistor R5 are both connected to the power supply, the resistance of the resistor R4 is equal to the resistance of R5, the transistor Q1 is connected to the base of Q2, and the collector of the transistor Q1 and Q2 The emitters are all grounded, the emitter of Q1 is connected to the inverting input of the comparator, the emitter of Q2 is connected to the same input of the comparator through the resistor R3, the resistor R1 is connected between the power supply and the base of the transistor Q1, and the resistor R2 is connected between the base of the transistor Q1 and the ground, and different detection threshold voltages can be obtained by adjusting the ratio of the resistors R1 and R2.

The area of the pole transistor Q1 is proportional to the area of Q2, wherein the area of Q2 is larger than the area of Q1.

According to the working principle of the circuit described in W.C.Yen’s paper, when VDD-Vb=Vref, the circuit outputs a reset signal, where Vref is the bandgap reference voltage, and VDD represents the power supply level. If you want to solve the problem of detecting different power supply voltages in practical applications Flat problem, the value of Vb must be changed. In order to achieve this goal, the utility model improves the power-on reset circuit proposed by W.C.Yen et al. Since the voltage difference between the emitter and the base of the triode and the voltage drop of the diode have the same negative temperature coefficient, the original circuit The proportional diodes in are replaced by equivalent proportional triodes and the bases of the two triodes are connected. Then resistors R1 and R2 are connected in series between the base of the triode, that is, point b and VDD, and between the base of the triode, that is, point b and the ground, so as to change the voltage Vb of point b and achieve the purpose of detecting different power supply levels. The circuit structure As shown in Figure 3.

The specific working principle is as follows:

即在

时输出复位信号，通过调节电阻R2与R1的比值可以得到不同的检测阈值电压，Vb为三极管基极电压，接地点电压为零电势。Let the bandgap reference voltage be Vref, according to the working principle of the circuit described in the WCYen paper, when VDD-Vb= _Vref , the circuit outputs a reset signal, in the circuit shown in Figure 3, ignoring the base currents of transistors Q1 and Q2, then there is

that is

When output reset signal, different detection threshold voltages can be obtained by adjusting the ratio of resistors R2 and R1, Vb is the base voltage of the triode, and the voltage of the grounding point is zero potential.

Beneficial effect

The power-on reset circuit designed by the utility model has small deviation with process and temperature, and can accurately detect the power supply voltage higher than the bandgap reference voltage.

Description of drawings

Below in conjunction with accompanying drawing, the utility model is further described:

Fig. 1 is the circuit diagram of the power-on reset structure used by W.C.Yen et al.;

Figure 2 shows the power-on reset circuit after replacing the diode with a triode;

Fig. 3 is a circuit diagram of an embodiment of the power-on reset circuit of the present invention;

Fig. 4 is the circuit diagram of an embodiment of the utility model power-on reset circuit;

Fig. 5 is the waveform diagram of the input terminal of the power-on reset circuit comparator of the utility model;

Detailed ways

Embodiment one

则有VDD＝1.18V_ref，即电路在电源电压为1.18V_ref时产生上升沿的复位信号。As shown in Figure 3, one end of the resistor R4 is connected to the same input end of the comparator, one end of the resistor R5 is connected to the inverting input end of the comparator, and the other end of the resistor R4 and the resistor R5 are both connected to the power supply. The resistance value of the resistor R4 Equal to the resistance of R5, the transistor Q1 is connected to the base of Q2, the collector and emitter of transistor Q1 and Q2 are both grounded, the emitter of Q1 is connected to the same input terminal of the comparator, and the emitter of Q2 is connected to the comparator through the resistor R3 Resistor R1 is connected between the power supply and the base of transistor Q1, and resistor R2 is connected between the base of transistor Q1 and ground. Different detection threshold voltages can be obtained by adjusting the ratio of resistors R1 to R2. Among them, the area ratio of Q1 and Q2 is 1:8, R1=665.6KΩ, R2=119.8KΩ, R3=43.3KΩ, R4=R5=459.2KΩ according to

Then there is VDD=1.18V _ref , that is, the circuit generates a reset signal with a rising edge when the power supply voltage is 1.18V _ref .

Embodiment two

As shown in Figure 4, one end of resistor R4 is connected to the inverting input end of the comparator, one end of resistor R5 is connected to the same input end of the comparator, the other end of resistor R4 and resistor R5 are both connected to the power supply, and the resistance value of resistor R4 Equal to the resistance of R5, the transistor Q1 is connected to the base of Q2, the collector and emitter of transistor Q1 and Q2 are grounded, the emitter of Q1 is connected to the inverting input of the comparator, and the emitter of Q2 is connected to the comparator through resistor R3 Resistor R1 is connected between the power supply and the base of transistor Q1, resistor R2 is connected between the base of transistor Q1 and ground, and different detection threshold voltages can be obtained by adjusting the ratio of resistors R1 and R2. Among them, the area ratio of Q1 and Q2 is 1:8, and

则有VDD＝1.23V_ref，即电路在电源电压为1.23V_ref时产生下降沿的复位信号。R1＝665.6KΩ, R2＝153.1KΩ, according to

Then there is VDD=1.23V _ref , that is, the circuit generates a reset signal with a falling edge when the power supply voltage is 1.23V _ref .

Claims (4)

1. A novel power-on reset circuit is characterized in that it comprises a comparator, transistor Q1, transistor Q2, resistor R1, resistor R2, resistor R3, resistor R4, and resistor R5; one end of resistor R4 is connected to the same To the input end, one end of the resistor R5 is connected to the inverting input end of the comparator, the other end of the resistor R4 and the resistor R5 are both connected to the power supply, the resistance of the resistor R4 is equal to the resistance of R5, and the transistor Q1 is connected to the base of Q2. The collectors and emitters of the transistors Q1 and Q2 are both grounded, the emitter of Q1 is connected to the same input terminal of the comparator, the emitter of Q2 is connected to the inverting input terminal of the comparator through the resistor R3, and the resistor R1 is connected to the power supply and the transistor Q1. Between the bases, the resistor R2 is connected between the base of the triode Q1 and the ground, and different detection threshold voltages can be obtained by adjusting the ratio of the resistors R1 to R2. 2. A new power-on reset circuit according to claim 1, characterized in that the areas of the triode Q1 and Q2 are proportional, wherein the area of Q2 is larger than the area of Q1. 3. A novel power-on reset circuit is characterized in that it comprises a comparator, a triode Q1, a triode Q2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, and a resistor R5; one end of the resistor R4 is connected to the reverse side of the comparator To the input terminal, one end of the resistor R5 is connected to the same input terminal of the comparator, the other end of the resistor R4 and the resistor R5 are connected to the power supply, the resistance of the resistor R4 is equal to the resistance of R5, and the transistor Q1 is connected to the base of Q2. The collectors and emitters of the transistors Q1 and Q2 are both grounded, the emitter of Q1 is connected to the inverting input of the comparator, the emitter of Q2 is connected to the same input of the comparator through the resistor R3, and the resistor R1 is connected to the power supply and the transistor Q1. Between the bases, the resistor R2 is connected between the base of the triode Q1 and the ground, and different detection threshold voltages can be obtained by adjusting the ratio of the resistors R1 to R2. 4. A new power-on reset circuit according to claim 3, characterized in that the area of the transistor Q1 is proportional to the area of Q2, wherein the area of Q2 is larger than the area of Q1.

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