Ultra-low power consumption quick response overvoltage protection circuit

Abstract

The invention provides an ultra-low power consumption quick response overvoltage protection circuit. The ultra-low power consumption quick response overvoltage protection circuit comprises a Zener diode circuit, a current mirror and an inverter U1, the first side input end of the current mirror is connected with an input voltage VIN through a Zener diode circuit; the input end of the second side of the current mirror is connected with the current source Ib on one hand and is connected with the input end of the inverter U1 on the other hand; and an equivalent parasitic capacitor Cp is arranged at an electrical connection point Va between the inverter U1 and the inverter U1. By utilizing the reverse breakdown characteristic of the Zener diode and combining with the current mirror, extremely low standby power consumption which is almost zero can be realized, and the index of overvoltage quick response can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of overvoltage protection circuits, and in particular to an ultra-low power consumption and fast response overvoltage protection circuit. Background Art

[0002] Traditional overvoltage protection circuits such as Figure 1 As shown, the entire OV circuit module consists of resistors R1, R2 and a comparator. Its basic function is: VIN is obtained through a voltage-dividing resistor string composed of resistors R1 and R2 to obtain Vin_div=VIN*R2 / (R1+R2). When Vin_div is greater than Vref, the overvoltage indication signal OV flips from low to high. This structure has defects in low-power applications. There is a fixed current power consumption on VIN, and its current size I=VIN / (R1+R2). If you want to reduce the current power consumption, you need to increase the resistance value. In the application scenario where VIN needs to have extremely low standby power consumption, it cannot meet the demand. Assuming VIN=10V, if the power consumption is required <1uA, (R1+R2)>10MΩ can be obtained. Another problem brought by low power consumption is slow speed. Cp is the equivalent sum of the parasitic capacitance of the resistor string and the comparator input. Its typical value is 1pF under 0.18BCD process. The establishment time of Vin_div can be expressed by the RC constant, τ=(R1 / / R2)*Cp. When R1=8MΩ, R2=2MΩ, the establishment time of Vin_div is τ=1.6M*1p=1.6us. In systems requiring fast response, the response time is usually required to be less than 100ns, so the traditional structure cannot meet both low standby power consumption and fast overvoltage response. Summary of the invention

[0003] The present invention aims to provide an ultra-low power consumption and fast response overvoltage protection circuit to simultaneously meet the requirements of low standby power consumption and fast overvoltage response.

[0004] The present invention provides an ultra-low power consumption fast response overvoltage protection circuit, comprising a Zener diode circuit, a current mirror and an inverter U1;

[0005] The first side input end of the current mirror is connected to the input voltage VIN via a Zener diode circuit;

[0006] The second side input terminal of the current mirror is connected to the current source Ib on one hand, and is connected to the input terminal of the inverter U1 on the other hand; an equivalent parasitic capacitance Cp is formed at the electrical connection point Va between the second side input terminal and the inverter U1.

[0007] In some embodiments, the Zener diode circuit includes a Zener diode D1 and a Zener diode D2 connected in series.

[0008] In some embodiments, the first-side input terminal of the current mirror is connected to the input voltage VIN via the anode and cathode of the Zener diode D2 and the anode and cathode of the Zener diode D1 in sequence.

[0009] In some embodiments, the current mirror includes a MOS transistor M1 and a MOS transistor M2.

[0010] In some embodiments, the source of the MOS tube M1 is connected to the input voltage VIN via a Zener diode circuit in sequence; the drain of the MOS tube M2 is connected to the current source Ib on one hand, and is connected to the input end of the inverter U1 on the other hand, and an equivalent parasitic capacitance Cp is present at an electrical connection point Va between the source of the MOS tube M2 and the inverter U1; the gate of the MOS tube M1 is connected to the gate of the MOS tube M2, and the source of the MOS tube M1 and the source of the MOS tube M2 are grounded; the gate and drain of the MOS tube M1 are connected.

[0011] In some embodiments, the MOS transistor M1 and the MOS transistor M2 are PMOS transistors.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0013] The present invention utilizes the reverse breakdown characteristic of a Zener diode and combines it with a current mirror to achieve extremely low standby power consumption of almost zero and meet the index of rapid overvoltage response. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a structural diagram of a traditional overvoltage protection circuit.

[0015] Figure 2 4 is a structural diagram of an ultra-low power consumption and fast response overvoltage protection circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In order to achieve extremely low standby power consumption of almost zero and meet the index of fast overvoltage response, this embodiment proposes an ultra-low power consumption fast response overvoltage protection circuit, including a Zener diode circuit, a current mirror and an inverter U1;

[0019] The first side input end of the current mirror is connected to the input voltage VIN via a Zener diode circuit;

[0020] The second side input terminal of the current mirror is connected to the current source Ib on one hand, and is connected to the input terminal of the inverter U1 on the other hand; an equivalent parasitic capacitance Cp is formed at the electrical connection point Va between the second side input terminal and the inverter U1.

[0021] In this embodiment, the ultra-low power consumption fast response overvoltage protection circuit is as follows: Figure 2 As shown, the specific structure is as follows:

[0022] The Zener diode circuit includes a Zener diode D1 and a Zener diode D2 connected in series.

[0023] MOS tube M1 and MOS tube M2 form a current mirror M1:M2=1:K;

[0024] The source of the MOS tube M1 is connected to the input voltage VIN after passing through the positive and negative electrodes of the Zener diode D2 and the positive and negative electrodes of the Zener diode D1 in sequence; the drain of the MOS tube M2 is connected to the current source Ib on one hand, and is connected to the input end of the inverter U1 on the other hand, and the electrical connection point Va between the source of the MOS tube M2 and the inverter U1 has an equivalent parasitic capacitance Cp; the gate of the MOS tube M1 is connected to the gate of the MOS tube M2, and the source of the MOS tube M1 and the source of the MOS tube M2 are grounded; the gate and drain of the MOS tube M1 are connected.

[0025] The working principle of the ultra-low power consumption fast response overvoltage protection circuit is as follows:

[0026] Utilizing the reverse breakdown characteristic of the Zener diode, the voltage across the diode must be greater than the reverse breakdown threshold Vbv to cause the diode to reverse breakdown.

[0027] When the input voltage VIN < (Vbv_D1 + Vbv_D2 + VGS_M1), the reverse breakdown threshold of the diode is not reached, and the static power consumption of the input voltage VIN is almost zero. Vbv_D1 is the reverse breakdown threshold of the diode D1, Vbv_D2 is the reverse breakdown threshold of the diode D2, and VGS_M1 is the voltage between the gate and source of the MOS tube M1;

[0028] When the input voltage VIN>(Vbv_D1+Vbv_D2+VGS_M1), the diode reverses and breaks down. The MOS tube saturation current formula can be used to calculate:

[0029] I1=(u nCoxW / 2L)*(VGS1-VTH)2=(u n CoxW / 2L)*(VIN-2Vbv-VTH)2

[0030] Among them, u n is the carrier mobility of the MOS tube, Cox is the gate oxide capacitance of the MOS tube, VTH is the threshold of the MOS tube, Vbv is the reverse breakdown voltage of the Zener diode, and W / L is the device size of the current mirror;

[0031] According to the current mirror M1:M2=1:K, I2=K*I1 is obtained. When I2>Ib, the voltage of the electrical connection point Va is pulled down, and the overvoltage indication signal OV turns high after passing through the inverter.

[0032] Critical turning point Ib=I2=K*I1=K*(u n CoxW / 2L)*(VIN-2Vbv-VTH)2, the overvoltage protection threshold of the input voltage VIN can be expressed as:

[0033]

[0034] Among them, the reverse breakdown voltage Vbv of the Zener diode, the threshold VTH of the MOS tube, and the carrier mobility u of the MOS tube are n The gate oxide capacitance Cox is a process parameter. The overvoltage protection threshold can be designed by the number of devices in series, the size of the current source Ib, the ratio of the current mirrors M1 and M2, and the device size W / L of the current mirror.

[0035] Another protection speed problem is that I2=K*(u n CoxW / 2L)*(VIN-2Vbv-VTH)2 shows that the current is the square of the input voltage VIN multiplied by K times, so I2 can easily obtain a current greater than 100uA. Because the electrical connection point Va is connected to the inverter U1, the input parasitic capacitance of the inverter U1 is usually less than 0.01pF, and Cp is the equivalent parasitic capacitance of the electrical connection point Va. Taking the worst condition Cp=0.1pF, the time T=Cp*5 / 100u=5ns for 100uA to discharge the equivalent parasitic capacitance Cp of 5V, the response time of the overvoltage protection circuit is 5ns.

[0036] The above overvoltage protection circuit solves the standby power consumption problem with almost zero power consumption when the input voltage VIN is working normally. At the same time, when the input voltage VIN is abnormally overvoltage, the overvoltage protection response time is 5ns under harsh conditions, meeting the demand for fast overvoltage response.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An ultra-low power consumption fast response overvoltage protection circuit, characterized in that: Includes a Zener diode circuit, a current mirror and an inverter U1; The first side input end of the current mirror is connected to the input voltage VIN via a Zener diode circuit; The second side input terminal of the current mirror is connected to the current source Ib on one hand, and is connected to the input terminal of the inverter U1 on the other hand; an equivalent parasitic capacitance Cp is formed at the electrical connection point Va between the second side input terminal and the inverter U1.

2. The ultra-low power consumption fast response overvoltage protection circuit according to claim 1, characterized in that: The Zener diode circuit includes a Zener diode D1 and a Zener diode D2 connected in series.

3. The ultra-low power consumption fast response overvoltage protection circuit according to claim 2, characterized in that: The first-side input terminal of the current mirror is connected to the input voltage VIN via the anode and cathode of the Zener diode D2 and the anode and cathode of the Zener diode D1 in sequence.

4. The ultra-low power consumption fast response overvoltage protection circuit according to claim 1, characterized in that: The current mirror includes a MOS transistor M1 and a MOS transistor M2.

5. The ultra-low power consumption fast response overvoltage protection circuit according to claim 4, characterized in that: The source of the MOS tube M1 is connected to the input voltage VIN via the Zener diode circuit in sequence; the drain of the MOS tube M2 is connected to the current source Ib on one hand, and is connected to the input end of the inverter U1 on the other hand, and the electrical connection point Va between the source of the MOS tube M2 and the inverter U1 has an equivalent parasitic capacitance Cp; the gate of the MOS tube M1 is connected to the gate of the MOS tube M2, and the source of the MOS tube M1 and the source of the MOS tube M2 are grounded; the gate and drain of the MOS tube M1 are connected.

6. The ultra-low power consumption fast response overvoltage protection circuit according to claim 4, characterized in that: The MOS tube M1 and the MOS tube M2 are PMOS tubes.

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