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Power failure detection circuit with hysteresis function and control system

A technology of power-off detection and hysteresis, which is applied in the direction of measuring current/voltage, measuring devices, and measuring electrical variables, etc. It can solve problems such as power-off signal interference and power-off detection signal jitter, so as to improve reliability and reduce maintenance cost, and the effect of increasing the application range

Pending Publication Date: 2021-10-08
杭州加速科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In the prior art, when the power supply voltage drops below the detection voltage VDET, a low-level power-down signal is output, but the actual power-down signal has interference, and because of different loads, the power-down waveform is also various , the result is that the power-down detection signal will jitter near the detection voltage VDET

Method used

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  • Power failure detection circuit with hysteresis function and control system
  • Power failure detection circuit with hysteresis function and control system
  • Power failure detection circuit with hysteresis function and control system

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0032] A power-down detection circuit with a hysteresis function, including a voltage divider circuit, a hysteresis control circuit, a reference voltage circuit and a comparison circuit;

[0033] The voltage divider circuit is used to set the power-off detection voltage and the hysteresis voltage; the reference voltage circuit is used to generate the reference voltage; the comparison circuit is used to compare the sampling voltage of the voltage divider circuit with the reference voltage of the reference voltage circuit, and transmit the comparison result to The hysteresis control circuit controls the hysteresis control circuit according to the detected voltage.

[0034] With the hysteresis control circuit, the hysteresis voltage can be flexibly adjusted according to the design requirements and application environment, so that the output power-off detection signal is real, effective and jitter-free, so as to ensure that each power-off process can be accurately executed.

[003...

Embodiment 2

[0041] On the basis of Embodiment 1, this embodiment further includes an output circuit, and the comparison result output by the comparison circuit is sent to the output circuit. It also includes an energy storage circuit and a power supply, the energy storage circuit and the power supply are connected in parallel; the energy storage circuit includes a capacitor C1. The energy storage circuit is used to store energy, and the energy supply is guaranteed when the power is off.

[0042] Parallel reference voltage source U2 is AD1580. By adopting the AD1580 reference voltage source chip, its reference optimization performance is better.

[0043] The output circuit includes resistor R5, resistor R6 and MOS tube Q1; one end of resistor R5 is grounded, and the other end is connected to the gate of MOS tube Q1; one end of resistor R6 is connected to the power supply, and the other end is connected to the drain of MOS tube Q1; Source ground. By changing the power supply voltage at t...

Embodiment 3

[0045] On the basis of the above-mentioned embodiments, in this embodiment, at the moment when the power supply starts to be powered on, the voltage of pin 1 of the voltage comparator U1 is greater than the voltage of pin 3, and the voltage of pin 4 of the comparator outputs a high level, and the output MOS transistor Q1 is turned on. The output signal VEN is low level, at the same time the hysteresis control MOS transistor Q2 is turned on, the resistor R3 is shorted, and the voltage divided by the resistor R2 and R1 is sent to the 3 pin of the voltage comparator U1, so the power-on process The calculation formula of detection voltage VDET_ON is as follows;

[0046]

[0047] In the formula, V DET_ON is the detection voltage at power-on; V REFis the reference voltage of the reference chip U2; R1 and R2 are voltage dividing resistors for setting the power-down detection voltage.

[0048] Before the power supply starts to lose power, the voltage of pin 1 of voltage comparato...

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Abstract

The invention relates to a power failure detection technology, and discloses a power failure detection circuit with a hysteresis function and a control system. The circuit comprises a voltage division circuit, a hysteresis control circuit, a reference voltage circuit, and a comparison circuit. The voltage division circuit is used for setting a power failure detection voltage and a hysteresis voltage; the reference voltage circuit is used for generating a reference voltage; the comparison circuit is used for comparing the sampling voltage of the voltage division circuit with the reference voltage of the reference voltage circuit and transmitting a comparison result to the hysteresis control circuit; and the hysteresis control circuit performs control according to the detected voltage. Hysteresis feedback is introduced near a power failure detection voltage threshold, so that a power failure detection signal is prevented from shaking near the power failure detection voltage threshold, the control system can correctly detect the power failure signal, smooth execution of the power failure process is ensured, and the reliability of the system is improved; by adjusting the resistance values of resistors R1, R2 and R3, the power failure detection voltage and the hysteresis voltage are flexibly set so as to adapt to different systems and different environments.

Description

technical field [0001] The invention relates to a power-down detection technology, in particular to a power-down detection circuit and a control system with a hysteresis function. Background technique [0002] As consumers have higher and higher requirements for the performance and intelligence of electronic products, the integration of electronic products is becoming more and more complex. CPUs, MPUs, FPGAs, and DSPs are widely used in electronic products. These complex integration Circuits usually have strict requirements on the power-on and power-on sequences of the system. If the power-on sequence is incorrect, the system may fail to start, so most engineers can achieve the correct power-on sequence, and the power-off sequence is usually ignored by most engineers, but If the power-off sequence is wrong, there is a serious risk of damaging the chip. [0003] To correctly control the power-off sequence, the system power-off signal must be detected in advance, and the powe...

Claims

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Application Information

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IPC IPC(8): G01R19/165
CPCG01R19/165
Inventor 邬刚海建伟王瑞金
Owner 杭州加速科技有限公司