A high-precision protection and hysteresis control circuit

Abstract

The present invention provides a high-precision protection and hysteresis control circuit, which includes an operational amplifier U1, a MOS transistor Q1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7; the resistor R1 is connected to the resistor R2, and the output end of the resistor R1 is connected to the non-inverting input end of the 1st pin of the operational amplifier U1; the resistor R3 is connected to the resistor R4, and the output end of the resistor R3 is connected to the inverting input end of the 3rd pin of the operational amplifier; the resistor R5 is connected to the first node, the MOS transistor Q1 couples the resistor R5 to the second node, and the resistor R6 couples the second node to the output end of the 4th pin of the operational amplifier U1. The signal at the output end of the 4th pin of the operational amplifier U1 is fed back to the inverting input end of the 3rd pin of the operational amplifier U1 to form positive feedback, and the signal at the output end of the 4th pin of the operational amplifier U1 undergoes a level conversion through the MOS transistor Q1 to improve the accuracy of the protection point and hysteresis.

Description

Technical Field

[0001] The present invention relates to the field of control circuits, and in particular to a high-precision protection and hysteresis control circuit. Background Art

[0002] In recent years, with the development of China's aerospace and aviation equipment towards the directions of intelligence, informatization, and lightweight, there are requirements for multi-electrification and all-electrification power supply systems for aerospace and aviation equipment to meet the needs of equipment intelligence, lightweight, etc. The demand for power supplies, especially DC / DC converters, is increasing, and higher requirements are put forward for the perfect protection function and accuracy of DC / DC converters.

[0003] However, the conventional control circuit detects the sampled voltage, compares it with the reference voltage to obtain high and low levels to control the turn-off or turn-on of the converter. The circuit is simple but can only achieve basic functions and is applied to occasions with low accuracy requirements. Summary of the Invention

[0004] To solve the above problems, the present invention proposes a high-precision protection and hysteresis control circuit.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention proposes a high-precision protection and hysteresis control circuit, including an operational amplifier U1, a MOS transistor Q1, resistors R1, R2, R3, R4, R5, R6, and R7.

[0007] The resistor R1 is connected in series with the resistor R2. The input end of the resistor R1 is connected to the VREF reference voltage terminal, and the output end of the resistor R1 is connected to the non-inverting input terminal of the 1st pin of the operational amplifier U1.

[0008] The resistor R3 is connected to the resistor R4. The input end of the resistor R3 is connected to the VIN detection voltage terminal, and the output end of the resistor R3 is connected to the inverting input terminal of the 3rd pin of the operational amplifier.

[0009] The resistor R5 is connected to the inverting input terminal of the 3rd pin of the operational amplifier. The MOS transistor Q1 couples the resistor R5 to the second node, and the resistor R6 couples the second node to the output terminal of the 4th pin of the operational amplifier U1.

[0010] Further, the high-precision protection and hysteresis control circuit further includes a resistor R7, and the resistor R7 couples the second node to the third node.

[0011] Further, the 5th pin of the operational amplifier U1 is connected to the VCC terminal, and the 2nd pin of the operational amplifier U1 is connected to the third node.

[0012] Further, the source of the MOS transistor Q1 is connected to the third node, the drain of the MOS transistor Q1 is connected to the output end of the resistor R5, and the gate of the MOS transistor Q1 is connected to the second node.

[0013] Further, the input end of the resistor R4 is connected to the output end of the resistor R3, and the output end of the resistor R4 is connected to the third node.

[0014] Further, the input end of the resistor R2 is connected to the output end of the resistor R1, the output end of the resistor R2 is connected to the third node, and the ground end is connected to the third node.

[0015] Further, the OFF end is connected to the output end of pin 4 of the operational amplifier U1.

[0016] The beneficial effects of the present invention: The high-precision protection and hysteresis control circuit proposed by the present invention includes an operational amplifier U1, a MOS transistor Q1, resistors R1, R2, R3, R4, R5, and R6; the resistor R1 is connected to the resistor R2, the input end of the resistor R1 is connected to the VREF reference voltage terminal, and the output end of the resistor R1 is connected to the non-inverting input terminal of pin 1 of the operational amplifier U1; the resistor R3 is connected to the resistor R4, the input end of the resistor R3 is connected to the VIN detection voltage terminal, and the output end of the resistor R3 is connected to the inverting input terminal of pin 3 of the operational amplifier; the resistor R5 is connected to the first node, the MOS transistor Q1 couples the resistor R5 to the second node, and the resistor R6 couples the second node to the output end of pin 4 of the operational amplifier U1. The signal at the output end of pin 4 of the operational amplifier U1 is fed back to the inverting input terminal of pin 3 of the operational amplifier U1 to form positive feedback, and the signal at the output end of pin 4 of the operational amplifier U1 undergoes level conversion through the MOS transistor Q1 to improve the accuracy of the protection point and hysteresis. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the high-precision protection and hysteresis control circuit. Detailed Embodiments

[0018] In order to more clearly and completely illustrate the technical solution of the present invention, the present invention will be further described below with reference to the drawings.

[0019] Please refer to Figure 1 The present invention proposes a high-precision protection and hysteresis control circuit, including an operational amplifier U1, a MOS transistor Q1, resistors R1, R2, R3, R4, R5, R6, and R7.

[0020] The resistor R1 is in series with the resistor R2. The input end of the resistor R1 is connected to the VREF reference voltage terminal, and the output end of the resistor R1 is connected to the non-inverting input terminal of pin 1 of the operational amplifier U1.

[0021] The resistor R3 is connected to the resistor R4. The input end of the resistor R3 is connected to the VIN detection voltage terminal, and the output end of the resistor R3 is connected to the inverting input terminal of pin 3 of the operational amplifier.

[0022] The detected sampling voltage and the reference voltage are respectively fed into the non-inverting input terminal of pin 1 and the inverting input terminal of pin 3 of the operational amplifier. The signal at the output terminal of pin 4 of the operational amplifier U1 is processed and then fed into the inverting input terminal of pin 3 of the operational amplifier U1 to form positive feedback.

[0023] The resistor R5 is connected to the first node. The MOS transistor Q1 couples the resistor R5 to the second node. The resistor R6 couples the second node to the output terminal of pin 4 of the operational amplifier U1.

[0024] In this embodiment, the signal at the non-inverting input terminal of pin 1 of the operational amplifier U1 is processed and then fed into the inverting input terminal of pin 3 of the operational amplifier U1 to form positive feedback. The signal at the output terminal of pin 4 of the operational amplifier U1 is fed back to the inverting input terminal of pin 3 of the operational amplifier U1 to form positive feedback. Moreover, the signal at the output terminal of pin 4 of the operational amplifier U1 undergoes level conversion through the MOS transistor Q1 to improve the accuracy of the protection point and the hysteresis.

[0025] Further, the high-precision protection and hysteresis control circuit further includes a resistor R7. The resistor R7 couples the second node to the third node.

[0026] Further, pin 5 of the operational amplifier U1 is connected to the VCC terminal, and pin 2 of the operational amplifier U1 is connected to the third node.

[0027] Further, the source of the MOS transistor Q1 is connected to the third node, the drain of the MOS transistor Q1 is connected to the output end of the resistor R5, and the gate of the MOS transistor Q1 is connected to the second node.

[0028] Further, the input end of the resistor R4 is connected to the output end of the resistor R3, and the output end of the resistor R4 is connected to the third node.

[0029] Further, the input end of the resistor R2 is connected to the output end of the resistor R1, the output end of the resistor R2 is connected to the third node, and the ground terminal is connected to the third node.

[0030] Further, the OFF end is connected to the output terminal of pin 4 of the operational amplifier U1.

[0031] VREF is the reference voltage, which is provided by a precision reference source (not shown in the figure) and is not affected by the operating state of the converter and the ambient temperature. After being divided by the resistor R1 and the resistor R2, it is sent to the non-inverting input terminal of pin 1 of the operational amplifier U1.

[0032] The detected sampling voltage VIN (input voltage, which can also be the output voltage, temperature signal or other detection signals) is sent to the inverting input terminal of pin 3 of the operational amplifier after being divided by the resistor R3 and the resistor R4.

[0033] When the high-precision protection and hysteresis control circuit of the present invention is used as an undervoltage protection circuit, when the level of the inverting input terminal of pin 3 of the operational amplifier U1 is slightly higher than that of the non-inverting input terminal of pin 1 of the operational amplifier U1, the output terminal of pin 4 of the operational amplifier U1 outputs a low level. After being divided by the resistor R6 and the resistor R7, the MOS transistor Q1 (field effect transistor) is turned off. At this time, the MOS transistor Q1 is equivalent to an open circuit, and the impedance is approximately infinite. Furthermore, the resistor R5 is left floating, and the level of the inverting input terminal of pin 3 of the operational amplifier U1 is higher, and the output voltage maintains a low-level output, thus forming a positive feedback.

[0034] At this time, the sampling action voltage is only related to the resistance values of the resistor R1, the resistor R2, the resistor R3, the resistor R4 and the VREF precision reference source, so extremely high undervoltage protection action point accuracy can be obtained.

[0035] When the level of the inverting input terminal of pin 3 of the operational amplifier U1 is slightly lower than that of the non-inverting input terminal of pin 1 of the operational amplifier U1, the output terminal of pin 4 of the operational amplifier U1 outputs a high level. After being divided by the resistor R6 and the resistor R7, it drives the MOS transistor Q1 (field effect transistor) with an extremely low on-resistance to conduct. Since the on-resistance of the MOS transistor Q1 is several milliohms, the output terminal of the resistor R5 is connected to the ground through the MOS transistor Q1 with an extremely low resistance, which is equivalent to the resistor R5 being connected in parallel to the resistor R4, so that the level of the inverting input terminal of pin 3 of the operational amplifier U1 is lower, and the output voltage maintains a high-level output, thus forming a positive feedback. At this time, the sampling recovery action voltage is only related to the resistance values of the resistor R1, the resistor R2, the resistor R3, the resistor R4, the resistor R5 and the VREF precision reference source, so extremely high undervoltage recovery action point accuracy can be obtained.

[0036] The difference between the protection action point and the recovery action point is the hysteresis, so the circuit of the present invention can obtain an extremely high-precision hysteresis value.

[0037] In this embodiment, the signal at the output terminal of pin 4 of the operational amplifier U1 is level-converted through a MOS transistor Q1 with an extremely low on-resistance, so that the positive feedback signal injected into the operational amplifier U1 is not affected by the power supply VCC voltage and the inconsistency of the high and low output levels of the operational amplifier, thereby greatly improving the control accuracy.

[0038] Of course, the present invention may have many other embodiments. Based on this embodiment, other embodiments obtained by those of ordinary skill in the art without any creative work belong to the scope protected by the present invention.

Claims

1. A high-precision protection and hysteresis control circuit, characterized in that It includes operational amplifier U1, MOS transistor Q1, resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, resistor R6, and resistor R7; The resistor R1 is connected to the resistor R2. The input end of the resistor R1 is connected to the VREF reference voltage terminal, and the output end of the resistor R1 is connected to the non-inverting input terminal of pin 1 of the operational amplifier U1. The resistor R3 is connected to the resistor R4. The input end of the resistor R3 is connected to the VIN detection voltage terminal, and the output end of the resistor R3 is connected to the inverting input terminal of pin 3 of the operational amplifier; The resistor R5 is connected to the first node; Pin 3 of the operational amplifier U1 is connected to the first node; The resistor R5 is connected to the inverting input terminal of pin 3 of the operational amplifier. The MOS transistor Q1 couples the resistor R5 to the second node, and the resistor R6 couples the second node to the output terminal of pin 4 of the operational amplifier U1; The high-precision protection and hysteresis control circuit further includes a resistor R7, and the resistor R7 couples the second node to the third node; Pin 5 of the operational amplifier U1 is connected to the VCC terminal, and pin 2 of the operational amplifier U1 is connected to the third node; The input end of the resistor R2 is connected to the output end of the resistor R1, the output end of the resistor R2 is connected to the third node, and the ground terminal is connected to the third node.

2. The high-precision protection and deadband control circuit according to claim 1, wherein The source of the MOS transistor Q1 is connected to the third node, the drain of the MOS transistor Q1 is connected to the output end of the resistor R5, and the gate of the MOS transistor Q1 is connected to the second node.

3. The high-precision protection and dead-band control circuit according to claim 2, characterized in that, The input end of the resistor R4 is connected to the output end of the resistor R3, and the output end of the resistor R4 is connected to the third node.

4. The high-precision protection and hysteresis control circuit according to claim 1, characterized in that, The OFF end is connected to the output terminal of pin 4 of the operational amplifier U1.

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