A switch input acquisition circuit capable of operating in a wide voltage range

Abstract

The present invention discloses a switching value input acquisition circuit capable of operating in a wide voltage range, comprising a first switching value input acquisition circuit consisting of a resistor R1, an N-channel depletion-type MOSFET tube V4, a resistor R4, a photocoupler D1, and a voltage stabilizing diode V5 connected in series; and a second switching value input acquisition circuit consisting of an anti-reverse connection diode V1, a resistor R3, a resistor R4, a photocoupler D1, and a voltage stabilizing diode V5 connected in series. The present invention has the characteristics of a wide input voltage power supply range, stable drive current, low power consumption, and a small size, and is particularly suitable for switching electrical control equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of switch electrical appliance control equipment, and relates to a switch value input acquisition circuit that can operate in a wide voltage range, and is particularly suitable for acquiring switch value input signals of switch electrical appliance equipment. Background Art

[0002] Switching electrical control equipment needs to collect various status signals of the switching electrical equipment, and these signals are input to the control equipment in the form of switching quantities.

[0003] In most applications, the control power supply voltage amplitude range of switching devices is very wide, which may cause some switching input acquisition circuits to be unable to normally acquire the status signals of the switching electrical appliances within the full voltage range.

[0004] Therefore, it is necessary to design a switching input isolation acquisition circuit to meet the requirements of switching electrical appliance status signal isolation acquisition under the amplitude and voltage power supply conditions of switching electrical appliance products. Summary of the Invention

[0005] The purpose of the present invention is to provide a switch value input acquisition circuit that can operate in a wide voltage range, can reliably acquire the switch value state within the power supply voltage range of DC24V~110V, drive the photoelectric coupler D1 with a relatively stable current within this voltage range, and realize the isolated acquisition of the switch value input signal within the wide voltage range.

[0006] The technical solution adopted by the present invention to solve its technical problems is: a switching value input acquisition circuit capable of operating in a wide voltage range, comprising a first switching value input acquisition circuit composed of a resistor R1, an N-channel depletion-type MOSFET tube V4, a resistor R4, a photocoupler D1 and a voltage stabilizing diode V5 connected in series; and a second switching value input acquisition circuit composed of an anti-reverse polarity diode V1, a resistor R3, a resistor R4, a photocoupler D1 and a voltage stabilizing diode V5 connected in series; one end of the resistor R1 is connected to the cathode of the anti-reverse polarity diode V1, and the other end is simultaneously connected to the drain of the N-channel depletion-type MOSFET tube V4 and the gate of the P-channel enhancement-type MOSFET tube V3; one end of the resistor R2 is connected to the cathode of the anti-reverse polarity diode V1, and the other end is connected to the source of the P-channel enhancement-type MOSFET tube V3. One end of resistor R3 is connected to the cathode of the anti-reverse polarity diode V1, and the other end is connected to resistor R4 and the source of N-channel depletion-type MOSFET tube V4. The gate of N-channel depletion-type MOSFET tube V4 and the other end of resistor R4 are connected to the anode of the input stage diode of photocoupler D1, that is, resistor R4 is connected between the gate and source of N-channel depletion-type MOSFET tube V4. The cathode of the input diode of photocoupler D1 is connected to the cathode of Zener diode V5. The anode of Zener diode V5 and the drain of P-channel enhancement-type MOSFET tube V3 are respectively connected to the negative electrode of the power supply VCC-. The positive electrode of the output end of photocoupler D1 is connected to resistor R5. The other end of resistor R5 is connected to the positive electrode of the isolation side power supply VDD. The output stage of photocoupler D1 is connected in parallel with capacitor C1 to output the switching signal DIN.

[0007] The switching input acquisition circuit capable of operating in a wide voltage range further includes a surge suppression circuit composed of a transient suppression diode V2. The cathode of the transient suppression diode V2 and the anode of the reverse polarity protection diode V1 are connected to the positive power supply electrode VCC+ through a switch SW1, and the anode of the transient suppression diode V2 is connected to the negative power supply electrode VCC-.

[0008] In a switching input acquisition circuit capable of operating in a wide voltage range, during voltage increase, the N-channel depletion-type MOSFET tube V4 enters the variable resistance region and finally the cutoff region from the saturation region, and the current flows into the input end of the photocoupler D1 through the anti-reverse polarity diode V1, the resistor R1, the MOSFET tube V4, and the resistor R4, and flows through the voltage stabilizing diode V5. The current also flows through the resistors R3 and R4, jointly driving the photocoupler D1 to conduct. When the voltage is low, the N-channel depletion-type MOSFET tube V4 operates in the saturation region, and the current can also flow through the resistor R3, the N-channel depletion-type MOSFET tube V4, and the resistor R4 into the input end of the photocoupler D1, and flows through the voltage stabilizing diode V5, driving the photocoupler D1 to conduct.

[0009] The beneficial effects of the present invention are as follows: a P-channel enhancement-type MOSFET tube V3 is used to replace a traditional resistor as a load of an N-channel depletion-type MOSFET tube V4 to form a complete MOSFET amplifier circuit; the conduction characteristics of the P-channel enhancement-type MOSFET tube V3 are utilized to enable it to operate in a variable resistance region and a cutoff region, and the resistance value is dynamically adjusted, thereby avoiding the use of high-power resistors and reducing the power consumption of the load circuit; and the characteristics of the N-channel depletion-type MOSFET tube that it is in an on state when no driving voltage is applied and gradually shifts to the variable resistance region and the cutoff region as the voltage increases are utilized to achieve dynamic adjustment of the loop resistance within a wide voltage range, and dynamically adjust the current of the switching value acquisition circuit so that the loop current is always maintained within the recommended operating current range of the input stage of the photoelectric coupler D1.

[0010] The present invention has the characteristics of wide input voltage power supply range, stable driving current, low power consumption and small size, and is particularly suitable for switch electrical control equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 2 is a circuit diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0012] To further illustrate the purpose and technical solutions of the present invention, the present invention will be described in further detail below with reference to the specific embodiments of the drawings.

[0013] Reference Figure 1 As shown, an embodiment of the present invention discloses a switch input acquisition circuit that can operate in a wide voltage range, including a power supply positive lead terminal VCC+ and a power supply negative lead terminal VCC-, a surge suppression circuit composed of a transient suppression diode V2, and an anti-power reverse connection circuit composed of a diode V1.

[0014] Resistor R1, N-channel depletion-mode MOSFET V4, resistor R4, photocoupler D1, and Zener diode V5 are connected in series to form the first switching value input acquisition circuit. Anti-reverse polarity diode V1, resistor R3, resistor R4, photocoupler D1, and Zener diode V5 are connected in series to form the second switching value input acquisition circuit. The passive switching nodes are connected in series to the switching value acquisition circuit.

[0015] One end of the resistor R1 is connected to the cathode of the anti-reverse polarity diode V1, and the other end is connected to the drain of the N-channel depletion-type MOSFET tube V4 and the gate of the P-channel enhancement-type MOSFET tube V3. One end of the resistor R2 is connected to the cathode of the anti-reverse polarity diode V1, and the other end is connected to the source of the P-channel enhancement-type MOSFET tube V3. One end of the resistor R3 is connected to the cathode of the anti-reverse polarity diode V1, and the other end is connected to the resistor R4 and the source of the N-channel depletion-type MOSFET tube V4. The gate of the N-channel depletion-type MOSFET tube V4 and the other end of the resistor R4 are connected to The anode of the input stage diode of the photocoupler D1, that is, the resistor R4, is connected between the gate and source of the N-channel depletion-mode MOSFET tube V4. The cathode of the input diode of the photocoupler D1 is connected to the cathode of the voltage-regulating diode V5. The anode of the voltage-regulating diode V5 and the drain of the P-channel enhancement-mode MOSFET tube V3 are respectively connected to the negative electrode of the power supply VCC-. The positive electrode of the output end of the photocoupler D1 is connected to the resistor R5. The other end of the resistor R5 is connected to the positive electrode of the isolation side power supply VDD. The output stage of the photocoupler D1 is connected in parallel with the capacitor C1 to output the switching signal DIN.

[0016] The functions of the above components are as follows: Switch SW1 provides a dry contact signal for digital input. The following analyzes the circuit's operation when switch SW1 is closed.

[0017] When the power supply VCC voltage is very low, the voltage regulator diode V5 does not conduct, and the switch input acquisition circuit does not operate. The voltage regulator diode V5 increases the circuit's operating voltage threshold, preventing false triggering. The voltage regulator diode V5 must be approximately 3V lower than the circuit's minimum operating voltage.

[0018] During operation, N-channel depletion-mode MOSFET V4 operates in the variable resistance region. P-channel enhancement-mode MOSFET V3, operating in this region, acts as a load for MOSFET V4, and resistor R2 acts as a load for P-channel enhancement-mode MOSFET V3. As the voltage increases, N-channel depletion-mode MOSFET V4 enters the variable resistance region from the saturation region. Current flows through reverse polarity protection diode V1, resistor R1, N-channel depletion-mode MOSFET V4, and resistor R4 into the input of optocoupler D1, then through Zener diode V5. Current also flows through resistors R1 and R2, turning on optocoupler D1. When the voltage continues to rise, turning off N-channel depletion-mode MOSFET V4, it enters the cutoff region and cannot conduct current. Current flows through V1, resistors R3, and R4 into the input of optocoupler D1, then through Zener diode V5, turning on D1.

[0019] When the voltage is low, N-channel depletion-mode MOSFET V4 operates in its saturation region. At this point, V4's on-resistance is very low. Current flows through resistor R3, N-channel depletion-mode MOSFET V4, and resistor R4 into the input of optocoupler D1. It then flows through Zener diode V5, turning on optocoupler D1. Zener diode V5 increases the circuit's on-threshold and improves its anti-interference capabilities.

[0020] When the power supply VCC voltage rises above the minimum operating voltage, the current flowing through the circuit of anti-reverse polarity diode V1, resistors R3 and R4, optocoupler D1, and Zener diode V5 is very small, far less than the minimum operating current at the input of optocoupler D1. Due to the characteristics of N-channel depletion-mode MOSFET V4, the MOSFET turns on at this point. The on-resistance of N-channel depletion-mode MOSFET V4 is very low, and the resistances of resistors R1 and R4 are also relatively small. Therefore, the current flowing through R1, V4, R4, optocoupler D1, and V5 reaches the conditions required to turn on D1. The first switching signal acquisition circuit drives optocoupler D1 to output a switching signal. At this point, the current flows through resistor R1, forming a gate drive voltage for P-channel enhancement-mode MOSFET V3. P-channel enhancement-mode MOSFET V3 operates in the variable resistance range, acting as a variable load for N-channel depletion-mode MOSFET V4. Resistor R2 serves as a load for the P-channel enhancement mode MOSFET V3, providing a path for the drain current of V3.

[0021] As the power supply voltage continues to rise, the current flowing through R1, V4, R4, D1, and V5 increases, raising the voltage across resistor R4. This in turn reverses the gate-source drive voltage of N-channel depletion-mode MOSFET V4, increasing the on-resistance of N-channel depletion-mode MOSFET V4 operating in the variable resistance range. Consequently, the current in the first switching acquisition circuit gradually decreases. As the voltage gradually rises, the resistance values of resistors R3 and R4 remain constant, causing the current in the second switching acquisition circuit, R3, R4, D1, and V5, to gradually increase. The currents from both the first and second switching acquisition circuits flow into photocoupler D1, turning it on and outputting a switching signal. As the voltage across resistor R4 continues to rise, N-channel depletion-mode MOSFET V4 turns off, blocking the current path through R1, V4, R4, D1, and V5. At this point, the current flowing through R1 stops, and the drive voltage to V3 is essentially zero, shutting off V3.

[0022] The power supply voltage continues to rise. At this time, the current of the first switching value acquisition circuit is cut off. The current of the second switching value acquisition circuit composed of the anti-reverse connection diode V1, resistor R3, resistor R4, photocoupler D1, and Zener diode V5 has reached the condition of driving D1 to turn on alone, driving D1 to output a switching signal.

[0023] The device parameters in the circuit of the present invention satisfy the following relationship: When the power supply VCC voltage is high, (VCCH-V V1 - V V5 ) / (R3+R4)>I D1F , that is, the current formed by the power supply flowing through V1, R3, R4, and V5 can drive D1 to turn on; when the power supply VCC voltage is low, (VCCL-V V1 - V V5 ) / (R1+R4)>I D1F , that is, the current formed by the power supply flowing through V1, R1, V4, R4, and V5 can drive D1 to turn on; when D1 is turned on, the current flowing through resistor R4 should be able to generate a voltage value of the V4 gate drive voltage turn-on threshold, that is, R4×I D1F ≈V VGS4th The current flowing through resistor R1 should be able to generate a voltage value that is equal to the gate drive voltage turn-on threshold of V3, that is, R1×I D1 F≈V VGS3th .

[0024] The circuit is described as follows: N-channel depletion-mode MOSFET V4 acts as a variable resistor, adjusting the current in the first switching value acquisition circuit at different voltage levels. This ensures the component consistently operates at low power consumption, facilitating component selection. The N-channel depletion-mode MOSFET, acting as a variable resistor, conducts when there is no drive voltage and voltage exists between the drain and source. At the moment SW1 turns on, N-channel depletion-mode MOSFET V4 also conducts.

[0025] The P-channel depletion-mode MOSFET V3 operates in the variable resistance range, serving as the variable resistance load for V4. When the first switching value acquisition circuit is turned on, current flows through R1, forming a drive voltage between the gate and source of the P-channel enhancement-mode MOSFET V3, turning it on and operating in the variable resistance range. The P-channel enhancement-mode MOSFET V3 serves as the load for the N-channel depletion-mode MOSFET V4, forming a complete MOSFET amplifier circuit.

[0026] When the power supply voltage VCC is still insufficient, the voltage across R1 does not reach the pinch-off voltage of the N-channel depletion-mode MOSFET V4, and V4 remains in the variable resistance range. As the VCC voltage increases, the voltage across R4 increases, and the gate drive voltage of V4 reverses, gradually increasing V4's on-resistance. This increase in loop voltage is accompanied by an increase in loop resistance, which in turn decreases the current flowing through optocoupler D1. At this time, the voltage across resistor R1 decreases, causing the on-resistance of V3 to gradually increase, reducing the current flowing through V3 and lowering V3's power consumption.

[0027] When the power supply voltage rises to a point where the voltage across resistor R4 approaches the pinch-off voltage of N-channel depletion-mode MOSFET V4, V4's on-resistance increases rapidly. At this point, the current flowing through the first switching value acquisition circuit is small and insufficient to drive optocoupler D1 alone. At this point, the current flowing through the second switching value acquisition circuit gradually increases. The currents from the first and second switching value acquisition circuits jointly drive optocoupler D1 to conduct, outputting a switching signal.

[0028] If the power supply voltage VCC is too high at this point, the voltage generated by the resistor R4 increases, and the gate drive voltage of V4 reaches its pinch-off voltage. V4's operating state shifts from the variable resistance range to the cutoff range, at which point V4 is cut off, and the first switching value acquisition circuit loses its current path. Simultaneously, there is no current loop across R1 and R2, and the potential between the gate and source of V3 is equal, preventing V3 from reaching the on-state condition and thus becoming cut off. The power supply voltage VCC is applied to the second switching value acquisition circuit, generating sufficient current to drive optocoupler D1 to conduct, outputting a switching value signal.

[0029] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A switch input acquisition circuit capable of operating in a wide voltage range, characterized by: The invention comprises a first switch value input acquisition circuit composed of a resistor R1, an N-channel depletion-type MOSFET tube V4, a resistor R4, a photocoupler D1 and a voltage-stabilizing diode V5 connected in series, and a second switch value input acquisition circuit composed of an anti-reverse diode V1, a resistor R3, a resistor R4, a photocoupler D1 and a voltage-stabilizing diode V5 connected in series; one end of the resistor R1 is connected to the cathode of the anti-reverse diode V1, and the other end is simultaneously connected to the drain of the N-channel depletion-type MOSFET tube V4 and the gate of the P-channel enhancement-type MOSFET tube V3; one end of the resistor R2 is connected to the cathode of the anti-reverse diode V1, and the other end is connected to the source of the P-channel enhancement-type MOSFET tube V3; the resistor R3 is connected to the cathode of the anti-reverse diode V1, and the other end is connected to the source of the P-channel enhancement-type MOSFET tube V3. The first end is connected to the cathode of the anti-reverse polarity diode V1, and the other end is connected to the resistor R4 and the source of the N-channel depletion-type MOSFET tube V4. The gate of the N-channel depletion-type MOSFET tube V4 and the other end of the resistor R4 are connected to the anode of the input stage diode of the photocoupler D1. The cathode of the input diode of the photocoupler D1 is connected to the cathode of the voltage-regulating diode V5. The anode of the voltage-regulating diode V5 and the drain of the P-channel enhancement-type MOSFET tube V3 are respectively connected to the negative electrode of the power supply VCC-. The positive electrode of the output end of the photocoupler D1 is connected to the resistor R5. The other end of the resistor R5 is connected to the positive electrode of the isolation side power supply VDD. The output stage of the photocoupler D1 is connected in parallel with the capacitor C1 to output the switching signal DIN.

2. The switch input acquisition circuit capable of operating in a wide voltage range according to claim 1, characterized in that: It also includes a surge suppression circuit composed of a transient suppression diode V2. The cathode of the transient suppression diode V2 and the anode of the anti-reverse polarity diode V1 are connected to the positive power supply VCC+ through a switch SW1, and the anode of the transient suppression diode V2 is connected to the negative power supply VCC-.

3. The switch input acquisition circuit capable of operating in a wide voltage range according to claim 2, characterized in that: When the voltage is low, the N-channel depletion-type MOSFET tube V4 operates in the saturation region, and the current flows through the resistor R1, the N-channel depletion-type MOSFET tube V4, the resistor R4, and flows into the input end of the photocoupler D1, and flows through the Zener diode V5, driving the photocoupler D1 to turn on.

4. The switch input acquisition circuit capable of operating in a wide voltage range according to claim 2, characterized in that: During the voltage increase process, the N-channel depletion-type MOSFET tube V4 enters the variable resistance region and finally enters the cutoff region from the saturation region. The current flows into the input end of the photocoupler D1 through the anti-reverse polarity diode V1, resistor R1, N-channel depletion-type MOSFET tube V4, and resistor R4, and flows through the voltage regulator diode V5. The current also flows through the resistors R3 and R4, jointly driving the photocoupler D1 to turn on.

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