CN209784800U - A Protection Circuit Considering Both NPN Type and PNP Type Load Output - Google Patents

Abstract

The utility model discloses a protection circuit giving consideration to NPN type and PNP type load output, which comprises a microprocessor U1, a load output form detection circuit, a voltage stabilizing circuit, an overvoltage protection detection circuit, a first switch circuit and a second switch circuit; the power supply voltage is supplied to the microprocessor U1 through the voltage stabilizing circuit, a signal input end IN of the microprocessor U1 receives a control signal of an external control circuit or a sensor, a load output form detection circuit detects an accessed load loop and outputs a load output form signal to the microprocessor U1, the microprocessor U1 controls the connection and disconnection of the first switch circuit and the second switch circuit according to the control signal and the load output form signal, the power supply voltage and a load form a first load loop through the first switch circuit, and the power supply voltage and the load form a second load loop through the second switch circuit. The utility model discloses automatic discernment load form and transmission signal give the load, can satisfy the requirement of NPN type and PNP type output form simultaneously.

Description

A Protection Circuit Considering Both NPN Type and PNP Type Load Output

technical field

The utility model relates to the technical field of industrial control, in particular to a protection circuit which takes both NPN type and PNP type load output into consideration.

Background technique

There are two types of connection between the traditional circuit output terminal and the load: NPN type and PNP type. When the output form of the circuit is NPN type, the load can only be connected as NPN type; when the output form of the circuit is PNP type, the load It can only be connected as PNP type; the traditional circuit cannot take into account both NPN type and PNP type output forms at the same time, and does not have the following protection functions: overvoltage protection function, overcurrent protection function, surge protection function, anti-static protection function, Inductive load fast demagnetization function, power supply voltage reverse polarity protection function, fault indication function.

Utility model content

The technical problem to be solved by the utility model is to provide a protection circuit that takes into account both NPN and PNP load output, which can automatically identify the load type and transmit the signal to the load.

In order to solve the above technical problems, the technical solution adopted by the utility model is: a protection circuit that takes into account both NPN type and PNP type load output, which includes a microprocessor U1, a load output form detection circuit, a voltage stabilizing circuit, and an overvoltage protection circuit. The detection circuit, the first switch circuit and the second switch circuit; the power supply voltage is supplied to the microprocessor U1 through the voltage stabilizing circuit, the signal input terminal IN of the microprocessor U1 receives the control signal of the external control circuit or sensor, and the load output form detection circuit Detect the connected load circuit, and output the load output form signal to the microprocessor U1, and the microprocessor U1 controls the on-off of the first switch circuit and the second switch circuit according to the control signal and the load output form signal, and the power supply The voltage forms a first load loop through the first switch circuit and the load, and the power supply voltage forms a second load loop through the second switch circuit and the load.

In the above technical solution, the load output form detection circuit includes a resistor R4, a resistor R7, a TVS tube D2 and a capacitor C2, the resistor R4 is connected in series between the load loop and the T2 port of the microprocessor U1, the resistor R7, the TVS tube D2 and After the capacitor C2 is connected in parallel, one end is grounded and the other end is connected to the node between the T2 port and the resistor R4.

In the above technical solution, the voltage stabilizing circuit includes a voltage stabilizing tube Z1 and a capacitor C1, and the voltage stabilizing tube Z1 and the capacitor C1 are connected in parallel.

In the above technical solution, the overvoltage protection detection circuit includes a resistor R9, a resistor R10, a TVS tube D4, and a capacitor C3, and the resistor R10, the TVS tube D4, and the capacitor C3 are connected in parallel with the resistor R9 in series, and connected to the loop, micro The T1 port of the processor U1 is connected to the node between the resistor R9 and the parallel module of the resistor R10, the TVS transistor D4 and the capacitor C3.

In the above technical solution, the first switching circuit includes a first switching tube Q1 and a second switching tube Q2, the control terminal of the second switching tube Q2 is connected to the OUT1 port of the microprocessor U1, and the input terminal of the second switching tube Q2 It is electrically connected to the control terminal of the first switching tube Q1, the input terminal of the first switching tube Q1 and the input terminal of the second switching tube Q2 are respectively electrically connected to the power supply voltage, and the output terminal of the first switching tube Q1 is connected to the signal terminal of the load ; When the first switch tube Q1 is turned on, the power supply voltage enters the load from the signal terminal of the load through the first switch tube Q1 and comes out from the negative terminal of the load to form a first load circuit.

In the above technical solution, the second switch circuit includes a third switch tube Q3, the control terminal of the third switch tube Q3 is electrically connected to the OUT2 port of the microprocessor U1, and the output terminal of the third switch tube Q3 is connected to the signal terminal of the load Electrical connection; when the third switch tube Q3 is turned on, the power supply voltage enters the load through the positive terminal of the load, and then comes out from the signal terminal of the load to form a second load circuit through the third switch tube Q3.

In the above technical solution, a TVS tube D5 is connected in series in the second load circuit where the positive terminal of the load is located, and a TVS tube D7 is connected in series in the first load circuit where the negative terminal of the load is located, and the TVS tube D5 and TVS tube D7 are used as power supplies Voltage reverse polarity protection circuit.

The above technical solution also includes a fault indicator circuit, including an indicator LED1 and a resistor R11.

In the above technical solution, a TVS transistor D1 is connected in parallel to the input end and output end of the first switch circuit, and a TVS transistor D3 is connected in parallel to the input end and output end of the second switch circuit to form a fast degaussing circuit for an inductive load.

In the above technical solution, a TVS tube D6 is electrically connected between the power supply voltage and the ground to form an anti-static and surge protection circuit.

The beneficial effects of the utility model are: through the detection circuit of the load output form, it can be judged whether the load mode is NPN type or PNP type; There is a flashing or constant light output, indicating that the circuit is faulty, and the indicator light will go out when the fault is eliminated; in addition, this circuit also has at least one of the following self-protection functions: surge protection, anti-static protection, fast degaussing of inductive loads, power supply Voltage reverse polarity protection, compared with traditional circuits, this utility model has more practical value and more application prospects.

Description of drawings

Fig. 1 is a schematic diagram of the circuit principle of the utility model.

Detailed ways

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

As shown in Figure 1, the signal input terminal IN can receive information from other control circuits or sensors; after the microprocessor U1 receives the control signal, it can analyze the control signal. The OUT2 port of the device U1 outputs a low level, so that the triode Q3 (or MOS tube) is cut off, and the OUT1 port of the microprocessor U1 outputs a low level, so that the triode Q1 and Q2 (or MOS tube) are cut off, and the load is disconnected from the power supply voltage. Open; if the input signal is low level, when the output form signal is NPN, the OUT2 port of the microprocessor U1 outputs high level, so that the triode Q3 (or MOS tube) is turned on, and the OUT1 port of the microprocessor U1 Output low level, so that the triode Q1 and Q2 (or MOS tube) are cut off, and the load is connected to the power supply voltage; if the input signal is low level, when the output form signal is PNP, the OUT1 port of the microprocessor U1 The output high level makes the triode Q1 and Q2 (or MOS tube) conduct, and the OUT2 port of the microprocessor U1 outputs a low level, so that the triode Q3 (or MOS tube) is cut off, and the load is connected to the power supply voltage.

Specifically, the regulator tube Z1, the capacitor C1 and the resistor R8 form a regulator circuit to supply power to the microprocessor U1.

Specifically, resistor R9, resistor R10, TVS tube D4, and capacitor C3 form an overvoltage protection detection circuit. When the power supply voltage of the entire circuit is too high, the microprocessor U1 will detect the information that the voltage is too high, and will drive the fault The indicator LED1 is blinking or always on.

Specifically, resistor R7, resistor R4, TVS tube D2, and capacitor C2 form a load output form detection circuit. When the load is connected to the positive pole of the power supply, the microprocessor U1 detects the information and judges that the output form is NPN type. When the load is connected to the negative pole of the power supply , the microprocessor U1 detects the information and judges that the output form is PNP.

Specifically, the TVS tube D1 and TVS tube D3 form an inductive load fast degaussing circuit, which can eliminate the high-voltage pulse generated by the inductive load at the moment of power failure, and protect the transistors Q1 and Q3 from breakdown and damage.

Specifically, the TVS tube D6 plays the role of surge protection and anti-static protection, and can protect the circuit from being damaged by surge voltage and electrostatic voltage breakdown.

Specifically, the TVS tube D5 and the TVS tube D7 form a power supply voltage reverse polarity protection circuit, even if the positive pole and the negative pole of the power supply voltage of the entire circuit are reversed, the entire circuit assembly will not be damaged.

In the figure, P1 is the access port of the load, including the positive terminal of pin 1, the signal terminal of pin 2, and the negative terminal of pin 3.

Working principle of the utility model:

The microprocessor U1 receives the control signal from the control circuit or the sensor, and the load output form detection circuit detects that the load output form signal is transmitted to the microprocessor U1, and the microprocessor U1 selects and controls the first switch circuit conduction according to the control signal and the load output form signal. The second switch circuit is turned off or the first switch circuit is turned off and the second switch circuit is turned on.

When the first switch circuit is turned on and the second switch circuit is turned off, the power supply voltage passes through the first switch circuit, the signal terminal of the load, the load, and the negative terminal of the load to the ground terminal, forming a first load circuit.

When the first switch circuit is turned off and the second switch circuit is turned on, the power supply voltage passes through the positive terminal of the load, the load, the signal terminal of the load, and the second switch circuit to the ground terminal to form a second load loop.

The above embodiments are only intended to illustrate rather than limit the utility model, so all equivalent changes or modifications made according to the method described in the scope of the patent application of the utility model are included in the scope of the patent application of the utility model.

Claims (10)

1. A protection circuit giving consideration to NPN type and PNP type load output is characterized in that: the device comprises a microprocessor U1, a load output form detection circuit, a voltage stabilizing circuit, an overvoltage protection detection circuit, a first switch circuit and a second switch circuit; the power supply voltage is supplied to the microprocessor U1 through the voltage stabilizing circuit, a signal input end IN of the microprocessor U1 receives a control signal of an external control circuit or a sensor, the load output form detection circuit detects a load loop accessed by the microprocessor U1 and outputs a load output form signal to the microprocessor U1, the microprocessor U1 controls the on-off of the first switch circuit and the second switch circuit according to the control signal and the load output form signal, the power supply voltage and the load form a first load loop through the first switch circuit, and the power supply voltage and the load form a second load loop through the second switch circuit.

2. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: the load output form detection circuit comprises a resistor R4, a resistor R7, a TVS tube D2 and a capacitor C2, wherein the resistor R4 is connected in series between a load loop and a T2 port of a microprocessor U1, and after the resistor R7, the TVS tube D2 and the capacitor C2 are connected in parallel, one end of the resistor is grounded and the other end of the resistor is connected to a node between a T2 port and the resistor R4.

3. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: the voltage stabilizing circuit comprises a voltage regulator tube Z1 and a capacitor C1, wherein the voltage regulator tube Z1 is connected with the capacitor C1 in parallel.

4. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: the overvoltage protection detection circuit comprises a resistor R9, a resistor R10, a TVS tube D4 and a capacitor C3, wherein the resistor R10, the TVS tube D4 and the capacitor C3 are connected in parallel and then are connected in series with the resistor R9 and are connected in parallel to the load loop, and a T1 port of the microprocessor U1 is connected to a node between the resistor R9 and a parallel module of the resistor R10, the TVS tube D4 and the capacitor C3.

5. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: the first switch circuit comprises a first switch tube Q1 and a second switch tube Q2, the control end of the second switch tube Q2 is connected with the OUT1 port of the microprocessor U1, the input end of the second switch tube Q2 is electrically connected with the control end of the first switch tube Q1, the input end of the first switch tube Q1 and the input end of the second switch tube Q2 are respectively electrically connected with a power supply voltage, and the output end of the first switch tube Q1 is connected with the signal end of a load; when the first switch Q1 is turned on, the power voltage enters the load from the signal terminal of the load through the first switch Q1 and exits from the negative terminal of the load to form a first load loop.

6. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: the second switching circuit comprises a third switching tube Q3, the control end of the third switching tube Q3 is electrically connected with the OUT2 port of the microprocessor U1, and the output end of the third switching tube Q3 is electrically connected with the signal end of the load; when the third switch tube Q3 is turned on, the power voltage enters the load through the positive terminal of the load, and then comes out from the signal terminal of the load and forms a second load loop through the third switch tube Q3.

7. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: a TVS tube D5 is connected in series to the second load circuit where the positive terminal of the load is located, a TVS tube D7 is connected in series to the first load circuit where the negative terminal of the load is located, and the TVS tube D5 and the TVS tube D7 serve as a power supply voltage reverse polarity protection circuit.

8. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: also included is a fault indicator circuit comprising an indicator LED1 and a resistor R11.

9. The protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: the input end and the output end of the first switch circuit are connected with a TVS tube D1 in parallel, and the input end and the output end of the second switch circuit are connected with a TVS tube D3 in parallel, so that the inductive load rapid demagnetization circuit is formed.

10. the protection circuit according to claim 1, wherein the protection circuit is configured to output both NPN-type and PNP-type loads, and further configured to: and a TVS tube D6 is electrically connected between the power supply voltage and the ground to form an anti-static and surge protection circuit.