Output circuit compatible with PNP and NPN sensors
By designing an output circuit compatible with PNP and NPN sensors, using components such as self-recovery fuses, sampling resistors and transistors, the interchangeability problems caused by differences in sensor signal polarity are solved, compatibility is achieved without unnecessary cables, and the flexibility and convenience of the sensor are improved.
Patent Information
- Application Number
- CN202422106751.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-28
- Publication Date
- 2025-06-24
- Estimated Expiration
- 2034-08-28
AI Technical Summary
In the prior art, the output signal polarity of the PNP type and NPN type sensors is opposite, resulting in the inequality of sensors of the same physical quantity being used interchangeably, and compatible solutions usually require extra cables and larger volume relays or optocoupler solutions.
An output circuit compatible with PNP and NPN sensors is designed, and signal compatibility and current limit protection are achieved through a first output interface including a self-recovery fuse and a sampling resistor, and NPN and PNP transistors, unidirectional diodes and current sampling chips are used.
This output circuit allows the NPN sensor or PNP sensor to use the same output without unnecessary cables. It realizes compatibility with the two models through simple configuration, improves the flexibility and convenience of sensor use, and provides convenience for industrial automation and the development of the Internet of Things.
Smart Images
Figure CN223024408U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of circuits, and particularly relates to an output circuit compatible with PNP and NPN sensors.
Background Art
[0002] There are two types of connections between the output end of the existing sensor and the load, namely PNP type and NPN type. Since the polarities of the output signals of the PNP type and the NPN type are completely opposite, sensors of the same physical quantity cannot be interchanged. Although some output circuits compatible with PNP type and NPN type have been designed in the industry, most of them adopt relay or multiple optocoupler schemes. This scheme requires an independent common terminal, so it requires extra cables and occupies a relatively large volume.
Content of the Utility Model
[0003] The purpose of the utility model is to provide an output circuit compatible with PNP and NPN sensors, so as to solve the problems in the prior art that extra cables are required due to the need for an independent common terminal and the occupied volume is relatively large.
[0004] To achieve the above purpose, the output circuit of the utility model compatible with PNP and NPN sensors includes a first output interface for connecting with PNP and NPN sensors, an NPN output enable terminal, and a PNP output enable terminal. Among them, the first output interface is connected in series with a self - reset fuse F7 and a sampling resistor R229. One end of the sampling resistor R229 is connected to the collector of the NPN transistor D54. The base of the NPN transistor D54 is connected to the NPN output enable terminal through a resistor R17, and the emitter of the NPN transistor D54 is grounded. In addition, the output circuit compatible with PNP and NPN sensors includes a PNP transistor Q6. The collector of the PNP transistor Q6 is connected to the collector of the NPN transistor D54 through a one - way diode D52. The emitter of the PNP transistor Q6 is connected to the 24V power supply through a self - reset fuse F4, and the base of the PNP transistor Q6 is connected to the 24V power supply through a resistor R210 and a resistor R209. Furthermore, the output circuit compatible with PNP and NPN sensors also includes an NPN transistor D50. The collector of the NPN transistor D50 is connected between the resistor R210 and the resistor R209, the emitter is grounded, and the base is connected to the PNP output enable terminal 13 through a resistor 211, and the base is also grounded through a resistor R212.
[0005] According to the above main features, a voltage - stabilizing diode D53 is connected between the collector and the emitter of the NPN transistor D54.
[0006] According to the above main features, the output circuit compatible with PNP and NPN sensors further includes a current-limiting dynamic protection circuit, including a current sampling chip. The current sampling chip U24 samples the voltage across the resistor R229. When the current when the load is connected reaches the current-limiting value, the current sampling chip outputs a voltage exceeding the threshold, and the level of the NPN output enable terminal or the PNP output enable terminal is pulled low to achieve current-limiting protection.
[0007] Compared with the prior art, the output circuit of the present utility model compatible with PNP and NPN sensors can enable the NPN sensor or the PNP sensor to use the same output terminal without extra cables. Whether the connected sensor is an NPN sensor or a PNP sensor, with simple configuration, a matching circuit can fully compatible with both NPN sensors and PNP sensors, improving the flexibility and convenience of using switch signal sensors, and providing convenience for the upgrade of industrial automation and the development of the Internet of Things.
Description of the Drawings
[0008] Figure 1 It is a schematic circuit diagram of the output circuit of the present utility model compatible with PNP and NPN sensors.
Detailed Embodiment
[0009] Please refer to Figure 1 As shown, the output circuit of the present utility model compatible with PNP and NPN sensors includes a first output interface 11 for connecting with PNP and NPN sensors ( Figure 1 EXTERNAL_P / N_OUTPUT1 terminal in Figure 1 ), an NPN output enable terminal 12 ( Figure 1 NPN_OUT1_ON terminal in
[0010] ), and a PNP output enable terminal 13 (
[0011] PNP_OUT1_ON terminal in
[0010] The first output interface 11 is connected in series with a self-resetting fuse F7 and a sampling resistor R229. One end of the sampling resistor R229 is connected to the collector of the NPN transistor D54. The base of the NPN transistor D54 is connected to the NPN output enable terminal 12 through a resistor R17, and the emitter of the NPN transistor D54 is grounded. In addition, a zener diode D53 is connected between the collector and the emitter of the NPN transistor D54 to provide surge protection. And a resistor R227 is connected between the base and the emitter of the NPN transistor D54.
[0011] As shown in the figure, when the NPN load is connected to the first output interface 11, the signal passes through the self - reset fuse F7, the sampling resistor R229, and the NPN transistor D54 in sequence and then reaches the common ground. When NPN output is selected, the NPN output enable terminal 12 is pulled to a high level, the NPN transistor D54 is turned on, and the NPN output works normally.
[0012] In addition, the output circuit for compatible PNP and NPN sensors implementing the present utility model further includes a current - limiting dynamic protection circuit. The current - limiting protection circuit includes a current - sampling chip U24. The current - sampling chip U24 samples the voltage across the resistor R229. When the current at the time of load connection reaches the current - limiting value (50 mA), the current - sampling chip outputs a voltage exceeding the threshold, pulling down the level of the NPN output enable terminal 12, and the NPN transistor D54 is turned off, achieving the purpose of current - limiting protection. In specific implementation, the current - sampling chip U24 follows a specific formula: the current on the resistor R229×resistance value×amplification factor + Vref = the output voltage on the current - sampling chip U24 ( Figure 1 the out pin of the current - sampling chip U24 in). When the ADC on the main control chip (not shown) samples a voltage exceeding the set value, the NPN output enable terminal 12 is set to a low level, thereby turning off the NPN transistor D54.
[0013] In addition, the output circuit for compatible PNP and NPN sensors implementing the present utility model includes a PNP transistor Q6. The collector of the PNP transistor Q6 is connected to the collector of the NPN transistor D54 through a one - way diode D52. The emitter of the PNP transistor Q6 is connected to the 24V power supply through a self - reset fuse F4, and the base of the PNP transistor Q6 is connected to the 24V power supply through the resistor R210 and the resistor R209.
[0014] Furthermore, the output circuit for compatible PNP and NPN sensors implementing the present utility model further includes an NPN transistor D50. The collector of the NPN transistor D50 is connected between the resistor R210 and the resistor R209, the emitter is grounded, and the base is connected to the PNP output enable terminal 13 through the resistor 211. And the base is also grounded through the resistor R212.
[0015] When the PNP load is connected to the first output interface 11, the signal passes through the self - resetting fuse F4, PNP transistor Q6, one - way diode D52, sampling resistor R229, and self - resetting fuse F7 in sequence at 24V and then reaches the PNP load. When PNP output is selected, the PNP output enable terminal 13 is pulled to a high level, the PNP transistor Q6 is turned on, and the PNP output works normally. When the current when the load is connected reaches the current - limiting value (50mA), the current - sampling chip U24 outputs a voltage exceeding the threshold, pulling down the level of the PNP output enable terminal 13 and turning off the NPN transistor D50 to achieve the purpose of current - limiting protection. In specific implementation, the current - sampling chip U24 will follow a specific formula: the current on resistor R229×resistance value×amplification factor + Vref = the output voltage on the current - sampling chip U24( Figure 1 (the out pin of the current - sampling chip U24 in). When the ADC on the main control chip (not shown) samples a voltage exceeding the set value, the PNP output enable terminal 13 is set to a low level, thereby turning off the NPN transistor D50.
[0016] Implementing the output circuit that is compatible with PNP and NPN sensors of the present utility model enables NPN sensors or PNP sensors to use the same output terminal without extra cables. Whether an NPN sensor or a PNP sensor is connected, with a simple configuration, a matching circuit can fully accommodate the use of both NPN sensors and PNP sensors of two models, improving the flexibility and convenience of using switch - quantity signal sensors and providing convenience for the upgrade of industrial automation and the development of the Internet of Things.
[0017] It can be understood that for those of ordinary skill in the art, equivalent substitutions or changes can be made according to the technical solution and the inventive concept of the present utility model, and all such changes or substitutions should fall within the protection scope of the appended claims of the present utility model.
Claims
1. An output circuit compatible with PNP and NPN sensors, characterized in that: The output circuit compatible with PNP and NPN sensors includes a first output interface for connecting to PNP and NPN sensors, an NPN output enable terminal and a PNP output enable terminal, wherein the first output interface is connected in series with a self-recovery fuse F7 and a sampling resistor R229, and one end of the sampling resistor R229 is connected to the collector of the NPN transistor D54, the base of the NPN transistor D54 is connected to the NPN output enable terminal through a resistor R17, and the emitter of the NPN transistor D54 is grounded. In addition, the output circuit compatible with PNP and NPN sensors includes a PNP transistor Q6, and the PNP transistor Q6 The collector of the PNP transistor Q6 is connected to the collector of the NPN transistor D54 through a unidirectional diode D52, the emitter of the PNP transistor Q6 is connected to the 24V power supply through a self-recovery fuse F4, and the base of the PNP transistor Q6 is connected to the 24V power supply through resistors R210 and R209. Furthermore, the output circuit compatible with PNP and NPN sensors also includes an NPN transistor D50, the collector of the NPN transistor D50 is connected between the resistors R210 and R209, the emitter is grounded, and the base is connected to the PNP output enable terminal 13 through a resistor 211, and the base is also grounded through a resistor R212.
2. The output circuit compatible with PNP and NPN sensors as claimed in claim 1, characterized in that: A voltage regulator tube D53 is connected between the collector and emitter of the NPN transistor D54.
3. The output circuit compatible with PNP and NPN sensors as claimed in claim 1, characterized in that: The output circuit compatible with PNP and NPN sensors also includes a current limiting dynamic protection circuit, including a current sampling chip. The current sampling chip U24 collects the voltage across the resistor R229. When the current when the load is connected reaches the current limiting value, the current sampling chip outputs a voltage exceeding the threshold value, and current limiting protection is achieved by lowering the level of the NPN output enable terminal or the PNP output enable terminal.