Voltage monitoring and on-off monitoring circuit

Abstract

The utility model belongs to the field of circuits, and particularly discloses a voltage monitoring and on-off monitoring circuit, which comprises an input voltage monitoring circuit, a contact on-off monitoring circuit and an isolation acquisition circuit, and is characterized in that the isolation acquisition circuit comprises a dual-channel photoelectric coupler working independently; the contact on-off monitoring circuit comprises a diode, a capacitor and a resistor which are connected in parallel, a pin 4 of the photoelectric coupler is connected to an input voltage positive end through a series current-limiting resistor, and a pin 3 of the photoelectric coupler is connected to an input voltage negative end; the input voltage monitoring circuit comprises a voltage comparator, a pin 1 of the photoelectric coupler is connected in series with a current-limiting resistor and is connected to an external input voltage positive end, and a pin 2 of the photoelectric coupler is connected with the voltage comparator and is connected to the external input voltage positive end after passing through a divider resistor. According to the utility model, reliable external voltage monitoring and on-off monitoring of an external link can be realized, and contact on-off monitoring and voltage input monitoring functions can be safely and reliably realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of circuits and specifically discloses a voltage monitoring and on-off monitoring circuit. Background Art

[0002] In the prior art, when electronic products monitor the voltage of a large external input voltage, they often use high-power resistors to divide and reduce the voltage, and then use the back-end processor circuit for monitoring. This method has major drawbacks. First, it cannot achieve effective isolation between the front and rear circuits. When there is a surge in the monitored voltage, it is easy to impact the rear circuit and cause a fault. At the same time, when monitoring the on and off of the external link, a mechanical switch is often used to generate an electric shock signal for monitoring. However, this method will affect the monitoring results due to the sensitivity of the electric shock switch, and the repeatability is poor, which is prone to false triggering. Utility Model Content

[0003] In order to solve the above technical problems, the utility model proposes a voltage monitoring and on-off monitoring circuit, including an input voltage monitoring circuit, a contact on-off monitoring circuit and an isolation acquisition circuit, wherein:

[0004] The isolation acquisition circuit includes a dual-channel independently operating photoelectric coupler;

[0005] The contact on-off monitoring circuit comprises a diode, a capacitor and a resistor connected in parallel, the pin 4 of the photoelectric coupler is connected to the positive end of the input voltage through a series current limiting resistor, and the pin 3 of the photoelectric coupler is connected to the negative end of the input voltage;

[0006] The input voltage monitoring circuit includes a voltage comparator, wherein pin 1 of the photoelectric coupler is connected to the positive terminal of the external input voltage via a series current limiting resistor, and pin 2 of the photoelectric coupler is connected to the voltage comparator and connected to the positive terminal of the external input voltage via a voltage dividing resistor.

[0007] Furthermore, the contact end of the pin 4 of the photoelectric coupler is a positive level V1, the contact end of the pin 3 of the photoelectric coupler is a signal ground V1_GND, and a diode is connected in parallel between the positive level V1 and the signal ground V1_GND.

[0008] The utility model uses photoelectric coupling devices for isolation collection, collects voltage signals and contact signals, and can realize reliable external voltage monitoring and external link on-off monitoring. The utility model can safely and reliably realize the contact on-off monitoring and voltage input monitoring functions, and can reduce the product volume and realize miniaturization design. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A circuit diagram of the utility model;

[0010] Figure 2This is the contact on-off monitoring circuit diagram;

[0011] Figure 3 It is the working flow chart of the contact on-off monitoring circuit;

[0012] Figure 4 This is the working flow diagram of the input voltage monitoring circuit. DETAILED DESCRIPTION

[0013] In order to better understand the purpose, technical solution and function of the utility model, the following Figure 1-4 , the utility model is further described in detail, but the utility model can be implemented in a variety of different ways as defined and covered by the claims. The drawings constituting a part of the utility model are used to provide a further understanding of the utility model, and the illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an improper limitation of the utility model.

[0014] The utility model uses a photoelectric coupling device, a voltage comparator, a matching resistor, and a filter capacitor to form a circuit. Figure 1 As shown, it includes a contact on-off monitoring circuit, an input voltage monitoring circuit and an isolation acquisition circuit.

[0015] The utility model circuit adopts a photocoupler as an isolation acquisition circuit, which can realize the isolation protection of the front and rear circuits, and prevent the interference crosstalk of the front acquisition circuit from entering the monitoring current of the rear stage. The photocoupler works independently in two channels, so it can realize the voltage detection and on-off monitoring functions at the same time; the voltage reference source FW431 is selected as the voltage comparator for voltage monitoring. The other components are discrete components such as resistors and capacitors.

[0016] The left side of the circuit is the optocoupler isolation input terminal. The positive input terminal 4 pin of the optocoupler is connected to the external input high level V1, and the negative input terminal 3 pin of the optocoupler is connected to the reference ground V1_GND of the external input high level V1. A protection circuit is added between V1 and V1_GND, and a reverse connection protection diode and a subsequent filter circuit are connected in parallel. A current limiting resistor is connected in series with V1 to protect the input terminal of the subsequent optocoupler.

[0017] The right side is connected to the post-stage monitoring circuit, that is, the processor part. Because the post-stage output of the photocoupler is an OC gate output, a pull-up resistor is added and connected to the processor circuit for collection.

[0018] The working process of the contact on-off monitoring circuit is as follows:

[0019] like Figure 2As shown, the photocoupler works independently in two channels, and the second channel is selected here to realize the contact on-off monitoring function; the input pins 3 and 4 on the left are connected to the contacts that need to be monitored outside the product, and are in contact with the plug-in end. In the utility model, the contact end of pin 4 is set to the positive level V1, and the contact end of pin 3 is set to the signal ground V1_GND; the diode connected in parallel between V1 and V1_GND is a protection circuit to prevent damage to the input end of the photocoupler due to reverse connection of the previous stage; when the external contact is not separated, pins 4 and 3 produce a voltage difference, at which time the photocoupler is turned on, and the output of pin 7 of the subsequent stage is a low level; when the external contacts are separated, pins 4 and 3 are suspended, at which time the photocoupler is not turned on, and the output of the subsequent stage is an OC gate, that is, a high level output. The subsequent monitoring circuit can judge the connection status of the external contacts of the product according to the high and low levels of the output signal of pin 7 to achieve the purpose of monitoring. Figure 3 This is the working flow diagram of the contact on-off monitoring circuit.

[0020] The first channel of the photocoupler is used to realize the input voltage monitoring function; the left side of the photocoupler is the external voltage input part, and the pin 1 of the photocoupler is connected to the input voltage terminal through a series resistor; the pin 2 is connected to the input voltage through a voltage comparator, a resistor, and a capacitor.

[0021] like Figure 4 As shown, the input voltage monitoring circuit works as follows:

[0022] The external input voltage is V2. Select R6 and R7 in series and divide the voltage with R8 to divide the input voltage V2, ensuring that when the input voltage is V2, the voltage at the REF terminal of the voltage comparator U1 is 2.5V. When the input voltage is less than V2, the voltage at the REF terminal is less than 2.5V, then V+ and V- of U1 are cut off, at this time the optocoupler is in the cut-off state, and the output of the subsequent stage is high level; when the input voltage is greater than V2, the voltage at the REF terminal is greater than 2.5V, then V+ and V- of U1 are turned on, at this time the optocoupler is in the on state, and the output of the subsequent stage is low level; the subsequent stage monitoring circuit can judge whether the level of the external input voltage of the product is greater than or less than the required input voltage according to the high and low levels of the output signal of pin 6, so as to achieve the purpose of monitoring.

[0023] The device selection requirements of a specific embodiment of the utility model may be:

[0024] B1: Select a photocoupler, the output end of which is an OC gate device;

[0025] U1: voltage comparator;

[0026] V1: Zener diode (breakdown voltage Vbr should be slightly greater than V1);

[0027] R1: value range 4.7K~10K;

[0028] R2, R3: value range 0.5K~1K;

[0029] R4: Value range: (V1-1.5V) / 20mA~(V1-1.5V) / 10mA;

[0030] R5: value range: (V2-1.5V) / 20mA~(V2-1.5V) / 10mA;

[0031] R6, R7, R8: The resistance value depends on the value of input voltage V2, ensuring that the voltage is 2.5V after R6+R7 and R8 divide the voltage;

[0032] C1, C2, C3, C4: Ceramic dielectric capacitors, which are filter capacitors.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various changes or modifications within the scope of the claims, which should all be included in the protection scope of the present invention.

Claims

1. A voltage monitoring and on-off monitoring circuit, characterized in that: It includes input voltage monitoring circuit, contact on / off monitoring circuit and isolation acquisition circuit, among which, The isolation acquisition circuit includes a dual-channel independently operating photoelectric coupler; The contact on-off monitoring circuit comprises a diode, a capacitor and a resistor connected in parallel, the pin 4 of the photoelectric coupler is connected to the positive end of the input voltage through a series current limiting resistor, and the pin 3 of the photoelectric coupler is connected to the negative end of the input voltage; The input voltage monitoring circuit includes a voltage comparator, wherein pin 1 of the photoelectric coupler is connected to the positive terminal of the external input voltage via a series current limiting resistor, and pin 2 of the photoelectric coupler is connected to the voltage comparator and connected to the positive terminal of the external input voltage via a voltage dividing resistor.

2. A voltage monitoring and on-off monitoring circuit according to claim 1, characterized in that: The contact end of the pin 4 of the photoelectric coupler is a positive level V1, the contact end of the pin 3 of the photoelectric coupler is a signal ground V1_GND, and a diode is connected in parallel between the positive level V1 and the signal ground V1_GND.

Images