Isolated digital output circuit

Abstract

The invention discloses an isolation digital output circuit, and relates to the field of electronic engineering, the isolation digital output circuit comprises a driving control circuit, an isolator and a driving circuit, the isolator comprises an isolation input end and an isolation output end, the isolation input end is provided with a first pin and a second pin, the isolation output end is provided with a third pin and a fourth pin, and the driving control circuit is connected with the isolation output end. The driving circuit comprises a first resistor and a triode; the output positive electrode end of the driving control circuit is connected with the first pin, the output negative electrode end of the driving control circuit is connected with the second pin, the first pin is the positive electrode pin of the isolated input end, and the second pin is the negative electrode pin of the isolated input end; a third pin of the isolated output end is connected with one end of the first resistor, the other end of the first resistor is connected with a collector of the triode, and a fourth pin of the isolated output end is connected with a base of the triode; the collector electrode of the triode is connected with the first output end of the driving circuit, and the emitter electrode of the triode is connected with the second output end of the driving circuit. According to the invention, the isolator is effectively protected through double current limitation.

Description

Technical Field

[0001] The present application relates to the field of electronic engineering technology, and in particular to an isolated digital output circuit. Background Art

[0002] In industrial applications, isolated digital output circuits are often used in the drive control design of frequency converters. The isolated digital output circuit includes an isolator and a drive circuit. The isolation device is used to isolate the drive circuit. The drive circuit is connected to external devices and a power supply respectively, and serves as a circuit between the power supply and the external device. Common isolators include optocouplers, mutual inductance isolation, and magnetic isolation. The frequency converter is connected to the isolated input terminal of the isolator, and the drive circuit is connected to the isolated output terminal of the isolator. The frequency converter controls the conduction of the isolated output terminal by controlling the isolated input terminal, thereby realizing the conduction and shutdown of the drive circuit, thereby realizing the switch state control of the external device.

[0003] If the current in the driving circuit suddenly becomes abnormal, such as the current suddenly increases and far exceeds the normal current range, it is easy to cause damage to the isolator. Therefore, how to protect the isolator in the isolated digital output circuit is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the above problems, the present application provides an isolated digital output circuit to achieve the purpose of effectively protecting the isolator. The specific scheme is as follows:

[0005] In a first aspect, the present application provides an isolated digital output circuit, the isolated digital output circuit comprising a drive control circuit, an isolator and a drive circuit, the isolator comprising an isolated input terminal and an isolated output terminal, the isolated input terminal having a first pin and a second pin, the isolated output terminal having a third pin and a fourth pin, the drive circuit comprising a first resistor and a triode;

[0006] The output positive terminal of the drive control circuit is connected to the first pin, and the output negative terminal of the drive control circuit is connected to the second pin, the first pin is the positive pin of the isolated input terminal, and the second pin is the negative pin of the isolated input terminal;

[0007] The third pin of the isolated output end is connected to one end of the first resistor, the other end of the first resistor is connected to the collector of the triode, and the fourth pin of the isolated output end is connected to the base of the triode;

[0008] The collector of the triode is connected to the first output end of the driving circuit, and the emitter of the triode is connected to the second output end of the driving circuit.

[0009] In a possible implementation, the drive circuit further includes a first diode, a second diode, a third diode, and a fourth diode;

[0010] The anode of the first diode is connected to the first output terminal of the drive circuit, and the cathode of the second diode is connected to the first output terminal of the drive circuit;

[0011] The anode of the third diode is connected to the second output terminal of the drive circuit, and the cathode of the fourth diode is connected to the second output terminal of the drive circuit;

[0012] The cathodes of the first diode and the third diode are both connected to the collector of the triode;

[0013] The anodes of the second diode and the fourth diode are both connected to the emitter of the triode.

[0014] In a possible implementation, the drive circuit further includes a bidirectional transient voltage suppression diode,

[0015] One end of the bidirectional transient voltage suppression diode is connected to the first output terminal of the drive circuit;

[0016] The other end of the bidirectional transient voltage suppression diode is connected to the second output terminal of the drive circuit.

[0017] In a possible implementation, the drive circuit further includes a first capacitor, and the first capacitor is connected between the third pin and the fourth pin.

[0018] In a possible implementation, the drive circuit further includes a second capacitor, and the second capacitor is connected between the first output terminal and the second output terminal.

[0019] In a possible implementation, the drive circuit further includes a second resistor;

[0020] The second resistor is connected between the collector and the emitter.

[0021] In a possible implementation, the drive circuit further includes a third resistor and a fourth resistor;

[0022] One end of the third resistor and one end of the fourth resistor are both connected to the second output terminal of the drive circuit;

[0023] The other end of the third resistor is connected to the fourth pin;

[0024] The other end of the fourth resistor is connected to the emitter of the triode.

[0025] In a possible implementation, the driving circuit further includes a first light-emitting element and a second light-emitting element;

[0026] The negative electrode of the first diode is connected in series with one of the first light-emitting elements, and the positive electrode of the fourth diode is connected in series with one of the first light-emitting elements;

[0027] The positive electrode of the second diode is connected in series with one of the second light-emitting elements, and the negative electrode of the third diode is connected in series with one of the second light-emitting elements.

[0028] In a possible implementation, the driving control circuit further includes a third capacitor, and the third capacitor is connected between the first pin and the second pin.

[0029] In a possible implementation, the isolator is an optocoupler, the isolated input end is the light emitter of the optocoupler, the isolated output end is the light receiver of the optocoupler, the third pin is the collector of the light receiver, and the fourth pin is the emitter of the light receiver;

[0030] One end of the third pin of the isolated output end is connected to one end of the first resistor, the other end of the first resistor is connected to the collector of the triode, and the fourth pin of the isolated output end is connected to the base of the triode, including:

[0031] The collector of the light receiver is connected to one end of the first resistor, the other end of the first resistor is connected to the collector of the triode, and the emitter of the light receiver is connected to the base of the triode.

[0032] With the above technical solution, an isolated digital output circuit provided by the present application, in this circuit, first, a first resistor is connected in series to the isolated output end of the isolator to limit the current on the current output side of the driving circuit. Further, a triode is connected in parallel to the isolated output end of the isolator. When the current is too large, the triode conducts, shunting the isolated output end of the isolator to limit the current passing through the isolated output end. This circuit can prevent damage to the isolator when the current changes suddenly through two-fold current limitation, and can effectively protect the isolator. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Combined with the drawings and referring to the following specific embodiments, the above and other features, advantages and aspects of the various embodiments of the present disclosure will become more obvious. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic, and the original components and elements are not necessarily drawn to scale.

[0034] Figure 1 It is a schematic structural diagram of an isolated digital output circuit provided by an embodiment of the present application;

[0035] Figure 2Schematic diagram of the circuit when the isolator provided in the embodiment of the present application is an optocoupler;

[0036] Figure 3 Schematic diagram of the structure of an overcurrent limiting unit provided in the embodiment of the present application;

[0037] Figure 4 Schematic diagram of the structure of an overcurrent limiting unit and a positive / negative phase compatibility unit provided in the embodiment of the present application;

[0038] Figure 5 Schematic diagram of the circuit flow in the drive circuit when the external terminals of the drive circuit are not reversely connected, provided in the embodiment of the present application;

[0039] Figure 6 Schematic diagram of the circuit flow in the drive circuit when the external terminals of the drive circuit are reversely connected, provided in the embodiment of the present application;

[0040] Figure 7 Schematic diagram of the structure of an overcurrent limiting unit, a positive / negative phase compatibility unit, and an overvoltage clamping unit provided in the embodiment of the present application;

[0041] Figure 8 Schematic diagram of the structure of a first capacitor, a second capacitor, and a third capacitor provided in the embodiment of the present application.

[0042] Reference numerals:

[0043] 001 - Drive control circuit; 002 - Isolator; 003 - Drive circuit; 1 - First pin; 2 - Second pin; 3 - Third pin; 4 - Fourth pin; R - Current limiting resistor; R0 - Freewheeling resistor; R1 - First resistor; Q - Triode; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; D1 - First diode; D2 - Second diode; D3 - Third diode; D4 - Fourth diode; L1 - First light-emitting element; L2 - Second light-emitting element; D5 - Bidirectional transient voltage suppression diode; C1 - First capacitor; C2 - Second capacitor; C3 - Third capacitor. Detailed implementation manners

[0044] The following describes the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. The terms used in the implementation manners section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0045] The following describes the embodiments of the present application with reference to the accompanying drawings. Those skilled in the art know that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are equally applicable to similar technical problems.

[0046] In the description of the present application and the above-mentioned drawings, terms such as "first", "second", etc. are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such terms can be interchanged under appropriate circumstances, which is only a way of distinguishing objects with the same attributes when describing embodiments of the present application. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion, so that a process, method, system, product or device including a series of units does not have to be limited to those units, but may include other units not clearly listed or inherent to these processes, methods, products or devices.

[0047] With the development of frequency converter technology, frequency converter technology has gradually been applied to various fields of industry. Therefore, the requirements for frequency converter technology are also getting higher and higher. The frequency converter can no longer only meet the basic functions such as driving and protecting the motor in terms of function, but also needs to combine the frequency converter with the application system to achieve the control of the application system. If the control of the application system is to be achieved, it is required that the frequency converter can control the switching function and hardware implementation of the switching device involved in the application system. Therefore, the isolated digital output circuit is also applied to the drive control design of the frequency converter, and the frequency converter realizes the state control of the switching device (such as an external electronic valve) through the isolated digital output circuit.

[0048] The isolated digital output circuit can be divided into an isolator and a drive circuit. The isolator can be a device that isolates the drive control circuit and the drive circuit, and its working principle can be optoelectronic isolation or magnetic isolation. The drive circuit is a circuit used to connect external devices and is controlled by the isolated drive control circuit through the isolator. Among them, optoelectronic isolation means isolation through an optocoupler. One end of the optocoupler is a light-emitting diode and the other end is a photosensitive triode. The signal is converted into an optical signal through the light-emitting diode, and then the optical signal is transmitted to the photosensitive triode through the isolation layer. The optical signal is converted into an electrical signal by the photosensitive triode. Magnetic isolation is achieved through the magnetic field generated by the magnetic induction coil, so that the signal sent by the drive control circuit can be transmitted to the drive circuit by electromagnetic induction, thereby realizing the isolation between the drive control circuit and the drive circuit.

[0049] When the drive control circuit inputs a signal, the isolator can convert the input signal into an optical signal or a magnetic signal, and transmit the signal to the drive circuit through the isolation layer (such as the isolation layer between the photosensitive element and the light-emitting element in the optoelectronic coupler, or the magnetic field coupling region in the magnetic coupler isolator).

[0050] For example, when the isolator is an optocoupler, the frequency converter controls the light-emitting diode (isolated input terminal) to emit light. The base of the photosensitive triode (isolated output terminal) has current, and the photosensitive triode conducts, then the drive circuit conducts, and the power supply and the external device are conducted, so the external device can be powered on and turned on. When the frequency converter controls the light-emitting diode not to emit light, the base of the photosensitive triode does not have current, then the photosensitive triode is cut off, the drive circuit does not conduct, the power supply and the external device are not conducted, and the external device cannot be powered on and cannot be turned on, which is in the off state.

[0051] The currently commonly used basic isolation digital output circuit has a simple circuit structure and can realize the switching state control of the external device connected to the drive circuit by the frequency converter. However, there are also some drawbacks. For example, the external terminals of the drive circuit need to be correctly connected to the positive potential and the reference ground (zero potential), and the voltage connected to the drive circuit needs to be within the rated range, such as 0 - 24V. And there is an easy situation of unstable voltage or current in the drive circuit. For example, when controlling the operation of a fan through the isolation digital output circuit, if the fan has an abnormal locked-rotor situation, the current in the drive circuit can increase and be much larger than the normal current range. If protection cannot be provided in time, the isolation digital output circuit can be burned out. Unstable voltage or current can damage the isolator in the isolation digital output circuit and affect the operation of the isolation digital output circuit. Further, there is often a situation where the user reversely connects the external terminals (output terminals of the drive circuit) of the drive circuit, so that the terminal that should be connected to the positive potential is connected to the reference ground, and the terminal that should be connected to the reference ground is connected to the positive potential. After the external terminals of the drive circuit are reversely connected, it is also easy to cause unstable current and damage the isolator, thereby affecting the operation of the isolation digital output circuit.

[0052] To solve the above problems, the embodiment of the present application provides an isolation digital output circuit. The isolation digital output circuit of the embodiment of the present application will be introduced in detail below with reference to the accompanying drawings.

[0053] Refer to Figure 1 , Figure 1 which is a schematic structural diagram of an isolation digital output circuit provided by the embodiment of the present application. As Figure 1 shown, the isolation digital output circuit provided by the embodiment of the present application includes a drive control circuit 001, an isolator 002, and a drive circuit 003. The isolator 002 includes an isolated input terminal and an isolated output terminal. The isolated input terminal has a first pin 1 and a second pin 2, and the isolated output terminal has a third pin 3 and a fourth pin 4. The drive control circuit 001 includes a current-limiting resistor R and a freewheeling resistor R0. One end of the current-limiting resistor R is connected to the output terminal of the frequency converter, and the other end of the current-limiting resistor R is connected to the second pin 2. The freewheeling resistor R0 is connected between the first pin and the second pin 2. The drive circuit 003 includes a first resistor R1 and a triode Q;

[0054] The positive output terminal of the drive control circuit 001 is connected to the first pin 1, and the negative output terminal of the drive control circuit 001 is connected to the second pin 2. The first pin 1 is the positive pin of the isolated input terminal, and the second pin 2 is the negative pin of the isolated input terminal;

[0055] The third pin 3 of the isolated output terminal is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the collector of the triode, and the fourth pin 4 of the isolated output terminal is connected to the base of the triode Q;

[0056] The collector of the triode Q is connected to the first output terminal of the drive circuit 003, and the emitter of the triode is connected to the second output terminal of the drive circuit 003.

[0057] Among them, the drive control circuit can be a circuit that controls the drive circuit through an isolator. The drive control circuit can include an inverter and a power supply. The isolator is an electronic component that isolates the drive control circuit and the drive circuit, and the drive circuit is a circuit connected to external devices. The first pin and the second pin of the isolator can be two terminals for connecting the drive control circuit, and the third pin and the fourth pin of the isolator can be two terminals for connecting the drive circuit. The first output terminal and the second output terminal of the drive circuit can be two external connection terminals of the drive circuit.

[0058] Specifically, as Figure 2 shown, in this embodiment, the isolator 002 can be an optocoupler. Then, at this time, the isolated input terminal is the light emitter of the optocoupler, the isolated output terminal is the light receiver of the optocoupler, the third pin 3 is the collector of the light receiver, the fourth pin 4 is the emitter of the light receiver, the collector of the light receiver is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the collector of the triode, and the emitter of the light receiver is connected to the base of the triode Q.

[0059] The drive control circuit can be connected to the isolated input terminal of the isolator through the first pin and the second pin of the isolator. The drive circuit can be connected to the isolated output terminal of the isolator through the third pin and the fourth pin of the isolator. The drive control circuit controls the current at the input terminal of the isolator through the inverter, thereby controlling the conduction condition of the isolated output terminal and indirectly controlling the conduction condition of the drive circuit connected to the isolated output terminal.

[0060] Since the drive circuit is connected to external devices and also to the isolated output of the isolator, current anomalies are likely to occur in the drive circuit. When a current anomaly occurs in the drive circuit, it can damage the isolated output of the isolator. Therefore, to protect the isolator in a timely manner, in this embodiment, a triode is connected to the isolated output. The third pin of the isolated output is connected to the collector of the triode, and the fourth pin of the isolated output is connected to the base of the triode. When the current in the drive circuit exceeds the limit and the drive control circuit controls the isolated output to conduct through the isolated output, current can flow through both the base and the collector of the triode, causing the triode to conduct. The conduction of the triode allows current to be shunted from the isolated output to which it is connected, limiting the current flowing through the isolated output and reducing the impact of current instability on the isolated output.

[0061] To further reduce the impact of current instability on the isolated output and the damage caused by large currents to the isolated output, in this embodiment, a first resistor can be connected in series to the third pin of the isolated output first, and then the other end of the first resistor is connected to the collector of the triode. The first resistor can limit the current flowing through the isolated output and prevent large currents from damaging the isolated output.

[0062] Furthermore, as Figure 3 shown, in this embodiment, a second resistor R2 can also be set in the drive circuit 003, and the second resistor R2 can be connected in parallel with the triode Q. The specific connection method can be: the second resistor R2 is connected between the collector and the emitter of the triode Q.

[0063] Due to the failure of external devices, a sudden increase in current is likely to occur in the drive circuit, resulting in an excessive voltage difference between the collector and the emitter of the triode, causing the triode to malfunction. Therefore, in this embodiment, considering the possibility of this situation and protecting the normal operation of the triode, a second resistor is connected in parallel with the triode. When the voltage difference between the collector and the emitter of the triode is excessive, it can shunt current for the triode, reducing the voltage difference between the collector and the emitter and protecting the normal operation of the triode. Therefore, in this embodiment, not only is the triode used to shunt current for the isolated output of the isolator to protect the isolated output of the isolator, but also the second resistor is used to shunt current for the triode to protect the triode.

[0064] In addition to the second resistor, as Figure 3 shown, in this embodiment, a third resistor R3 and a fourth resistor R4 are also set for the triode Q. The specific connection method can be: one end of the third resistor R3 and one end of the fourth resistor R4 are both connected to the second output of the drive circuit 003; the other end of the third resistor R3 is connected to the fourth pin; the other end of the fourth resistor R4 is connected to the emitter of the triode Q.

[0065] Among them, the third resistor is the pull-down resistor of the triode. The pull-down resistor of the triode refers to the resistor connected from the input terminal of the triode (such as the base or collector) to the low level or negative power supply (such as ground GND). The third resistor can effectively connect the input terminal of the triode to the low level or ground, ensuring that when there is no external signal input, the input terminal of the triode remains at a stable low level state, thereby preventing the triode from entering an uncertain state, such as the triode being misoperated due to noise interference. The fourth resistor can be the current-limiting resistor of the triode, mainly used to limit the current passing through the emitter of the triode, prevent the current from being too large and damaging the triode and other circuit components, and ensure that the current flows within a safe range.

[0066] Therefore, as Figure 3 shown, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4 and the triode Q can form an overcurrent limiting unit of the drive circuit 003. When the current in the drive circuit 003 exceeds the limit value, the triode Q conducts, shunting current for the optocoupler. The first resistor R1 limits the input current of the isolation input terminal, and the second resistor R2 shunts current for the triode Q.

[0067] An isolation digital output circuit provided by an embodiment of the present application. In this circuit, first, a first resistor is connected in series to the isolation output terminal of the isolator to limit the current on the current output side of the drive circuit. Further, a triode is connected in parallel to the isolation output terminal of the isolator. When the current is too large, the triode conducts, shunting current for the isolation output terminal of the isolator and limiting the current passing through the isolation output terminal. This circuit can prevent damage to the isolator when the current changes suddenly through two-fold current limiting, and can effectively protect the isolator.

[0068] To avoid the harm caused by the reverse connection of the external terminals of the drive circuit, as Figure 4 shown, this embodiment can also set a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4 for the isolation digital output circuit, so that when the external terminals are reversely connected, the current still flows in from the third pin 3 of the isolation output terminal and flows out from the fourth pin 4 of the isolation output terminal.

[0069] As Figure 4As shown, based on the overcurrent limiting unit in this embodiment, two sets of reverse-connected diodes can form the driving circuit 003. In the forward and reverse compatibility unit of the driving circuit 003, the specific connection methods of the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4 can be: the positive electrode of the first diode D1 is connected to the first output terminal of the driving circuit 003, and the negative electrode of the second diode D2 is connected to the first output terminal of the driving circuit 003; the positive electrode of the third diode D3 is connected to the second output terminal of the driving circuit 003, and the negative electrode of the fourth diode D4 is connected to the second output terminal of the driving circuit 003; the negative electrodes of the first diode D1 and the third diode D3 are both connected to the collector of the triode Q; the positive electrodes of the second diode D2 and the fourth diode D4 are both connected to the emitter of the triode Q.

[0070] When the external terminals of the driving circuit are not reversely connected, the current flow in the driving circuit can be as Figure 5 shown by the multiple black arrows in, and when the external terminals of the driving circuit are reversely connected, the current flow in the driving circuit can be as Figure 6 shown by the multiple black arrows in.

[0071] In order to more clearly show the current flow in the two cases in this embodiment, this embodiment can set a first light-emitting element and a second light-emitting element for the driving circuit. As Figure 4 shown, the specific connection method can be: a first light-emitting element L1 is connected in series to the negative electrode of the first diode D1, and another first light-emitting element L1 is connected in series to the positive electrode of the fourth diode D4; a second light-emitting element L2 is connected in series to the positive electrode of the second diode D2, and another second light-emitting element L2 is connected in series to the negative electrode of the third diode D3. Then when the external terminals of the driving circuit 003 are not reversely connected, the two first light-emitting elements L1 can emit light, indicating whether there is current passing through and the direction of the current flow at this time; and when the external terminals of the driving circuit 003 are reversely connected, the two second light-emitting elements L2 can emit light, indicating whether there is current passing through and the direction of the current flow at this time. The first light-emitting element and the second light-emitting element can be light-emitting diodes.

[0072] In another alternative embodiment, the first diode, the second diode, the third diode, and the fourth diode can all be light-emitting diodes. In this way, this application does not need to separately set the light-emitting elements as Figure 3 shown, and can directly use the first diode, the second diode, the third diode, and the fourth diode to indicate the current through light emission.

[0073] Based on the above overcurrent limiting unit and positive / negative phase compatibility unit, an overvoltage clamping unit can also be provided for the drive circuit in this embodiment. The overvoltage clamping unit includes a bidirectional transient voltage suppression diode. A bidirectional transient voltage suppression diode is an overvoltage protection device with bidirectional voltage stabilization characteristics and bidirectional negative resistance characteristics, used to suppress instantaneous overvoltage. Its principle is: when an instantaneous overvoltage appears in the protected circuit, the bidirectional transient voltage suppression diode can quickly break down in Zener mode, changing from a high-resistance state to a low-resistance state, shunting and clamping the instantaneous overvoltage, thereby protecting each component in the circuit from being damaged by the instantaneous overvoltage.

[0074] As Figure 7 shown, in this embodiment, one end of the bidirectional transient voltage suppression diode D5 is connected to the first output terminal of the drive circuit 003; the other end of the bidirectional transient voltage suppression diode D5 is connected to the second output terminal of the drive circuit 003, ensuring the amplitude range of the voltage at the output terminal of the drive circuit 003, and the bidirectional transient voltage suppression diode D5 can be insensitive to the positive voltage direction of the drive circuit 003, so that even when the external terminals of the drive resistor are in a reverse-connected state, overvoltage damage to the drive circuit 003 can still be prevented.

[0075] In this embodiment, the positive / negative phase compatibility unit can ensure that when the external terminals of the drive circuit are in a reverse-connected state, the current still flows in from the third pin of the isolation output terminal and out from the fourth pin of the isolation output terminal, and at this time the overvoltage clamping unit can still protect the drive circuit and prevent overvoltage damage to the drive circuit.

[0076] In summary, an overcurrent limiting unit, a positive / negative phase compatibility unit, and an overvoltage clamping unit can be provided for the drive circuit in this embodiment. The overcurrent limiting unit can achieve overcurrent protection for the isolator, preventing damage to the isolator caused by large current fluctuations or current instability in the drive circuit; the positive / negative phase compatibility unit can avoid the harm caused by reverse connection of the external terminals of the drive circuit (the voltage and current in the drive circuit enter the drive circuit in reverse phase, damaging the isolator); the overvoltage clamping unit can achieve overvoltage protection for the isolator when the voltage of the drive circuit fluctuates. Through the above three units, the reliability of the isolated digital output circuit can be effectively improved.

[0077] In addition, in order to effectively eliminate high-frequency noise during signal transmission, improve the quality and accuracy of the signal, and help stabilize the voltage signal of the drive circuit, as Figure 8As shown, in this embodiment, a first capacitor C1 and a second capacitor C2 can be provided in the driving circuit 003. The specific connection manner can be as follows: for the first capacitor C1, the first capacitor C1 is connected between the third pin 3 and the fourth pin 4; for the second capacitor C2, the second capacitor C2 is connected between the first output terminal and the second output terminal. The first capacitor C1 and the second capacitor C2 can form a filtering unit in the driving circuit 003. Of course, in addition to providing a filtering unit in the driving circuit 003, a third capacitor C3 can also be provided in the driving control circuit 001 as a filtering unit in the driving control circuit 001 to filter high-frequency noise, ripple or interference and obtain a smoother output. The specific connection manner of the third capacitor C3 can be: the third capacitor C3 is connected between the first pin 1 and the second pin 2.

[0078] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the apparatus embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for the related parts, reference can be made to the partial description of the method embodiments.

[0079] The above are only the embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An isolated digital output circuit, characterized in that, The isolated digital output circuit includes a drive control circuit, an isolator, and a drive circuit. The isolator includes an isolated input end and an isolated output end. The isolated input end has a first pin and a second pin, and the isolated output end has a third pin and a fourth pin. The drive circuit includes a first resistor and a triode. The positive output terminal of the drive control circuit is connected to the first pin, and the negative output terminal of the drive control circuit is connected to the second pin. The first pin is the positive pin of the isolated input end, and the second pin is the negative pin of the isolated input end. The third pin of the isolated output end is connected to one end of the first resistor, the other end of the first resistor is connected to the collector of the triode, and the fourth pin of the isolated output end is connected to the base of the triode. The collector of the triode is connected to the first output terminal of the drive circuit, and the emitter of the triode is connected to the second output terminal of the drive circuit.

2. The isolated digital output circuit according to claim 1, wherein The drive circuit further includes a first diode, a second diode, a third diode, and a fourth diode. The positive electrode of the first diode is connected to the first output terminal of the drive circuit, and the negative electrode of the second diode is connected to the first output terminal of the drive circuit. The positive electrode of the third diode is connected to the second output terminal of the drive circuit, and the negative electrode of the fourth diode is connected to the second output terminal of the drive circuit. The negative electrodes of the first diode and the third diode are both connected to the collector of the triode. The positive electrodes of the second diode and the fourth diode are both connected to the emitter of the triode.

3. The isolated digital output circuit according to claim 1 or 2, characterized in that The drive circuit further includes a bidirectional transient voltage suppression diode. One end of the bidirectional transient voltage suppression diode is connected to the first output terminal of the drive circuit. The other end of the bidirectional transient voltage suppression diode is connected to the second output terminal of the drive circuit.

4. The isolated digital output circuit according to claim 1, wherein The drive circuit further includes a first capacitor, and the first capacitor is connected between the third pin and the fourth pin.

5. The isolated digital output circuit according to claim 1, wherein The drive circuit further includes a second capacitor, and the second capacitor is connected between the first output terminal and the second output terminal.

6. The isolated digital output circuit according to claim 1, wherein The drive circuit further includes a second resistor. The second resistor is connected between the collector and the emitter.

7. The isolated digital output circuit according to claim 1, wherein Therefore, the drive circuit further includes a third resistor and a fourth resistor. One end of the third resistor and one end of the fourth resistor are both connected to the second output terminal of the drive circuit. The other end of the third resistor is connected to the fourth pin. The other end of the fourth resistor is connected to the emitter of the triode.

8. The isolated digital output circuit according to claim 2, wherein The drive circuit further includes a first light-emitting element and a second light-emitting element. The negative electrode of the first diode is connected in series with a first light-emitting element, and the positive electrode of the fourth diode is connected in series with a first light-emitting element. The positive electrode of the second diode is connected in series with a second light-emitting element, and the negative electrode of the third diode is connected in series with a second light-emitting element.

9. The isolated digital output circuit according to claim 1, wherein The drive control circuit further includes a third capacitor, and the third capacitor is connected between the first pin and the second pin.

10. The isolated digital output circuit according to claim 1, wherein The isolator is an optocoupler. The isolated input terminal is the light emitter of the optocoupler, the isolated output terminal is the light receiver of the optocoupler, the third pin is the collector of the light receiver, and the fourth pin is the emitter of the light receiver; One end of the first resistor is connected to the third pin of the isolated output terminal, the other end of the first resistor is connected to the collector of the triode, and the fourth pin of the isolated output terminal is connected to the base of the triode, including: The collector of the light receiver is connected to one end of the first resistor, the other end of the first resistor is connected to the collector of the triode, and the emitter of the light receiver is connected to the base of the triode.

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