Circuit for limiting output of operational amplifier

Abstract

The utility model relates to a circuit for limiting operational amplifier output. The circuit for limiting the operational amplifier output comprises a voltage amplification module, an output end and a voltage limiting module, wherein the output end is electrically connected with the voltage amplification module; the voltage limiting module comprises an adjusting unit, a current limiting unit and a protection unit, the adjusting unit is electrically connected with the voltage amplification module and the output end, the current limiting unit is electrically connected with the adjusting unit, and the protection unit is electrically connected with the current limiting unit. According to the scheme provided by the invention, the voltage output of the operational amplifier can be limited, so that the printer mainboard is prevented from being burnt out.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit design, in particular to a circuit for limiting output of an operational amplifier. Background Art

[0002] At present, laser printers usually require the voltage output by the op amp in the high voltage power supply board to be a low voltage to the printer main board for operation, and the voltage value of the low voltage is usually within 3.3V. However, the output voltage of the op amp is affected by the size of the input level signal. The larger the input level signal, the higher the output voltage will be, which can generally reach 24V, which can easily burn out the printer main board. Utility Model Content

[0003] The utility model aims to overcome the shortcomings of the prior art and provide a circuit for limiting the output of an operational amplifier, which can limit the voltage output of the operational amplifier and thus prevent the printer mainboard from burning out.

[0004] The purpose of this utility model is achieved through the following technical solutions:

[0005] In a first aspect, the present application provides a circuit for limiting the output of an operational amplifier, comprising: a voltage amplification module; an output end, the output end being electrically connected to the voltage amplification module; a voltage limiting module, the voltage limiting module comprising a regulating unit, a current limiting unit and a protection unit, the regulating unit being electrically connected to the voltage amplification module and the output end, respectively, the current limiting unit being electrically connected to the regulating unit, and the protection unit being electrically connected to the current limiting unit.

[0006] The regulating unit includes a resistor R2, a resistor R5 and a diode U1, the first end of the resistor R2 is electrically connected to the first end of the resistor R5, the second end of the resistor R2 is electrically connected to the output end, the first end of the resistor R5 is also electrically connected to the diode U1, and the second end of the resistor R5 is grounded.

[0007] The current limiting unit includes a resistor R3 and a resistor R4. A first end of the resistor R3 is electrically connected to the diode U1. A second end of the resistor R3 is electrically connected to a first end of the resistor R4. A second end of the resistor R4 is grounded.

[0008] The protection unit includes a diode D1 , a first end of the diode D1 is electrically connected to the second end of the resistor R3 , and a second end of the diode D1 is electrically connected to the voltage amplification module.

[0009] The voltage limiting module further includes a capacitor C1 , and the capacitor C1 is electrically connected to the diode U1 .

[0010] The voltage limiting module further includes a resistor R1 , and a first end of the resistor R1 is electrically connected to the diode U1 .

[0011] The voltage limiting module further includes a first power supply end, and the first power supply end is electrically connected to the second end of the resistor R1.

[0012] The voltage amplification module includes an operational amplifier and a resistor R7 , a first end of the operational amplifier is electrically connected to the output end, and a second end of the operational amplifier is electrically connected to a first end of the resistor R7 .

[0013] The voltage amplification module further includes a second power supply terminal, and the second power supply terminal is electrically connected to the second end of the resistor R7.

[0014] The voltage amplification module further includes a third power supply terminal and a resistor R8, wherein the third power supply terminal is electrically connected to a first terminal of the resistor R8, and a second terminal of the resistor R8 is electrically connected to a third terminal of the operational amplifier.

[0015] Compared with the prior art, the utility model has at least the following advantages:

[0016] By setting a voltage limiting module, the voltage outputted from the output end can be limited so that the voltage outputted from the output end is within the tolerable range of the printer main board, thereby preventing the main board from burning out. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for use in the embodiments are briefly introduced below.

[0018] Figure 1 This is a functional module diagram of a circuit for limiting the output of an operational amplifier in one embodiment of the utility model;

[0019] Figure 2 4 is a circuit diagram of a circuit for limiting the output of an operational amplifier in one embodiment of the utility model. DETAILED DESCRIPTION

[0020] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0021] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] See also Figure 1 A circuit for limiting the output of an operational amplifier includes: a voltage amplification module 100, an output end 200 and a voltage limiting module 300, wherein the output end 200 is electrically connected to the voltage amplification module 100; the voltage limiting module 300 includes a regulating unit, a current limiting unit and a protection unit, wherein the regulating unit is electrically connected to the voltage amplification module 100 and the output end 200 respectively, the current limiting unit is electrically connected to the regulating unit, and the protection unit is electrically connected to the current limiting unit.

[0024] It should be noted that the voltage amplification module 100 is used to amplify the voltage, the output terminal 200 is used to output the voltage to the printer mainboard, and the voltage limiting module 300 is used to limit the voltage output by the output terminal. In this way, by setting the voltage limiting module 300, the voltage output by the output terminal 200 can be limited, so that the voltage output by the output terminal 200 is within the tolerable range of the printer mainboard, thereby preventing the mainboard from burning out.

[0025] See also Figure 2 Specifically, the adjustment unit includes a resistor R2, a resistor R5 and a diode U1, a first end of the resistor R2 is electrically connected to a first end of the resistor R5, a second end of the resistor R2 is electrically connected to the output end 200, a first end of the resistor R5 is also electrically connected to the diode U1, and a second end of the resistor R5 is grounded.

[0026] It should be noted that the resistance value of resistor R2 is 3K, the resistance value of resistor R5 is 10K, and the reference voltage of the R pin of diode U1 is 2.5V. Therefore, according to calculation, the output voltage of the second end of resistor R2 is: 2.5V / (R5 / (R2+R5)), and the obtained value is 3.25V. Furthermore, since the reference voltage of diode U1 is 2.5V, the output end 200 will be fed back to the third end of the operational amplifier to limit the output when it exceeds 3.25V, so as to control the voltage of the output end 200 within 3.3V, thereby preventing the motherboard from burning out.

[0027] See also Figure 2 Specifically, the current limiting unit includes a resistor R3 and a resistor R4, a first end of the resistor R3 is electrically connected to the diode U1, a second end of the resistor R3 is electrically connected to a first end of the resistor R4, and a second end of the resistor R4 is grounded.

[0028] It should be noted that the resistor R3 and the resistor R4 are both current limiting resistors.

[0029] See also Figure 2 Specifically, the protection unit includes a diode D1, a first end of the diode D1 is electrically connected to the second end of the resistor R3, and the second end of the diode D1 is electrically connected to the voltage amplification module. Specifically, the voltage limiting module also includes a resistor R1, a first end of the resistor R1 is electrically connected to the diode U1. Specifically, the voltage limiting module also includes a first power supply end, and the first power supply end is electrically connected to the second end of the resistor R1.

[0030] It should be noted that the diode D1 plays a role of current reversal to prevent the voltage input from the first power supply terminal from being directly transmitted to the operational amplifier. The voltage of the first power supply terminal is 24V, and the resistor R1 is a sampling resistor for collecting the voltage of the first power supply terminal.

[0031] See also Figure 2 Specifically, the voltage limiting module 300 further includes a capacitor C1, and the capacitor C1 is electrically connected to the diode U1. It should be noted that the capacitor C1 is a filter capacitor.

[0032] See also Figure 2 Specifically, the voltage amplification module 100 includes an operational amplifier and a resistor R7, wherein a first end of the operational amplifier is electrically connected to the output end, and a second end of the operational amplifier is electrically connected to a first end of the resistor R7. Specifically, the voltage amplification module 100 also includes a second power supply end, and the second power supply end is electrically connected to a second end of the resistor R7. Specifically, the voltage amplification module 100 also includes a third power supply end and a resistor R8, wherein the third power supply end is electrically connected to a first end of the resistor R8, and a second end of the resistor R8 is electrically connected to a third end of the operational amplifier.

[0033] It should be noted that the second power supply terminal is Vin, the third power supply terminal is input +2.5V, the second terminal of the operational amplifier is the inverting input terminal, and the third terminal is the non-inverting input terminal. The signal can be amplified through internal calculation.

[0034] The scheme of the present application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of the various embodiments have their own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. Those skilled in the art should also be aware that the actions and modules involved in the specification are not necessarily required for the present application. In addition, it can be understood that the steps in the method of the embodiment of the present application can be adjusted in order, merged and deleted according to actual needs, and the modules in the device of the embodiment of the present application can be merged, divided and deleted according to actual needs.

[0035] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A circuit for limiting the output of an operational amplifier, characterized in that: include: Voltage amplifier module; An output end, the output end is electrically connected to the voltage amplification module; A voltage limiting module, the voltage limiting module comprising a regulating unit, a current limiting unit and a protection unit, the regulating unit being electrically connected to the voltage amplification module and the output end respectively, the current limiting unit being electrically connected to the regulating unit, and the protection unit being electrically connected to the current limiting unit; The regulating unit includes a resistor R2, a resistor R5 and a diode U1, the first end of the resistor R2 is electrically connected to the first end of the resistor R5, the second end of the resistor R2 is electrically connected to the output end, the first end of the resistor R5 is also electrically connected to the diode U1, and the second end of the resistor R5 is grounded.

2. The circuit for limiting the output of an operational amplifier according to claim 1, characterized in that: The current limiting unit includes a resistor R3 and a resistor R4. A first end of the resistor R3 is electrically connected to the diode U1. A second end of the resistor R3 is electrically connected to a first end of the resistor R4. A second end of the resistor R4 is grounded.

3. The circuit for limiting the output of an operational amplifier according to claim 2, characterized in that: The protection unit includes a diode D1 , a first end of the diode D1 is electrically connected to the second end of the resistor R3 , and a second end of the diode D1 is electrically connected to the voltage amplification module.

4. The circuit for limiting the output of an operational amplifier according to claim 2, characterized in that: The voltage limiting module further includes a capacitor C1 , and the capacitor C1 is electrically connected to the diode U1 .

5. The circuit for limiting the output of an operational amplifier according to claim 2, characterized in that: The voltage limiting module further includes a resistor R1 , and a first end of the resistor R1 is electrically connected to the diode U1 .

6. The circuit for limiting the output of an operational amplifier according to claim 5, characterized in that: The voltage limiting module further includes a first power supply end, and the first power supply end is electrically connected to the second end of the resistor R1.

7. The circuit for limiting the output of an operational amplifier according to claim 1, characterized in that: The voltage amplification module includes an operational amplifier and a resistor R7 , a first end of the operational amplifier is electrically connected to the output end, and a second end of the operational amplifier is electrically connected to a first end of the resistor R7 .

8. The circuit for limiting the output of an operational amplifier according to claim 7, characterized in that: The voltage amplification module further includes a second power supply terminal, and the second power supply terminal is electrically connected to the second end of the resistor R7.

9. The circuit for limiting the output of an operational amplifier according to claim 8, characterized in that: The voltage amplification module further includes a third power supply terminal and a resistor R8, wherein the third power supply terminal is electrically connected to a first terminal of the resistor R8, and a second terminal of the resistor R8 is electrically connected to a third terminal of the operational amplifier.

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