CN214255058U - Constant current source driving circuit - Google Patents

Constant current source driving circuit Download PDF

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Publication number
CN214255058U
CN214255058U CN202120439110.3U CN202120439110U CN214255058U CN 214255058 U CN214255058 U CN 214255058U CN 202120439110 U CN202120439110 U CN 202120439110U CN 214255058 U CN214255058 U CN 214255058U
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resistor
electrode
transistor
resistance
constant current
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林树珠
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Shenzhen Xinjiexun Technology Co ltd
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Shenzhen Xinjiexun Technology Co ltd
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Abstract

The utility model discloses a constant current source drive circuit, including MCU, operational amplifier, transistor, first resistance, second resistance, third resistance, fourth resistance and fifth resistance. The voltage output end of the MCU is connected with the first end of the first resistor, and the second end of the first resistor is connected with the in-phase end of the operational amplifier and the first end of the third resistor. The first end of the second resistor is grounded, and the second end of the second resistor is connected with the inverting end of the operational amplifier and the first end of the fourth resistor. The output end of the operational amplifier is connected with a first electrode of the transistor, a second electrode of the transistor is connected with a power supply end, and a second end of the fourth resistor is connected with a third electrode of the transistor and a first end of the fifth resistor. The second end of the third resistor is connected with the second end of the fifth resistor and the positive end of the device to be driven, and the negative end of the device to be driven is grounded. The sum of the resistance values of the first resistor and the third resistor is far larger than the internal resistance of the device to be driven. The device has the advantages of few components, lower cost, smaller volume and reliable performance.

Description

Constant current source driving circuit
Technical Field
The utility model belongs to the technical field of electronic circuit, especially, relate to a constant current source drive circuit.
Background
In the conventional optical module laser constant current source design, an IDAC (current analog) output of an MCU (micro controller unit) or a special constant current source chip is adopted. However, both the MCU with IDAC output and the dedicated constant current source chip are expensive and bulky, and are not suitable for application to optical module lasers.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a constant current source drive circuit can solve above-mentioned technical problem.
To achieve the purpose, the utility model adopts the following technical proposal:
a constant current source driving circuit comprises an MCU, an operational amplifier, a transistor with three electrodes, a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor;
the MCU is provided with a voltage output end, the voltage output end is connected with a first end of the first resistor, and a second end of the first resistor is connected with a non-inverting end of the operational amplifier and a first end of the third resistor;
the first end of the second resistor is grounded, and the second end of the second resistor is connected with the inverting end of the operational amplifier and the first end of the fourth resistor;
the output end of the operational amplifier is connected with a first electrode of the transistor, a second electrode of the transistor is connected with a power supply end, and a second end of the fourth resistor is connected with a third electrode of the transistor and a first end of the fifth resistor;
the second end of the third resistor is connected with the second end of the fifth resistor and the positive end of the device to be driven, and the negative end of the device to be driven is grounded;
the sum of the resistance values of the first resistor and the third resistor is larger than the internal resistance of the equipment to be driven.
Optionally, the transistor is an N-type MOS transistor, and the first electrode, the second electrode, and the third electrode are a gate, a drain, and a source, respectively.
Optionally, the transistor is an NPN type triode, and the first electrode, the second electrode, and the third electrode are a base electrode, a collector electrode, and an emitter electrode, respectively.
Optionally, a ratio of the sum of the resistance values to the internal resistance is greater than or equal to 100.
Optionally, a ratio of the first resistance to the third resistance is equal to a ratio of the second resistance to the fourth resistance.
Optionally, the device to be driven is an optical module laser.
Optionally, the voltage output terminal is a VDAC port of the MCU.
Compared with the prior art, the embodiment of the utility model provides a following beneficial effect has:
the output voltage provided by the MCU is utilized, the first resistor, the second resistor, the third resistor, the fourth resistor and the fifth resistor are matched with the operational amplifier and the transistor to build the driving circuit, and under the condition that the sum of the resistance values of the first resistor and the third resistor is larger than the internal resistance of the device to be driven, the current flowing through the fifth resistor can be approximately equal to the current flowing through the device to be driven, so that constant current output is realized.
The embodiment of the utility model provides a pair of constant current source drive circuit, the components and parts that use are few, and the cost is lower, and the volume is littleer, the dependable performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
The structure, ratio, size and the like shown in the present specification are only used for matching with the content disclosed in the specification, so as to be known and read by people familiar with the technology, and are not used for limiting the limit conditions which can be implemented by the present invention, so that the present invention has no technical essential significance, and any structure modification, ratio relationship change or size adjustment should still fall within the range which can be covered by the technical content disclosed by the present invention without affecting the efficacy and the achievable purpose of the present invention.
Fig. 1 is a circuit diagram of a constant current source driving circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the embodiments of the present invention are clearly and completely described with reference to the drawings in the embodiments of the present invention, and obviously, the embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
Please refer to fig. 1.
The embodiment provides a constant current source driving circuit which can be applied to driving an optical module laser.
Specifically, the constant current source drive circuit includes an MCU, an operational amplifier a, a transistor Q having three electrodes, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor RS.
The MCU is provided with a voltage output end. For example, the MCU may be implemented by providing a VDAC port. The VDAC port may provide an analog voltage. Optionally, the power supply of the MCU is from a power supply terminal VCC.
Specifically, as shown in fig. 1, the voltage output terminal is connected to a first terminal of a first resistor R1, and a second terminal of the first resistor R1 is connected to the non-inverting terminal of the operational amplifier a and a first terminal of a third resistor R3. The first end of the second resistor R2 is grounded, and the second end of the second resistor R2 is connected to the inverting terminal of the operational amplifier a and the first end of the fourth resistor R4. The output terminal of the operational amplifier a is connected to the first electrode G of the transistor Q, the second electrode D of the transistor Q is connected to the power supply terminal VCC, and the second terminal of the fourth resistor R4 is connected to the third electrode S of the transistor Q and the first terminal of the fifth resistor RS. The second end of the third resistor R3 is connected with the second end of the fifth resistor RS and the positive terminal of the TOSA, and the negative terminal of the TOSA is grounded.
Therefore, the following relation may hold:
(Vin-V+)/R1＝(V+-V2)/R3；V-/R2＝(V1-V-)/R4。
according to the virtual short characteristic of the operational amplifier, V+＝V-The following can be obtained:
Vin＝R1(V+-V2)/R3+R2(V1-V+)/R4。
if R1/R3 is R2/R4, Vin is R1 (V1-V2)/R3.
Therefore, if R1/R3 is fixed, the voltage across the fifth resistor RS is only related to the voltage at the voltage output terminal of the MCU.
If the voltage at the voltage output end of the MCU is fixed and the resistance of the fifth resistor RS is fixed, the current flowing through the fifth resistor RS is also fixed and equal to (Vin × R3)/(R1 × RS).
Therefore, when the sum of the resistance values of the first resistor R1 and the third resistor R3 is far greater than the internal resistance of the TOSA to be driven, the current flowing through the fifth resistor RS is approximately equal to the current flowing through the TOSA to be driven, and constant current output to the TOSA to be driven can be achieved.
Further, the MCU can flexibly adjust the size of Vin. Therefore, Vin with a corresponding size can be flexibly selected according to the requirement of the TOSA of the device to be driven so as to meet the current size requirement of the constant current source. Optionally, the TOSA to be driven is an optical module laser.
In summary, the constant current source driving circuit provided by the embodiment uses fewer components, has lower cost, smaller volume, reliable performance and flexible operation.
It should be noted that in the field of electronic circuits, one resistance value is much larger than the other, which can generally mean that the former resistance value is at least two orders of magnitude larger than the latter resistance value.
Therefore, as an optional way of this embodiment, the ratio of the sum of the resistance values to the internal resistance is greater than or equal to 100.
As an alternative manner of this embodiment, the transistor is an N-type MOS transistor, and the first electrode G, the second electrode D, and the third electrode S are a gate, a drain, and a source, respectively.
As an optional manner of this embodiment, the transistor is an NPN type triode, and the first electrode G, the second electrode D, and the third electrode S are a base electrode, a collector electrode, and an emitter electrode, respectively.
In this embodiment, since the NPN type transistor is a temperature-sensitive device, the constant current source driving circuit constructed by the NPN type transistor can be used in an environment with low temperature change, and the constant current source driving circuit constructed by the N type MOS transistor can be used in various environment environments.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are intended to be inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed and illustrated, unless explicitly indicated as an order of performance. It should also be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being "on" … … "," engaged with "… …", "connected to" or "coupled to" another element or layer, it can be directly on, engaged with, connected to or coupled to the other element or layer, or intervening elements or layers may also be present. In contrast, when an element or layer is referred to as being "directly on … …," "directly engaged with … …," "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship of elements should be interpreted in a similar manner (e.g., "between … …" and "directly between … …", "adjacent" and "directly adjacent", etc.). As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region or section from another element, component, region or section. Unless clearly indicated by the context, use of terms such as the terms "first," "second," and other numerical values herein does not imply a sequence or order. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as "inner," "outer," "below," "… …," "lower," "above," "upper," and the like, may be used herein for ease of description to describe a relationship between one element or feature and one or more other elements or features as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below … …" can encompass both an orientation of facing upward and downward. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted.
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention in its corresponding aspects.

Claims (7)

1. A constant current source driving circuit is characterized by comprising an MCU, an operational amplifier, a transistor with three electrodes, a first resistor, a second resistor, a third resistor, a fourth resistor and a fifth resistor;
the MCU is provided with a voltage output end, the voltage output end is connected with a first end of the first resistor, and a second end of the first resistor is connected with a non-inverting end of the operational amplifier and a first end of the third resistor;
the first end of the second resistor is grounded, and the second end of the second resistor is connected with the inverting end of the operational amplifier and the first end of the fourth resistor;
the output end of the operational amplifier is connected with a first electrode of the transistor, a second electrode of the transistor is connected with a power supply end, and a second end of the fourth resistor is connected with a third electrode of the transistor and a first end of the fifth resistor;
the second end of the third resistor is connected with the second end of the fifth resistor and the positive end of the device to be driven, and the negative end of the device to be driven is grounded;
the sum of the resistance values of the first resistor and the third resistor is larger than the internal resistance of the equipment to be driven.
2. The constant current source driving circuit according to claim 1, wherein the transistor is an N-type MOS transistor, and the first electrode, the second electrode, and the third electrode are a gate, a drain, and a source, respectively.
3. The constant current source driving circuit according to claim 1, wherein the transistor is an NPN type transistor, and the first electrode, the second electrode, and the third electrode are a base, a collector, and an emitter, respectively.
4. The constant current source drive circuit according to claim 1, wherein a ratio of the sum of the resistance values to the internal resistance is 100 or more.
5. The constant current source drive circuit according to claim 1, wherein a ratio of the first resistance to the third resistance is equal to a ratio of the second resistance to the fourth resistance.
6. The constant current source drive circuit according to claim 1, wherein the device to be driven is an optical module laser.
7. The constant current source drive circuit according to claim 1, wherein the voltage output terminal is a VDAC port of the MCU.
CN202120439110.3U 2021-03-01 2021-03-01 Constant current source driving circuit Active CN214255058U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202120439110.3U CN214255058U (en) 2021-03-01 2021-03-01 Constant current source driving circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202120439110.3U CN214255058U (en) 2021-03-01 2021-03-01 Constant current source driving circuit

Publications (1)

Publication Number Publication Date
CN214255058U true CN214255058U (en) 2021-09-21

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Country Status (1)

Country Link
CN (1) CN214255058U (en)

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