CN211603490U - Lithium battery pack single battery voltage detection circuit and equipment based on open-loop optocoupler - Google Patents
Lithium battery pack single battery voltage detection circuit and equipment based on open-loop optocoupler Download PDFInfo
- Publication number
- CN211603490U CN211603490U CN202020022080.1U CN202020022080U CN211603490U CN 211603490 U CN211603490 U CN 211603490U CN 202020022080 U CN202020022080 U CN 202020022080U CN 211603490 U CN211603490 U CN 211603490U
- Authority
- CN
- China
- Prior art keywords
- resistor
- signal conditioning
- circuit
- optical coupler
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 31
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 31
- 238000001514 detection method Methods 0.000 title claims abstract description 21
- 230000003750 conditioning effect Effects 0.000 claims abstract description 73
- 230000003287 optical effect Effects 0.000 claims abstract description 49
- 230000000087 stabilizing effect Effects 0.000 claims description 4
- 238000000034 method Methods 0.000 abstract description 4
- 238000012546 transfer Methods 0.000 description 7
- 238000013519 translation Methods 0.000 description 3
- 238000013178 mathematical model Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Images
Landscapes
- Secondary Cells (AREA)
Abstract
The application discloses lithium cell group battery cell voltage detection circuitry and equipment based on open-loop opto-coupler. The detection circuit comprises a micro control unit, an analog multiplexer, a multi-path controllable standard voltage output circuit, an analog-to-digital converter and a signal conditioning circuit based on an optical coupler; the signal conditioning circuit is used for being connected with single batteries of the lithium battery pack and is used for being connected with the analog multiplexer; the analog multiplexer is connected with the analog-to-digital converter; the analog-to-digital converter is connected with the micro control unit; the multi-path controllable standard voltage output circuit is used for outputting standard voltage to the signal conditioning circuit; the signal conditioning circuit comprises a plurality of first signal conditioning subcircuits; the first signal conditioning sub-circuit comprises an optical coupler, a first resistor, a second resistor, a third resistor, a fourth resistor and a voltage regulator tube. The method and the device can realize safe, reliable, accurate and low-cost detection of the single battery of the lithium battery pack.
Description
Technical Field
The application relates to the technical field of voltage detection of single batteries of battery packs, in particular to a voltage detection circuit and a voltage detection device of the single batteries of a lithium battery pack based on an open-loop optocoupler.
Background
Lithium battery packs generally consist of a plurality of cells connected in series; in the using process, the voltage of each battery cell needs to be monitored in real time, and the over-discharge and over-charge of the battery cells are avoided.
When the number of the batteries in the battery pack is increased, the voltage of the electrodes at the two ends of the high-end battery monomer on the negative electrode of the battery pack is higher, and the battery pack cannot be directly connected to an Analog-to-Digital Converter (ADC) circuit for measurement.
The above background disclosure is only for the purpose of assisting in understanding the inventive concepts and technical solutions of the present application and does not necessarily pertain to the prior art of the present application, and should not be used to assess the novelty and inventive step of the present application in the absence of explicit evidence to suggest that such matter has been disclosed at the filing date of the present application.
SUMMERY OF THE UTILITY MODEL
The application provides a lithium cell group battery voltage detection circuitry and equipment based on open-loop opto-coupler can realize safe, reliable, accurate, the low-cost detection of lithium cell group battery.
In a first aspect, the application provides a lithium battery pack single battery voltage detection circuit based on an open-loop optical coupler, which comprises a micro control unit, an analog multiplexer, a multi-path controllable standard voltage output circuit, an analog-to-digital converter and a signal conditioning circuit based on the optical coupler;
one side of the signal conditioning circuit is used for being connected with a single battery of the lithium battery pack; the other side of the signal conditioning circuit is used for being connected with the analog multiplexer;
the analog multiplexer is connected with the analog-to-digital converter;
the analog-to-digital converter is connected with the micro control unit;
the multi-path controllable standard voltage output circuit is used for outputting standard voltage to the signal conditioning circuit;
the signal conditioning circuit comprises a plurality of first signal conditioning subcircuits; the first signal conditioning sub-circuit comprises an optical coupler, a first resistor, a second resistor, a third resistor, a fourth resistor and a voltage regulator tube;
the first resistor is connected with the third resistor in series; one end of the third resistor is connected with one end of a light emitter of the optocoupler; one end of the first resistor is used for being connected with the single battery; one end of the second resistor is connected between the first resistor and the third resistor; the other end of the second resistor is connected with one end of the voltage stabilizing tube; the other end of the voltage stabilizing tube is connected to the other end of the light emitter of the optocoupler; the other end of the light emitter of the optical coupler is used for being connected with the single battery;
one end of the fourth resistor is connected with one end of a light receiver of the optical coupler; the other end of the fourth resistor is connected to a reference ground; and the other end of the light receiver of the optical coupler is used for being connected with a power supply.
In some preferred embodiments, the signal conditioning circuit further comprises two second signal conditioning subcircuits; the circuit structure of the second signal conditioning sub-circuit is the same as that of the first signal conditioning sub-circuit;
the signal input end of the second signal conditioning subcircuit is used for connecting a first reference voltage; the signal input end of the other second signal conditioning circuit is used for connecting a second reference voltage;
the first reference voltage corresponds to the upper limit of the working voltage range of the lithium battery of the type to be measured; and the second reference voltage corresponds to the lower limit of the working voltage range of the lithium battery of the measured type.
In some preferred embodiments, the optical coupler is a nonlinear optical coupler.
In a second aspect, the present application provides an apparatus, which includes the above open-loop optical coupler-based single cell voltage detection circuit for a lithium battery pack.
Compared with the prior art, the beneficial effect of this application has:
the first resistor, the second resistor and the voltage regulator tube of each first signal conditioning sub-circuit can realize the scaling and translation of input level, so that a signal output to the optical coupler is converted into a small signal under large bias, and the nonlinearity of the circuit can be reduced because the linearity of the small signal characteristic of the optical coupler is good.
Drawings
Fig. 1 is a schematic structural diagram of a single battery voltage detection circuit of a lithium battery pack based on an open-loop optocoupler according to an embodiment of the present application;
FIG. 2 illustrates a circuit configuration of a first signal conditioning sub-circuit of one embodiment of the present application;
fig. 3 shows a circuit configuration of two second signal conditioning subcircuits according to an embodiment of the present application.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the embodiments of the present application more clearly apparent, the present application is further described in detail below with reference to fig. 1 to 3 and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected to the other element. The connection may be for fixation or for circuit connection.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present application, "a plurality" means two or more unless specifically defined otherwise.
Referring to fig. 1, the present embodiment provides a lithium battery pack single battery voltage detection circuit based on an open-loop optical coupler, which includes a micro control unit 1 (also called MCU), an analog multiplexer 2, a multi-path controllable standard voltage output circuit 3, an analog-to-digital converter 5, and a signal conditioning circuit 7 based on an optical coupler.
The signal conditioning circuit 7 comprises a photoelectric coupler (optical coupler for short); one side of the signal conditioning circuit 7 is used for being connected with a single battery of the lithium battery pack; the other side of the signal conditioning circuit 7 is for connection to the analog multiplexer 2. The signal conditioning circuit 7 transmits the voltage signal of the unit cell from one side to the other side by using the transmission characteristic of the optical coupler OC. In this embodiment, the optical coupler OC of the signal conditioning circuit 7 is a nonlinear optical coupler, specifically a digital optical coupler.
The analog multiplexer 2 is connected to an analog-to-digital converter 5.
The analog-to-digital converter 5 is connected to the micro control unit 1.
The micro control unit 1 can control the multi-path controllable standard voltage output circuit 3, so that the multi-path controllable standard voltage output circuit 3 outputs the standard voltage to the signal conditioning circuit 7.
The voltage of the single battery is converted into a voltage with EP2 as reference ground through the optical coupler-based signal conditioning circuit 7, and then is connected to the analog-to-digital converter 5 through the analog multiplexer 2, so that the voltage of the multiple single batteries in the lithium battery pack is measured.
In the present embodiment, referring to fig. 1, the signal conditioning circuit 7 includes a plurality of first signal conditioning subcircuits 7A. The circuit configuration of each first signal conditioning sub-circuit 7A is the same. Referring to fig. 2, each of the first signal conditioning sub-circuits 7A includes an optical coupler OC, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a voltage regulator D1. Wherein, the voltage regulator tube D1 is a voltage regulator diode; the optical couplers OC of the first signal conditioning subcircuits 7A are products of the same batch.
The first resistor R1 and the third resistor R3 are connected in series and then are connected to one end of a light emitter of the optical coupler OC; specifically, one end of the third resistor R3 is connected to one end, namely the positive electrode, of the light emitter of the optocoupler OC, and one end of the first resistor R1 is used for being connected to the single battery.
One end of the second resistor R2 is connected between the first resistor R1 and the third resistor R3. The other end of the second resistor R2 is connected to one end of a voltage regulator tube D1. The other end of the voltage regulator tube D1 is connected to the other end of the light emitter of the optical coupler OC, namely the negative electrode. In addition, the other end of the light emitter of the optical coupler OC is also used for being connected with the single battery.
One end of the fourth resistor R4 is connected with one end of a light receiver of the optical coupler OC; the other end of the fourth resistor R4 is connected to a reference ground EP 2; the other end of the light receiver of the optocoupler OC is used for being connected with a power supply VCC.
Through the first resistor R1, the second resistor R2 and the voltage regulator tube D1, the scaling and the translation of the input level can be realized, so that the output signal Vx is converted into a small signal under large bias, and the transfer relationship is as follows:
R1is the resistance of the first resistor R1; r2Is the resistance of the second resistor R2; vD1Is the voltage of the zener diode D1; vbatnIs the voltage of the cell. By adjusting R in the formula (1)1、R2And VD1The scale and offset value of the input level scaling may be adjusted. The output signal Vx is input to the light emitter of the opto-coupler OC, i.e. as the input signal of the opto-coupler OC.
The linearity of the small signal characteristic of the optical coupler is good, so that the nonlinearity of the circuit can be reduced.
Referring to fig. 2, an isolation voltage signal transmission circuit based on the optocoupler is formed by the third resistor R3, the optocoupler OC and the fourth resistor R4, so that the output signal Vn of the optocoupler OC can be electrically isolated from the input signal Vx of the optocoupler OC, and the proportional relationship between the output signal Vn and the input signal Vx of the optocoupler OC can be properly adjusted. The transfer relationship is as follows (2).
R3Is the resistance of the third resistor R3;R4is the resistance of the fourth resistor R4. By adjusting R3And R4The transfer gain can be adjusted to adjust the output range of the output signal Vn of the opto-coupler OC to match the input range of the analog-to-digital converter 5.
By combining the two formulas (1) and (2), the output signal Vn of the optical coupler OC and the voltage V of the single battery can be obtainedbatnThe transfer relationship (2) is as follows (3).
Wherein, CTRFor the current transfer ratio, VZDIs the nominal regulated voltage, V, of the stabilivolt D1DThe light emitter which is an optical coupler also inputs the conducting voltage of the LED.
According to the above, in this embodiment, the first resistor R1, the second resistor R2, and the voltage regulator tube D1 of each first signal conditioning sub-circuit can implement scaling and translation of the input level, so that the signal output to the optical coupler is converted into a small signal under a large bias.
The CTR of the optical coupler is relatively stable within a certain temperature and a certain small signal input range; at this time, the output signal Vn of the optical coupler OC and the voltage V of the single batterybatnIs relatively linear, so the compensation can be carried out by a linear fitting method; however, since the CTR varies with temperature, a dynamic linear fit, i.e. temperature compensation, must be performed.
The temperature compensation will be explained. In the signal conditioning circuit, the resistance parameter, the stable voltage of the voltage regulator tube and the conduction voltage input by the optical coupler to the LED are relatively stable, but the CTR of the optical coupler is sensitive to the temperature, so that the temperature characteristic of the CTR needs to be further compensated. For this purpose, with reference to fig. 1, the signal conditioning circuit 7 also comprises two second signal conditioning sub-circuits 7B.
Referring to fig. 3, the circuit configuration of the second signal conditioning sub-circuit 7B is the same as that of the first signal conditioning sub-circuit 7A, and alsoThat is, the second signal conditioning sub-circuit 7B is configured identically to the first signal conditioning sub-circuit 7A for detecting the battery cell. However, the signal input of the first signal conditioning subcircuit 7A is used for connection to a cell, while the signal input of a second signal conditioning subcircuit 7B is used for connection to a first reference voltage Vref1The signal input end of the other second signal conditioning subcircuit 7B is used for connecting a second reference voltage Vref2. A first reference voltage Vref1And the upper limit of the working voltage range of the lithium battery corresponding to the measured type. Second reference voltage Vref2And corresponding to the lower limit of the working voltage range of the lithium battery of the measured type.
Additionally adding two paths of signals, respectively inputting two paths of reference voltages V to two second signal conditioning subcircuits 7Bref1And Vref2Thereby obtaining two input and output points (V)ref1,Vr1) And (V)ref2,Vr2). Two points define a line, and the input interval of the calibration signal conditioning circuit is [ V ]ref1,Vref2]The transfer relationship after calibration is as follows (4).
Vr1Is the output signal of the opto-coupler OC of a second signal conditioning sub-circuit 7B. Vr2Is the output signal of the optocoupler OC of the further second signal conditioning sub-circuit 7B. The voltage V of the single battery can be obtained according to the formula (4)batn。
In this embodiment, by using the same structure compensation method, the input-output characteristics of the second signal conditioning sub-circuit 7B are linearly modeled by two paths of second signal conditioning sub-circuits 7B with given reference voltages, so as to obtain an input-output mathematical model of the second signal conditioning sub-circuit 7B in the current environment. Since the circuit structure of each signal conditioning sub-circuit is the same, the model can be applied to other channels, i.e., other signal conditioning sub-circuits. With this mathematical model, the detected voltages V1-Vn can be converted into corresponding cell voltages.
From the above, the present embodimentFor example, the two second signal conditioning sub-circuits 7B can realize linear fitting to compensate the optical coupler, and can reduce or eliminate the influence of temperature on the current transfer ratio CTR of the optical coupler, thereby improving the voltage V of the single batterybatnThe accuracy of (2).
The present embodiment may also implement offset calibration. Inputting a reference voltage Vref (generally getting the midpoint of the working voltage of the battery) to each channel, that is, each signal conditioning sub-circuit such as the first signal conditioning sub-circuit, by an external reference voltage source, and measuring each channel to obtain a measured voltage VmeasureThe offset value V of each channel can be obtained from the following equation (5)biasn. According to the offset value VbiasnThe accuracy can be further improved by individually calibrating the offsets of the channels.
Vbiasn＝Vmeasure-Vref(5)
The resistance values of the third resistor R3 and the fourth resistor R4 are flexibly adjusted according to the CTR characteristic of the optocoupler, the working interval of the voltage of a battery monomer (lithium iron: 2.5V-3.7V, ternary lithium: 2.7V-4.2V) and the input level range of the analog-to-digital converter 5. By adjusting the resistance values of the third resistor R3 and the fourth resistor R4, the output voltage range can be adjusted, thereby conveniently matching the measuring range of the analog-to-digital converter 5 at the rear end.
In the present embodiment, various operations are performed by the micro control unit 1, including the operation of temperature compensation and the operation of offset calibration.
The embodiment also provides equipment, in particular measuring equipment. The device comprises the single battery voltage detection circuit of the lithium battery pack based on the open-loop optocoupler.
The circuit of the embodiment is simple and low in cost, voltage conversion of the single battery can be completed only by using a common optical coupler, a voltage regulator tube and a plurality of common resistors, and the precision of voltage detection can be improved; the embodiment has strong expandability and can be used for lithium battery packs with any number of sections connected in series.
The embodiment can electrically isolate the measuring circuit from the single battery to be measured, transmits voltage signals, can compensate the CTR nonlinearity and the temperature drift characteristic of the optical coupler, and can realize safe, reliable, accurate and low-cost detection of the single battery of the lithium battery pack.
In this embodiment, the two second signal conditioning sub-circuits 7B are used as references for linear fitting, so as to realize temperature compensation for the first signal conditioning sub-circuit 7A, and further improve the measurement accuracy. In addition, the expansibility of the embodiment is strong, and the embodiment can be expanded to be used in a battery pack with any battery.
The foregoing is a further detailed description of the present application in connection with specific/preferred embodiments and is not intended to limit the present application to that particular description. For a person skilled in the art to which the present application pertains, several alternatives or modifications to the described embodiments may be made without departing from the concept of the present application, and these alternatives or modifications should be considered as falling within the scope of the present application.
Claims (4)
1. The utility model provides a lithium cell group battery voltage detection circuitry based on open-loop opto-coupler which characterized in that: the system comprises a micro-control unit, an analog multiplexer, a multi-path controllable standard voltage output circuit, an analog-to-digital converter and a signal conditioning circuit based on an optical coupler;
one side of the signal conditioning circuit is used for being connected with a single battery of the lithium battery pack; the other side of the signal conditioning circuit is used for being connected with the analog multiplexer;
the analog multiplexer is connected with the analog-to-digital converter;
the analog-to-digital converter is connected with the micro control unit;
the multi-path controllable standard voltage output circuit is used for outputting standard voltage to the signal conditioning circuit;
the signal conditioning circuit comprises a plurality of first signal conditioning subcircuits; the first signal conditioning sub-circuit comprises an optical coupler, a first resistor, a second resistor, a third resistor, a fourth resistor and a voltage regulator tube;
the first resistor is connected with the third resistor in series; one end of the third resistor is connected with one end of a light emitter of the optocoupler; one end of the first resistor is used for being connected with the single battery; one end of the second resistor is connected between the first resistor and the third resistor; the other end of the second resistor is connected with one end of the voltage stabilizing tube; the other end of the voltage stabilizing tube is connected to the other end of the light emitter of the optocoupler; the other end of the light emitter of the optical coupler is used for being connected with the single battery;
one end of the fourth resistor is connected with one end of a light receiver of the optical coupler; the other end of the fourth resistor is connected to a reference ground; and the other end of the light receiver of the optical coupler is used for being connected with a power supply.
2. The open-loop optical coupler-based single battery voltage detection circuit of the lithium battery pack as claimed in claim 1, wherein: the signal conditioning circuit further comprises two second signal conditioning subcircuits; the circuit structure of the second signal conditioning sub-circuit is the same as that of the first signal conditioning sub-circuit;
the signal input end of the second signal conditioning subcircuit is used for connecting a first reference voltage; the signal input end of the other second signal conditioning circuit is used for connecting a second reference voltage;
the first reference voltage corresponds to the upper limit of the working voltage range of the lithium battery of the type to be measured; and the second reference voltage corresponds to the lower limit of the working voltage range of the lithium battery of the measured type.
3. The open-loop optical coupler-based single battery voltage detection circuit of the lithium battery pack as claimed in claim 1, wherein: the optical coupler is a nonlinear optical coupler.
4. An apparatus, characterized by: the open-loop optical coupler-based single cell voltage detection circuit of the lithium battery pack comprises any one of claims 1 to 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020022080.1U CN211603490U (en) | 2020-01-06 | 2020-01-06 | Lithium battery pack single battery voltage detection circuit and equipment based on open-loop optocoupler |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020022080.1U CN211603490U (en) | 2020-01-06 | 2020-01-06 | Lithium battery pack single battery voltage detection circuit and equipment based on open-loop optocoupler |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211603490U true CN211603490U (en) | 2020-09-29 |
Family
ID=72600590
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020022080.1U Expired - Fee Related CN211603490U (en) | 2020-01-06 | 2020-01-06 | Lithium battery pack single battery voltage detection circuit and equipment based on open-loop optocoupler |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211603490U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112269083A (en) * | 2020-10-20 | 2021-01-26 | 江苏新安电器股份有限公司 | Control panel voltage detection and conversion device for automatic test equipment |
-
2020
- 2020-01-06 CN CN202020022080.1U patent/CN211603490U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112269083A (en) * | 2020-10-20 | 2021-01-26 | 江苏新安电器股份有限公司 | Control panel voltage detection and conversion device for automatic test equipment |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP3480605B1 (en) | Current detection system, method and device | |
| CN201159746Y (en) | Current detection circuit | |
| CN109884377B (en) | Hall signal measuring device and method with automatically adjusted detection range | |
| CN103837253B (en) | A kind of CMOS temperature transmitter | |
| CN102109579B (en) | Signal monitoring system for controlling electric light source and signal monitoring method | |
| CN113503988B (en) | Temperature sensor calibration method and system and temperature sensor | |
| CN211603490U (en) | Lithium battery pack single battery voltage detection circuit and equipment based on open-loop optocoupler | |
| CN203241165U (en) | Thermal resistor temperature measurement circuit based on three-wire system | |
| CN101895336B (en) | Monitoring circuit, method for outputting monitor signal, and optical receiver | |
| CN109307550A (en) | A kind of temperature-compensation method improving light power meter stability | |
| CN102520360A (en) | Battery voltage detection system in battery pack and method for detecting voltage and correcting error by employing system | |
| CN211626739U (en) | PT100 platinum thermal resistance temperature sampling circuit | |
| CN216208769U (en) | High-precision online dissolved oxygen measuring instrument | |
| CN109540313A (en) | A kind of linear temperature measurement circuit based on silicon-based diode and NTC thermistor | |
| CN115060962A (en) | Source meter capable of rapidly switching measuring range and temperature compensation method thereof | |
| CN212988630U (en) | Temperature acquisition circuit, control panel and electrical equipment | |
| CN204422104U (en) | A kind of furnace temperature instrument compensated with oxygen determination | |
| KR100516796B1 (en) | Current detection circuit of a/f sensor | |
| RU2082129C1 (en) | Converter of pressure to electric signal | |
| SU661369A1 (en) | Differential voltage calibrator-voltmeter | |
| CN215375584U (en) | Battery pack voltage detection circuit | |
| CN219456305U (en) | Current detection circuit and electronic equipment | |
| CN211824797U (en) | Temperature measuring circuit | |
| CN218240227U (en) | Intelligent instrument circuit based on constant current source measured resistance value | |
| CN217786375U (en) | Three-wire system thermal resistor temperature sampling circuit for remote transmission |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200929 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |