CN112558670B - High-precision voltage-current converter - Google Patents
High-precision voltage-current converter Download PDFInfo
- Publication number
- CN112558670B CN112558670B CN202011521030.9A CN202011521030A CN112558670B CN 112558670 B CN112558670 B CN 112558670B CN 202011521030 A CN202011521030 A CN 202011521030A CN 112558670 B CN112558670 B CN 112558670B
- Authority
- CN
- China
- Prior art keywords
- coupled
- resistor
- node
- voltage
- field effect
- 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.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/561—Voltage to current converters
Abstract
The invention discloses a high-precision voltage-current converter, which comprises a voltage-controlled current source and an output circuit coupled with the voltage-controlled current source, wherein the output circuit comprises a current limiting circuit, and a current output node is coupled to the current limiting circuit; the voltage-controlled current source comprises an operational amplifier, a mirror current source, a first field effect transistor and a setting resistor; the first field effect transistor is coupled between the mirror current source and the setting resistor, and the setting resistor is grounded; a first node is arranged between the first field effect transistor and the setting resistor; the same-direction input end of the operational amplifier is coupled with a voltage input node, the reverse-direction input end of the operational amplifier is coupled with the first node, and the output end of the operational amplifier is coupled with the grid electrode of the first field effect transistor; the input terminal of the current limiting circuit is coupled with the mirror current source. The high-precision voltage-current converter has the advantages of small volume, low cost, good linearity, high precision, strong anti-interference capability and high reliability.
Description
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a high-precision voltage-current converter.
Background
The voltage/current conversion, i.e. V/I conversion, converts an input voltage signal into a current signal satisfying a certain relationship, and the converted current is equivalent to a constant current source with adjustable output, and the output current of the constant current source can be kept stable and will not change with the change of a load. Generally, the voltage-current conversion circuit is realized through negative feedback, which can be current series negative feedback or current parallel negative feedback, and is mainly used in industrial control and many sensor applications. With the development of electronic technology, higher requirements are put forward on a V/I conversion circuit, and particularly in the industrial field, common standard signals of various sensors are 0-5V voltage signals and 0-20mA and 4-20mA current signals, and the condition that the voltage signals need to be converted into the current signals is often used because the interference resistance is strong in the transmission process of the current signals. At present, V/I conversion is mostly realized by adding a plurality of discrete elements to an IC, but the scheme has large volume, poor reliability, poor linearity and low precision due to low IC precision and poor linearity and is externally connected with a plurality of discrete elements.
Disclosure of Invention
In view of the drawbacks of the prior art, the present invention provides a high-precision voltage-current converter to solve the technical problems mentioned in the background.
A high precision voltage to current converter comprising a voltage controlled current source and an output circuit coupled to the voltage controlled current source, the output circuit comprising a current limiting circuit having a current output node coupled thereto; wherein
The voltage-controlled current source comprises an operational amplifier, a mirror current source, a first field effect transistor and a setting resistor; the first field effect transistor is coupled between the mirror current source and the setting resistor, and the setting resistor is grounded; a first node is arranged between the first field effect transistor and the setting resistor; the same-direction input end of the operational amplifier is coupled with a voltage input node, the reverse-direction input end of the operational amplifier is coupled with the first node, and the output end of the operational amplifier is coupled with the grid electrode of the first field effect transistor;
the input terminal of the current limiting circuit is coupled with the mirror current source.
Further, the first field effect transistor is an NMOS transistor, a source of the first field effect transistor is coupled to the setting resistor, and a drain of the first field effect transistor is coupled to the mirror current source.
Further, a calibration voltage is coupled to the mirror current source.
Further, the calibration voltage is 24V.
Further, the current limiting circuit comprises a second field effect transistor, a first transistor, a second transistor, a first resistor and a second resistor;
the first resistor, the first transistor, the second field effect transistor and the current output node are sequentially connected, the first resistor is coupled with the mirror current source, a second node is arranged between the first resistor and the mirror current source, a third node is arranged between the first resistor and the first transistor, and a fourth node is arranged between the first transistor and the second field effect transistor;
the grid electrode of the second field effect transistor is coupled with the grid electrode driving end;
the second transistor is connected in series with a second resistor and then coupled between the second node and a fourth node, and the base of the second transistor is coupled with the third node; the base of the first transistor is coupled between the second transistor and a second resistor.
Further, the resistance value of the first resistor is 15 Ω, and the resistance value of the second resistor is 5K Ω.
Further, the second field effect transistor is a PMOS transistor, and a drain electrode of the second field effect transistor is connected with the current output node.
Further, the model of the second field effect transistor is BSP 170P.
Further, a gate drive and turn-off switch circuit is coupled between the calibration voltage and the gate drive terminal, the gate drive and turn-off switch circuit comprising a gate drive, a first diode, a second diode, a third resistor and an OD switch;
the first diode and the second diode are sequentially connected and then coupled between the calibration voltage and the ground, the cathode of the first diode is connected with the calibration voltage, the anode of the second diode is grounded, a fifth node is arranged between the first diode and the calibration voltage, and a sixth node is arranged between the first diode and the second diode;
the third resistor is coupled between the sixth node and the gate drive;
the input end of the third diode is connected between the third resistor and the gate drive, and the output end of the third diode is connected with the fifth node;
one end of the OD switch is connected between the third resistor and the gate drive, and the other end of the OD switch is connected with the fifth node;
the gate driving terminal is coupled to the sixth node.
Further, the resistance value of the third resistor is 3K Ω.
The invention has the beneficial effects that:
the high-precision voltage-current converter has the advantages of small volume, low cost, good linearity, high precision, strong anti-interference capability and high reliability.
Drawings
In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.
FIG. 1 is a circuit diagram of a high precision voltage to current converter;
FIG. 2 is a circuit diagram of a current limiting circuit of a high precision voltage to current converter;
fig. 3 is a circuit diagram of a gate drive and turn-off switching circuit of a high-precision voltage-to-current converter.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.
It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.
As shown in fig. 1, a high precision voltage-to-current converter includes a voltage-controlled current source and an output circuit coupled to the voltage-controlled current source, the output circuit including a current limiting circuit having a current output node coupled thereto.
The voltage-controlled current source comprises an operational amplifier, a mirror current source, a first field effect transistor and a setting resistor; the first field effect transistor is coupled between the mirror current source and the setting resistor, and the setting resistor is grounded; a first node is arranged between the first field effect transistor and the setting resistor; the same-direction input end of the operational amplifier is coupled with a voltage input node, the reverse-direction input end of the operational amplifier is coupled with the first node, and the output end of the operational amplifier is coupled with the grid electrode of the first field effect transistor; the input terminal of the current limiting circuit is coupled with the mirror current source. The first field effect transistor is an NMOS transistor, the source electrode of the first field effect transistor is coupled with the setting resistor, and the drain electrode of the first field effect transistor is coupled with the mirror current source.
Specifically, a calibration voltage VSP is coupled to the mirror current source, and the calibration voltage VSP is 24V.
The setting resistor determines the conversion ratio between the input voltage and the output current, the input voltage of the front stage can change the current of the mirror current source by setting the size of the resistor, and the mirror current source outputs the current to the output circuit to drive the load.
In the embodiment, the input voltage Vin controls the output current through Rset by means of I-Mirror, and the I-Mirror can generate current gain output of 10 times. The relationship between input voltage and output current is as follows:
Iout＝10(Vin/Rset)
iout is the output current of the voltage-current converter, Vin is the input voltage of the voltage-current converter, and Rset is the set resistor.
The voltage-controlled current source can generate a voltage-controlled current source of 0-36 mA, and the power supply voltage can reach 40V and 44V at most. The voltage-current ratio is defined by an external setting resistor Rset, so the input voltage range can be set according to actual needs.
No current limiting IS provided internally to the voltage controlled current source, although the internal mirror current source controls the current, the large current between IS and ground creates a voltage clamp between the calibration voltages VSP and IS, which results in a low impedance path, and the current can only be limited by the load impedance and the current capability of the external FET.
Large currents burn out the voltage controlled current source and therefore require a current limiting circuit to limit the output current. Specifically, as shown in fig. 2, the improved current limiting circuit includes a second field effect transistor, a first transistor, a second transistor, a first resistor R6, and a second resistor R8. The first resistor R6, the first transistor, the second field effect transistor and the current output node are sequentially connected, the first resistor R6 is coupled with the mirror current source, a second node is arranged between the first resistor R6 and the mirror current source, a third node is arranged between the first resistor R6 and the first transistor, and a fourth node is arranged between the first transistor and the second field effect transistor. The gate of the second fet is coupled to the gate driver VG. The second transistor is connected in series with a second resistor R8 and then coupled between a second node and a fourth node, and the base of the second transistor is coupled with a third node; the base of the first transistor is coupled between the second transistor and the second resistor R8. The first resistor R6 has a resistance of 15 Ω, and the second resistor R8 has a resistance of 5K Ω.
Specifically, the second field effect transistor is a PMOS transistor, and a drain electrode of the second field effect transistor is connected to the current output node. The second fet is model BSP 170P. The P-MOSFET in the output circuit ensures high output impedance and a wide range of voltage output and good stability of the output voltage.
The 15 ohm resistance of the first resistor R6 will limit the output current to within about 37mA by being connected in series with a P-channel MOSFET source drain to accommodate large voltage power bleeds. The extremely high output impedance and the wide voltage range ensure the suppression of typical interfering signals in an industrial environment.
In this embodiment, the first transistor and the second transistor are both PNP transistors. The PNP transistor, model KST2907, should allow a peak current of several hundred mA. The second transistor IS connected to the source of the second field effect transistor through a second resistor R8, and discharges the source of the second field effect transistor, so that leakage current IS prevented from flowing from IS to VG.
The output circuit requires an external transistor to form a source-drain loop for the output current. The maximum rated voltage of the transistor is larger than Vout and the power generated by current and voltage can be discharged. As shown in fig. 3, a gate drive and turn-off switch circuit is coupled between the calibration voltage and the gate drive terminal.
The gate drive and turn-off switch circuit includes a gate drive, a first diode, a second diode, a third resistor, and an OD switch. The first diode and the second diode are sequentially connected and then coupled between the calibration voltage and the ground, the cathode of the first diode is connected with the calibration voltage, the anode of the second diode is grounded, a fifth node is arranged between the first diode and the calibration voltage, and a sixth node is arranged between the first diode and the second diode. The third resistor is coupled between the sixth node and the gate drive. And the input end of the third diode is connected between the third resistor and the gate drive, and the output end of the third diode is connected with the fifth node. One end of the OD switch is connected between the third resistor and the gate drive, and the other end of the OD switch is connected with the fifth node. The gate driving terminal is coupled to the sixth node. The resistance of the third resistor is 3K omega.
The gate drive terminal VG can output a drive voltage from a voltage drop close to the power supply to 16V, and most commonly used MOSFETs support a maximum VGs of 20V, in which case the MOSFET needs to have a protective clamp added if there is a large source-gate parasitic capacitance and the gate voltage exceeds the rated voltage of the MOSFET. The gate drive is turned off by pulling the OD terminal high and the switch is closed to connect a 3K ohm resistor from VSP to VG, which can discharge the charge stored at the gate of the external FET and turn the device off. For the MOSFET selection, to avoid external capacitance from IS, this capacitance can be compensated by adding an additional capacitance between VG and IS. In addition, for this application, the breakdown voltage between the drain and the source is sufficiently high, surge voltage protection is required for negative overvoltage, and for positive overvoltage, a 24V clamp diode is recommended to protect the reverse voltage of the MOSFET. For the above reasons, the second fet of the present embodiment selects a BSP170P type P-channel MOSFET transistor.
In conclusion, the high-precision voltage-current converter has the advantages of small volume, low cost, good linearity, high precision, strong anti-interference capability and high reliability.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (8)
1. A high precision voltage to current converter, characterized by: the output circuit comprises a current limiting circuit, and a current output node is coupled to the current limiting circuit; wherein
The voltage-controlled current source comprises an operational amplifier, a mirror current source, a first field effect transistor and a setting resistor; the first field effect transistor is coupled between the mirror current source and the setting resistor, and the setting resistor is grounded; a first node is arranged between the first field effect transistor and the setting resistor; the same-direction input end of the operational amplifier is coupled with a voltage input node, the reverse-direction input end of the operational amplifier is coupled with the first node, and the output end of the operational amplifier is coupled with the grid electrode of the first field effect transistor;
the input end of the current limiting circuit is coupled with the mirror current source;
a calibration voltage is coupled to the mirror current source;
the current limiting circuit comprises a second field effect transistor, a first transistor, a second transistor, a first resistor and a second resistor;
the first resistor, the first transistor, the second field effect transistor and the current output node are sequentially connected, the first resistor is coupled with the mirror current source, a second node is arranged between the first resistor and the mirror current source, a third node is arranged between the first resistor and the first transistor, and a fourth node is arranged between the first transistor and the second field effect transistor;
the grid electrode of the second field effect transistor is coupled with the grid electrode driving end;
the second transistor is connected in series with a second resistor and then coupled between the second node and a fourth node, and the base of the second transistor is coupled with the third node; the base of the first transistor is coupled between the second transistor and a second resistor.
2. A high precision voltage to current converter according to claim 1, wherein: the first field effect transistor is an NMOS transistor, a source electrode of the first field effect transistor is coupled with the setting resistor, and a drain electrode of the first field effect transistor is coupled with the mirror current source.
3. A high precision voltage to current converter according to claim 1, wherein: the calibration voltage is 24V.
4. A high precision voltage to current converter according to claim 1, wherein: the resistance value of the first resistor is 15 omega, and the resistance value of the second resistor is 5K omega.
5. A high precision voltage to current converter according to claim 1, wherein: the second field effect transistor is a PMOS transistor, and the drain electrode of the second field effect transistor is connected with the current output node.
6. A high accuracy voltage to current converter according to claim 5, wherein: the model of the second field effect transistor is BSP 170P.
7. A high precision voltage to current converter according to claim 1, wherein: a gate drive and turn-off switch circuit is coupled between the calibration voltage and the gate drive end, and comprises a gate drive, a first diode, a second diode, a third resistor and an OD switch;
the first diode and the second diode are sequentially connected and then coupled between the calibration voltage and the ground, the cathode of the first diode is connected with the calibration voltage, the anode of the second diode is grounded, a fifth node is arranged between the first diode and the calibration voltage, and a sixth node is arranged between the first diode and the second diode;
the third resistor is coupled between the sixth node and the gate drive;
the input end of the third diode is connected between the third resistor and the gate drive, and the output end of the third diode is connected with the fifth node;
one end of the OD switch is connected between the third resistor and the gate drive, and the other end of the OD switch is connected with the fifth node;
the gate driving terminal is coupled to the sixth node.
8. A high accuracy voltage to current converter according to claim 7, wherein: and the resistance value of the third resistor is 3K omega.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011521030.9A CN112558670B (en) | 2020-12-21 | 2020-12-21 | High-precision voltage-current converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011521030.9A CN112558670B (en) | 2020-12-21 | 2020-12-21 | High-precision voltage-current converter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112558670A CN112558670A (en) | 2021-03-26 |
| CN112558670B true CN112558670B (en) | 2022-03-04 |
Family
ID=75032024
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011521030.9A Active CN112558670B (en) | 2020-12-21 | 2020-12-21 | High-precision voltage-current converter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112558670B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201233548Y (en) * | 2008-07-25 | 2009-05-06 | 深圳市远望谷信息技术股份有限公司 | Voltage-current conversion circuit |
| US9098103B1 (en) * | 2013-03-06 | 2015-08-04 | Maxim Integrated Products, Inc. | Current limit circuit for DC-DC converter |
| CN106647909A (en) * | 2016-12-21 | 2017-05-10 | 北京时代民芯科技有限公司 | Output adjustable driver circuit |
| CN110032233A (en) * | 2019-04-30 | 2019-07-19 | 深圳市明微电子股份有限公司 | A kind of adaptive constant-flow device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4835487A (en) * | 1988-04-14 | 1989-05-30 | Motorola, Inc. | MOS voltage to current converter |
-
2020
- 2020-12-21 CN CN202011521030.9A patent/CN112558670B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201233548Y (en) * | 2008-07-25 | 2009-05-06 | 深圳市远望谷信息技术股份有限公司 | Voltage-current conversion circuit |
| US9098103B1 (en) * | 2013-03-06 | 2015-08-04 | Maxim Integrated Products, Inc. | Current limit circuit for DC-DC converter |
| CN106647909A (en) * | 2016-12-21 | 2017-05-10 | 北京时代民芯科技有限公司 | Output adjustable driver circuit |
| CN110032233A (en) * | 2019-04-30 | 2019-07-19 | 深圳市明微电子股份有限公司 | A kind of adaptive constant-flow device |
Non-Patent Citations (1)
| Title |
|---|
| 太阳敏感器电模拟器设计;赵光权等;《计算机测量与控制》;20110831;第19卷(第8期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112558670A (en) | 2021-03-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2006016456A1 (en) | Circuit protection method, protection circuit and power supply device using the protection circuit | |
| US6166530A (en) | Current-Limited switch with fast transient response | |
| CN110086455B (en) | Novel switch circuit structure | |
| US10797689B2 (en) | Over-voltage clamp circuit | |
| US20130307627A1 (en) | Integrated start-up bias boost for dynamic error vector magnitude enhancement | |
| JP2005333691A (en) | Overcurrent detection circuit and power supply having it | |
| EP2650919B1 (en) | Tunable capacitor | |
| EP0499921B1 (en) | Current control device, particularly for power circuits in MOS technology | |
| CN101118450A (en) | Returning type current limiting circuit used for linearity voltage stabilizer | |
| CN216959308U (en) | Current limiting circuit | |
| CN115903985A (en) | Current limiting circuit suitable for LDO circuit with wide input voltage range | |
| CN114167771A (en) | Output drive control circuit for AC-DC controller | |
| CN112558670B (en) | High-precision voltage-current converter | |
| US11336191B1 (en) | Power supply device with low loss | |
| EP3330829A1 (en) | Base current compensation for a bjt current mirror | |
| US20220382306A1 (en) | Low dropout linear regulator with high power supply rejection ratio | |
| US7508188B2 (en) | On-chip current sensing methods and systems | |
| CN111897389A (en) | Linear voltage stabilizing circuit based on triode series connection | |
| CN114326913B (en) | Circuit capable of selectively outputting input voltage range | |
| CN215581091U (en) | IGBT gate pole drive circuit | |
| CN115167591B (en) | Floating high-end power supply generating circuit based on zener diode | |
| US20240039494A1 (en) | Operational Amplifier | |
| CN113702790B (en) | Current detection circuit in high voltage application | |
| US8766699B2 (en) | Switching circuit | |
| CN210804143U (en) | Voltage regulating circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |