CN211827061U - Constant current source generating module - Google Patents
Constant current source generating module Download PDFInfo
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- CN211827061U CN211827061U CN202020869574.3U CN202020869574U CN211827061U CN 211827061 U CN211827061 U CN 211827061U CN 202020869574 U CN202020869574 U CN 202020869574U CN 211827061 U CN211827061 U CN 211827061U
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- operational amplifier
- constant current
- current source
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Abstract
The utility model aims at providing a constant current source production module that the error is little and stability is good. The utility model discloses a first operational amplifier, second operational amplifier, reference resistance and load resistance, first operational amplifier's syntropy input is connected with reference voltage, first operational amplifier's reverse input ground connection, first operational amplifier's output and SENSE end all through reference resistance with second operational amplifier's syntropy input is connected, second operational amplifier's syntropy input still with load resistance connects, load resistance's other end ground connection, second operational amplifier's reverse input and output all with first operational amplifier's REF end is connected. The utility model discloses be applied to power structure's technical field.
Description
Technical Field
The utility model discloses be applied to power structure's technical field, in particular to on-line test's constant current source produces module.
Background
The power supply is needed to provide electric energy in the online tests of the online resistance, the diode and the open circuit and short circuit of the PCB. Generally, a constant current source is used as a power supply, and the constant current source has the characteristic of constant current, so that test data can be acquired more accurately. In-line testing is a standard test means for inspecting defects in manufacturing and defects of components by testing electrical properties and electrical connections of in-line components. The method mainly checks the on-line single component and the open and short circuit conditions of each circuit network, and has the characteristics of simple, quick and accurate operation, accurate fault location and the like. As shown in fig. 1, in the current online test, a low voltage linear regulator or a transistor is mostly used to generate current, and the current error generated by the low voltage linear regulator or the transistor is large, and it is known from the formula Io = Iadj + Vout/Rref of the current that the magnitude of the local current Iadj affects the magnitude of the constant current Io, and the magnitude of the local current Iadj is also easily affected by temperature.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that overcome prior art not enough, provide a constant current source production module that the error is little and stability is good.
The utility model adopts the technical proposal that: the utility model discloses a first operational amplifier, second operational amplifier, reference resistance and load resistance, first operational amplifier's syntropy input is connected with reference voltage, first operational amplifier's reverse input ground connection, first operational amplifier's output and SENSE end all through reference resistance with second operational amplifier's syntropy input is connected, second operational amplifier's syntropy input still with load resistance connects, load resistance's other end ground connection, second operational amplifier's reverse input and output all with first operational amplifier's REF end is connected.
In the above-described embodiment, the first operational amplifier forms an adder, and the second operational amplifier forms a follower. The four resistors in the first operational amplifier have equal values, so that a formula of constant current Io = (VB-VA)/Rref exists, wherein VB is the voltage of the equidirectional input end of the first operational amplifier, VA is the voltage of the inverted input end of the first operational amplifier, and Rref is the resistance value of the reference resistor. The load resistor RLoad is in a state of 0 ohm and the load voltage is in a state of 1V, and the voltage Vo' of the output end of the operational amplifier is deduced to rise and fall along with the load voltage Vo in an equal ratio, so that the sum of the passing current is constant, and the ratio of the end voltage of the reference resistor to the input voltage is fixed.
Preferably, the model of the first operational amplifier is INA105KU, and the model of the second operational amplifier is LF 356M.
Drawings
FIG. 1 is a circuit schematic of a prior art in-line test power supply;
fig. 2 is a schematic circuit diagram of the present invention.
Detailed Description
As shown in fig. 2, in the present embodiment, the present invention includes a first operational amplifier U1, a second operational amplifier U2, a reference resistor Rref and a load resistor Rload, the same-direction input terminal of the first operational amplifier U1 is connected to a reference voltage, the reverse-direction input terminal of the first operational amplifier U1 is grounded, the output terminal and the SENSE terminal of the first operational amplifier U1 are both connected to the same-direction input terminal of the second operational amplifier U2 through the reference resistor Rref, the same-direction input terminal of the second operational amplifier U2 is also connected to the load resistor Rload, the other end of the load resistor Rload is grounded, and the reverse-direction input terminal and the output terminal of the second operational amplifier U2 are both connected to the REF terminal of the first operational amplifier U1.
In this embodiment, the first operational amplifier U1 and the second operational amplifier U2 are both low noise, low offset, high open loop gain bipolar operational amplifiers. The first operational amplifier U1 is a four-resistor differential amplifier, and the four resistors inside the differential amplifier have equal resistance values. The model of the first operational amplifier U1 is INA105KU, and the model of the second operational amplifier U2 is LF 356M.
The utility model discloses a theory of operation:
the voltage across the reference resistor Rref is equal to the voltage at the non-inverting input terminal of the first operational amplifier U1 by 2.5V, so that the constant current Io = Uref/Rref =2.5/Rref, and the magnitude of the constant current Io can be changed by adjusting the resistance value of the reference resistor Rref.
Wherein the variation range of the constant current Io is 10nA-20 mA; the variation range of the load voltage Vo is 0V-8V.
Claims (2)
1. A constant current source generating module, comprising: the operational amplifier comprises a first operational amplifier (U1), a second operational amplifier (U2), a reference resistor (Rref) and a load resistor (Rload), wherein the same-direction input end of the first operational amplifier (U1) is connected with a reference voltage, the reverse input end of the first operational amplifier (U1) is grounded, the output end and the SENSE end of the first operational amplifier (U1) are connected with the same-direction input end of the second operational amplifier (U2) through the reference resistor (Rref), the same-direction input end of the second operational amplifier (U2) is also connected with the load resistor (Rload), the other end of the load resistor (Rload) is grounded, and the reverse input end and the output end of the second operational amplifier (U2) are connected with the REF end of the first operational amplifier (U1).
2. The constant current source generation module according to claim 1, wherein: the model of the first operational amplifier (U1) is INA105KU, and the model of the second operational amplifier (U2) is LF 356M.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020869574.3U CN211827061U (en) | 2020-05-22 | 2020-05-22 | Constant current source generating module |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020869574.3U CN211827061U (en) | 2020-05-22 | 2020-05-22 | Constant current source generating module |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211827061U true CN211827061U (en) | 2020-10-30 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020869574.3U Active CN211827061U (en) | 2020-05-22 | 2020-05-22 | Constant current source generating module |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211827061U (en) |
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2020
- 2020-05-22 CN CN202020869574.3U patent/CN211827061U/en active Active
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