CN206378762U - A kind of reference voltage sample circuit controlled for constant-current source - Google Patents
A kind of reference voltage sample circuit controlled for constant-current source Download PDFInfo
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- CN206378762U CN206378762U CN201621400921.8U CN201621400921U CN206378762U CN 206378762 U CN206378762 U CN 206378762U CN 201621400921 U CN201621400921 U CN 201621400921U CN 206378762 U CN206378762 U CN 206378762U
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- resistance
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- reference voltage
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- constant
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Abstract
The utility model is related to a kind of reference voltage sample circuit controlled for constant-current source, including voltage source, single-chip microcomputer, shunt resistance, reference resistance, current-limiting resistance, reference voltage output end and divider resistance, voltage source connects one end of current-limiting resistance, the other end connection divider resistance of current-limiting resistance, reference resistance is grounded after being connected in series with divider resistance, on the branch road drawn between one end access current-limiting resistance and divider resistance of shunt resistance, the other end connects the I/O mouths of single-chip microcomputer, reference voltage output end is connected on the branch road drawn between divider resistance and reference resistance；The resistance value ratio of divider resistance and reference resistance is more than 8.This circuit structure is simple, it is easily achieved, by accessing a divider resistance between shunt resistance and reference voltage output end and adjusting whether the shunt resistance in parallel with divider resistance is accessed in bleeder circuit to obtain precision voltage reference as needed, it is adaptable to minimum current and the maximum current application scenario bigger than very.
Description
Technical field
The utility model belongs to the reference voltage sampling technique field of constant-current source control, specifically a kind of to be used for constant current
The reference voltage sample circuit of source control.
Background technology
In constant-current source circuit, it usually needs a high-precision reference voltage is compared with the sampling voltage in load
Compared with this determination and the size of control constant current, therefore, the precision of the reference voltage largely determines constant-current source
Precision.Meanwhile, in order to lower the power consumption of circuit and improve efficiency, common high power constant-current source will flow through load end electric current
Sampling voltage be designed to very low, general control is in below 0.5V.And in order to simplify circuit, existing many constant-current source circuit handles
Reference voltage and sampling voltage carry out current control using comparator, are so also accomplished by reference voltage also in below 0.5V.
Existing constant-current source circuit is required to export two or more different constant currents respectively as needed, and this is just needed
There are two or more precision voltage references.Most of reference voltages are obtained by the way of precision resister partial pressure,
When needing two or more precision voltage references, required in said reference voltage acquisition pattern mechanical switch,
Relay or single-chip microcomputer are to control shunt resistance whether to access bleeder circuit to obtain different reference voltages.Wherein using machinery
Although switch is compared high with the control mode control accuracy of relay（The contact resistance very little of mechanical switch and relay, can be neglected
Slightly disregard）, but there is complex operation and be relatively difficult to the defect of intelligent control, therefore in current intellectualization times, use
The control mode of single-chip microcomputer is increasing, and its circuit is as shown in Figure 1.
When require constant-current source circuit constant current output electric current can change as requested and minimum current and maximum current ratio very
Big application scenario, this requires reference voltage in large-scope change.In Fig. 1, needed when constant current output low current constant current
Shunt resistance R3 is turned on by single-chip microcomputer and accessed, and R3 is in parallel with R2, and R3 resistance is smaller, and conducting resistance during single-chip microcomputer conducting
For 20 ohms and error is larger.Therefore the equivalent resistance in parallel with R2 is R3 and conducting resistance sum, due to electric conduction
The error of resistance is big, and R3 is suitable with the resistance measurement level of conducting resistance, and this results in the error of conducting resistance to circuit precision
Influence to become big, sample circuit precision will be reduced to cause error during constant-current source circuit output low current constant current big.
Utility model content
The purpose of this utility model is a kind of reference voltage sample circuit controlled for constant-current source of offer, and the circuit is adopted
Whether accessed to obtain a variety of reference voltages in bleeder circuit with single-chip microcomputer control shunt resistance, so that output constant current can
Change as requested, circuit structure is simple, constant current accuracy is high, it is adaptable to minimum reference voltage very little and excursion is very big（I.e.
Minimum current is with maximum current than very big）Application scenario.
To achieve these goals, the technical solution adopted in the utility model is, a kind of benchmark controlled for constant-current source
Voltage sample circuit, including voltage source, single-chip microcomputer, shunt resistance, reference resistance, current-limiting resistance, reference voltage output end and point
Piezoresistance, the voltage source connects one end of current-limiting resistance, and the other end of current-limiting resistance connects divider resistance, and reference resistance is with dividing
Piezoresistance is grounded after being connected in series, the branch road drawn between one end access current-limiting resistance and divider resistance of the shunt resistance
On, the other end connects the I/O mouths of single-chip microcomputer, and the reference voltage output end is connected between divider resistance and reference resistance and drawn
Branch road on；The resistance of the divider resistance is more than the resistance of reference resistance.
As a kind of improvement of the present utility model, the resistance value ratio of the divider resistance and reference resistance is more than 8.
As a kind of improvement of the present utility model, the voltage source is using the negligible High-accuracy direct current electricity of internal resistance
Potential source, the output voltage of the direct voltage source is 5V.
As a kind of improvement of the present utility model, the resistance of the current-limiting resistance is 5-10k Ω.
As a kind of improvement of the present utility model, the output voltage of the single-chip processor i/o mouthful is 0.2V.
Relative to prior art, the reference voltage sample circuit that the utility model is proposed will be by that will connect single-chip processor i/o
The shunt resistance of mouth is not joined directly together with reference voltage output end（Accessed i.e. not at reference voltage point（Disconnect）Shunt resistance）,
But increase a divider resistance on reference voltage output end, increase a dividing point, and shunt resistance is accessed into this partial pressure
On point, and the resistance of divider resistance is taken as to 8 times more than reference resistance resistance so that shunt resistance is much larger than single-chip microcomputer
Conducting resistance so that sample circuit precision is not influenceed by the error present in conducting resistance substantially, so as to improve constant current accuracy.
This circuit structure is simple, it is easy to accomplish and sampling precision is high, it is adaptable to minimum current and the maximum current application scenario bigger than very.
Brief description of the drawings
Fig. 1 is the constant current source control circuit figure that existing use single-chip microcomputer controls shunt resistance.
Fig. 2 is the circuit theory diagrams of the utility model preferred embodiment.
Embodiment
In order to deepen, to understanding and cognition of the present utility model, the utility model to be further described below in conjunction with the accompanying drawings
And introduction.
As shown in Fig. 2 it is a kind of for constant-current source control reference voltage sample circuit, including voltage source E, single-chip microcomputer, point
Leakage resistance R3, reference resistance R2, current-limiting resistance R1, reference voltage output end UA and divider resistance R11, the voltage source E connections
Current-limiting resistance R1 one end, current-limiting resistance R1 other end connection divider resistance R11, reference resistance R2 and divider resistance R11 string
It is grounded after connection connection, on the branch road drawn between one end access current-limiting resistance R1 and divider resistance R11 of the shunt resistance R3,
The other end connects the I/O mouths of single-chip microcomputer, and the reference voltage output end UA is connected between divider resistance R11 and reference resistance R2
On the branch road of extraction；The resistance of the divider resistance R11 is more than reference resistance R2 resistance.
It is preferred that, in order to obtain higher low current sampling precision, by divider resistance R11 and reference resistance R2 resistance value ratio
It is set to be more than 8.
It is further preferred that power supplys of the voltage source E as bleeder circuit, using the negligible high accuracy of internal resistance
Direct voltage source E, and direct voltage source E output voltage is 5V.
It is further preferred that in order to obtain higher low current sampling precision, current-limiting resistance R1 resistance is taken as into 5-10k
Ω。
Further above-mentioned reference voltage sample circuit is illustrated using preferred embodiment below：
Include reference voltage sample circuit in certain electric car charger, the electric car charger requires that constant current output is
0.1A and 2.5A, its load current sampling voltage is respectively 0.01V and 0.25V, therefore it is required that reference voltage be respectively 0.01V and
0.25V。
If reference voltage sample circuit is the structure shown in Fig. 1, by UA=R2*E/（R1+R2）R2=UA*R1/ can be obtained
(E-UA)。
（1）When requiring reference voltage UA=0.25V, single-chip processor i/o mouthful is not turned on, and shunt resistance R3 does not access partial pressure electricity
Road, then
R2= UA*R1/(E-UA)=0.25R1（5-0.25）=0.0526R1
The k Ω of R1=10 are taken, then the Ω of R2=526.
（2）When requiring reference voltage UA=0.01V, single-chip processor i/o mouthful conducting, shunt resistance R3 is accessed in bleeder circuit,
Shunt resistance R3 is connected in parallel with reference resistance R2, takes the k Ω of R1=10, and set shunt resistance R3 it is in parallel with reference resistance R2 after
Equivalent resistance is R, then
R= UA*R1/(E-UA)=0.01*10/（5-0.01）=0.022kΩ
Due to R=R3*R2/（R3+R2）；
Therefore, the Ω of R3=R*R2/ (R2-R)=0.022*0.526/ (0.526-0.022)=0.023 k Ω=23.
During single-chip processor i/o mouthful conducting, conducting resistance and error are in specifications in equal no standard, practical application, its conducting
Ω of resistance about 20 or so, error is about 10%.Therefore, actual desirable 3 Ω of shunt resistance R3 or so.Usual shunt resistance R3 tools
There is 1% precision, therefore, the error of the bleeder circuit is 0.01*3/23+0.1*20/23=8.8%, and this greatly reduces reference voltage
Precision.
And if reference voltage sample circuit is the structure shown in Fig. 2, being calculated as follows：
（1）When requiring reference voltage UA=0.25V, single-chip processor i/o mouthful is not turned on, and shunt resistance R3 does not access partial pressure electricity
Road, it is 526 Ω to take reference resistance R2, then, the k Ω of R11+R1=10.（R11+R1 herein is the R1 in Fig. 1）For convenience
Calculate, take R11=R1, then can obtain the K Ω of R11=R1=5.
（2）It is required that during reference voltage UA=0.01V, single-chip processor i/o mouthful conducting, shunt resistance R3 is accessed in bleeder circuit, then
UB=UA*(R2+R11)/R2=0.01*(0.526+5)/0.526=0.104V（It is higher than UA nearly 10 times)
I1=(E-UB)/R1=(5-0.104)/5=0.9792 mA
I2=UA/R2=0.01/0.526=0.019 mA
I3=I1-I2=0.9792-0.019=0.9602 mA
The Ω of k Ω of R3=UB/I3=0.104/0.9602=0.108=108 can be obtained
The Ω of single-chip microcomputer conducting resistance 20 is subtracted from the R3 calculated, then shunt resistance R3 resistance is 88 Ω.When point
Leakage resistance R3 error is 1%, when the error of single-chip microcomputer conducting resistance is 10%, and the error of the bleeder circuit is 1%*88/108+
10%*20/108=2.6%。
The circuit structure that Fig. 1 and Fig. 2 is respectively adopted by comparing said reference voltage sample circuit is requiring reference voltage
During UA=0.01V, if other position resistance precisions of two circuits are identical, figure is used using the sampling precision ratio of Fig. 2 circuit
The sampling precision of 1 circuit is higher by 3.38 times.As can be seen here, the reference voltage sample circuit proposed using the utility model can
Sampling precision is greatly improved, so as to improve constant current accuracy.In addition, in actual applications, if by divider resistance R11 resistance and base
It is appropriate that quasi- resistance R2 resistance ratio is selected, then shunt resistance R3 can obtain higher resistance, so as to effectively ignore monolithic
The error of machine conducting resistance, in favor of improving constant current accuracy.
Technological means disclosed in the utility model scheme is not limited only to the technological means disclosed in above-mentioned embodiment, also
Including being combined constituted technical scheme by above technical characteristic.It should be pointed out that for the ordinary skill of the art
For personnel, on the premise of the utility model principle is not departed from, some improvements and modifications can also be made, these improve and moistened
Decorations are also considered as protection domain of the present utility model.
Claims (4)
1. a kind of reference voltage sample circuit controlled for constant-current source, it is characterised in that：Including voltage source, single-chip microcomputer, shunting
Resistance, reference resistance, current-limiting resistance, reference voltage output end and divider resistance, the voltage source connect one end of current-limiting resistance,
The other end connection divider resistance of current-limiting resistance, reference resistance is grounded after being connected in series with divider resistance, the shunt resistance
One end is accessed on the branch road drawn between current-limiting resistance and divider resistance, and the other end connects the I/O mouths of single-chip microcomputer, the benchmark electricity
Pressure output end is connected on the branch road drawn between divider resistance and reference resistance；The resistance of the divider resistance is more than benchmark electricity
The resistance of resistance.
2. a kind of reference voltage sample circuit controlled for constant-current source as claimed in claim 1, it is characterised in that described point
The resistance value ratio of piezoresistance and reference resistance is more than 8.
3. a kind of reference voltage sample circuit controlled for constant-current source as claimed in claim 2, it is characterised in that the electricity
Potential source uses the negligible High-accuracy direct current voltage source of internal resistance, and the output voltage of the direct voltage source is 5V.
4. a kind of reference voltage sample circuit controlled for constant-current source as claimed in claim 3, it is characterised in that the limit
The resistance of leakage resistance is 5-10k Ω.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621400921.8U CN206378762U (en) | 2016-12-20 | 2016-12-20 | A kind of reference voltage sample circuit controlled for constant-current source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621400921.8U CN206378762U (en) | 2016-12-20 | 2016-12-20 | A kind of reference voltage sample circuit controlled for constant-current source |
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| Publication Number | Publication Date |
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| CN206378762U true CN206378762U (en) | 2017-08-04 |
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| CN201621400921.8U Expired - Fee Related CN206378762U (en) | 2016-12-20 | 2016-12-20 | A kind of reference voltage sample circuit controlled for constant-current source |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117707278A (en) * | 2024-02-01 | 2024-03-15 | 苏州萨沙迈半导体有限公司 | Reference voltage generating circuit and parallel voltage reference chip |
-
2016
- 2016-12-20 CN CN201621400921.8U patent/CN206378762U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117707278A (en) * | 2024-02-01 | 2024-03-15 | 苏州萨沙迈半导体有限公司 | Reference voltage generating circuit and parallel voltage reference chip |
| CN117707278B (en) * | 2024-02-01 | 2024-05-07 | 苏州萨沙迈半导体有限公司 | Reference voltage generating circuit and parallel voltage reference chip |
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| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20170804 Termination date: 20171220 |
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| CF01 | Termination of patent right due to non-payment of annual fee |