CN206431197U - A kind of new load current sample circuit - Google Patents
A kind of new load current sample circuit Download PDFInfo
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- CN206431197U CN206431197U CN201720069570.5U CN201720069570U CN206431197U CN 206431197 U CN206431197 U CN 206431197U CN 201720069570 U CN201720069570 U CN 201720069570U CN 206431197 U CN206431197 U CN 206431197U
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Abstract
The utility model discloses a kind of new load current sample circuit, it is connected with a load, the load current sample circuit includes single-chip microcomputer, first resistor, second resistance and FET, one end of the load is connected with dc source, the other end is connected with the drain electrode of FET, the source ground of the FET, grid is connected by first resistor with the PWM output ends of single-chip microcomputer, the source electrode of the FET is also directly connected by second resistance with its grid, the drain electrode of the FET is also connected by 3rd resistor and electric capacity with the A/D mouths of single-chip microcomputer.Above-mentioned load current sample circuit is simple in construction, occupy little space, cost is relatively low.
Description
Technical field
The utility model is related to a kind of sample circuit, more particularly to a kind of new load current sample circuit.
Background technology
Conventional load current size detection, is that load current is switched into voltage signal by sampling resistor to send monolithic machine examination
Survey.For being worked using FET driving DC load, only needing to carry out necessary detection and limitation to maximum load current
The application scenario of (to ensure that using for product is safe), because load current is very big, if using conventional additional sampling resistor
Mode carries out load current sampling, and the power of sampling resistor must just select very big, can so cause that the sampling resistor bodily form is excessive, account for
With the problem of space is big, heating is excessively serious.On the other hand, it is also individual that the material cost of high-power sampling resistor and device, which are customized,
Problem.
Utility model content
The utility model embodiment technical problem to be solved be the provision of it is a kind of it is simple in construction, occupy little space,
Lower-cost load current sample circuit.
A kind of new load current sample circuit provided by the utility model, is connected with a load, the load electricity
Flowing sample circuit includes single-chip microcomputer, first resistor, second resistance and FET, one end and the dc source phase of the load
Even, the other end is connected with the drain electrode of FET, and the source ground of the FET, grid passes through first resistor and single-chip microcomputer
PWM output ends be connected, the source electrode of the FET is also directly connected by second resistance with its grid, the FET
Drain electrode be also connected by 3rd resistor and electric capacity with the A/D mouths of single-chip microcomputer.
Wherein, the resistance to electric current of the FET is more than 2-3 times of maximum load operating current, the FET conducting
When required grid and source electrode between minimum drive voltage be less than the power supply value of single-chip microcomputer, its turn on internal resistance precision should ±
In the range of 10%.
Wherein, the resistance of the first resistor is 0~100 ohm.
Wherein, the resistance of the second resistance is 10K~100K ohm.
Wherein, the resistance of the 3rd resistor is 1K~10K ohm.
Wherein, the capacitance of the electric capacity is 0.1uF~1uF/50V.
Internal resistance when above-mentioned new load current sample circuit is turned on using FET utilizes field as sampling resistor
The conducting internal resistance of effect pipe is small, advantage that is small, can leading to high current of generating heat, simultaneous to play a part of sampling resistor, and then realizes whole
Individual load current sample circuit is simple in construction, occupy little space, lower-cost advantage.
Brief description of the drawings
, below will be to embodiment in order to illustrate more clearly of the utility model embodiment or technical scheme of the prior art
Or the accompanying drawing used required in description of the prior art is briefly described, it should be apparent that, drawings in the following description are only
It is some embodiments of the present utility model, for those of ordinary skill in the art, is not paying the premise of creative work
Under, other accompanying drawings can also be obtained according to these accompanying drawings；
Fig. 1 is a kind of circuit diagram of the better embodiment of new load current sample circuit of the utility model.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is carried out
Clearly and completely describe, it is clear that described embodiment is only a part of embodiment of the utility model, rather than whole
Embodiment.Based on the embodiment in the utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment obtained, belongs to the scope of the utility model protection.
First, before embodiment is described, it is necessary to which some herein presented terms are explained.Example
Such as：
If occurring describing various elements using the term such as " first ", " second " herein, but these elements should not
Limited by these terms.These terms are only used for distinguishing an element and another element.Therefore, " first " element can also
It is referred to as " second " element without departing from teaching of the present utility model.
In addition, it is to be understood that when referring to an element " connection " or " coupled " to another element, it can be direct
Ground connects or is directly coupled to another element or can also have intermediary element.An element is referred on the contrary, working as " directly
When connection " or " directly coupling " arrive another element, then in the absence of intermediary element.
The various terms occurred herein are used only for describing the purpose of specific embodiment and being not intended as to this
The restriction of utility model.Unless context is clearly dictated otherwise, then singulative is intended to also include plural form.
When using term " comprising " and/or " including " in this manual, these terms specify the feature, whole
Body, step, operation, the presence of element and/or part, but be also not excluded for more than one other feature, entirety, step, operation,
Element, part and/or the presence of its group and/or additional.
On embodiment：
Fig. 1 is referred to, Fig. 1 is a kind of electricity of the better embodiment of new load current sample circuit of the utility model
Lu Tu.The load current sample circuit is connected with a load 16, and its better embodiment includes single-chip microcomputer 18, resistance R1-R3
And FET Q1, one end of the load 16 is connected with dc source VCC, the drain electrode phase of the other end and FET Q1
Even, the source ground of the FET Q1, grid is connected by resistance R1 with the PWM output ends of single-chip microcomputer 18, the field effect
Should pipe Q1 source electrode be also directly connected by resistance R2 with its grid, the drain electrode of the FET Q1 also directly passes through resistance R3
It is connected with the A/D mouths of single-chip microcomputer 18, the A/D mouths of the single-chip microcomputer 18 are also directly grounded by electric capacity C1.
The operation principle to above-mentioned load current sample circuit is simply described below：
The single-chip microcomputer 18 arrives FET by its A/D mouthfuls of output control level through resistance R1 and R2 partial pressure is after-applied
Between Q1 grid and source electrode so that FET Q1 is turned on and driven the load 16 to work, and load current I flows through field-effect
Inside conducting resistance between pipe Q1 drain electrode and source electrode produces voltage drop U, wherein voltage drop U=I × R, and R is FET
Q1 inside conducting resistance.The A/D mouths of the single-chip microcomputer 18 are responsible for being monitored the electric current for flowing through FET Q1, when described
The voltage drop U that the A/D mouths of single-chip microcomputer 18 are collected through resistance R3 between FET Q1 drain electrode and source electrode reaches required control
During the numerical value of system, you can judge that load current I has reached corresponding controlling value.Due to flow through FET Q1 pipes drain electrode with
The conducting internal resistance of FET corresponding to the different electric currents of source electrode is also different, so must be according to the required load electricity monitored
Internal resistance value, calculated in advance are turned between stream numerical values recited and the FET drain electrode corresponding in the load current and source electrode
Voltage drop between the drain electrode of good FET and source electrode.The single-chip microcomputer A/D sample voltage value different by detecting, you can control
Flow through FET Q1 load current size.There is abnormal increase simultaneously once detecting and flowing through FET Q1 load current
During beyond the numerical value of required control, single-chip microcomputer is that exportable low level closes FET Q1 or takes reduction FET Q1
Drive waveforms dutycycle in the way of reducing load average electric current, it is ensured that the safe handling of load.
In this circuit, the resistance R3 and electric capacity C1 play filter action, and two of the drain electrode and source electrode to FET Q1
The voltage signal at end is smoothed, and filtering is entrained in signal noise therein, suppresses possible load current spike pair
The impact of single-chip microcomputer.The resistance R2 may insure to be in low level when standby between FET Q1 grid and source electrode,
Avoid accumulation of static electricity FET false triggering caused by grid can not release.
On the basis of previous technique scheme, for FET Q1 type selecting, its resistance to electric current have to be larger than maximum load
2~3 times of operating current, more than one times of the pressure-resistant supply voltage that should be FET Q1, while FET conducting when institute
Minimum drive voltage should be less than the power supply value of single-chip microcomputer between the grid and source electrode that need, and it turns on internal resistance precision should be ± 10%
In the range of.The resistance R1 can select 0~100 Ω, the resistance R2 that 10K~100K, the resistance R3 can be selected to select 1K
~10K, the filter capacitor C1 can select 0.1uF~1uF/50V.
Embodiment of the present utility model is these are only, the scope of the claims of the present utility model, every profit is not thereby limited
The equivalent structure or equivalent flow conversion made with the utility model specification and accompanying drawing content, or directly or indirectly it is used in it
The technical field of his correlation, is similarly included in scope of patent protection of the present utility model.
Claims (6)
1. a kind of new load current sample circuit, is connected with a load, it is characterised in that：The load current sample circuit
Including single-chip microcomputer, first resistor, second resistance and FET, one end of the load is connected with dc source, the other end
It is connected with the drain electrode of FET, the source ground of the FET, grid is exported by the PWM of first resistor and single-chip microcomputer
End is connected, and the source electrode of the FET is also directly connected by second resistance with its grid, and the drain electrode of the FET is also
It is connected by 3rd resistor and electric capacity with the A/D mouths of single-chip microcomputer.
2. load current sample circuit as claimed in claim 1, it is characterised in that：The resistance to electric current of the FET is more than most
2-3 times of heavy load operating current, minimum drive voltage is small between required grid and source electrode during the FET conducting
In the power supply value of single-chip microcomputer.
3. load current sample circuit as claimed in claim 1, it is characterised in that：The resistance of the first resistor is 0~100
Ohm.
4. load current sample circuit as claimed in claim 1, it is characterised in that：The resistance of the second resistance be 10K~
100K ohm.
5. load current sample circuit as claimed in claim 1, it is characterised in that：The resistance of the 3rd resistor be 1K~
10K ohm.
6. load current sample circuit as claimed in claim 1, it is characterised in that：The capacitance of the electric capacity be 0.1uF~
1uF/50V。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720069570.5U CN206431197U (en) | 2017-01-19 | 2017-01-19 | A kind of new load current sample circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720069570.5U CN206431197U (en) | 2017-01-19 | 2017-01-19 | A kind of new load current sample circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206431197U true CN206431197U (en) | 2017-08-22 |
Family
ID=59583550
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201720069570.5U Active CN206431197U (en) | 2017-01-19 | 2017-01-19 | A kind of new load current sample circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN206431197U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107632191A (en) * | 2017-10-25 | 2018-01-26 | 上海伟世通汽车电子系统有限公司 | A kind of current measurement circuit |
| CN110174545A (en) * | 2019-04-30 | 2019-08-27 | 上海芯导电子科技有限公司 | A kind of multiplexing current detection circuit |
-
2017
- 2017-01-19 CN CN201720069570.5U patent/CN206431197U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107632191A (en) * | 2017-10-25 | 2018-01-26 | 上海伟世通汽车电子系统有限公司 | A kind of current measurement circuit |
| CN107632191B (en) * | 2017-10-25 | 2024-05-28 | 上海伟世通汽车电子系统有限公司 | Current measuring circuit |
| CN110174545A (en) * | 2019-04-30 | 2019-08-27 | 上海芯导电子科技有限公司 | A kind of multiplexing current detection circuit |
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