CN208421059U - A kind of current detection circuit - Google Patents
A kind of current detection circuit Download PDFInfo
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- CN208421059U CN208421059U CN201821074234.0U CN201821074234U CN208421059U CN 208421059 U CN208421059 U CN 208421059U CN 201821074234 U CN201821074234 U CN 201821074234U CN 208421059 U CN208421059 U CN 208421059U
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- current detection
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Abstract
The utility model relates to a kind of current detection circuits, pass through the selecting module as composed by two resistance and four control switches, it can be different inspection flow paths to be selected, to realize the accurate detection of bidirectional current in charged state or discharge condition according to module to be measured.In addition, the current conversion module being made of amplifier, transistor and analog-digital converter, may be implemented sample rate current being quickly converted to voltage, entire circuit structure is simple, and cost is relatively low.
Description
Technical field
The utility model relates to electronic circuit fields, and in particular to a kind of current detection circuit.
Background technique
The demand of generally existing current detecting in power-supply management system.On the one hand, when battery is to system power supply, power supply
Management module needs to monitor the size of current of battery discharge, and when battery discharge current is excessive, instruction system reduces power demands,
To play a protective role to whole system；On the other hand, when charging to battery, charging circuit is also required to filling for monitoring battery
Electric current while guaranteeing faster charging rate, guarantees battery and charging by current control in suitable magnitude range
The safety of circuit.Some power-supply management systems also need to monitor the remaining capacity of battery at any time, in battery charging, discharge process
In, require the accurate current size of real-time monitoring battery.Realize that the circuit structure of the power management module of these functions compares
Complexity, volume is larger, is unfavorable for product miniaturization.
Utility model content
The utility model provides a kind of current detection circuit, it can be achieved that the bidirectional current of charging current and discharge current is examined
It surveys, while circuit structure is fairly simple, cost is relatively low.The specific technical solution of the utility model is as follows:
A kind of current detection circuit, for detecting the charging current and discharge current of module to be measured.The current detecting electricity
Road include first resistor, second resistance, the first control switch, the second control switch, third control switch, the 4th control switch,
Amplifier, NMOS tube, the first PMOS tube, the second PMOS tube, 3rd resistor and analog-digital converter.Wherein: the first resistor
First input end of the one end as the current detection circuit is connected to the module to be measured；The other end of the first resistor
The positive input terminal of the amplifier is then connected to by first control switch, the other end of the first resistor also passes through institute
State the negative input end that the second control switch is connected to the amplifier；One end of the second resistance is as the current detecting electricity
Second input terminal on road is connected to the module to be measured；The other end of the second resistance then passes through the third control switch
It is connected to the negative input end of the amplifier, the other end of the second resistance is also connected to institute by the 4th control switch
State the positive input terminal of amplifier.The output end of the amplifier connects the grid of the NMOS tube, and the source electrode of the NMOS tube connects
The negative input end of the amplifier is connect, the drain electrode of the NMOS tube connects the drain electrode of first PMOS tube；First PMOS
Pipe and the source electrode of second PMOS tube connect external power supply, the grid of first PMOS tube and second PMOS tube jointly
It is commonly connected to the drain electrode of the NMOS tube；The drain electrode of second PMOS tube is grounded by the 3rd resistor；Described second
The drain electrode of PMOS tube and the common end of the 3rd resistor are connected to the input terminal of the analog-digital converter；The analog-digital converter
Output end be then used as the output end of the current detection circuit.
Further, the module to be measured includes power supply to be measured and inspection leakage resistance, and the cathode of the power supply to be measured passes through institute
State inspection leakage resistance ground connection；The first input end of the current detection circuit is connected to the power supply to be measured and the inspection leakage resistance
Common end, the second input terminal of the current detection circuit are connected to the ground terminal of the inspection leakage resistance.
Further, the resistance value of the first resistor is equal with the resistance value of the second resistance.
Further, the resistance value of the 3rd resistor is 20 times of the resistance value of the first resistor.
Further, the dimension scale of second PMOS tube and first PMOS tube is 5.
Further, the current detection circuit is integrated in chip piece.
Current detection circuit described in the utility model, by being selected as composed by two resistance and four control switches
Module can be to select different inspection flow paths in charged state or discharge condition according to module to be measured, to realize double
Accurate detection to electric current.In addition, the current conversion module being made of amplifier, transistor and analog-digital converter, may be implemented
Sample rate current is quickly converted to voltage, and entire circuit structure is simple, and cost is relatively low.
Detailed description of the invention
Fig. 1 is the circuit diagram when current detection circuit is in control switch fully open state.
Fig. 2 is the circuit diagram when current detection circuit carries out charging current detection.
Fig. 3 is the circuit diagram when current detection circuit carries out discharge current detection.
Fig. 4 is the flow diagram of the electric current detecting method.
Specific embodiment
The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model
Detailed description.It should be appreciated that specific embodiment disclosed below is only used for explaining the utility model, it is not used to limit this reality
With novel.
As shown in Figure 1, a kind of current detection circuit, can be used for detecting the charging current and discharge current of module to be measured.
The current detection circuit includes first resistor R1, second resistance R2, the first control switch S1, the second control switch S2, third
Control switch S3, the 4th control switch S4, amplifier OP, NMOS tube MN1, the first PMOS tube MP1, the second PMOS tube MP2, third
Resistance R3 and analog-digital converter ADC.Wherein:
First input end of the one end of the first resistor R1 as the current detection circuit, is connected to the mould to be measured
Block；The other end of the first resistor R1 is then connected to the positive input of the amplifier OP by the first control switch S1
End, the other end of the first resistor R1 are also connected to the negative input of the amplifier OP by the second control switch S2
End；Second input terminal of the one end of the second resistance R2 as the current detection circuit, is connected to the module to be measured；Institute
The other end for stating second resistance R2 is then connected to the negative input end of the amplifier OP by the third control switch S3, described
The other end of second resistance R2 is also connected to the positive input terminal of the amplifier OP by the 4th control switch S4.
The output end of the amplifier OP connects the grid of the NMOS tube MN1, and the source electrode of the NMOS tube MN1 connects institute
The negative input end of amplifier OP is stated, the drain electrode of the NMOS tube MN1 connects the drain electrode of the first PMOS tube MP1；Described first
The source electrode of PMOS tube MP1 and the second PMOS tube MP2 connect external power supply VDD jointly, the first PMOS tube MP1 and described
The grid of second PMOS tube MP2 is commonly connected to the drain electrode of the NMOS tube MN1；The drain electrode of the second PMOS tube MP2 passes through
The 3rd resistor R3 ground connection；The drain electrode of the second PMOS tube MP2 and the common end of the 3rd resistor R3 are connected to described
The input terminal of analog-digital converter ADC；The output end of the analog-digital converter ADC is then used as the output of the current detection circuit
End.
The module to be measured includes power supply to be measured and inspection leakage resistance RS.The cathode of the power supply to be measured passes through the inspection galvanic electricity
Hinder RS ground connection；The first input end of the current detection circuit is connected to the power supply to be measured and examines the public of leakage resistance RS with described
End, the second input terminal of the current detection circuit are connected to the ground terminal of the inspection leakage resistance RS.The power supply to be measured is can
Rechargeable battery.The inspection leakage resistance RS uses precision resistance.
The current detection circuit, can basis by the selecting module as composed by two resistance and four control switches
Module to be measured is different inspection flow paths to be selected, to realize the accurate of bidirectional current in charged state or discharge condition
Detection.In addition, the current conversion module being made of amplifier OP, transistor and analog-digital converter ADC, may be implemented sample rate current
To being quickly converted for voltage, entire circuit structure is simple, and cost is relatively low.
Preferably, the resistance value of the first resistor R1 is equal with the resistance value of the second resistance R2.
Preferably, the resistance value of the 3rd resistor R3 is 20 times of the resistance value of the first resistor R1.
Preferably, the dimension scale of the second PMOS tube MP2 and the first PMOS tube MP1 is 5.
Preferably, the current detection circuit is integrated in chip piece, to realize the Highgrade integration of component, is contracted
Miscellaneous goods volume has widened products application range.
As shown in figure 4, a kind of electric current detecting method based on above-mentioned current detection circuit, includes the following steps: step S1:
Judge whether the module to be measured is in charged state, that is, judges whether the battery as power supply to be measured is charging.If
It is then to enter step S2, carries out the detection of charging current.If it is not, then showing that battery is in discharge condition, S3 is entered step,
Carry out the detection of discharge current.
In step s 2, the first control switch S1 and third control switch S3 closure is controlled, controls described the
Two control switch S2 and the 4th control switch S4 disconnect (referring to fig. 2), at this point, the first PMOS tube MP1 and described
The electric current that NMOS tube MN1 is generated flows through second resistance R2, generates pressure drop, as the input voltage of amplifier OP negative input end, and
No electric current on first resistor R1, the voltage of amplifier OP positive input terminal is directly equal to the pressure drop of inspection leakage resistance RS, then, by putting
Big device OP and subsequent transistor are converted, and are formed output voltage VO to analog-digital converter ADC, are finally turned by the modulus
After the conversion of parallel operation ADC, export for characterizing the digital voltage parameter of size of current as testing result.
In step s3, the second control switch S2 and the 4th control switch S4 closure is controlled, controls described the
One control switch S1 and the third control switch S3 disconnect (referring to Fig. 3), at this point, the first PMOS tube MP1 and described
The electric current that NMOS tube MN1 is generated flows through first resistor R1, and the voltage of generation is superimposed with the pressure drop on inspection leakage resistance RS, as amplification
The voltage of the input voltage of device OP negative input end, and no electric current on second resistance R2, amplifier OP positive input terminal is equal to 0.So
Afterwards, it is converted by amplifier OP and subsequent transistor, forms output voltage VO to analog-digital converter ADC, finally pass through institute
After the conversion for stating analog-digital converter ADC, export for characterizing the digital voltage parameter of size of current as testing result.
The detection of the charged state or discharge condition of above-mentioned battery and the on-off control of control switch, can be by electricity
Source control module carries out, and can also be carried out by processors such as MCU or CPU.
The electric current detecting method is to select different inspection stream in charged state or discharge condition according to module to be measured
Path, to realize the accurate detection of the bidirectional current of charging current and discharge current, detection efficiency is also relatively high.
Specifically, under charging current detecting state, as shown in Fig. 2, the first control switch S1 and third control switch S3
Closure, the second control switch S2 and the 4th control switch S4 are opened.The electric current I1 and battery charge of first PMOS tube MP1
IC should meet following relational expression: I1*R2=IC*RS.And the electric current of the electric current I1 of the first PMOS tube MP1 and the second PMOS tube MP2
I2 is proportional to their dimension scale relationship: I1/I2=(W1/L1)/(W2/L2).Therefore, the voltage VO that current detecting obtains=
I2*R3=((W2/L2)/(W1/L1)) * (R3/R1) * IC*RS.VO obtains corresponding digital voltage parameter DO after ADC is converted.
Here current detecting exactly measures the size of electric current, before the magnitude of current is converted to a voltage, this voltage
Amount can do analog-to-digital conversion, available corresponding digital voltage parameter, for characterizing size of current through ADC.
Specifically, under discharge current detecting state, as shown in figure 3, the second control switch S2 and the 4th control switch S4
Closure, the first control switch S1 and third control switch S3 are opened.The electric current I1 and battery charge of first PMOS tube MP1
IC should meet following relational expression: I1*R1=ID*RS.And the electric current of the electric current I1 of the first PMOS tube MP1 and the second PMOS tube MP2
I2 is proportional to their dimension scale relationship: I1/I2=(W1/L1)/(W2/L2).Therefore, the voltage VO that current detecting obtains=
I2*R3=((W2/L2)/(W1/L1)) * (R3/R1) * ID*RS.VO obtains corresponding digital voltage parameter DO after ADC is converted,
Here current detecting exactly measures the size of electric current, before the magnitude of current is converted to a voltage, this voltage
Amount can do analog-to-digital conversion, available digital voltage parameter, for characterizing size of current through ADC.
From above-mentioned derivation process it is found that the circuit need to only guarantee R1=R2, while meeting required proportionate relationship with R3, with
And the size of MP1 and MP2 meets required proportionate relationship, then testing result is exactly accurate.It is full for integrated circuit
These relative value relationships of foot are easier to realize.
Finally, it should be noted that each embodiment in this specification is described in a progressive manner, each embodiment emphasis
What is illustrated is all differences from other embodiments, and same or similar part may refer to each other between each embodiment, respectively
Technical solution between embodiment can be combined with each other.The above various embodiments is merely to illustrate the technical side of the utility model
Case, rather than its limitations, although the present invention has been described in detail with reference to the aforementioned embodiments, this field it is common
Technical staff is still possible to modify the technical solutions described in the foregoing embodiments, either to part of or complete
Portion's technical characteristic is equivalently replaced；And these are modified or replaceed, it does not separate the essence of the corresponding technical solution, and this is practical
The range of novel each embodiment technical solution.
Claims (6)
1. a kind of current detection circuit, for detecting the charging current and discharge current of module to be measured, which is characterized in that the electricity
Current detection circuit includes first resistor, second resistance, the first control switch, the second control switch, third control switch, the 4th control
Make switch, amplifier, NMOS tube, the first PMOS tube, the second PMOS tube, 3rd resistor and analog-digital converter, in which:
First input end of the one end of the first resistor as the current detection circuit is connected to the module to be measured；Institute
The other end for stating first resistor is then connected to the positive input terminal of the amplifier, first electricity by first control switch
The other end of resistance is also connected to the negative input end of the amplifier by second control switch；One end of the second resistance
As the second input terminal of the current detection circuit, it is connected to the module to be measured；The other end of the second resistance then leads to
The negative input end that the third control switch is connected to the amplifier is crossed, the other end of the second resistance also passes through described
Four control switches are connected to the positive input terminal of the amplifier；
The output end of the amplifier connects the grid of the NMOS tube, and the source electrode of the NMOS tube connects the negative of the amplifier
Input terminal, the drain electrode of the NMOS tube connect the drain electrode of first PMOS tube；First PMOS tube and the 2nd PMOS
The source electrode of pipe connects external power supply jointly, and the grid of first PMOS tube and second PMOS tube is commonly connected to described
The drain electrode of NMOS tube；The drain electrode of second PMOS tube is grounded by the 3rd resistor；The drain electrode of second PMOS tube and
The common end of the 3rd resistor is connected to the input terminal of the analog-digital converter；The then conduct of the output end of the analog-digital converter
The output end of the current detection circuit.
2. circuit according to claim 1, which is characterized in that the module to be measured include power supply to be measured and inspection leakage resistance,
The cathode of the power supply to be measured is grounded by the inspection leakage resistance；The first input end of the current detection circuit is connected to described
The common end of power supply to be measured and the inspection leakage resistance, the second input terminal of the current detection circuit are connected to the inspection leakage resistance
Ground terminal.
3. circuit according to claim 1, which is characterized in that the resistance of the resistance value of the first resistor and the second resistance
It is worth equal.
4. circuit according to claim 1, which is characterized in that the resistance value of the 3rd resistor is the resistance of the first resistor
20 times of value.
5. circuit according to claim 1, which is characterized in that the size of second PMOS tube and first PMOS tube
Ratio is 5.
6. circuit according to any one of claim 1 to 5, which is characterized in that the current detection circuit is integrated in one
In block chip.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821074234.0U CN208421059U (en) | 2018-07-09 | 2018-07-09 | A kind of current detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201821074234.0U CN208421059U (en) | 2018-07-09 | 2018-07-09 | A kind of current detection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108845181A (en) * | 2018-07-09 | 2018-11-20 | 珠海市微半导体有限公司 | current detection circuit and detection method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108845181A (en) * | 2018-07-09 | 2018-11-20 | 珠海市微半导体有限公司 | current detection circuit and detection method |
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