CN105242190B - Current detection circuit - Google Patents
Current detection circuit Download PDFInfo
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- CN105242190B CN105242190B CN201510675379.0A CN201510675379A CN105242190B CN 105242190 B CN105242190 B CN 105242190B CN 201510675379 A CN201510675379 A CN 201510675379A CN 105242190 B CN105242190 B CN 105242190B
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Abstract
The invention discloses a kind of current detection circuits, by to obtain current detection signal using the first current detection circuit when the electric current for flowing through power transistor is greater than certain threshold value, when the electric current for flowing through power transistor is less than certain threshold value, current detection signal is intermittently obtained using the second current detection circuit, reach and obtain the higher current detection signal of precision, and not will increase the purpose of the excess loss of system.
Description
Technical field
The present invention relates to a kind of power electronic technique, more specifically to a kind of crystal applied in electronic product
The current detection circuit of pipe.
Background technique
In power electronic system, it is typically necessary detection circuit, to detect in main circuit or site of deployment
Signal forms corresponding control signal further according to these signals and according to the job requirement of system.According to needing for system
Voltage detecting circuit and current detection circuit.
In application occasions such as USB mobile power sources (Power Bank), the system that usually requires that carries out unloaded (or underloading) detection,
To judge whether system needs to enter sleep pattern.Here the inspection of loading condition is carried out with regard to needing a current detection circuit
It surveys, to indicate that system enters corresponding operating mode.
In the prior art, the not no occasion of integrated power transistor in some chips, as shown in Figure 1, needing in power
Connect a detection resistance Rsense in supply path, realizes current detection function by the pressure difference at detection resistance both ends.This
The shortcomings that sample is done is：1, due to the electric current very little of required detection, it is the pressure difference very little at event resistance both ends, needs highly accurate
Circuit just can be carried out accurately current detecting.2, due to a detection resistance of connecting on power supply path, so increasing
Extra power consumption.
It is integrated with the occasion of power transistor in inside, by detecting its electric current flowed through, to judge the big of load current
It is small.Common current detection circuit, it is higher to the required precision of component when electric current is lesser, otherwise examined in low current
Time determination error is very big.The shortcomings that this current detection mode, is：Since it is desired that low current is accurately detected, to component essence
The requirement of degree is very high, and cost can be significantly greatly increased.
Summary of the invention
In view of this, the present invention provides a kind of current detection circuit, to solve in the prior art, current detection accuracy is not
Problem high or that loss is larger.
In a first aspect, a kind of current detection circuit is provided, for the size of detection stream overpower transistor current, including：
It is negative to obtain characterization for the current signal of detection stream overpower transistor in the first condition for first detection circuit
Carry the first current detection signal of situation；
It is negative to obtain characterization for the current signal of detection stream overpower transistor in a second condition for second detection circuit
Carry the second current detection signal of situation；
Comparison circuit receives first current detection signal and first threshold, exports comparison signal；
Logic circuit receives the comparison signal and a clock signal, output detection circuit selection signal；
Wherein, the current detection circuit selects the first detection circuit or second according to the detection circuit selection signal
Detection circuit is used for the current signal of detection stream overpower transistor.
Preferably, first detection circuit includes：
Second transistor, drain electrode are connected with the drain electrode of the power transistor, the grid of grid and the power transistor
Extremely it is connected, source electrode is connected to the first input end of first error amplifier；
The first error amplifier, the second input terminal are connected to the source electrode of the power transistor, export first error
Amplified signal；
Third transistor, one end are connected to the first input end of the first error amplifier, and the other end is connected to first
The first end of detection resistance, control terminal receive the first error amplified signal；
First detection resistance, the second termination control, the voltage in first end is the first current detection signal.
Preferably, second detection circuit includes：
4th transistor, drain electrode are connected by 3rd resistor with the drain electrode of the power transistor, source electrode and the function
The source electrode of rate transistor is connected, and grid is also connected with the grid of the power transistor；
Second error amplifier, first input end are connected to the source electrode of the power transistor by a voltage source, and second
Input terminal is connected to the drain electrode of the power transistor, exports the second error amplification signal, and second error amplification signal is used
In the control power transistor and the 4th transistor；
Third error amplifier, first input end are connected to the points of common connection of the 4th resistance and a current source, and second is defeated
Enter the points of common connection that end is connected to the 5th resistance and another current source, exports third error amplification signal, the 5th resistance
Also it is connected with the 3rd resistor；
5th transistor, one end is connected to the first input end of the third error amplifier, another to be connected to the second inspection
The first end of measuring resistance, control terminal receive the third error amplification signal；
Second detection resistance, the second termination control, the voltage in first end is the second current detection signal；
Wherein, when second detection circuit works, the power transistor and the 4th transistor work
Variable resistance area.
Preferably, under the same gate source voltage, the conducting resistance of the second transistor and the 4th transistor with it is described
The conducting resistance of power transistor is proportional, and the conducting resistance of the power transistor be less than the second transistor and
The conducting resistance of 4th transistor.
Preferably, the comparison circuit includes：
Comparator, first input end receive first current detection signal, and the second input terminal receives the first threshold,
Export comparison signal；
The comparison signal is significant level when the first threshold is greater than first current detection signal.
Preferably, the logic circuit is when the clock signal and the comparison signal are significant level, exports and is
The detection circuit selection signal of significant level.
Preferably, the current detection circuit further includes first switch and the second switch, and the first switch is used when being connected
It is worked with accessing first detection circuit in current detection circuit, to be examined described second when the second switch is connected
It works in slowdown monitoring circuit access current detection circuit；
The first switch and the second switch are controlled by the detection circuit selection signal on or off, wherein
When the detection circuit selection signal is significant level, the second switch conducting, the first switch shutdown；In the inspection
When slowdown monitoring circuit selection signal is inactive level, the first switch conducting, the second switch shutdown.
Preferably, when being switched to second detection circuit work from first detection circuit, the second detection electricity
Road generates the second current detection signal after postponing the scheduled time, and the scheduled time is to switch the power transistor
On state.
Preferably, the width for adjusting the clock signal significant level, to change the work of second detection circuit
Time.
Second aspect provides a kind of control circuit, including：
Current detection circuit as described above.
The technology of the present invention is passed through so that being examined when the electric current for flowing through power transistor is greater than certain threshold value using the first electric current
Slowdown monitoring circuit obtains current detection signal, when the electric current for flowing through power transistor is less than certain threshold value, intermittently uses second
Current detection circuit obtains current detection signal, reaches and obtains the higher current detection signal of precision, and not will increase system
The purpose of excess loss.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
The embodiment of invention for those of ordinary skill in the art without creative efforts, can also basis
The attached drawing of offer obtains other attached drawings.
Fig. 1 is the circuit structure diagram of the current detection circuit of the prior art；
Fig. 2 is the circuit structure diagram of the current detection circuit of the embodiment of the present invention；
Fig. 3 is the circuit diagram of the first detection circuit in the current detection circuit of the embodiment of the present invention；
Fig. 4 is the circuit diagram of the second detection circuit in the current detection circuit of the embodiment of the present invention；
Fig. 5 is the working waveform figure of the current detection circuit of the embodiment of the present invention.
Specific embodiment
Below based on embodiment, present invention is described, but the present invention is not restricted to these embodiments.Under
Text is detailed to describe some specific detail sections in datail description of the invention.Do not have for a person skilled in the art
The present invention can also be understood completely in the description of these detail sections.In order to avoid obscuring essence of the invention, well known method, mistake
There is no narrations in detail for journey, process, element and circuit.
In addition, it should be understood by one skilled in the art that provided herein attached drawing be provided to explanation purpose, and
What attached drawing was not necessarily drawn to scale.
It will also be appreciated that in the following description, " circuit " refers to be passed through electrically by least one element or sub-circuit
The galvanic circle that connection or electromagnetism connect and compose.When title element or the " connection of another element of circuit " being connected to " or element/circuit
" between two nodes when, it, which can be, is directly coupled or connected another element or there may be intermediary element, element it
Between connection can be physically, in logic or its combination.On the contrary, when claiming element " being directly coupled to " or " directly connecting
Be connected to " another element when, it is meant that the two be not present intermediary element.
Unless the context clearly requires otherwise, "include", "comprise" otherwise throughout the specification and claims etc. are similar
Word should be construed as the meaning for including rather than exclusive or exhaustive meaning；That is, be " including but not limited to " contains
Justice.
In the description of the present invention, it is to be understood that, term " first ", " second " etc. are used for description purposes only, without
It can be interpreted as indication or suggestion relative importance.In addition, in the description of the present invention, unless otherwise indicated, the meaning of " multiple "
It is two or more.
Fig. 2 show the circuit structure diagram of the current detection circuit of the embodiment of the present invention, as shown in Fig. 2, the present invention is implemented
The current detection circuit of example includes the first detection circuit 21, the second detection circuit 22, comparison circuit 23 and logic circuit 24,
In：
First detection circuit 21, the current signal for detection stream overpower transistor M1 in the first condition is to obtain table
Levy the first current detection signal Vsense1 of loading condition.
Second detection circuit 22, the current signal for detection stream overpower transistor M1 in a second condition is to obtain table
Levy the second current detection signal Vsense2 of loading condition.
Comparison circuit 23 is in embodiments of the present invention comparator CMP, and first input end receives the first current detecting
Signal Vsense1, the second input terminal receive the first threshold Vth, export comparison signal Vcmp.First threshold Vth corresponds to
The a certain predetermined value for flowing through the electric current Io of power transistor M1 is less than first threshold Vth in the first current detection signal Vsense1
When, characterization flow through transistor M1 electric current Io is smaller namely light load.Since the positive input of comparator CMP terminates the first threshold
Value Vth, negative input terminate the first current detection signal Vsense1, therefore in the first current detection signal Vsense1 less than the first threshold
When value Vth, the comparison signal Vcmp of comparator CMP output is high level, i.e. significant level.
Logic circuit 24 receives a comparison signal Vcmp and clock signal clock, output detection circuit selection signal
Vcho.Current detection circuit selects the first detection circuit 21 or the second detection circuit 22 according to detection circuit selection signal Vcho
Current signal Io for detection stream overpower transistor M1.Logic circuit 24 is in clock signal clock and comparison signal Vcmp
When being significant level, the detection circuit selection signal Vcho for significant level is exported.According to this logical relation, logic circuit 24
It can be realized using such as with circuit door.
Current detection circuit further includes first switch K1 and second switch K2, to examine first when first switch K1 is connected
Slowdown monitoring circuit 21 is accessed in current detection circuit and is worked, to examine the second detection circuit 22 access electric current when second switch K2 is connected
It works in slowdown monitoring circuit.The first switch K1 and second switch K2 is controlled by detection circuit selection signal Vcho on or off,
Wherein, when detection circuit selection signal Vcho is significant level, second switch K2 conducting, first switch K1 shutdown；It is detecting
When circuit selection signal Vcho is inactive level, first switch K1 conducting, second switch K2 shutdown.
The current detection circuit of the embodiment of the present invention obtains characterization using the first detection circuit 21 when starting to work
First current detection signal Vsense1 of loading condition, and compared with first threshold Vth, if the first current detection signal
Vsense1 be greater than first threshold Vth, then characterization then flow through transistor M1 electric current Io it is larger, system be in work normally shape
State, the required precision of current detecting can be met using the first current detection circuit, and the first current detection signal Vsense1 is
The output signal of current detection circuit；If the first current detection signal Vsense1 is less than first threshold Vth, characterizes and flow at this time
Cross transistor M1 electric current Io is smaller namely light load, current detecting is no longer satisfied using the first current detection circuit
Required precision, make at this time current detection circuit enter intermittently using the second current detection circuit work mode, namely
When clock signal clock is significant level, current detecting is carried out using the second detection circuit, it is effective to adjust clock signal clock
The width of level, thus it is possible to vary the working time of second detection circuit.Reason for doing so is that if in order to meet electric current
The required precision of detection uses always the second current detection circuit to carry out current detecting when electric current Io is smaller, will cause larger
Excess loss.And by the way of intermittent, it is also based in most of underloadings or spaceborne system to current detecting i.e.
When property and successional of less demanding just makes the technology of the present invention that the accurate detection of low current may be implemented but will not increase again simultaneously
Add excessive power consumption.The circuit structure and work of the first current detection circuit 21 and the second current detection circuit 22 is described in detail below
Make principle：
Fig. 3 is the circuit diagram of the first detection circuit 21 in the current detection circuit of the embodiment of the present invention.Such as Fig. 3 institute
Show, the first current detection circuit 21 includes：
Second transistor M2, drain electrode are connected with the drain electrode of power transistor M1, the grid of grid and power transistor M1
It is connected, source electrode is connected to the first input end of first error amplifier EA1；
First error amplifier EA1, the second input terminal are connected to the source electrode of power transistor M1, output first error amplification
Signal Vea1；
Third transistor M3, one end is connected to the first input end of first error amplifier EA1, another to be connected to the first inspection
The first end of measuring resistance, control terminal receive the first error amplified signal Vea1；
First detection resistance R1, the second termination control, the voltage in first end is the first current detection signal
Vsense1。
Power transistor M1 in the embodiment of the present invention is the Power FET being internally integrated, by detecting its electricity flowed through
Flow Io, it can be determined that the size of load current.In 21 in the first detection circuit, the effective width specific power of second transistor M2
Transistor M1 is much smaller, and the effective width of power transistor should be thousands of even tens of thousands of times or more of second transistor M2.The
When two-transistor M2 is identical as the gate source voltage of power transistor M1, the conducting resistance of conducting resistance and power transistor M1 at
Certain proportion, and the conducting resistance of power transistor M1 is far smaller than the conducting resistance of second transistor M2, in the present embodiment, is
1/K times of second transistor M2 conducting resistance.By the leakage with power transistor M1 respectively of the drain and gate of second transistor M2
Pole is connected with grid, and two input terminals of first error amplifier EA1 are separately connected the source electrode and the second crystalline substance of power transistor M1
The source electrode of body pipe M2, makes the source voltage of second transistor M2 follow the source voltage of power transistor M1, that is, will have one
The voltage of each corresponding pole of the power transistor M1 and second transistor M2 of certainty ratio conducting resistance be disposed as it is identical, such as
This, according to the working characteristics of transistor, the electric current for flowing through second transistor M2 can reflect the M1's for flowing through power transistor
Electric current, but the electric current Io of power transistor is flowed through since this electric current is far smaller than, therefore its damage on the first detection resistance R1
Consumption is also smaller, and the voltage of the first detection resistance R1 first end is the first current detection signal Vsense1.
Such current detection mode is although simple and easy, but higher to the required precision of first error amplifier EA1,
If the biggish occasion first error amplifier EA1 of electric current has biasing, still meet the required precision of current detecting, electric current compared with
Small or even when close to zero, the biasing of first error amplifier EA1 will lead to current detecting and great error occurs.
Fig. 4 is the circuit diagram of the second detection circuit 22 in the current detection circuit of the embodiment of the present invention.Such as Fig. 4 institute
Show, the second current detection circuit 22 includes：
4th transistor M4, drain electrode are connected by 3rd resistor R3 with the drain electrode of power transistor M1, source electrode and power
The source electrode of transistor M1 is connected, and grid is also connected with the grid of power transistor M1；
Second error amplifier EA2, first input end are connected to the source electrode of the transistor M1 by a voltage source Vs, the
Two input terminals are connected to the drain electrode of power transistor M1, export the second error amplification signal Vea2, the second error amplification signal
Vea2 is for controlling power transistor M1 and the 4th transistor M4；
Third error amplifier EA3, first input end are connected to the commonly connected of a 4th resistance R4 and current source Ib1
Point, the second input terminal are connected to the points of common connection of the 5th resistance R5 and another current source Ib2, export third error amplification signal
Vea3, what the 5th resistance R5 was also connected to the 3rd resistor R3；
5th transistor M5, one end is connected to the first input end of third error amplifier EA3, another to be connected to the second inspection
The first end of measuring resistance R2, control terminal receive the third error amplification signal Vea3；
Second detection resistance R2, the second termination control, the voltage in first end is the second current detection signal
Vsense2。
It is understood that in other embodiments, the second detection resistance can share same with the first detection resistance
A resistance, with this, the first current detection signal Vsense1 and the second current detection signal Vsense2 can be from circuits
The same node obtains, while also saving a resistance, reduces volume and cost.
In the second detection circuit 22, the effective width ratio power transistor M1 of the 4th transistor M4 is much smaller, and power is brilliant
The effective width of body pipe should be thousands of even tens of thousands of times or more of the 4th transistor M4.4th transistor M4 and power transistor
When the gate source voltage of M1 is identical, conducting resistance and the conducting resistance of power transistor M1 are proportional, and power transistor
The conducting resistance of M1 is far smaller than the conducting resistance of the 4th transistor M4.In embodiments of the present invention, the 4th transistor M4 is chosen
It is identical model with second transistor M2, i.e. its conducting resistance is power transistor M1 electric conduction under the same conditions
K times of resistance, then its electric current flowed through is Io/K.It is, of course, understood that as the 4th transistor M4 and second transistor M2
Conducting resistance and power transistor M1 conducting resistance proportionate relationship difference when, be also allowed, can pass through adjust circuit
In other components parameter so that the benchmark of the first current detection signal Vsense1 and the second current detection signal Vsense2
Unanimously.
Wherein, when the second detection circuit 22 works, since the non-inverting input terminal of the second error amplifier EA2 is connected to function
The drain electrode of rate transistor M1, inverting input terminal is connected to the source electrode of power transistor M1 by a voltage source Vs, and second is missed
Grid voltage of the output signal Vea2 of poor amplifier EA2 as power transistor M1, so can be by power transistor M1
Drain-source voltage difference it is constant in second threshold Vth2 so that power transistor M1 work is in variable resistance area, also referred to as saturation region.
The grid and source electrode of 4th transistor M4 is connected with the grid of power transistor M1 and source electrode respectively, though drain electrode passes through third electricity
Resistance R3 is connected to the drain electrode of power transistor M1, but since 3rd resistor R3 is typically small, thereon with the pressure difference of very little, institute
Can consider that the 4th transistor M4 and the voltage of each pole of power transistor M1 are consistent, power transistor M1 and the 4th is brilliant
Body pipe M4 works in variable resistance area.Therefore the electric current that the 4th transistor M4 flows through is Io/K, it is upper with power transistor M1
The electric current Io crossed is at certain proportionate relationship, and K is far longer than 1.
Second current detection circuit 22 further includes two current values identical small current source Ib1 and Ib2.Current source Ib1
One end ground connection, another inverting input terminal for being connected to third error amplifier EA3；One end of current source Ib2 is grounded, the other end
It is connected to the non-inverting input terminal of third error amplifier EA3.The output signal Vea3 of third error amplifier EA3 is as the 5th crystal
The grid voltage of pipe M5.According to circuit theory, in third error amplifier EA3 steady operation, non-inverting input terminal and reverse phase
The voltage of input terminal can remain equal, it can be concluded that, the value of the second current detection signal Vsense2 is (R3/R4) * (Io/ accordingly
K) * R2 flows through power transistor M1 size of current Io so as to characterize.
In the second detection circuit 22, since the second error amplifier EA2 is only so that power transistor M1 and the 4th is brilliant
Body pipe M4 work variable resistance area, thus it is not high to its required precision, when system power is smaller, even if the second error
There are certain biasing, the second detection circuits 22, and the current detecting of higher precision also may be implemented by amplifier EA2.Moreover, brilliant
Body pipe works at variable resistance area, its electric current is constant value under specific grid source current, this also considerably increases second
The operating accuracy and reliability of detection circuit 22.And if third error amplifier EA3 exist biasing, biasing value compared to two
The input voltage of a input terminal is also smaller, and the influence to input signal is little, therefore not will lead to detection error.Thus, it is possible to see
Out, when the electric current for flowing through power transistor M1 is smaller, the second detection circuit 22 can satisfy the required precision of current detecting.
However, the second detection circuit 22 is at work, power transistor M1 works in variable resistance area, does not lead completely
Logical, conducting resistance is larger, so biggish power loss can be generated.But the embodiment of the present invention passes through a clock signal
Clock, the second detection circuit 22 of control intermittently work, i.e., are less than first threshold in the first current detection signal Vsense1
Vth, and clock signal be effective high level when, just switch to the second detection circuit 22 start to work and carry out current detecting.
If therefore the time of clock signal clock high level account for a cycle ratio it is smaller when, the second detection circuit 22 work when
Not long, influence to system loss is simultaneously little, thus can when the electric current for flowing through power transistor M1 is smaller, accurately into
Row current detecting.This is also based on of less demanding to the instantaneity and continuity of detection electric current in most no-load detection system, institute
The detection of electric current can be carried out in variable resistance area by the way that intermittently power transistor M1 works.In this way,
Power loss can hardly be increased while realizing the accurate detection of low current.
Fig. 5 is the working waveform figure of the current detection circuit of the embodiment of the present invention.
Within the t1 period, current detection circuit carries out current detecting, first obtained at this time using the first detection circuit 21
Current detection signal Vsense1 is greater than first threshold Vth, therefore switch K1 is tended to remain on, and is continued the first detection circuit 21
It accesses in current detection circuit.During this period, the drain-source voltage of power transistor M1 is greater than second threshold Vth2, grid electricity
Pressure is also higher, and power transistor M1 works in fully on state.
Within the t2 period, the first current detection signal Vsense1 is less than first threshold Vth, but clock signal is invalid
Low level, so when logic circuit 24 export detection circuit selection signal Vcho be inactive level, current detection circuit is still
Continue to carry out current detecting using the first detection circuit 21.
Within the t3 period, clock signal clock is changed into effective high level, the detection electricity that logic circuit 24 exports at this time
Road selection signal Vcho is significant level, so that switch K2 is connected, switch K1 is turned off, and current detection circuit is switched to using the
Two detection circuits 22 carry out current detecting.The grid voltage V of power transistor M1 is controlled by the second error amplifier EA2GATE,
So that the hourglass source electrode V of power transistor M1DS(VD-VS) constant in second threshold Vth2, even if power transistor M1 starts to work
In variable resistance area.Since power transistor M1 is changing to work from work in fully on state in variable resistance at this time
Zone state, so the stage is not detected electric current.
Within the t4 period, power transistor M1 has been fully operational in variable resistance area, utilizes the second detection circuit at this time
Obtain the second current detection signal Vsense2.
And the work judgement of subsequent period is carried out with this logic.
Preferably, when the first current detection signal Vsense1 is greater than first threshold Vth, the first detection circuit 21 can be with
The first current detection signal Vsense1 is obtained in real time；When the first current detection signal Vsense1 is less than first threshold Vth, it is
System is intermittently generating the second current detection signal Vsense2 using the second detection circuit 22 according to clock signal clock, or
Person generates the first current detection signal Vsense1 using the first detection circuit 21, and within this stage, current detection circuit can shield
The first current detection signal Vsense1 is covered, the second current detection signal Vsense2 conduct is only obtained from the second detection circuit 22
Current detection signal, to improve the precision of current detecting.
As a result, according to embodiments of the present invention, two kinds of current detection circuits can be respectively adopted in varied situations and obtain essence
Higher current detection signal is spent, and not will increase the excess loss of system.The above description is only a preferred embodiment of the present invention,
It is not intended to restrict the invention, to those skilled in the art, the invention can have various changes and changes.It is all in this hair
Any modification, equivalent replacement, improvement and so within bright spirit and principle, should be included in protection scope of the present invention it
It is interior.
Claims (11)
1. a kind of current detection circuit, the size for detection stream overpower transistor current, which is characterized in that the electric current inspection
Slowdown monitoring circuit includes：
First detection circuit, for the current signal of detection stream overpower transistor in the first condition to obtain characterization load feelings
First current detection signal of condition, the power transistor work in fully on state under first situation；
Second detection circuit, for the current signal of detection stream overpower transistor in a second condition to obtain characterization load feelings
Second current detection signal of condition, the power transistor work in variable resistance area in said second condition；
Comparison circuit receives first current detection signal and first threshold, exports comparison signal；
Logic circuit receives the comparison signal and a clock signal, output detection circuit selection signal；
Wherein, the current detection circuit selects the first detection circuit or the second detection according to the detection circuit selection signal
Circuit is used for the current signal of detection stream overpower transistor.
2. current detection circuit according to claim 1, which is characterized in that first detection circuit includes：
Second transistor, drain electrode are connected with the drain electrode of the power transistor, the grid phase of grid and the power transistor
Even, source electrode is connected to the first input end of first error amplifier；
The first error amplifier, the second input terminal are connected to the source electrode of the power transistor, output first error amplification
Signal；
Third transistor, one end are connected to the first input end of the first error amplifier, and the other end is connected to the first detection
The first end of resistance, control terminal receive the first error amplified signal；
First detection resistance, the second termination control, the voltage in first end is the first current detection signal.
3. current detection circuit according to claim 1, which is characterized in that second detection circuit includes：
4th transistor, drain electrode are connected by 3rd resistor with the drain electrode of the power transistor, and source electrode and the power are brilliant
The source electrode of body pipe is connected, and grid is also connected with the grid of the power transistor；
Second error amplifier, first input end are connected to the source electrode of the power transistor, the second input by a voltage source
End is connected to the drain electrode of the power transistor, exports the second error amplification signal, second error amplification signal is for controlling
Make the power transistor and the 4th transistor；
Third error amplifier, first input end are connected to the points of common connection of the 4th resistance and a current source, the second input terminal
Be connected to the points of common connection of the 5th resistance and another current source, export third error amplification signal, the 5th resistance also with
The 3rd resistor is connected；
5th transistor, one end is connected to the first input end of the third error amplifier, another to be connected to the second detection electricity
The first end of resistance, control terminal receive the third error amplification signal；
Second detection resistance, the second termination control, the voltage in first end is the second current detection signal；
Wherein, when second detection circuit works, the power transistor and the 4th transistor work variable
Resistance area.
4. current detection circuit according to claim 2, which is characterized in that under the same gate source voltage, described second
The conducting resistance of transistor and the conducting resistance of the power transistor are proportional, and the electric conduction of the power transistor
Resistance is less than the conducting resistance of the second transistor.
5. current detection circuit according to claim 3, which is characterized in that under the same gate source voltage, the described 4th
The conducting resistance of transistor and the conducting resistance of the power transistor are proportional, and the electric conduction of the power transistor
Resistance is less than the conducting resistance of the 4th transistor.
6. current detection circuit according to claim 1, which is characterized in that the comparison circuit includes：
Comparator, first input end receive first current detection signal, and the second input terminal receives the first threshold, output
Comparison signal；
The comparison signal is significant level when the first threshold is greater than first current detection signal.
7. current detection circuit according to claim 6, which is characterized in that the logic circuit in the clock signal and
When the comparison signal is significant level, the detection circuit selection signal for significant level is exported.
8. current detection circuit according to claim 7, which is characterized in that the current detection circuit further includes first opening
Pass and second switch work when the first switch is connected to access first detection circuit in current detection circuit,
It works when the second switch is connected to access second detection circuit in current detection circuit；
The first switch and the second switch are controlled by the detection circuit selection signal on or off, wherein in institute
When to state detection circuit selection signal be significant level, second switch conducting, the first switch shutdown；In the detection electricity
When road selection signal is inactive level, the first switch conducting, the second switch shutdown.
9. current detection circuit according to claim 8, which is characterized in that be switched to from first detection circuit described
When second detection circuit works, second detection circuit generates the second current detection signal after postponing the scheduled time, described
On state of the scheduled time to switch the power transistor.
10. current detection circuit according to claim 1, which is characterized in that adjust the clock signal significant level
Width, to change the working time of second detection circuit.
11. a kind of control circuit, which is characterized in that including：
Current detection circuit according to claim 1 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510675379.0A CN105242190B (en) | 2015-10-19 | 2015-10-19 | Current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510675379.0A CN105242190B (en) | 2015-10-19 | 2015-10-19 | Current detection circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN105242190A CN105242190A (en) | 2016-01-13 |
| CN105242190B true CN105242190B (en) | 2018-11-27 |
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| US10746806B2 (en) | 2016-03-22 | 2020-08-18 | Infineon Technologies Ag | Transistor bridge failure test |
| CN106787717A (en) * | 2016-12-12 | 2017-05-31 | 深圳市派捷电子科技有限公司 | A kind of four line programmable power supply circuits |
| CN108696270B (en) * | 2018-05-24 | 2022-02-01 | 上海艾为电子技术股份有限公司 | Analog switch circuit |
| US10679938B2 (en) * | 2018-07-31 | 2020-06-09 | Texas Instruments Incorporated | Power transistor coupled to multiple sense transistors |
| CN112187267B (en) * | 2019-07-01 | 2022-09-16 | 江阴圣邦微电子制造有限公司 | Current sampling circuit and control method thereof |
| CN111030640B (en) * | 2019-12-27 | 2021-05-28 | 苏州市新诚氏通讯电子股份有限公司 | Surface-mounted miniature superposed circuit attenuation sheet and preparation method thereof |
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