CN112014623B - Current sampling circuit and power supply changer - Google Patents
Current sampling circuit and power supply changer Download PDFInfo
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- CN112014623B CN112014623B CN202010905446.4A CN202010905446A CN112014623B CN 112014623 B CN112014623 B CN 112014623B CN 202010905446 A CN202010905446 A CN 202010905446A CN 112014623 B CN112014623 B CN 112014623B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
A current sampling circuit and a power supply changer, the circuit comprising: the current sampling circuit comprises a mirror current source, a current regulating circuit and a voltage sampling branch circuit; one output branch of the mirror current source is connected with the current regulating circuit, the output current of the mirror current source is changed along with the change of the input current of the load through the current regulating circuit, and the mirror current source has the characteristic of the output voltage of the two output branches, so that the voltage division detection is only needed to be carried out on the other output branch of the mirror current source, the resistance of the voltage sampling branch on the other output branch can be set at will, the influence on the input current of the load is avoided, and the resistance of the voltage sampling branch can be set larger during sampling, thereby realizing the accurate detection of the input current of the load.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a current sampling circuit and a power supply changer.
Background
Power supply type products are widely used in various electronic devices, and function to change a power supply from one form to another, for example, to convert ac power collected by a power grid into dc power.
The power supply changer is one of the basic components of the power supply type product, and the power supply changer consists of a power level circuit and a control loop. The control loop is used for keeping the output voltage or the output current of the power converter stable by adjusting the on and off time of a switching tube and a rectifying tube in the power stage circuit when the input voltage and the external load change. When the output voltage and the current are controlled, the basic reference parameter is the load current, so that in the control process, whether the load current can be accurately sampled is very important, the current sampling technology mainly tests the voltage difference between two ends of a sampling resistor, the sampling resistor can be the on-resistance of the power tube or a separated high-precision resistor, and the separated high-precision resistor is usually selected as the sampling resistor in a plurality of occasions with higher precision requirements because the on-resistance of the power tube fluctuates greatly. In order to reduce the power consumption generated on the sampling resistor, the resistance is usually very small, for example, 20 milliohms, so that the voltage difference between two ends of the sampling resistor is very small, and a high-precision amplifier is required to be designed inside the chip to improve the sampling precision.
The current sampling circuit usually adopts an operational amplifier to amplify the sampling signal, and the circuit design is complex.
Disclosure of Invention
In view of the above, the embodiments of the present invention provide a current sampling circuit and a power supply changer to reduce the complexity of circuit design.
In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:
a current sampling circuit, comprising:
the current sampling circuit comprises a mirror current source, a current regulating circuit and a voltage sampling branch circuit;
the first output end of the mirror current source is connected with a current source interface of the current regulating circuit, the second output end of the mirror current source is grounded through the voltage sampling branch, and the common end of the mirror current source and the voltage sampling branch is used as the output end of the current sampling circuit;
the output end of the current regulating circuit is connected with a load, and the current regulating circuit is used for controlling the output current of the mirror current source to change along with the change of the current input into the load.
Optionally, in the above current sampling circuit, the current adjusting circuit includes: a current sampling branch and a load power supply branch;
the current sampling branch circuit comprises a first direct current source, a first resistor and a second resistor which are sequentially connected in series, one end of the second resistor which is not connected with the first resistor is connected with the input end of the load, and one end of the second resistor which is connected with the first resistor is used for obtaining a target voltage signal output by a target voltage signal source;
the load power supply branch comprises a second direct current source and a third resistor which are sequentially connected in series, the input end of the second direct current source is connected with the input end of the first direct current source, and one end of the third resistor which is not connected with the second direct current source is connected with the input end of the load;
and a first output end of the mirror current source is connected with a common end of the second direct current source and the third resistor.
Optionally, in the above current sampling circuit, the voltage sampling branch includes:
and the first end of the fourth resistor is connected with the second output end of the mirror current source, the second end of the fourth resistor is grounded, and the first end of the fourth resistor is used as the output end of the current sampling circuit.
Optionally, in the above current sampling circuit, the current sampling circuit further includes:
the first synchronous switch is arranged in the current sampling branch and the load power supply branch and is used for controlling the current sampling branch and the load power supply branch to be conducted when the current flows through the load power supply branch. 5. The current sampling circuit of claim 4 wherein said first synchronous switch comprises:
the first sampling MOS tube and the first load MOS tube;
the first sampling MOS tube is arranged between the first direct current source and the first resistor;
the first load MOS tube is arranged between the second direct current source and the third resistor, and the control end of the first load MOS tube is connected with the input end;
the control ends of the first sampling MOS tube and the first load MOS tube are interconnected.
Optionally, in the above current sampling circuit, the current adjusting circuit 200 includes N current sampling branches, where the N current sampling branches are connected in parallel, and N is a positive integer not less than 2, and second resistors in different current sampling branches are used to obtain target voltage signals output by different target voltage signal sources;
the current sampling circuit further includes: a mirror current selection switch;
the mirror current selection switch comprises N selection switch MOS tubes which are in one-to-one correspondence with the N current sampling branches, the input end of each selection switch MOS tube is connected with the first output end of the mirror current source, the output end of each selection switch MOS tube is connected with one end of the third resistor which is not connected with a load, and the control end of each selection switch MOS tube is connected with the output end of the first current source in the corresponding current sampling branch.
Optionally, in the above current sampling circuit, the current sampling circuit further includes:
and the second synchronous switch is arranged in the current sampling branch and the load power supply branch and is used for controlling the N current sampling branches to be conducted with the load power supply branch when current flows through the load power supply branch.
Optionally, in the above current sampling circuit, the second synchronous switch includes:
the N second sampling MOS transistors and the second load MOS transistor are arranged in each current sampling branch circuit;
each second sampling MOS tube is arranged between a second direct current source and a first resistor in the corresponding current sampling branch;
the second load MOS tube is arranged between the second direct current source and the third resistor, and the control end of the second load MOS tube is connected with the input end;
the N second sampling MOS tubes are connected with the control ends of the second load MOS tubes.
Optionally, in the above current sampling circuit, the target voltage signal source is a dc output circuit in a power supply changer that supplies power to the load.
A power supply changer, comprising: the current sampling circuit according to any one of the above.
Optionally, the power supply changer includes a dc output circuit, where the dc output circuit is configured to provide a target voltage signal as the target voltage signal source.
Optionally, in the power supply changer, the current sampling branches are in one-to-one correspondence with the dc output circuits, one end of the second resistor in the current sampling branch, which is not connected to the load, is connected to an output end of the dc output circuit corresponding to the second resistor, and the dc output circuit is used as the target voltage signal source to provide a target voltage signal to the current sampling branch corresponding to the target voltage signal source.
Optionally, in the power supply changer, the power supply further includes:
and the output current modulation module is used for outputting a current modulation signal to a direct current output circuit in the power supply changer based on a comparison result of the voltage signal of the output end of the current sampling circuit and a preset voltage signal, so that the output current of the direct current output circuit changes along with the change of the current modulation signal.
Based on the above technical solution, according to the above solution provided by the embodiments of the present invention, when the current sampling circuit is used to collect the input current of the load, one output branch of the mirror current source is connected to the current adjusting circuit, and the output current of the mirror current source is changed along with the change of the input current of the load through the current adjusting circuit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a current sampling circuit according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a current sampling circuit according to another embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a current sampling circuit according to another embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a current sampling circuit according to another embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a power supply transformer according to an embodiment of the present disclosure.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Aiming at the problems that the current sampling circuit in the prior art can realize accurate measurement of sampling results by amplifying sampling signals by adopting an operational amplifier and has complex circuit design, the application provides a current sampling circuit which has simple circuit design and does not need to amplify the sampling signals by adopting the operational amplifier.
Referring to fig. 1, fig. 1 is a current sampling circuit provided in an embodiment of the present application, and is characterized in that the current sampling circuit includes:
a mirror current source 100, a current regulation circuit 200, and a voltage sampling branch 300;
the first output end of the mirror current source 100 is connected to the current source interface of the current regulating circuit 200, the second output end of the mirror current source 100 is grounded through the voltage sampling branch 300, the common end of the mirror current source 100 and the voltage sampling branch 300 is used as the output end of the current sampling circuit, the structure of the mirror current source 100 can be selected by the user according to the user's requirement, and the mirror current source 100 with any structure in the prior art can be selected as the mirror current source 100 disclosed in the embodiment of the present application;
the output end of the current regulating circuit 200 and the load R 7 In connection, the current regulating circuit 200 is configured to control the output current of the mirror current source 100 to vary with the current input to the load.
In the above-mentioned scheme, based on the characteristic that the output currents of the two output ends of the mirror current source 100 are equal, one output branch of the mirror current source 100 is connected to the current adjusting circuit 200, the branch may be denoted as a first output end, the other output branch of the mirror current source 100 is denoted as a second output end, and the output currents of the first output end and the second output end are equal, by connecting the current source interfaces of the first output end and the current adjusting circuit 200, the output current of the first output end of the mirror current source 100 is controlled by the current adjusting circuit 200 to change along with the change of the current input to the load, and then the output current of the second output end is changed along with the change of the current of the load, and by detecting the voltage values of the two ends of the voltage sampling branch 300, the output current of the second output end is detected, and the output current of the second output end is changed along with the change of the current of the load, so that the input current of the two ends of the voltage sampling branch 300 can be calculated according to the change of the voltage sampling branch.
Therefore, only the voltage division detection needs to be performed on the second output end of the mirror current source 100, and the resistance of the voltage sampling branch 300 on the second output end can be set arbitrarily, which does not affect the load input current, so that the resistance of the voltage sampling branch 300 can be set larger during sampling, thereby realizing accurate detection of the load input current.
In the technical solution disclosed in the embodiments of the present application, the specific structure of the modulation circuit may be set according to the needs of the user, so long as it is ensured that the first output terminal of the mirror current source 100 can be controlled to be changed along with the change of the current input to the load, for example, referring to fig. 2, in the technical solution disclosed in the embodiments of the present application, the modulation circuit may include a current sampling branch 201 and a load power supply branch 202;
the current sampling branch 201 comprises a first direct current source DC1, a first resistor R, which are sequentially connected in series 4 And a second resistor R 1 The output current of the first direct current source DC1 is I 1 The second resistor R 1 Is not in contact with the first resistor R 4 One end connected with the input end of the load, the second resistor R 1 With the first resistor R 4 One end connected with the current sampling circuit is used for acquiring a target voltage signal output by a target voltage signal source, and the target voltage signal source is an external direct current output power supply relative to the current sampling circuit provided by the application;
a load power supply branch 202, said load power supply branch 202 comprising a second direct current source DC2 and a third resistor R connected in series in turn 3 The input end of the second direct current source DC2 is connected with the input end of the first direct current source DC1, and the third resistor R 3 In the technical solution disclosed in the embodiments of the present application, the specifications of the second DC source DC2 and the first DC source DC1 may be the same, that is, the output current of the second DC source DC2 is also I 1 The third resistor R 3 And the first resistor R 4 The resistors with the same type of resistance can be adopted;
the first output terminal of the mirror current source 100 is connected to the current source interface of the current adjusting circuit 200, and is specifically shown as follows:
the first output terminal of the mirror current source 100 is connected to the common terminal of the second DC source DC2 and the third resistor R3, and at this time, the common terminal of the second DC source DC2 and the third resistor R3 serves as a current source interface of the current adjusting circuit 200.
In the above circuit, the second resistor R 1 Can be a high-precision sampling resistor, and the port A is connected with the resistorFirst resistor R 4 And a second resistor R 1 A port connected to the third resistor R for obtaining a target voltage signal source, port A being a circuit node with current driving capability 3 And a first resistor R 4 The port C in the figure is connected to the common terminal of the mirror current source and the voltage sampling branch 300, and the port C is used as the output terminal of the current sampling circuit. The working principle of the current sampling circuit and the related formula derivation will be explained in detail below:
in the above circuit, V 1 Representing the input voltage of the load, V 2 Representing the application to said second resistor R 1 Voltage on I 1 For the output current of the first and second DC power supplies, the I 2 Is the output current of the first output of the mirrored current source 100.
In the above circuit, there is the following parameter relationship:
V 1 +(I 1 +I 2 )*R 3 ＝V 2 +I 1 *R 4 the R is 3 For the third resistor R 3 Resistance value of R 4 For the first resistor R 4 Resistance value of (2);
since R at design time 3 ＝R 4 Therefore, the following steps are obtained:
I 2 *R 3 ＝V 2 -V 1
V 7 ＝I 2 *R 6 ＝(V 2 -V 1 )*R 6 /R 3 the V is 7 For the voltage applied across the voltage sampling branch 300;
in the current sampling circuit in the design, the port C is used as a signal output end of the current sampling circuit, the output voltage signal is used for representing a load current signal, the load current signal is transmitted to the next module through the current sampling circuit port C, and the equivalent resistance value and the third resistance R of the voltage sampling branch 300 3 The ratio of the resistance values of (a) is the amplification factor of the load current signal, and the equivalent resistance value and the third resistance of the voltage sampling branch 300 are adjustedR 3 The amplification factor of the voltage applied to the voltage sampling branch 300 can be adjusted, so that an operational amplifier is not required, and the design structure of the sampling circuit is simplified.
In the current sampling circuit disclosed in another embodiment of the present application, the structure of the voltage sampling branch 300 may be selected according to the requirement of the user, as long as it can provide a certain voltage division, for example, referring to fig. 2, in this scheme, the voltage sampling branch may be formed by only one resistor, and the resistor may be denoted as a fourth resistor R 6 The fourth resistor R 6 Is connected to the second output terminal of the mirror current source 100, the fourth resistor R 6 The second end of the resistor R is grounded 6 Is applied to the fourth resistor R as the output end of the current sampling circuit 6 The voltage at two ends is V 7 。
In another embodiment of the present application, the technical solution disclosed in the present application may further include a synchronous switch, which is denoted as a first synchronous switch, and the synchronous switch is disposed in the current sampling branch 201 and the load power supply branch 202, and is configured to control the current sampling branch 201 and the load power supply branch 202 to be turned on when a current flows through the load power supply branch 202.
Specifically, referring to fig. 3, when the current sampling branch 201 is one, the synchronous switch is denoted as a first synchronous switch, and the first synchronous switch may include:
first sampling MOS tube M 1 And a first load MOS tube M 2 Wherein, the first sampling MOS tube M 1 And the first load MOS tube M 2 The specifications of the first sampling MOS tube M can be the same 1 And the first load MOS tube M 2 The control ends of the first sampling MOS tube M are interconnected 1 First sampling MOS tube M 1 Gate electrode of (c) and the first load MOS tube M 2 Gate of (a) and the first load MOS tube M 2 Is connected with the drain electrode of the transistor;
the first sampling MOS tube M 1 Is arranged on the first direct current source DC1 and the firstResistor R 4 Between them;
the first load MOS tube M 2 Is arranged between the second DC source DC2 and the third resistor R 3 The first load MOS tube M 2 Is connected with the input terminal.
In the above scheme, due to the first sampling MOS tube M 1 And a first load MOS tube M 2 The first sampling MOS tube M can be made to have the same size by neglecting channel modulation effect 1 And a first load MOS tube M 2 Is kept synchronized.
In the technical solution disclosed in another embodiment of the present application, the current adjusting circuit 200 may include N current sampling branches 201, where the N current sampling branches 201 are connected in parallel, and N is a positive integer not less than 2, and the second resistors R1 in different current sampling branches 201 are used to obtain target voltage signals output by different target voltage signal sources; in the technical solution disclosed in this embodiment of the present application, the target voltage signal source may be a dc output circuit in a power source changer that supplies power to the load, and the current sampling branch 201 and the dc output circuit have a unique corresponding correspondence relationship, that is, each dc output circuit in the power source changer may be used as a target voltage signal source, and the corresponding current sampling branch 201 applies a target voltage signal.
The current sampling circuit further includes: an image current selection switch, wherein the image current source 100 selection switch is used for sampling a first resistor R in the branch 201 with a current corresponding to a maximum target voltage signal source 4 And a second resistor R 1 The voltages at the two ends are used as control signals to guide the current output by the first output end of the mirror current source 100 to the load power supply branch 202; specifically, the mirrored current source 100 selection switch includes: n selection switch MOS tubes M corresponding to the N current sampling branches 201 one by one 3 Each selection switch MOS tube M 3 Is connected to a first output of the mirrored current source 100, an output and the third resistor R 3 One end not connected with load, controlAnd the terminal is connected to the output terminal of the first dc power supply in its corresponding current sampling branch 201.
When the number of the current sampling branches 201 is N, the synchronous switch is denoted as a second synchronous switch, and the second synchronous switch is disposed in the current sampling branches and the load power supply branches, and is used for controlling the N current sampling branches and the load power supply branches to be turned on when the current flows through the load power supply branches. Specifically, the second synchronous switch includes: the N second sampling MOS transistors and the second load MOS transistor are arranged in each current sampling branch circuit; each second sampling MOS tube is arranged between a second direct current source and a first resistor in the corresponding current sampling branch; the second load MOS tube is arranged between the second direct current source and the third resistor, and the control end of the second load MOS tube is connected with the input end; the N second sampling MOS tubes are connected with the control ends of the second load MOS tubes.
For example, referring to fig. 4, taking the value of N as 2 as an example, the structure and the working principle of the current sampling circuit are described, the current sampling circuit may include: two current sampling branches 201 with the same structure, a second synchronous switch and two selective switch MOS tubes, in order to facilitate distinguishing, in this embodiment, the components in different current sampling branches 201 and different selective switch MOS tubes M 3 Named differently, for example, one current sampling branch 201 is denoted as a first current sampling branch 201a, and a second sampling MOS transistor in the second synchronous switch located in the first current sampling branch 201a is denoted as MN 2 The first resistance in the first current sampling branch 201a is denoted as R 4 The second resistance in the first current sampling branch 201a is denoted as R 1 The other current sampling branch 201 is denoted as a second current sampling branch 201b, and a second sampling MOS transistor in the second current sampling branch 201b in the second synchronous switch is denoted as MN 3 The first resistance in the second current sampling branch 201b is denoted as R 5 The second resistance in the second current sampling branch 201b is denoted as R 2 Selective switch to be connected to the first current sampling branch 201aThe MOS transistor is marked as M N4 The selection switch MOS tube connected with the second current sampling branch 201b is denoted as M N5 The second load MOS tube is marked as M N1 ；
At this time, the current sampling circuit operates as follows:
in FIG. 2, due to MOS transistor M N1 ～～M N3 The same size ignores the channel modulation effect, assuming M N4 And M N5 All have current, then due to M N1 ～～M N3 All work in the saturation region, and the formula of the saturation region combined with the MOS tube is easy to know V 4 ＝V 5 ＝V 6 The following equation is obtained at the same time:
V 1 +(I 1 +I 2 +I 3 )*R 3 ＝V 2 +I 1 *R 4
V 1 +(I 1 +I 2 +I 3 )*R 3 ＝V 3 +I 1 *R 5
since r3=r4=r5, the following is found:
(I 2 +I 3 )*R 3 ＝V 2 -V 1
(I 2 +I 3 )*R 3 ＝V 3 -V 1
when V is 2 -V 1 And V 3 -V 1 When equal, I2 and I3 may be any combination, assuming i3=0:
when V is 2 -V 1 And V 3 -V 1 When not equal, the formula (I) 2 +I 3 )*R 3 ＝V 2 -V 1 And (I) 2 +I 3 )*R 3 ＝V 3 -V 1 It can be seen that hypothesis M N4 And M N5 Both have incorrect currents and only one can be on and the other can be off. Reasoning easy-to-know V 2 -V 1 And V 3 -V 1 Branch with larger medium pressure differenceIs turned on. For example V 2 -V 1 ＞V 3 -V 1 M is then N4 Conducting current through M N5 In the off state, i.e. I 3 =0, then
Combining the above analysis and formulas
And formula->
It can be seen that the resistor R can be used in the current sampling circuit 1 And resistance R 2 Comparing and screening out the voltage difference between two ends and converting the load current signal into a voltage signal V 7 To the next module, resistor R 6 And resistance R 3 The ratio of the current sampling circuit is the amplification factor of the load current signal, and the value of the V7 signal output by the current sampling circuit is +.>
The derivation of the formula shows that the current sampling circuit can realize equal current sampling coefficients as long as the matching property of the first current sampling branch and the second current sampling branch is ensured, so that the influence of detection precision caused by process mismatch is also required to be considered in the real design process. In order to further weaken the influence of the channel modulation effect of the MOS tube on the measurement result, in the technical scheme disclosed by the embodiment of the application, the MOS tube M N1 MOS tube M N2 MOS tube M N3 The gate length proposal of (2) is 5um or more; in order to improve the matching degree, the influence MOS tube M caused by mismatch is reduced N1 MOS tube MN 2 MOS tube M N3 The gate width of the MOS transistor M is also recommended to be 5um or more, and in order to ensure the reliability of the working state of the circuit when designing the circuit, the MOS transistor M can also be used for the circuit N1 MOS tube M N2 MOS tube and method for manufacturing the sameM N3 And redundant devices are added at both ends of the circuit board.
In the above circuit, in order to facilitate signal output and input of the current sampling circuit, the circuit may further include a plurality of voltage ports and signal output ports, the voltage ports are in one-to-one correspondence with the current sampling branches 201, and each voltage port is in one-to-one correspondence with the first resistor R of the corresponding current sampling branch 201 4 And a second resistor R 1 For providing a target voltage signal to the current sampling branch 201, for example, in the above scheme, the voltage ports may refer to port a and port B in fig. 4; the signal output port is connected to the first end of the voltage sampling branch 300, and is used for outputting a detection voltage, and the signal output interface may refer to a port C in fig. 4.
In the above solution disclosed in the embodiment of the present application, the first sampling MOS transistor M 1 First load MOS tube M 2 The type of the MOS transistor of the selection switch can be selected according to the user requirement, for example, the first sampling MOS transistor M 1 First load MOS tube M 2 The MOS transistors of the selection switch can be N-type MOS transistors, and similarly, the two MOS transistors in the mirror current source can be P-type MOS transistors, for example, the mirror current source in FIG. 2 is composed of P-type MOS transistor M P1 And P-type MOS tube M P2 The composition is formed.
In the technical solution disclosed in the embodiments of the present application, in order to simplify the circuit structure, the first DC source DC1 in the current sampling branch 201 and the second DC source DC2 in the load power supply branch 202 may be the same DC power source.
Corresponding to the current sampling circuit, the application also discloses a power supply changer applying the current sampling circuit with any one of the embodiments.
In the above power supply variation, the power supply changer has a dc output circuit, an output terminal of the dc output circuit and the first resistor R in the current sampling circuit 4 And a second resistor R 1 Is connected to the common terminal of the DC output circuit for providing the target voltage signalThe source provides a target voltage signal, the power supply changer may have N dc output circuits therein, the current sampling branch 201 may be in one-to-one correspondence with the dc output circuits, and the second resistor R in the current sampling branch 201 1 One end which is not connected with a load is connected with the output end of the direct current output circuit corresponding to the load, and the direct current output circuit is used as the target voltage signal source to provide a target voltage signal for the current sampling branch 201 corresponding to the target voltage signal source.
Further, in order to ensure stability of an output signal of the power supply changer, an output current modulation module is further provided in the power supply changer, and the modulation mode is used for outputting a current modulation signal to a direct current output circuit in the power supply changer based on a comparison result of a voltage value of a first end of a fourth resistor R6 of the current sampling circuit and a preset voltage value, so that an output current of the direct current output circuit changes along with a change of the current modulation signal.
Referring to fig. 4, in this embodiment, the current modulation module and a part of the components in the current sampling circuit are encapsulated in a high-precision current sampling module, where the part of the components in the current sampling circuit refers to the second resistor R except the current sampling branch 201 1 Other elements than those described above.
Referring to fig. 5, the power supply transformer provided in the embodiment of the present application may be a power supply transformer having a plurality of DC output circuits DC-DC, where the number of DC output circuits DC-DC in the power supply transformer is the same as the number of current sampling branches 201 in the current sampling circuit, referring to fig. 5, and the output end of each power supply transformer is equal to the second resistor R in one of the current sampling branches 201 1 Is connected to the first end of the second resistor R 1 Refers to the first end of the second resistor R 1 With the first resistor R 4 One end of the connection.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (13)
1. A current sampling circuit, comprising:
the current sampling circuit comprises a mirror current source, a current regulating circuit and a voltage sampling branch circuit;
the first output end of the mirror current source is connected with a current source interface of the current regulating circuit, the second output end of the mirror current source is grounded through the voltage sampling branch, and the common end of the mirror current source and the voltage sampling branch is used as the output end of the current sampling circuit;
the output end of the current regulating circuit is connected with a load, and the current regulating circuit is used for controlling the output current of the mirror current source to change along with the change of the current input into the load.
2. The current sampling circuit of claim 1, wherein said current regulating circuit 200 comprises: a current sampling branch and a load power supply branch;
the current sampling branch circuit comprises a first direct current source, a first resistor and a second resistor which are sequentially connected in series, one end of the second resistor which is not connected with the first resistor is connected with the input end of the load, and one end of the second resistor which is connected with the first resistor is used for obtaining a target voltage signal output by a target voltage signal source;
the load power supply branch comprises a second direct current source and a third resistor which are sequentially connected in series, the input end of the second direct current source is connected with the input end of the first direct current source, and one end of the third resistor which is not connected with the second direct current source is connected with the input end of the load;
and a first output end of the mirror current source is connected with a common end of the second direct current source and the third resistor.
3. The current sampling circuit of claim 2, wherein said voltage sampling branch comprises:
and the first end of the fourth resistor is connected with the second output end of the mirror current source, the second end of the fourth resistor is grounded, and the first end of the fourth resistor is used as the output end of the current sampling circuit.
4. The current sampling circuit of claim 2, further comprising:
the first synchronous switch is arranged in the current sampling branch and the load power supply branch and is used for controlling the current sampling branch and the load power supply branch to be conducted when the current flows through the load power supply branch.
5. The current sampling circuit of claim 4 wherein said first synchronous switch comprises:
the first sampling MOS tube and the first load MOS tube;
the first sampling MOS tube is arranged between the first direct current source and the first resistor;
the first load MOS tube is arranged between the second direct current source and the third resistor, and the control end of the first load MOS tube is connected with the input end;
the control ends of the first sampling MOS tube and the first load MOS tube are interconnected.
6. The current sampling circuit according to claim 2, wherein the current adjusting circuit 200 includes N current sampling branches, the N current sampling branches are connected in parallel, N is a positive integer not less than 2, and the second resistors in different current sampling branches are used for obtaining target voltage signals output by different target voltage signal sources;
the current sampling circuit further includes: a mirror current selection switch;
the mirror current selection switch comprises N selection switch MOS tubes which are in one-to-one correspondence with the N current sampling branches, the input end of each selection switch MOS tube is connected with the first output end of the mirror current source, the output end of each selection switch MOS tube is connected with one end of the third resistor which is not connected with a load, and the control end of each selection switch MOS tube is connected with the output end of the first current source in the corresponding current sampling branch.
7. The current sampling circuit of claim 6, further comprising:
and the second synchronous switch is arranged in the current sampling branch and the load power supply branch and is used for controlling the N current sampling branches to be conducted with the load power supply branch when current flows through the load power supply branch.
8. The current sampling circuit of claim 7 wherein said second synchronous switch comprises:
the N second sampling MOS transistors and the second load MOS transistor are arranged in each current sampling branch circuit;
each second sampling MOS tube is arranged between a second direct current source and a first resistor in the corresponding current sampling branch;
the second load MOS tube is arranged between the second direct current source and the third resistor, and the control end of the second load MOS tube is connected with the input end;
the N second sampling MOS tubes are connected with the control ends of the second load MOS tubes.
9. The current sampling circuit of claim 2 wherein the target voltage signal source is a dc output circuit in a power supply converter that supplies power to the load.
10. A power supply changer, comprising: the current sampling circuit of any one of claims 1-9.
11. The power supply changer of claim 10, comprising a dc output circuit for providing a target voltage signal as a target voltage signal source.
12. The power supply changer of claim 11, wherein,
the current sampling branches included in the current regulating circuit are in one-to-one correspondence with the direct current output circuits, one end of the second resistor in the current sampling branch, which is not connected with a load, is connected with the output end of the direct current output circuit corresponding to the second resistor, and the direct current output circuit is used as the target voltage signal source to provide a target voltage signal for the current sampling branch corresponding to the direct current output circuit.
13. The power supply changer of claim 10, further comprising:
and the output current modulation module is used for outputting a current modulation signal to a direct current output circuit in the power supply changer based on a comparison result of the voltage signal of the output end of the current sampling circuit and a preset voltage signal, so that the output current of the direct current output circuit changes along with the change of the current modulation signal.
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| CN112491012B (en) * | 2021-02-03 | 2021-04-16 | 四川蕊源集成电路科技有限公司 | Current-limiting double-protection circuit and current-limiting double-protection method of circuit |
| CN113252949B (en) * | 2021-05-13 | 2021-11-05 | 北京芯格诺微电子有限公司 | High-precision current sampling circuit with on-chip real-time calibration |
| CN116031830B (en) * | 2023-03-28 | 2023-06-13 | 深圳市德晟达电子科技有限公司 | Load switch protection circuit adopting impedance detection |
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