CN107290581B - Current detection circuit of switch circuit and switch circuit - Google Patents
Current detection circuit of switch circuit and switch circuit Download PDFInfo
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- CN107290581B CN107290581B CN201710520112.3A CN201710520112A CN107290581B CN 107290581 B CN107290581 B CN 107290581B CN 201710520112 A CN201710520112 A CN 201710520112A CN 107290581 B CN107290581 B CN 107290581B
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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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- 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
The invention discloses a current detection circuit of a switching circuit and the switching circuit, which comprises a switching tube, an inductor and a sampling resistor, wherein the connection point between the switching tube and the inductor is a switching node, the inductor is connected to the switching node through the sampling resistor, and the current detection circuit comprises a voltage-to-current circuit and a power supply circuit; two ends of the sampling resistor are respectively connected to two input ends of a voltage-to-current circuit, and an output end of the voltage-to-current circuit obtains sampling current; the power supply circuit comprises a first capacitor, a first end of the first capacitor is connected to a switch node, and the switch node is a reference standard of the voltage-to-current circuit. Because the power supply end and the reference of the voltage-to-current circuit are stable relative to the input current sampling signal, common mode noise can be effectively restrained, current detection precision is improved, and system control precision is improved.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a current detection circuit of a switching circuit and the switching circuit.
Background
In a switching circuit, the current of a switching tube is sampled by a sampling resistor, and the current on the switching tube is detected, so that the switching tube is controlled to be turned on and off. Because the switching tube is switched on and off, the voltage at two ends of the sampling resistor is always changed, and the power supply of the current sampling circuit is fixed, but the input voltage of the current sampling circuit is always changed, so that larger common mode noise is caused, and the current sampling is caused to have errors, thereby influencing the control precision of the system. In a switching circuit, a sampling resistor is typically connected in series to each of an input side and an output side for detecting an input/output current. The input and output sampling currents have errors due to unmatched resistors at the input and output sides and other components. And two sets of sampling circuits are needed, so that the system cost is increased, and the system efficiency is reduced due to two sampling resistors.
Taking a four-switch-tube Buck-Boost voltage-boosting circuit as an example, the topology structure of the four-switch-tube Buck-Boost voltage-boosting circuit is shown in fig. 1 (a). The circuit comprises four power switching tubes Q01, Q02, Q03 and Q04, an energy storage inductor L, an input end capacitor C01 and an output end capacitor C02. The switching tube Q01 is connected with the switching tube Q02 in series, the common end of the switching tube Q01 and the switching tube Q02 is a first node SW1, the switching tube Q01 is connected to the input end, the switching tube Q02 is connected to the ground, the input end is connected to the ground through a capacitor C01, the switching tube Q03 is connected with the switching tube Q04 in series, the common end of the switching tube Q03 and the switching tube Q04 is a second node SW2, the switching tube Q03 is connected to the output end, the switching tube Q04 is connected to the ground, the output end is connected to the ground through a capacitor C02, and an inductor L is connected between the first node SW1 and the second node SW 2.
When the input voltage V IN Specific output voltage V O When a certain value is large, the circuit works in a Buck Buck mode, the switching tubes Q01 and Q02 work in a high-frequency switching state, the switching tube Q03 is always on, and the switching tube Q04 is always off; when the input voltage V IN Specific output voltage V O When the value is smaller than a certain value, the circuit works in a Boost mode, the switching tube Q03 and the switching tube Q04 work in a high-frequency switching state, the switching tube Q01 is always on, and the switching tube Q02 is always off; when V is IN And V is equal to O When the circuit is close to the high-frequency switch, the circuit works in a Buck-Boost Buck mode, and the switch tubes Q01, Q02, Q03 and Q04 are all in a high-frequency switch state.
In the prior art, the input end and the output end of a four-switch circuit are respectively connected with sampling resistors R01 and R02, two ends of the sampling resistors are respectively connected with two input ends of a voltage-to-current circuit 101, the voltage-to-current circuit 101 obtains sampling current i1 by detecting the voltage on the sampling resistor R01, the voltage-to-current circuit 101 obtains sampling current i2 by detecting the voltage on the sampling resistor R02, a power supply end VCC of the voltage-to-current circuit 101 is grounded to a fixed voltage, and the ground potential of the voltage-to-current circuit 101 is grounded to the ground potential of the four-switch circuit. Because the resistors R01 and R02 at the input side and the output side are not matched with components of the voltage-to-current circuit 101, errors exist in input and output sampling currents, errors exist in current sampling, and the control precision of the system is affected; two sets of sampling circuits are needed, so that the system cost is increased; two sampling resistors reduce the system efficiency.
Taking a Buck circuit as an example, the topology is shown in fig. 1 (b). The circuit comprises a switching tube Q01, a freewheeling diode D01, an energy storage inductor L, an input end capacitor C01 and an output end capacitor C02. The switch tube Q01 and the freewheeling diode D01 are connected in series, the common end is a switch node SW, the switch tube Q01 is connected to the input end, the freewheeling diode D01 is connected to the ground, the input end is connected to the ground through a capacitor C01, and the switch node SW is connected to the output end Vout through an inductor L and a sampling resistor R01. The reference of the Buck circuit serves as the reference of the voltage to current circuit 101. Although the voltages at the two ends of the sampling resistor R01 are stable relative to the reference, when the circuit is started, the voltage at the output end is zero or very low enough to supply power to the voltage-to-current circuit 101, when the circuit is started, and stable operation is performed, the voltage at the output end supplies power to the voltage-to-current circuit 101, so that the power supply of the voltage-to-current circuit 101 needs to be switched, and two sets of power supply circuits are generally needed for high and low output voltages. The two sets of power supply circuits increase the design complexity, and the components of the two sets of power supply circuits have the problem of mismatch, so that the power supply voltage of the voltage-to-current circuit 101 can jump during switching, and interference is generated to the operation of the voltage-to-current circuit 101.
Disclosure of Invention
Therefore, the present invention is directed to a current detection circuit and a switching circuit of a four-switch tube circuit, which are used for solving the problems of error in input/output current sampling and large common mode noise in the prior art.
The technical solution of the present invention is to provide a current detection circuit of a switching circuit, comprising: the switching tube, inductance and sampling resistance, the switching tube with the tie point between the inductance is the switch node, the inductance passes through sampling resistance is connected to the switch node, the electric current is followed sampling resistance's first end flows to sampling resistance's second end, its characterized in that, current detection circuit includes: a voltage-to-current circuit and a power supply circuit,
two ends of the sampling resistor are respectively connected to two input ends of the voltage-to-current circuit, and the output end of the voltage-to-current circuit obtains sampling current;
the power supply circuit comprises a first capacitor, a first end of the first capacitor is connected to the switch node, the switch node is a reference standard of the voltage-to-current circuit, and a second end of the first capacitor is a power supply end of the voltage-to-current circuit.
Optionally, the voltage-to-current circuit converts the sampled voltage at the input terminal into a sampled current in proportion.
Optionally, the voltage-to-current circuit comprises a first resistor, a second resistor, an operational amplifier, a voltage-controlled current source and a current mirror circuit,
the first end of the sampling resistor is connected to the first input end of the operational amplifier through the first resistor, the second end of the sampling resistor is connected to the second input end of the operational amplifier through the second resistor, the output end of the operational amplifier is connected to the control end of the voltage-controlled current source, the first end of the voltage-controlled current source is connected to the common end of the operational amplifier and the second resistor, the second end of the voltage-controlled current source is connected to the input end of the current mirror circuit, the output end of the current mirror circuit is the output end of the voltage-to-current circuit, and the power supply end and the reference of the operational amplifier and the current mirror circuit are respectively connected to the power supply end and the reference of the voltage-to-current circuit.
Optionally, the switch circuit is a four-switch circuit, including a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, the first switch tube with the second switch tube is established ties, the common end of first switch tube with the second switch tube is first node, first switch tube is connected to the input, the second switch tube is connected to ground, the third switch tube with the fourth switch tube is established ties, the common end of third switch tube with the fourth switch tube is the second node, the third switch tube is connected to the output, the fourth switch tube is connected to ground, the inductance is connected between first node with the second node, first node or the second node is the switch node.
Optionally, the switch circuit is a BUCK circuit, a BOOST circuit or a BUCK-BOOST circuit; the upper tube of the BUCK circuit is a main switching tube, and the lower tube of the BUCK circuit is a synchronous rectifying tube or a freewheeling diode; the lower tube of the BOOST circuit is a main switch tube, and the upper tube is a synchronous rectifying tube or a freewheeling diode.
Optionally, the switching device further comprises an input/output current detection circuit, wherein the input/output current detection circuit converts the sampling current into a current or a voltage representing an input or/and output current according to the switching state of a switching tube of the switching circuit.
Optionally, the input/output current detection circuit includes a third resistor, a fourth resistor, a fifth switch, a sixth switch and a second capacitor, the output end of the voltage/current conversion circuit is connected to the first end of the third resistor, the second end of the third resistor is connected to ground, the first end of the third resistor is connected to the first end of the second capacitor through the fifth switch and the fourth resistor, the second end of the second capacitor is grounded, the sixth switch is connected between the common end of the fifth switch and the fourth resistor and ground, the switch state of the sixth switch is opposite to the switch state of the fifth switch,
when the fifth switch is synchronized with the first switching tube of the four-switch circuit, the voltage on the first end of the second capacitor represents the input current of the four-switch circuit;
or when the fifth switch is synchronized with a third switching tube of the four-switch circuit, the voltage on the first end of the second capacitor represents the output current of the four-switch circuit;
or when the fifth switch is synchronized with the upper pipe of the BUCK circuit, the voltage on the first end of the second capacitor represents the input current of the BUCK circuit;
or when the fifth switch is synchronized with the upper pipe of the BOOST circuit, the voltage on the first end of the second capacitor represents the output current of the BOOST circuit.
Optionally, the input/output current detection circuit further includes a fifth resistor, a seventh switch, an eighth switch, and a third capacitor, wherein a first end of the third resistor is connected to a first end of the third capacitor through the seventh switch and the fifth resistor, a second end of the third capacitor is grounded, the eighth switch is connected between a common end of the seventh switch and the fifth resistor and ground, a switching state of the eighth switch is opposite to a switching state of the seventh switch,
the fifth switch is synchronized with the first switching tube of the four-switch circuit, and the voltage on the first end of the second capacitor represents the input current of the four-switch circuit;
the seventh switch is synchronized with a third switching tube of the four-switch circuit, and a voltage on a first end of the third capacitor characterizes an output current of the four-switch circuit.
Optionally, the input/output current detection circuit includes a sixth resistor, a ninth switch, and a fourth capacitor, where the fourth capacitor is connected in parallel with the sixth resistor, the output terminal of the voltage-to-current circuit is connected to a first terminal of the sixth resistor through the ninth switch, the second terminal of the sixth resistor is connected to ground,
when the ninth switch is synchronized with the first switching tube of the four-switch circuit, the voltage on the first end of the fourth capacitor represents the input current of the four-switch circuit;
or when the ninth switch is synchronized with a third switching tube of the four-switch circuit, the voltage on the first end of the fourth capacitor characterizes the output current of the four-switch circuit;
or when the ninth switch is synchronized with the upper tube of the BUCK circuit, the voltage on the first end of the fourth capacitor characterizes the input current of the BUCK;
or when the ninth switch is synchronized with the upper pipe of the BOOST circuit, the voltage on the first terminal of the fourth capacitor characterizes the output current of the BOOST.
A further technical solution of the present invention is to provide a switching circuit.
Compared with the prior art, the circuit structure provided by the invention has the following advantages: the current value of the switching tube at any moment can be measured by only one sampling resistor, and the voltage on the sampling resistor is fixed relative to the reference standard, so that errors are not caused. In addition, as the power supply end of the voltage-to-current circuit and the reference standard are stable relative to the input current sampling signal, common mode noise can be effectively inhibited, current detection precision is improved, and system control precision is improved; the input and output current can be obtained by only one sampling resistor, so that the system efficiency is improved; and the power supply voltage of the voltage-to-current circuit is stable, so that the working stability of the voltage-to-current circuit is ensured.
Drawings
FIG. 1 (a) is a prior art four-switch-tube Buck-Boost circuit and its current sampling circuit;
FIG. 1 (b) is a prior art Buck circuit and its current sampling circuit;
FIG. 2 (a) is a circuit diagram of a current detection circuit 200 when the second terminal of the sampling resistor of the present invention is connected to a switch node;
FIG. 2 (b) is a circuit diagram of the current detection circuit 200 when the first end of the sampling resistor of the present invention is connected to the switch node SW;
FIG. 3 (a) is a circuit diagram of the voltage-to-current circuit 201 when the second terminal of the sampling resistor is connected to the switch node SW;
FIG. 3 (b) is a circuit diagram of the voltage-to-current circuit 201 when the first terminal of the sampling resistor is connected to the switch node SW;
fig. 4 (a) is a circuit diagram of an operational amplifier 2011 and a voltage controlled current source 2012 of the present invention;
fig. 4 (b) is another circuit diagram of the operational amplifier 2011 and the voltage controlled current source 2012 of the present invention;
FIG. 5 is a circuit diagram of a current mirror circuit 2013 of the present invention;
FIG. 6 (a) is a schematic diagram of a four-switch Buck-Boost circuit and a current detection circuit 200 thereof when the second terminal of the sampling resistor of the present invention is connected to a switch node;
FIG. 6 (b) shows a four-switch Buck-Boost circuit and a current detection circuit 200 thereof when a first terminal of the sampling resistor of the present invention is connected to a switch node;
FIG. 7 is a BUCK circuit and current detection circuit 200 thereof;
FIG. 8 is a BOOST circuit and a current detection circuit 200 thereof;
fig. 9 (a) is a circuit diagram of the input/output current detection circuit 203;
fig. 9 (b) is another circuit diagram of the input/output current detection circuit 203;
fig. 9 (c) is a circuit diagram of the input/output current detection circuit 203.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments only. The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention.
In the following description of preferred embodiments of the invention, specific details are set forth in order to provide a thorough understanding of the invention, and the invention will be fully understood to those skilled in the art without such details.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. It should be noted that the drawings are in a simplified form and are not to scale precisely, but rather are merely intended to facilitate and clearly illustrate the embodiments of the present invention. It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly coupled to" or "directly connected to" another element, there are no intervening elements present.
Referring to fig. 2 (a) and 2 (b), a circuit diagram of a current detection circuit of the switching circuit of the present invention is illustrated. The switching circuit includes a switching tube, an inductor L and a sampling resistor R20, a connection point between the switching tube and the inductor L is a switching node SW, the inductor L is connected to the switching node SW through the sampling resistor R20, a current flows from a first end of the sampling resistor R20 to a second end of the sampling resistor R20, and the current detection circuit 200 includes: the voltage-to-current circuit 201 and the power supply circuit 202, two ends of the sampling resistor R20 are respectively connected to two input ends IN1 and IN2 of the voltage-to-current circuit 200, and the output end of the voltage-to-current circuit 201 obtains a sampling current i20, wherein the sampling current i20 represents the current on the inductor L;
the power supply circuit 202 includes a first capacitor C20, a first end of the first capacitor C20 is connected to the switch node SW, the switch node SW is a reference of the voltage-to-current circuit 200, and a second end of the first capacitor C20 is a power supply end BST of the voltage-to-current circuit 200.
Referring to fig. 2 (a), a first end of the sampling resistor R20 is connected to the inductor L, a second end of the sampling resistor R20 is connected to the switching node SW, and an inductor current i L From the inductance L to the sampling resistor R20, the second end of the sampling resistor R20 is a reference of the voltage-to-current circuit 200, and the first end of the sampling resistor R20 is a positive voltage with respect to the reference, that is, the input of the voltage-to-current circuit 200 is a positive voltage.
Referring to fig. 2 (b), a second end of the sampling resistor R20 is connected to the inductor L, a first end of the sampling resistor R20 is connected to the switching node SW, and an inductor current i L The current flows from the sampling resistor R20 to the inductor L, the first end of the sampling resistor R20 is a reference of the voltage-to-current circuit 200, and the second end of the sampling resistor R20 is a negative voltage with respect to the reference, that is, the input of the voltage-to-current circuit 200 is a negative voltage.
In one embodiment, the power supply circuit 202 further includes a unidirectional conducting element 2021, the unidirectional conducting element 2021 being connected to the second end of the first capacitor C20.
In one embodiment, the power supply circuit 202 further includes a first power supply VDD opposite to ground, and the first power supply VDD is connected to the second end of the first capacitor C20 through the unidirectional conductive element 2021.
In one embodiment, the unidirectional conducting element 2021 is a diode, the anode of which is connected to the first power supply VDD, and the cathode of which is connected to the power supply terminal of the voltage-to-current circuit 201.
The diode can also be implemented as a MOS transistor or triode. The grid electrode and the drain electrode of the NMOS are connected and serve as the anode of the diode, and the source electrode of the NMOS serves as the cathode of the diode; the grid electrode and the drain electrode of the PMOS are connected and serve as the cathode of the diode, and the source electrode of the PMOS serves as the anode of the diode.
In one embodiment, the voltage-to-current circuit converts the sampled voltage at the input to a sampled current in proportion. The magnitude of the sampled current is indicative of the magnitude of the current on the inductor.
Referring to fig. 3 (a) and 3 (b), in one embodiment, the voltage to current circuit 201 includes a first resistor R30, a second resistor R31, an operational amplifier 2011, a voltage controlled current source 2012 and a current mirror circuit 2013,
the first end of the sampling resistor R20 is connected to the first input end I1 of the operational amplifier 2011 through the first resistor R30, the second end of the sampling resistor R20 is connected to the second input end I2 of the operational amplifier 2011 through the second resistor R31, the output end O1 of the operational amplifier 2011 is connected to the control end CTL of the voltage-controlled current source 2012, the first end O2 of the voltage-controlled current source 2012 is connected to the common end of the operational amplifier 2011 and the second resistor R31, the second end O3 of the voltage-controlled current source 2012 is connected to the input end I3 of the current mirror circuit 2013, the output end O4 of the current mirror circuit 2013 is the output end of the voltage-to-current circuit 201, and the power supply end and the reference ground of the operational amplifier 2011 and the current mirror circuit 2013 are connected to the power supply end and the reference ground of the voltage-to-current circuit 201, respectively. Referring to fig. 3 (a), when the second terminal of the sampling resistor R20 is connected to the switching node SW, the reference ground of the voltage-to-current circuit 201 is the second terminal of the sampling resistor R20; the operational amplifier 2011 and the current mirror circuit 2013 are referenced to ground as a second terminal of the sampling resistor R20. The first input terminal I1 of the operational amplifier 2011 samples the voltage on the sampling resistor R20 through the first resistor R30, the operational amplifier 2011 adjusts the current of the voltage-controlled current source 2012 so that the output current of the controllable current source 2012 passes through the voltage on the second resistor R31, that is, the voltage of the second input terminal I2 of the operational amplifier 2011 is equal to the voltage of the first input terminal I1, and the current mirror circuit 2013 mirrors the current of the voltage-controlled current source 2012 to obtain the sampled current. The ratio between the output current and the input current of the current mirror circuit 2013 is k, and thus the sampling current i OUT And inductor current i L The relation between the two is: i.e L =i OUT X R31/(R20 x k). Referring to fig. 3 (b), when the second terminal of the sampling resistor R20 is connected to the switch node SW, the voltage-to-current circuit 201 is referenced to groundA first end of sample resistor R20; the operational amplifier 2011 and the reference ground of the current mirror circuit 2013 are the first ends of the sampling resistor R20. Unlike fig. 3 (a), the sampled voltage across the sampling resistor R20, i.e., the voltage at the second terminal of the sampling resistor R20, is negative with respect to the reference of the voltage-to-current circuit 201. Sampling current i OUT And inductor current i L The relationship between is still: i.e L =i OUT ×R31/(R20×k)。
In one embodiment, the voltage controlled current source 2012 is an NMOS or PMOS.
Referring to fig. 4 (a), when the voltage-controlled current source 2012 is an NMOS, the gate of the NMOS is the control terminal CTL of the voltage-controlled current source 2012, the source of the NMOS is the first terminal O2 of the voltage-controlled current source 2012, and the drain of the NMOS is the second terminal O3 of the voltage-controlled current source 2012. The first input terminal I1 of the operational amplifier 2011 is a non-inverting input terminal, and the second input terminal I2 is an inverting input terminal.
Referring to fig. 4 (b), when the voltage-controlled current source 2012 is a PMOS, the gate of the PMOS is the control terminal of the voltage-controlled current source 2012, the drain of the PMOS is the first terminal of the voltage-controlled current source, and the source of the PMOS is the second terminal of the voltage-controlled current source. The first input terminal I1 of the operational amplifier 2011 is an inverting input terminal, and the second input terminal I2 is a non-inverting input terminal.
Referring to fig. 5, in one embodiment, the current mirror circuit 2013 is composed of two PMOS, the gates of the two PMOS Q30 and Q31 are connected together and connected to the drain of the PMOS Q30 as the input terminal of the current mirror circuit 2013, the sources of the two PMOS are connected together and connected to the power supply terminal VD of the current mirror circuit 2013, and the drain of the PMOS Q31 is the output terminal of the current mirror circuit 2013.
Referring to fig. 6 (a) and 6 (b), in one embodiment, the switching circuit is a four-switch circuit, including a first switching tube Q01, a second switching tube Q02, a third switching tube Q03, and a fourth switching tube Q04, the first switching tube Q01 and the second switching tube Q02 are connected in series, a common terminal of the first switching tube Q01 and the second switching tube Q02 is connected to the first node SW1, the first switching tube Q01 is connected to an input terminal Vin, the second switching tube Q02 is connected to a ground, a common terminal of the third switching tube Q03 and the fourth switching tube Q04 is connected to the second node SW2, the third switching tube Q03 is connected to an output terminal Vout, and the fourth switching tube Q04 is connected to a ground. Wherein fig. 6 (a) is a schematic circuit diagram of the second terminal of the sampling resistor R20 connected to the switch node SW, i.e. the second node SW 2; fig. 6 (b) is a schematic circuit diagram of the first terminal of the sampling resistor R20 connected to the switching node SW, i.e. the first node SW 1. In the four-switch circuit, only one sampling resistor is needed, and the current value of the inductor at any moment can be measured. In addition, since the power supply terminal BST and the reference SW of the voltage-to-current circuit 201 are stable with respect to the sampling signal, that is, the voltages at both ends of the sampling resistor, common mode noise can be effectively suppressed, current detection accuracy can be improved, and system control accuracy can be improved.
Referring to fig. 7, in one embodiment, the switching circuit is a BUCK circuit, including a switching tube Q50 and a freewheeling diode D50, where the switching tube Q50 and the freewheeling diode D50 are connected in series, the switching tube Q50 is connected to the input terminal Vin, the freewheeling diode D50 is connected to ground, the common terminal of the switching tube Q50 and the freewheeling diode D50 is a switching node SW, and the switching node SW is connected to the output terminal Vout through a sampling resistor R20 and an inductor L. The two ends of the sampling resistor R20 are respectively connected to two input ends of the voltage-to-current circuit 200, and the output end of the voltage-to-current circuit 201 obtains a sampling current i20, and the sampling current i20 represents the current on the inductor L.
Referring to fig. 8, in one embodiment, the switching circuit is a BOOST circuit, and includes a switching tube Q60 and a freewheeling diode D60, where the switching tube Q60 and the freewheeling diode D60 are connected in series, the freewheeling diode D50 is connected to the output terminal Vout, the switching tube Q60 is connected to ground, the common terminal of the switching tube Q60 and the freewheeling diode D60 is a switching node SW, and the switching node SW is connected to the input terminal Vout through a sampling resistor R20 and an inductor L. The two ends of the sampling resistor R20 are respectively connected to two input ends of the voltage-to-current circuit 200, and the output end of the voltage-to-current circuit 201 obtains a sampling current i20, and the sampling current i20 represents the current on the inductor L.
In one embodiment, the current detection circuit 200 of the switching circuit further comprises an input/output current detection circuit 203, and the input/output current detection circuit 203 converts the sampling current i20 representing the inductor current into a current or a voltage representing the input or/and output current according to the switching state of the switching tube of the switching circuit;
referring to fig. 9 (a), in one embodiment, the input/output current detection circuit 203 includes a third resistor R40, a fourth resistor R41, a fifth switch S40, a sixth switch S40B, and a second capacitor C40, the output terminal of the voltage to current conversion circuit 201 is connected to the first terminal of the third resistor R40, the second terminal of the third resistor R40 is connected to the ground, the first terminal of the third resistor R40 is connected to the first terminal of the second capacitor C40 through the fifth switch S40 and the fourth resistor R41, the second terminal of the second capacitor C40 is grounded, the sixth switch S40B is connected between the common terminal of the fifth switch S40 and the fourth resistor R41 and the ground, the switch state of the sixth switch S40B is opposite to the switch state of the fifth switch S40,
the first end voltage of the third resistor R40 represents an inductor current, when the fifth switch S40 is synchronous with the first switch tube Q01 of the four-switch circuit, the average value of the common end voltages of the fifth switch S40 and the fourth resistor R41 represents the input current of the four-switch circuit, and after the average value of the common end voltages of the fifth switch S40 and the fourth resistor R41 is obtained through the filtering of the fourth resistor R41 and the second capacitor C40, namely, the voltage on the first end of the second capacitor C40 represents the input current of the four-switch circuit;
or when the fifth switch S40 is synchronized with the third switching tube Q03 of the four-switch circuit, the voltage on the first terminal of the second capacitor C40 characterizes the output current of the four-switch circuit;
or when the fifth switch S40 is synchronized with the switching tube of the BUCK circuit, the voltage on the first terminal of the second capacitor C40 characterizes the input current of the BUCK circuit;
or when the fifth switch S40 is synchronized with the switching tube of the BOOST circuit, the voltage on the first terminal of the second capacitor C40 characterizes the output current of the BOOST circuit.
Referring to fig. 9 (B), in one embodiment, the input/output current detection circuit 203 further includes a fifth resistor R42, a seventh switch S42, an eighth switch S42B, and a third capacitor C42, wherein a first end of the third resistor R40 is connected to a first end of the third capacitor C42 through the sixth switch S42 and the fifth resistor R42, a second end of the third capacitor C42 is grounded, the eighth switch S42B is connected between a common end of the seventh switch S42 and the fifth resistor R42 and ground, a switching state of the eighth switch S42B is opposite to a switching state of the seventh switch S42,
the fifth switch S40 is synchronized with the first switching tube Q01 of the four-switch circuit, and the voltage on the first end of the second capacitor C40 characterizes the input current of the four-switch circuit;
the seventh switch S42 is synchronized with the third switching tube Q03 of the four-switch circuit, and the voltage on the first terminal of the third capacitor C42 characterizes the output current of the four-switch circuit.
In a four-switch circuit, only one current i20 characterizing the inductance is needed to obtain voltages characterizing both the input and output currents.
Referring to fig. 9 (C), in one embodiment, the input/output current detection circuit 203 includes a sixth resistor R43, a ninth switch S43, and a fourth capacitor C43, where the fourth capacitor C43 is connected in parallel with the sixth resistor R43, the output terminal of the voltage-to-current circuit 201 is connected to the first terminal of the sixth resistor R43 through the ninth switch S43, the second terminal of the sixth resistor R43 is connected to ground,
when the ninth switch S43 is synchronized with the first switching tube Q01 of the four-switch circuit, the voltage on the first terminal of the fourth capacitor C43 characterizes the input current of the four-switch circuit;
or when the ninth switch S43 is synchronized with the third switching tube of the four-switch circuit, the voltage on the first terminal of the fourth capacitor C43 characterizes the output current of the four-switch circuit;
in contrast to fig. 9 (b), in a four-switch circuit, a current i20 representing the inductance can only be obtained representing the voltage of the input current or representing the voltage of the output current. Thus, if a voltage is required that characterizes both the input current and the output current, two currents characterizing the inductance are required.
Or when the ninth switch S43 is synchronized with the switching tube of the BUCK circuit, the voltage on the first terminal of the fourth capacitor C43 characterizes the input current of the BUCK;
or when the ninth switch S43 is synchronized with the switching tube of the BOOST circuit, the voltage on the first terminal of the fourth capacitor C43 characterizes the output current of the BOOST.
In addition, although the embodiments are described and illustrated separately above, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and that reference may be made to another embodiment without explicitly recited in one of the embodiments.
The above-described embodiments do not limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the above embodiments should be included in the scope of the present invention.
Claims (9)
1. A current detection circuit of a switching circuit, the switching circuit comprising a switching tube, an inductor and a sampling resistor, a connection point between the switching tube and the inductor being a switching node, the inductor being connected to the switching node through the sampling resistor, a current flowing from a first end of the sampling resistor to a second end of the sampling resistor, the current detection circuit comprising: a voltage-to-current circuit and a power supply circuit,
two ends of the sampling resistor are respectively connected to two input ends of the voltage-to-current circuit, and the output end of the voltage-to-current circuit obtains sampling current;
the power supply circuit comprises a first capacitor, a first end of the first capacitor is connected to the switch node, the switch node is a reference standard of the voltage-to-current circuit, and a second end of the first capacitor is a power supply end of the voltage-to-current circuit;
the voltage-to-current circuit comprises an operational amplifier and a current mirror circuit, and a power supply end and a reference standard of the operational amplifier and the current mirror circuit are respectively connected to the power supply end and the reference standard of the voltage-to-current circuit.
2. The current detection circuit of a switching circuit according to claim 1, wherein: the voltage-to-current circuit converts the sampling voltage at the input end into sampling current in proportion.
3. The current detection circuit of claim 2, wherein: the voltage-to-current circuit further comprises a first resistor, a second resistor and a voltage-controlled current source,
the first end of the sampling resistor is connected to the first input end of the operational amplifier through the first resistor, the second end of the sampling resistor is connected to the second input end of the operational amplifier through the second resistor, the output end of the operational amplifier is connected to the control end of the voltage-controlled current source, the first end of the voltage-controlled current source is connected to the common end of the operational amplifier and the second resistor, the second end of the voltage-controlled current source is connected to the input end of the current mirror circuit, and the output end of the current mirror circuit is the output end of the voltage-to-current circuit.
4. The current detection circuit of a switching circuit according to claim 1, wherein: the switching circuit is a four-switch circuit and comprises a first switching tube, a second switching tube, a third switching tube and a fourth switching tube, wherein the first switching tube and the second switching tube are connected in series, the common end of the first switching tube and the second switching tube is a first node, the first switching tube is connected to an input end, the second switching tube is connected to the ground, the third switching tube and the fourth switching tube are connected in series, the common end of the third switching tube and the fourth switching tube is a second node, the third switching tube is connected to an output end, the fourth switching tube is connected to the ground, the inductor is connected between the first node and the second node, and the first node or the second node is the switching node;
or the switching circuit is a BUCK circuit or a BOOST circuit or a BUCK-BOOST circuit; the upper tube of the BUCK circuit is a main switching tube, and the lower tube of the BUCK circuit is a synchronous rectifying tube or a freewheeling diode; the lower tube of the BOOST circuit is a main switch tube, and the upper tube is a synchronous rectifying tube or a freewheeling diode.
5. The current detection circuit of claim 4, wherein: the input/output current detection circuit converts the sampling current into a current or a voltage representing the input or/and output current according to the switching state of a switching tube of the switching circuit.
6. The current detection circuit of claim 5, wherein: the input/output current detection circuit comprises a third resistor, a fourth resistor, a fifth switch, a sixth switch and a second capacitor, wherein the output end of the voltage/current conversion circuit is connected to the first end of the third resistor, the second end of the third resistor is connected to the ground, the first end of the third resistor is connected to the first end of the second capacitor through the fifth switch and the fourth resistor, the second end of the second capacitor is grounded, the sixth switch is connected between the common end of the fifth switch and the fourth resistor and the ground, the switch state of the sixth switch is opposite to the switch state of the fifth switch,
when the fifth switch is synchronized with the first switching tube of the four-switch circuit, the voltage on the first end of the second capacitor represents the input current of the four-switch circuit;
or when the fifth switch is synchronized with a third switching tube of the four-switch circuit, the voltage on the first end of the second capacitor represents the output current of the four-switch circuit;
or when the fifth switch is synchronized with the upper pipe of the BUCK circuit, the voltage on the first end of the second capacitor represents the input current of the BUCK circuit;
or when the fifth switch is synchronized with the upper pipe of the BOOST circuit, the voltage on the first end of the second capacitor represents the output current of the BOOST circuit.
7. The current detection circuit of claim 6, wherein: the input/output current detection circuit further comprises a fifth resistor, a seventh switch, an eighth switch and a third capacitor, wherein a first end of the third resistor is connected to a first end of the third capacitor through the seventh switch and the fifth resistor, a second end of the third capacitor is grounded, the eighth switch is connected between a common end of the seventh switch and the fifth resistor and ground, a switching state of the eighth switch is opposite to a switching state of the seventh switch,
the fifth switch is synchronized with the first switching tube of the four-switch circuit, and the voltage on the first end of the second capacitor represents the input current of the four-switch circuit;
the seventh switch is synchronized with a third switching tube of the four-switch circuit, and a voltage on a first end of the third capacitor characterizes an output current of the four-switch circuit.
8. The current detection circuit of claim 5, wherein: the input/output current detection circuit comprises a sixth resistor, a ninth switch and a fourth capacitor, the fourth capacitor is connected with the sixth resistor in parallel, the output end of the voltage-to-current conversion circuit is connected to the first end of the sixth resistor through the ninth switch, the second end of the sixth resistor is connected to the ground,
when the ninth switch is synchronized with the first switching tube of the four-switch circuit, the voltage on the first end of the fourth capacitor represents the input current of the four-switch circuit;
or when the ninth switch is synchronized with a third switching tube of the four-switch circuit, the voltage on the first end of the fourth capacitor characterizes the output current of the four-switch circuit;
or when the ninth switch is synchronized with the upper tube of the BUCK circuit, the voltage on the first end of the fourth capacitor characterizes the input current of the BUCK;
or when the ninth switch is synchronized with the upper pipe of the BOOST circuit, the voltage on the first terminal of the fourth capacitor characterizes the output current of the BOOST.
9. A switching circuit, characterized in that: a current detection circuit as claimed in any one of claims 1 to 8.
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| CN107888053B (en) * | 2017-11-14 | 2019-05-03 | 中国电子产品可靠性与环境试验研究所 | Sample circuit and electric pressure converter |
| CN107947578B (en) * | 2017-12-04 | 2020-09-15 | 成都芯源系统有限公司 | Current sampling circuit applied to buck-boost circuit and control method thereof |
| CN108152758B (en) * | 2017-12-14 | 2023-06-23 | 杰华特微电子股份有限公司 | Current detection circuit, detection method and switching circuit |
| WO2022110205A1 (en) * | 2020-11-30 | 2022-06-02 | 华为数字能源技术有限公司 | Voltage conversion circuit, voltage converter and electronic device |
| CN112994425B (en) * | 2021-02-07 | 2022-07-15 | 杰华特微电子股份有限公司 | Noise suppression method, noise suppression circuit and switching circuit |
| CN117872081A (en) * | 2022-05-24 | 2024-04-12 | 上海沛塬电子有限公司 | High-precision current detection unit and chip module |
| CN116047147B (en) * | 2023-01-28 | 2023-06-20 | 苏州贝克微电子股份有限公司 | High-precision current detecting circuit |
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| US6753801B2 (en) * | 2002-08-23 | 2004-06-22 | Micron Technology, Inc. | Fully differential reference driver for pipeline analog to digital converter |
| CN101820162B (en) * | 2010-05-18 | 2012-12-12 | 北京星网锐捷网络技术有限公司 | Overcurrent protector |
| EP2594948A4 (en) * | 2011-03-15 | 2015-03-18 | Sunsun Lighting China Co Ltd | Current sensing circuit and control circuit thereof and power converter circuit |
| CN103575964B (en) * | 2012-07-19 | 2016-03-23 | 快捷半导体(苏州)有限公司 | A kind of over-current detection circuit of power switch pipe and method |
| CN203759090U (en) * | 2014-03-14 | 2014-08-06 | 中国铁道科学研究院机车车辆研究所 | Current sampling circuit of rail-transit traction data acquisition system |
| CN104166034B (en) * | 2014-08-12 | 2017-11-14 | 成都信息工程学院 | A kind of high-precision difference sample circuit |
| CN105572463A (en) * | 2014-10-14 | 2016-05-11 | 北京谊安医疗系统股份有限公司 | Accurate measurement circuit for bus current of direct-current brushless motor |
| CN105763047B (en) * | 2016-03-08 | 2018-11-02 | 中山大学 | A kind of all-wave inductive current sample circuit |
| CN106787730B (en) * | 2017-02-15 | 2023-07-18 | 杰华特微电子股份有限公司 | Control method and control circuit of switching circuit and switching circuit |
| CN207215887U (en) * | 2017-06-30 | 2018-04-10 | 杰华特微电子（张家港）有限公司 | The current detection circuit and on-off circuit of on-off circuit |
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