CN107742983B - Constant-current constant-voltage control module, voltage reducing circuit and compensation method for sharing compensation - Google Patents
Constant-current constant-voltage control module, voltage reducing circuit and compensation method for sharing compensation Download PDFInfo
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- CN107742983B CN107742983B CN201711224604.4A CN201711224604A CN107742983B CN 107742983 B CN107742983 B CN 107742983B CN 201711224604 A CN201711224604 A CN 201711224604A CN 107742983 B CN107742983 B CN 107742983B
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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
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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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
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Abstract
The invention provides a constant current and constant voltage control module, a voltage reducing circuit and a compensation method for sharing compensation, which comprise the following steps: a voltage input module; an inductance for outputting stable electric energy; a load; an output current sampling module for generating an output current sampling signal; an output voltage feedback module that generates an output voltage feedback signal; the constant-current constant-voltage control module is used for generating compensation current according to the output current sampling signal and the output voltage feedback signal and performing constant-current constant-voltage control; and a loop compensation module for generating a compensation voltage. And obtaining an output voltage feedback signal and an output current sampling signal, comparing the larger of the output voltage feedback signal and the output current sampling signal with a reference voltage under the same working voltage, and obtaining a common compensation voltage, so as to adjust the pulse width of a switch control signal and control the output to be constant. The invention processes the current loop signal and the voltage loop signal, shares one compensation network, realizes the buck conversion with constant current and constant voltage output characteristics, reduces the number of components of the peripheral compensation network by half, and saves the cost.
Description
Technical Field
The invention relates to a switching type voltage reduction integrated circuit driving and converting technology, in particular to a constant current and constant voltage control module sharing compensation, a voltage reduction circuit and a compensation method.
Background
Over the years, control ICs (integrated circuits) for various buck power supplies have been developed and used to achieve control of constant current or constant voltage output, with applications including backup power supplies for LED drivers, chargers, and mobile devices.
In the prior art, voltage information of an output end is obtained by carrying out partial pressure sampling on the output end, a current sampling resistor is connected in series to the output end, information of the current of the output end is obtained according to the pressure difference between two ends of the current sampling resistor, and the control of constant-current and constant-voltage output is realized by amplifying errors between two paths of signals and a calibration point and controlling the duty ratio of a switch and utilizing the follow current characteristic of an inductor. In loop control formed by two paths of signals, in order to stabilize loops, loop compensation is carried out on the two loops, so that more components are used for compensating a network, the whole circuit is large in size, and integration is not facilitated.
In summary, the current loop signal and the voltage loop signal respectively adopt one compensation network, so that the problems of more components, complicated circuit structure, large volume and the like of the compensation network are one of the problems to be solved urgently by those skilled in the art.
Disclosure of Invention
In view of the above drawbacks of the prior art, the present invention aims to provide a constant current and constant voltage control module, a voltage reducing circuit and a compensation method for sharing compensation, which are used for solving the problems of more components, complicated circuit structure, large volume and the like of a compensation network in the prior art.
To achieve the above and other related objects, the present invention provides a constant current and constant voltage control module with common compensation, the constant current and constant voltage control module at least includes:
the device comprises a voltage conversion unit, a signal selection unit, a voltage-to-current amplification unit, a pulse width modulation unit, a first switch and a second switch;
the voltage conversion unit receives an output current sampling signal of the voltage reduction circuit, amplifies or reduces the output current sampling signal into an output current conversion signal, and the working voltage of the output current conversion signal is consistent with the working voltage of an output voltage feedback signal of the voltage reduction circuit;
the signal selection unit is connected with the output end of the voltage conversion unit and receives the output voltage feedback signal to select the larger one of the output current conversion signal and the output voltage feedback signal as an output signal;
the input end of the voltage-to-current amplifying unit is respectively connected with the signal selecting unit and a reference signal, the output signal of the signal selecting unit is compared with the reference signal, the comparison result is converted into a current signal, and then compensation current is output, and the compensation current is connected with the external loop compensation module and is converted into compensation voltage;
the pulse width modulation unit is connected to the output end of the voltage-to-current amplification unit, and adjusts the duty ratio of the control signal of the first switch or the second switch according to the compensation voltage;
the first switch is connected between the input voltage of the voltage reduction circuit and the inductor of the voltage reduction circuit and is used for controlling the storage and the release of electric energy of the inductor so as to control the output current and the output voltage of the voltage reduction circuit to be constant;
one end of the second switch is connected with a connecting node of the first switch and the inductor, and the other end of the second switch is grounded and used for controlling a follow current channel from ground to the inductor so as to reduce voltage drop and loss.
Preferably, a filtering unit is further connected between the voltage conversion unit and the output current sampling signal, and the filtering unit is an RC filtering unit.
Preferably, the voltage conversion unit comprises an operational amplifier, an NMOS tube, a current source, a first resistor and a second resistor; the positive input end of the operational amplifier is connected with a front-stage output signal, the output end of the operational amplifier is connected with the gate end of the NMOS tube, the current source, the first resistor and the second resistor are sequentially connected in series and then grounded, and the drain end of the NMOS tube is connected with the output end of the current source and outputs the output current conversion signal, and the source end is grounded; and the connection nodes of the first resistor and the second resistor are connected with the inverting input end of the operational amplifier.
Preferably, the signal selection unit comprises a comparator, a first transmission gate and a second transmission gate, wherein the non-inverting input end of the comparator is connected with the output current conversion signal, and the inverting input end of the comparator is connected with the output voltage feedback signal; the input end of the first transmission gate is connected with the output current conversion signal, the output end of the first transmission gate is connected with the output end of the second transmission gate and used as the output end of the signal selection unit, the positive control signal is connected with the output signal of the comparator, and the negative control signal is connected with the negative signal of the output signal of the comparator; the input end of the second transmission gate is connected with the output voltage feedback signal, the output end of the second transmission gate is connected with the output end of the first transmission gate, the positive control signal is connected with the inverse signal of the output signal of the comparator, and the negative control signal is connected with the output signal of the comparator.
To achieve the above and other related objects, the present invention also provides a common-compensated buck circuit, including at least:
the device comprises a voltage input module, the constant-current constant-voltage control module, a loop compensation module, an inductor, an output voltage feedback module, a load and output current sampling module;
the voltage input module provides input voltage;
one end of the inductor is connected with the constant-current constant-voltage control module, and the other end of the inductor is used as a voltage output end and is used for outputting stable output voltage and output current;
one end of the load is connected with output voltage, the other end of the load is grounded after passing through the output current sampling module, and the output current sampling module generates an output current sampling signal;
the output voltage feedback module is connected between the output voltage and the ground and is used for generating an output voltage feedback signal;
the constant-current constant-voltage control module is connected with the output ends of the voltage input module, the output voltage feedback module and the output current sampling module, generates compensation current according to the output current sampling signal and the output voltage feedback signal, and performs constant control on the output voltage and the output current under the control of the loop compensation module;
the loop compensation module is connected with the constant-current constant-voltage control module and is used for generating corresponding compensation voltage according to the compensation current.
Preferably, the output voltage feedback module includes a first sampling resistor and a second sampling resistor connected in series, where the first sampling resistor and the second sampling resistor divide the output voltage to obtain the output voltage feedback signal.
Preferably, the loop compensation module comprises a compensation resistor and a first compensation capacitor, one end of the compensation resistor is connected with the constant-current constant-voltage control module, the other end of the compensation resistor is connected with the first compensation capacitor, and the other end of the first compensation capacitor is grounded.
Preferably, the loop compensation module further comprises a second compensation capacitor, wherein one end of the second compensation capacitor is connected with the constant-current constant-voltage control module, and the other end of the second compensation capacitor is grounded.
Preferably, the buck circuit with common compensation further comprises an output capacitor, wherein one end of the output capacitor is connected with the voltage output end, and the other end of the output capacitor is grounded.
To achieve the above and other related objects, the present invention provides a common compensation method for a voltage reduction circuit, the common compensation method for a voltage reduction circuit at least includes:
sampling output current and output voltage, obtaining an output voltage feedback signal and an output current sampling signal, comparing the larger one of the output voltage feedback signal and the output current sampling signal under the same working voltage with a reference voltage, obtaining corresponding common compensation voltage according to a comparison result, and performing pulse width modulation on a switch control signal by using the compensation voltage so as to control output constant voltage and constant current.
Preferably, the output current sampling signal is subjected to voltage conversion to obtain an output current conversion signal, so that the output voltage feedback signal and the output current conversion signal are located at the same working voltage, and the following formula is satisfied: senbf=k·sen; wherein SENBF is an output current conversion signal; k is a fixed constant, and
V FB is a feedback voltage calibration point in constant voltage output, V CS And (5) sampling a voltage calibration point for constant current output.
Preferably, the constant current of the output current is adjusted by controlling the compensation voltage, and the following relation is satisfied:
wherein I is OUT To output current, V CS For the sampling voltage calibration point in constant current output, R 16 A sampling resistor for the output current.
Preferably, the constant current of the output voltage is adjusted by controlling the compensation voltage, so as to satisfy the following relation:
wherein V is OUT To output voltage V FB For the feedback voltage calibration point at constant voltage output, < >>
Dividing resistance ratio for the output voltageValues.
Preferably, the constant current or constant voltage control further includes:
when the larger of the output voltage feedback signal and the output current sampling signal under the same working voltage is larger than the reference voltage, the compensation voltage is reduced; the compensation voltage increases when a larger one of the output voltage feedback signal and the output current sampling signal at the same operating voltage is less than the reference voltage.
As described above, the constant current and constant voltage control module, the voltage reducing circuit and the compensation method for common compensation have the following beneficial effects:
the constant current and constant voltage control module, the voltage reducing circuit and the compensation method for the common compensation realize the voltage reducing conversion with constant current and constant voltage output characteristics by processing the current loop signals and the voltage loop signals and sharing one compensation network, so that the number of components serving as a peripheral compensation network is halved, and the chip area can be reduced more if the compensation network is built in a chip, thereby saving the application cost.
Drawings
Fig. 1 is a schematic diagram of a buck circuit with common compensation according to the present invention.
Fig. 2 is a schematic diagram of a filter unit according to the present invention.
Fig. 3 is a schematic diagram of a voltage converting unit according to the present invention.
Fig. 4 is a schematic diagram showing the structure of the signal selecting unit according to the present invention.
Description of element reference numerals
1. Voltage reducing circuit sharing compensation
11. Voltage input module
12. Constant-current constant-voltage control module
121. Filtering unit
1211. Filtering resistor
1212. Filter capacitor
122. Voltage conversion unit
1221. Operational amplifier
1222 NMOS tube
1223. Current source
1224. First resistor
1225. Second resistor
123. Signal selection unit
1231. Comparator with a comparator circuit
1232. First transmission gate
1233. Second transmission gate
1234. Inverter with a high-speed circuit
124. Voltage-to-current amplifying unit
125. Pulse width modulation unit
126. First switch
127. Second switch
13. Inductance
14. Output voltage feedback module
141. First sampling resistor
142. Second sampling resistor
15. Load(s)
16. Output current sampling module
17. Output capacitor
18. Loop compensation module
181. Compensation resistor
182. First compensation capacitor
183. Second compensation capacitor
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to fig. 1-4. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
As shown in fig. 1, the present invention provides a common-compensated step-down circuit 1, the common-compensated step-down circuit 1 including:
the device comprises a voltage input module 11, a constant-current and constant-voltage control module 12, an inductor 13, an output voltage feedback module 14, a load 15, an output current sampling module 16, an output capacitor 17 and a loop compensation module 18.
As shown in fig. 1, the voltage input module 11 is connected to an input end of the constant current and constant voltage control module 12, and is configured to provide an input voltage VIN.
Specifically, in this embodiment, the voltage input module 11 is a voltage source. The voltage input module 11 may also convert an ac power to the input voltage VIN by using a rectifying circuit, which is not limited to the embodiment.
As shown in fig. 1, one end of the inductor 13 is connected to the constant current and constant voltage control module 12, and the other end outputs a stable output voltage VOUT and output current IOUT.
As shown in fig. 1, the output voltage feedback module 14 is connected between the output voltage VOUT and ground for generating an output voltage feedback signal VFB.
Specifically, the output voltage feedback module 14 includes a first sampling resistor 141 and a second sampling resistor 142, and the first sampling resistor 141 and the second sampling resistor 142 divide the output voltage VOUT to obtain the output voltage feedback signal VFB.
As shown in fig. 1, one end of the load 15 is connected to the output voltage VOUT, and the other end is grounded after passing through the output current sampling module 16.
Specifically, the output current sampling module 16 is connected in series with the load 15, and converts the current flowing through the load 15 into an output current sampling signal VCS, where the output current sampling signal VCS is a voltage signal. In this embodiment, the output current sampling module 16 is a third sampling resistor.
As shown in fig. 1, one end of the output capacitor 17 is connected to the output voltage VOUT, and the other end is grounded.
As shown in fig. 1, the constant-current and constant-voltage control module 12 is connected to the output ends of the voltage input module 11, the output voltage feedback module 14 and the output current sampling module 16, generates a compensation current according to the output voltage feedback signal VFB and the output current sampling signal VCS, and is controlled by the loop compensation module 18 to perform constant control on the output voltage VOUT or the output current IOUT.
Specifically, the constant-current and constant-voltage control module 12 includes a filtering unit 121, a voltage converting unit 122, a signal selecting unit 123, a voltage-to-current amplifying unit 124, a pulse width modulating unit 125, a first switch 126, and a second switch 127.
More specifically, as shown in fig. 2, the filtering unit 121 receives the output current sampling signal VCS and filters the output current sampling signal VCS. The filtering unit 121 includes, but is not limited to, an RC filtering unit. In this embodiment, the filtering unit 121 includes a filtering resistor 1211 and a filtering capacitor 1212; one end of the filter resistor 1211 is connected to the output current sampling signal VCS, and the other end is used as an output end of the filter unit 121; one end of the filter capacitor 1212 is connected to the output end of the filter unit 121, and the other end is grounded.
More specifically, as shown in fig. 3, the voltage conversion unit 122 receives the output voltage SEN of the filter unit 121, and outputs the output voltage SEN of the filter unit 121 (equivalent to the output powerThe stream sampling signal VCS) is amplified or reduced to an output current conversion signal SENBF whose operating voltage is kept identical to the operating voltage of the output voltage feedback signal VFB. In the present embodiment, the voltage conversion unit 122 includes an operational amplifier 1221, an NMOS tube 1222, a current source 1223, a first resistor 1224, and a second resistor 1225. The non-inverting input end of the operational amplifier 1221 is connected with the output voltage SEN of the filtering unit 121, and the output end is connected with the gate end of the NMOS tube 1222; the current source 1223 and the first resistor 1224 and the second resistor 1225 are sequentially connected in series and then grounded; the drain terminal of the NMOS tube 1222 is connected to the output terminal of the current source 1223, and outputs the output current conversion signal SENBF, and the source terminal is grounded; the connection nodes of the first resistor 1224 and the second resistor 1225 are connected to the inverting input terminal of the operational amplifier 1221. The output current conversion signal SENBF satisfies the following relationship: senbf=k·sen; wherein K is a fixed constant, an
V FB Is a feedback voltage calibration point in constant voltage output, V CS Sampling voltage calibration points when constant current is output; SEN is the output current sampling signal. In this embodiment, according to the principle of virtual short and virtual break, the connection node of the first resistor 1224 and the second resistor 1225 is forced to be equal to the output voltage SEN of the filter unit 121, then ∈ ->
By setting the first resistance 1224 and the second resistance 1225, let +.>
The required output current conversion signal SENBF can be obtained.
More specifically, as shown in fig. 4, the signal selecting unit 123 is connected to the output terminal of the voltage converting unit 122 and receives the output voltage feedback signal VFB to select the larger one of the output current converting signal SENBF and the output voltage feedback signal VFB as the output signal DS. The signal selecting unit 123 may be implemented by an optional circuit, and is not limited to the specific structure listed in the present embodiment. In the present embodiment, the signal selecting unit 123 includes a comparator 1231, a first transmission gate 1232, a second transmission gate 1233, and an inverter 1234. The comparator 1231 has a non-inverting input connected to the output current conversion signal SENBF, an inverting input connected to the output voltage feedback signal VFB, and an output connected to the inverter 1234. The input end of the first transmission gate 1232 is connected to the output current conversion signal SENBF, the output end thereof is connected to the output end of the second transmission gate 1233 and serves as the output end of the signal selection unit 123, the positive control signal thereof is connected to the output signal of the comparator 1231, and the negative control signal thereof is connected to the output end of the inverter 1234; the input end of the second transmission gate 1233 is connected to the output voltage feedback signal VFB, the output end thereof is connected to the output end of the first transmission gate 1232, the normal phase control signal is connected to the output end of the inverter 1234, and the reverse phase control signal is connected to the output signal of the comparator 1231.
More specifically, the input end of the voltage-to-current amplifying unit 124 is connected to the signal selecting unit 123 and a reference signal VREF, respectively, and compares the output signal DS of the signal selecting unit 123 with the reference signal VREF, and converts the comparison result into a current signal, and then outputs a compensation current, which is connected to the external loop compensation module and converted into a compensation voltage VCOMP. In this embodiment, the inverting input terminal of the voltage-to-current amplifying unit 124 is connected to the output terminal of the signal selecting unit 123, and the non-inverting input terminal is connected to the reference voltage VREF. In practical applications, the polarity of the input terminal of the voltage-to-current amplifying unit 124 can be changed by adding an inverter, which is not limited to the present embodiment.
More specifically, the pulse width modulation unit 125 is connected to the output end of the voltage-to-current amplifying unit 124, and adjusts the duty ratio of the control signal of the first switch 126 or the second switch 127 according to the compensation voltage VCOMP.
More specifically, the first switch 126 is connected between the input voltage VIN and the inductor 13, and is used for controlling the storage and release of the electric energy of the inductor 13, so as to control the output current IOUT and the output voltage VOUT of the voltage-reducing circuit 1 to be constant. When the first switch 126 is turned on, the input voltage VIN charges the inductor 13; when the first switch 126 is turned off, the inductor 13 discharges. The first switch 126 may be implemented with MOS switches including, but not limited to, NMOS and PMOS.
More specifically, one end of the second switch 127 connects the connection node of the first switch 126 and the inductor 13, and the other end is grounded, so as to control a freewheeling path from ground to the inductor 13 to reduce voltage drop and loss. The second switch 127 may be implemented by a MOS switch, including but not limited to an NMOS and a PMOS, and in this embodiment, the second switch 127 is an NMOS transistor.
As shown in fig. 1, the loop compensation module 18 is connected to the constant current and constant voltage control module 12, and is configured to generate a corresponding compensation voltage VCOM according to the compensation current.
Specifically, the loop compensation module 18 includes a compensation resistor 181, a first compensation capacitor 182, and a second compensation capacitor 183, where one end of the compensation resistor 181 is connected to the constant current and constant voltage control module 12, the other end is connected to the first compensation capacitor 182, and the other end of the first compensation capacitor 182 is grounded; one end of the second compensation capacitor 183 is connected to the constant current and constant voltage control module 12, and the other end is grounded. In some implementations, the second compensation capacitor 183 may be omitted.
The invention also provides a common compensation method of the voltage-reducing circuit, which comprises the following steps:
sampling output current and output voltage, obtaining an output voltage feedback signal and an output current sampling signal, comparing the larger one of the output voltage feedback signal and the output current sampling signal under the same working voltage with a reference voltage, obtaining corresponding common compensation voltage according to a comparison result, and performing pulse width modulation on a switch control signal by using the compensation voltage so as to control output constant voltage and constant current.
In the present embodiment, the step-down circuit 1 based on the common compensation realizes a common compensation method.
Specifically, the output voltage feedback signal VFB and the output current sampling signal VCS are obtained based on the output voltage feedback module 14 and the output current sampling module 16, respectively.
Specifically, the output current sampling signal VCS is filtered based on the filtering unit 121, to obtain a signal SEN after the output current sampling signal VCS is filtered.
Specifically, the signal SEN (or the output current sampling signal VCS) filtered by the output current sampling signal VCS is amplified or reduced to the output current conversion signal SENBF based on the voltage conversion unit 122, and the operation voltage of the output current conversion signal SENBF is consistent with the operation voltage of the output voltage feedback signal VFB, so that comparison of subsequent circuits is facilitated. In this embodiment, according to the principle of virtual short and virtual break, the connection node of the first resistor 1224 and the second resistor 1225 is forced to be equal to the output voltage SEN of the filtering unit 121
By setting the first resistance 1224 and the second resistance 1225, let +.>
The required output current conversion signal SENBF is obtained, so that the two input signals of the signal selection unit 123 are located at the same level. The required output current conversion signal SENBF satisfies the following relation: senbf=k·sen; wherein K is a fixed constant and +.>
V FB Is a feedback voltage calibration point in constant voltage output, V CS And (5) sampling a voltage calibration point for constant current output.
Specifically, the larger one of the output current conversion signal SENBF and the output voltage feedback signal VFB is selected based on the signal selection unit 123 and is used as the output signal DS.
Specifically, the output signal DS of the signal selecting unit 123 is compared with the reference signal VREF based on the voltage-to-current amplifying unit 124, and the comparison result is converted into a current signal to output a compensation current.
Specifically, the compensation current is received based on the loop compensation module 18 and converted to a compensation voltage VCOMP. When the larger of the output voltage feedback signal VFB and the output current conversion signal SENBF is greater than the reference voltage VREF, the compensation voltage VCOMP decreases; when the larger of the output voltage feedback signal VFB and the output current conversion signal SENBF is smaller than the reference voltage VREF, the compensation voltage VCOMP increases.
Specifically, the pulse width modulation unit 125 adjusts the on-time of the first switch 126 and the second switch 127 under the control of the compensation voltage VCOMP to achieve the constant output voltage VOUT of the buck circuit 1 with the common compensation and the constant output current IOUT through the load 15. In this embodiment, the output voltage VOUT satisfies the following relationship:
wherein V is OUT To output voltage V FB Is a feedback voltage calibration point in constant voltage output,
a dividing resistance ratio for the output voltage; the output current IOUT satisfies the following relation: />
Wherein I is OUT To output current, V CS For the sampling voltage calibration point in constant current output, R 16 A sampling resistor for the output current.
More specifically, the first switch control signal HS of the pwm unit 125 controls the first switch 126, and in each period, the first switch control signal HS adjusts the on-time of the first switch 126 according to the difference of the compensation voltage VCOMP values, which are in positive relationship. The second switch 127 is controlled by a second switch control signal LS of the pulse width modulation unit 125, which is related to the operation states of the first switch 126 and the inductor 13. The first switch 126 and the second switch 127 form two current loops: a first loop, in which when the first switch control signal HS controls the first switch 126 to be turned on and the second switch control signal LS controls the second switch 127 to be turned off, the voltage input module 11 is pressurized to the high level at the lx end of the inductor 13 through the first switch 126, and then flows through the load 15 and the output current sampling module 16 after the VOU ends of the first switch 126 and the inductor 13 are pressurized to the high level, and returns to the ground end of the voltage input module 11; in the second loop, after the first switch control signal HS controls the first switch 126 to be turned off, because of the freewheeling characteristic of the inductor 13, the voltage at two ends of the inductor 13 is inverted, the VOUT end is at a high level, the LX end is at a low level, the current gradually decreases, the current passes from the ground to the LX end through the second switch 127 and flows into the inductor 13, and then returns to the ground through the load 15 and the output current sampling module 16, and when the current decreases to zero, that is, the voltage at the LX end is the same as the ground, the second switch control signal LS controls the second switch 127 to be turned off. That is, the first switch control signal HS and the second switch control signal LS control the first switch 126 and the second switch 127, which are characterized in that: when the first switch 126 is turned on, the second switch 127 is turned off; the second switch 127 is only turned on when the first switch 126 is turned off and LX voltage is lower than ground.
The constant-current and constant-voltage control module, the voltage reducing circuit and the compensation method share one compensation network through processing the current loop signal and the voltage loop signal, so that the voltage reducing conversion with constant-current and constant-voltage output characteristics is realized, the number of components of the peripheral compensation network is halved, and the chip area can be reduced more when the compensation network is arranged in a chip.
In summary, the present invention provides a constant current and constant voltage control module, a voltage reduction circuit and a compensation method for common compensation, including: a voltage input module for providing an input voltage; an inductance for outputting stable electric energy; a load; an output current sampling module for generating an output current sampling signal; an output voltage feedback module that generates an output voltage feedback signal; the constant-current constant-voltage control module generates compensation current according to the output current sampling signal and the output voltage feedback signal and is controlled by the loop compensation module to perform constant-current constant-voltage control; and the loop compensation module generates corresponding compensation voltage according to the compensation current. Sampling output current and output voltage, obtaining an output voltage feedback signal and an output current sampling signal, comparing the larger one of the output voltage feedback signal and the output current sampling signal under the same working voltage with a reference voltage, obtaining corresponding common compensation voltage according to a comparison result, and performing pulse width modulation on a switch control signal by using the compensation voltage so as to control output of constant voltage or constant current. The constant-current and constant-voltage control module, the voltage reducing circuit and the compensation method share one compensation network by processing the current loop signal and the voltage loop signal, so that the voltage reducing conversion with constant-current and constant-voltage output characteristics is realized, the number of components serving as a peripheral compensation network is halved, and the chip area can be reduced more when the compensation network is arranged in a chip. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (14)
1. The utility model provides a constant current constant voltage control module of sharing compensation which characterized in that: the constant current and constant voltage control module at least comprises:
the device comprises a voltage conversion unit, a signal selection unit, a voltage-to-current amplification unit, a pulse width modulation unit, a first switch and a second switch;
the voltage conversion unit receives an output current sampling signal of the voltage reduction circuit, amplifies or reduces the output current sampling signal into an output current conversion signal, and the working voltage of the output current conversion signal is consistent with the working voltage of an output voltage feedback signal of the voltage reduction circuit;
the signal selection unit is connected with the output end of the voltage conversion unit and receives the output voltage feedback signal to select the larger one of the output current conversion signal and the output voltage feedback signal as an output signal;
the input end of the voltage-to-current amplifying unit is respectively connected with the signal selecting unit and a reference signal, the output signal of the signal selecting unit is compared with the reference signal, the comparison result is converted into a current signal, and then compensation current is output, and the compensation current is connected with the external loop compensation module and is converted into compensation voltage;
the pulse width modulation unit is connected to the output end of the voltage-to-current amplification unit, and adjusts the duty ratio of the control signal of the first switch or the second switch according to the compensation voltage;
the first switch is connected between the input voltage of the voltage reduction circuit and the inductor of the voltage reduction circuit and is used for controlling the inductor to store and release electric energy so as to control the output current and the output voltage of the voltage reduction circuit to be constant;
one end of the second switch is connected with a connecting node of the first switch and the inductor, and the other end of the second switch is grounded and used for controlling a follow current channel from ground to the inductor so as to reduce voltage drop and loss.
2. The constant current and constant voltage control module according to claim 1, wherein: and a filtering unit is further connected between the voltage conversion unit and the output current sampling signal, and the filtering unit is an RC filtering unit.
3. The constant current and constant voltage control module according to claim 1 or 2, characterized in that: the voltage conversion unit comprises an operational amplifier, an NMOS tube, a current source, a first resistor and a second resistor; the positive input end of the operational amplifier is connected with a front-stage output signal, the output end of the operational amplifier is connected with the gate end of the NMOS tube, the current source, the first resistor and the second resistor are sequentially connected in series and then grounded, and the drain end of the NMOS tube is connected with the output end of the current source and outputs the output current conversion signal, and the source end is grounded; and the connection nodes of the first resistor and the second resistor are connected with the inverting input end of the operational amplifier.
4. The constant current and constant voltage control module according to claim 1, wherein: the signal selection unit comprises a comparator, a first transmission gate and a second transmission gate, wherein the non-inverting input end of the comparator is connected with the output current conversion signal, and the inverting input end of the comparator is connected with the output voltage feedback signal; the input end of the first transmission gate is connected with the output current conversion signal, the output end of the first transmission gate is connected with the output end of the second transmission gate and used as the output end of the signal selection unit, the positive control signal is connected with the output signal of the comparator, and the negative control signal is connected with the negative signal of the output signal of the comparator; the input end of the second transmission gate is connected with the output voltage feedback signal, the output end of the second transmission gate is connected with the output end of the first transmission gate, the positive control signal is connected with the inverse signal of the output signal of the comparator, and the negative control signal is connected with the output signal of the comparator.
5. A common-compensated buck circuit, comprising:
a voltage input module, a constant-current and constant-voltage control module, a loop compensation module, an inductor, an output voltage feedback module, a load and output current sampling module according to any one of claims 1 to 4;
the voltage input module provides input voltage;
one end of the inductor is connected with the constant-current constant-voltage control module, and the other end of the inductor is used as a voltage output end and is used for outputting stable output voltage and output current;
one end of the load is connected with output voltage, the other end of the load is grounded after passing through the output current sampling module, and the output current sampling module generates an output current sampling signal;
the output voltage feedback module is connected between the output voltage and the ground and is used for generating an output voltage feedback signal;
the constant-current constant-voltage control module is connected with the output ends of the voltage input module, the output voltage feedback module and the output current sampling module, generates compensation current according to the output current sampling signal and the output voltage feedback signal, and performs constant control on the output voltage and the output current under the control of the loop compensation module;
the loop compensation module is connected with the constant-current constant-voltage control module and is used for generating corresponding compensation voltage according to the compensation current.
6. The buck circuit of claim 5, wherein: the output voltage feedback module comprises a first sampling resistor and a second sampling resistor which are connected in series, and the first sampling resistor and the second sampling resistor divide the output voltage so as to obtain the output voltage feedback signal.
7. The buck circuit of claim 5, wherein: the loop compensation module comprises a compensation resistor and a first compensation capacitor, one end of the compensation resistor is connected with the constant-current constant-voltage control module, the other end of the compensation resistor is connected with the first compensation capacitor, and the other end of the first compensation capacitor is grounded.
8. The buck circuit of claim 7, wherein: the loop compensation module further comprises a second compensation capacitor, wherein one end of the second compensation capacitor is connected with the constant-current constant-voltage control module, and the other end of the second compensation capacitor is grounded.
9. The buck circuit of claim 5, wherein: the voltage reducing circuit with the common compensation further comprises an output capacitor, wherein one end of the output capacitor is connected with the voltage output end, and the other end of the output capacitor is grounded.
10. A method of common compensation for a voltage step-down circuit, implemented based on the common compensation as claimed in any one of claims 5-9, characterized in that the method of common compensation for a voltage step-down circuit comprises at least:
sampling output current and output voltage, obtaining an output voltage feedback signal and an output current sampling signal, comparing the larger one of the output voltage feedback signal and the output current sampling signal under the same working voltage with a reference voltage, obtaining corresponding common compensation voltage according to a comparison result, and performing pulse width modulation on a switch control signal by using the compensation voltage so as to control output constant voltage and constant current.
11. The common compensation method of a voltage-reducing circuit according to claim 10, wherein: and performing voltage conversion on the output current sampling signal to obtain an output current conversion signal, so that the output voltage feedback signal and the output current conversion signal are positioned at the same working voltage, and the following formula is satisfied: senbf=k·sen; wherein SENBF is an output current conversion signal; k is a fixed constant, and
V FB is a feedback voltage calibration point in constant voltage output, V CS Sampling voltage calibration points when constant current is output; SEN is the output current sampling signal.
12. The common compensation method of a voltage-reducing circuit according to claim 10, wherein: and regulating the constant current of the output current through the control of the compensation voltage, wherein the following relation is satisfied:
wherein I is OUT To output current, V CS For the sampling voltage calibration point in constant current output, R 16 A sampling resistor for the output current.
13. The common compensation method of a voltage-reducing circuit according to claim 10, wherein: and regulating the constant current of the output voltage by controlling the compensation voltage, wherein the following relation is satisfied:
wherein V is OUT To output voltage V FB For the feedback voltage calibration point at constant voltage output, < >>
Is the voltage dividing resistance ratio of the output voltage.
14. The common compensation method of a voltage-reducing circuit according to claim 10, wherein: the constant current or constant voltage control further includes:
when the larger of the output voltage feedback signal and the output current sampling signal under the same working voltage is larger than the reference voltage, the compensation voltage is reduced; the compensation voltage increases when a larger one of the output voltage feedback signal and the output current sampling signal at the same operating voltage is less than the reference voltage.
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| CN103532378A (en) * | 2012-07-05 | 2014-01-22 | 晶豪科技股份有限公司 | Voltage converter capable of suppressing output voltage overshooting |
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| CN103532378A (en) * | 2012-07-05 | 2014-01-22 | 晶豪科技股份有限公司 | Voltage converter capable of suppressing output voltage overshooting |
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