CN105763052A - Average current control circuit and average current control method - Google Patents
Average current control circuit and average current control method Download PDFInfo
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- CN105763052A CN105763052A CN201610262432.9A CN201610262432A CN105763052A CN 105763052 A CN105763052 A CN 105763052A CN 201610262432 A CN201610262432 A CN 201610262432A CN 105763052 A CN105763052 A CN 105763052A
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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
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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
- H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
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Abstract
The invention discloses an average current control circuit and an average current control method. In the circuit, one input terminal of an average current detection module is connected to a reference voltage signal output terminal of a band gap reference source, and another input terminal is connected to a source terminal of a power switch. A voltage transmission signal output terminal of the average current detection module is connected to an input terminal of a current regulator. Another input terminal of the current regulator is connected to the reference voltage signal output terminal of the band gap reference source, and an output terminal is connected to a negative input terminal of a comparator. An oblique wave generator input terminal is connected to the source terminal of the power switch, and an output terminal is connected to a positive input terminal of the comparator. An input terminal of a logic and driving circuit is connected to an output terminal of the comparator, another input terminal is connected to a switch starting pulse output terminal of an oscillator and an output terminal is connected to a grid terminal of the power switch. The source terminal of the power switch is connected to a grounding terminal via a detection resistor and a drain electrode is connected to a switch power supply module. Constant current precision is high, a current ripple wave is small and anti-noise performance is superior.
Description
Technical field
The invention belongs to microelectronics and technical field of power management, be specifically related to a kind of Average Current Control circuit and average current conversion method.
Background technology
Average Current Control circuit is the control program that constant current source is common, and at energy-saving illuminating circuit, screen back light source, there is important application in the field such as high-power illumination.Compared with peak current control circuitry and hysteresis current control circuit, the advantages such as the circuit of average current control mode has control accuracy height, and current ripples is little, and noise robustness is superior.But the restriction of its controlled principle often circuit structure is complicated, design difficulty is big, and response speed is slower.
Common Average Current Control circuit needs directly detection to flow through the electric current of inductance, therefore sampling resistor must be in series with inductance and detect the change of resistance both end voltage signal, for adjusting and voltage-reduction switch power supply, no matter adopt which kind of topological structure, this detection any one end of resistance is all without being practically, therefore want the change in voltage at detection resistance two ends, can only adopt and reset a chip ground, so higher designing requirement can be proposed control circuit other parts, or need to detect the voltage at resistance two ends simultaneously, but so it is not suitable for high-voltage applications circuit, even low-voltage circuit, being also required to more complicated current detection module by the photovoltaic conversion at resistance two ends is electric current.Due to the complexity of current detecting, the serious application limiting Average Current Control circuit, also increase the design complexities of circuit, occupy bigger chip area, add power consumption.
Summary of the invention
The technical problem to be solved in the present invention there is provided a kind of novel Average Current Control circuit, by novel current detecting and control mode, is substantially reduced the complexity of Average Current Control circuit design, reduces hardware spending and power attenuation.
For solving the problems referred to above, the present invention provides a kind of Average Current Control circuit and Average Current Control method, circuit includes power switch, inductance, electric capacity, detection resistance, band gap reference, comparator, agitator, logical AND drive circuit, average current detection module, rheonome and ramp generator, wherein, average current detection module, the circuit structure of rheonome and ramp generator and annexation, it it is the innovation of the present invention, constitute the core of Average Current Control circuit, the work process of integrated circuit constitutes the Average Current Control method of the present invention, function and the annexation of nucleus module are as follows:
Average current detection module, by inputting the reference voltage signal that the voltage detection signal detecting ohmically reflected load size of current produces with band gap reference, generate voltage transmission signal, when power switch turns on, the output of average current detection module is produced voltage detection signal on sampling resistor；When power switch turns off, reference voltage signal produced by average current detection module output band gap reference；
Rheonome, it is integrated by voltage being transmitted the difference of signal and reference voltage signal, the control signal generated is sent to described comparator, control the meansigma methods of voltage transmission signal equal to reference voltage signal, during system stability, reference voltage signal is, divided by the size of detection resistance, the average current size controlled；
Ramp generator, by voltage detection signal integration and reset, producing ramp signal, be sent to described comparator, the control signal to produce with rheonome compares, and controls the shutoff of power switch.
Described average current detection module includes first, second switch；
Above-mentioned signal, for controlling reflecting that the voltage detection signal of switching current size sends rheonome on detection resistance during power switch turns on, is isolated by described first switch when power switch turns off；
Above-mentioned signal, for controlling to send the reference voltage signal that band gap reference produces to rheonome during power switch turns off, is isolated by described second switch when power switch turns on；
Wherein, described first switch one end connects the non-ground-end of described detection resistance, and the other end connects described rheonome, and it controls end and is connected to logical AND drive circuit；
Described second switch one end connects the reference voltage signal that described band gap reference produces, and the other end connects described rheonome, and it controls end end and is connected to logical AND drive circuit.
Described rheonome includes resistance, integrating capacitor, operational amplifier；
Described resistance is for controlling the size of integration current；
Described integrating capacitor is for producing to control voltage to current integration；
Described operational amplifier is for making its positive and negative input terminal voltage consistent by negative feedback；
Wherein, described resistance one end connects described average current detection module outfan, other end concatenation operation amplifier negative input end, and integrating capacitor；
Described integrating capacitor one end connects resistance and operational amplifier negative input end, other end concatenation operation amplifier out, and described comparator negative input end；
Described operational amplifier positive input terminal connects the reference voltage signal that described band gap reference produces, and negative input end connects integrating capacitor and resistance, and outfan connects the integrating capacitor other end and described comparator negative input end.
Described ramp generator input is connected to the non-ground-end of detection resistance, and output ramp signal is connected to the positive input terminal of comparator, specifically includes operational amplifier, feedback transistor, current-limiting resistance, current mirror, integrating capacitor, and reset switch；
Described operational amplifier is for making its positive and negative input terminal voltage consistent by negative feedback；
Described feedback transistor is for regulating the electric current flowing through current mirror；
Described current-limiting resistance is for being converted into electric current by input voltage；
Described current mirror is for replicating electric current in proportion, and proportionate relationship sets according to resistance, capacitance, and circuit work frequency；
Described integrating capacitor is for current integration, producing oblique wave rising signals；
Described reset switch is for resetting to ramp signal during turning off at power switch；
Wherein, described operational amplifier positive input terminal connects detection resistance non-ground-end, and negative input end connects current-limiting resistance non-ground-end and feedback transistor source, and outfan connects feedback transistor grid end；
Described feedback transistor source concatenation operation amplifier negative input end, and current-limiting resistance non-ground-end, drain terminal connects current mirror input, grid end concatenation operation amplifier out；
Described current-limiting resistance one end concatenation operation amplifier negative input end, and feedback transistor source, the other end connects ground；
Described current mirror one end connects feedback transistor drain terminal, and the other end connects integrating capacitor non-ground-end and reset switch non-ground-end；
Described integrating capacitor one end connects reset switch non-ground-end and current mirror outputs, and the other end connects ground；
Described reset switch one end connects ground, and the other end connects integrating capacitor non-ground-end and current mirror outputs.
Described Average Current Control method, comprises the steps:
Step 1: when power switch turns on, the electric current of power switch is flow through in the detection of average current current detection module, and the voltage detection signal of reflection size of current is sent to rheonome input；
Step 2: when power switch turns on, ramp generator will flow through the electric current integration in proportion of power switch, and proportionate relationship is by the current mirror ratio detecting resistance and ramp generator, and resistance determines with capacitance, and oblique wave rising signals is sent to comparator positive input terminal；
Step 3: when power switch turns off, the reference voltage signal that average current detection module input band gap reference produces, reference voltage signal is sent to rheonome input；
Step 4: when power switch turns off, ramp generator resets, and low level signal is sent to comparator positive input terminal；
Step 5: the reference voltage signal that voltage transmission signal and the band gap reference that average current detection module is exported by rheonome produces does after the recovery integration, produces control signal, is sent to comparator negative input end；
Step 6: the signal of input positive input terminal and negative input end is compared by comparator, when ramp signal voltage is higher than control signal voltage, comparator upset output high level, produce power switch cut-off signals, be sent to logic circuit；
Step 7: during each cycle internal oscillator high level, produces power switch Continuity signal, is sent to logic circuit；
Step 8: logic circuit receives power switch cut-off signals and power switch Continuity signal, controls shutoff and the conducting of power switch.
Described step 1 specifically includes: when power switch turns on, average current detection module the first switch conduction, the voltage signal of the reflection power switch size of current that output detections resistance detection arrives.
Described step 3 specifically includes: when power switch turns off, and current detection module second switch turns on, the reference voltage signal that output band gap reference produces.
Compared with prior art, beneficial effects of the present invention:
1, detecting resistance in technical solution of the present invention directly to connect with power switch, rather than connect with inductance, only during power switch turns on, just have electric current to flow through detection resistance, compared to holocyclic detection, power consumption penalty is less；
2, average current detection module inputs signal switching between detection resistive voltage and reference voltage within each cycle, by subsequent control circuit, by only gathering current signal during power switch conducting, rather than complete period curent change, the size of load average electric current can be controlled.Make testing circuit be greatly simplified, it also avoid chip circuit under high-voltage applications simultaneously and to redefine chip ground, reduce design difficulty；
3, ramp generator is to pass through operational amplifier, resistance and current-mirror structure produce accurate voltage-controlled current source and load capacitance are charged, produce oblique wave rising signals, when power switch closes, load capacitance is resetted, more accurate ramp signal slope must can be controlled, the capacity of resisting disturbance of circuit is greatly increased, and adds a feedback loop, improves response speed；
In sum, technical solution of the present invention is that the constant current source adopting Average Current Control circuit provides a new detection and control method, both the advantage of Average Current Control circuit itself had been remained, namely constant current accuracy is high, and current ripples is little, and noise robustness is superior, the shortcoming that compensate for again it to a certain extent, improve current detection scheme, optimize current detection circuit, reduce the complexity of power attenuation and circuit design.The needs of application are better met.
Accompanying drawing explanation
The Average Current Control electrical block diagram that Fig. 1 provides for one embodiment of the invention；
The Average Current Control circuit detailed construction schematic diagram that Fig. 2 provides for one embodiment of the invention；
Waveform diagram during the Average Current Control circuit stability that Fig. 3 provides for one embodiment of the invention.
Detailed description of the invention
For making the purpose of the present invention, content and advantage clearly, below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following example are only for clearly illustrating technical scheme, and can not limit the scope of the invention with this.
First, explain that the key feature of technical solution of the present invention is in that:
1) average current detection module controls load average electric current by the electric current during sampled power switch conduction；
2) voltage-controlled current source of ramp generator is to consist of operational amplifier, resistance and current-mirror structure, it is possible to the more precise control oblique wave rate of rise.
Embodiment
First the present embodiment describes the major architectural structure of a kind of Average Current Control circuit provided by the present invention and corresponding Average Current Control method.
As it is shown in figure 1, described Average Current Control circuit, including load LED, power switch NMOS, inductance L0, electric capacity C0, detection resistance Rcs, band gap reference, agitator；Comparator and logic and driver circuitry；
Additionally, this control circuit also includes:
Current detection module, during power switch turns on, is connected to the source of the NMOS of described power switch and the non-ground-end of detection resistance Rcs, and the electric current of power switch NMOS is flow through in detection, during power switch turns off, is connected to described band gap reference；
Ramp generator, during power switch turns on, is connected to the source of the NMOS of described power switch and the non-ground-end of detection resistance Rcs, produces voltage-controlled oblique wave rising signals, and during power switch turns off, ramp generator resets；
Rheonome, it is connected to described average current detection module, the reference voltage signal produced for the output voltage of average current detection module transmits signal and band gap reference does after the recovery and is integrated in proportion, proportionate relationship is determined by the resistance in rheonome and electric capacity, during final control balance, voltage transmission signal is equal with reference voltage signal, makes load average electric current equal to reference voltage signal divided by detection resistance；
Comparator, connects described rheonome and ramp generator, and when in each cycle, ramp signal exceedes rheonome integrated signal, comparator overturns, and produces power switch and turns off pulse signal；
Logical AND drive circuit, connects described comparator and agitator, produces the control signal for controlling described power switch NMOS.
Described Average Current Control method comprises the steps:
Step 1: when power switch NMOS turns on, the electric current of power switch is flow through in the detection of average current detection module, and the voltage detection signal of reflection size of current is sent to rheonome input；
Step 2: when power switch NMOS turns on, ramp generator will flow through the electric current integration in proportion of power switch, and oblique wave rising signals is sent to comparator positive input terminal；
Step 3: when power switch NMOS turns off, the reference voltage signal that average current detection module input band gap reference produces, reference voltage signal is sent to rheonome input；
Step 4: when power switch NMOS turns off, ramp generator resets, and low level signal is sent to comparator positive input terminal；
Step 5: the reference voltage signal that the voltage signal that current detection module is inputted by rheonome and band gap reference produce does after the recovery integration, produces control signal, is sent to comparator negative input end；
Step 6: the signal of input positive input terminal and negative input end is compared by comparator, when ramp signal voltage is higher than control signal voltage, comparator upset output high level, produce power switch and turn off pulse signal, be sent to logical AND drive circuit；
Step 7: during each cycle internal oscillator output high level, produce power switch conduction pulses signal, be sent to logical AND drive circuit；
Step 8: logical AND drive circuit receives power switch cut-off signals and power switch Continuity signal, controls shutoff and the conducting of power switch.
Next the current detection module that described average current controller comprises, rheonome, and the concrete structure of ramp generator and corresponding workflow are specifically described.
As in figure 2 it is shown, described average current detection module includes first, second switch S1, S2；
Described first switch S1 reflects that the voltage detection signal of switching current size sends rheonome to for controlling will detect during power switch NMOS turns on resistance, is isolated by above-mentioned signal when switching NMOS and turning off；
Above-mentioned signal, for controlling to send the reference voltage signal that band gap reference produces to rheonome during power switch NMOS turns off, is isolated by described second switch S2 when switching NMOS conducting；
Wherein, described first switch S1 one end connects the non-ground-end of described detection resistance Rcs, and the other end connects described rheonome, and it controls end and is connected to logical AND drive circuit；
Described second switch S2 one end connects the reference voltage signal that described band gap reference produces, and the other end connects described rheonome, and it controls end and is connected to logical AND drive circuit；
The workflow of described average current detection module is specific as follows:
When power switch NMOS turns on, the first switch S1 conducting, the input of average current detection module flows through, for what detection resistance Rcs detected, the voltage detection signal that NMOS electric current converts；
When power switch NMOS turns off, second switch S2 turns on, the reference voltage signal that the input of average current detection module produces for band gap reference；
It addition, about described rheonome, including resistance R1, integrating capacitor C1, operational amplifier；
Described resistance R1 is for controlling the size of integration current；
Described integrating capacitor C1 is for producing to control voltage to current integration；
Described operational amplifier is for making positive and negative input terminal voltage consistent by negative feedback control；
Wherein, described resistance R1 one end connects described average current detection module outfan, other end concatenation operation amplifier negative input end, and integrating capacitor C1；
Described integrating capacitor C1 one end connects resistance R1 and operational amplifier negative input end, other end concatenation operation amplifier out, and described comparator negative input end；
Described operational amplifier positive input terminal connects the reference voltage signal that described band gap reference produces, and negative input end connects integrating capacitor C1 and resistance R1, and outfan connects the integrating capacitor C1 other end and the negative input end of described comparator.
Described rheonome workflow is specific as follows:
When power switch NMOS turns on, if the voltage transmission signal of average current detection module output is less than reference voltage signal, then the control signal voltage of actuator output increases, and makes the moment that ramp signal reaches the control signal that integrator exports postpone, increase dutycycle, make load current signal increase；If the voltage transmission signal that average current detection module exports is more than reference voltage signal, then the control signal voltage of actuator output reduces, and makes the moment that ramp signal reaches the control signal voltage that actuator exports shift to an earlier date, reduces dutycycle, make load current reduce；If the voltage transmission signal of average current detection module output is first less than reference voltage signal in switch conduction times, again more than reference voltage signal, and the downward integration amount of actuator and upwards integration amount is equal, then regulator output voltage reaches dynamic equilibrium, system enters steady statue, namely the current average flowing through load is equal to reference voltage signal divided by detection resistance Rcs.
When power switch NMOS turns off, the voltage transmission signal that average current detection module exports out is equal to reference voltage signal, and the control signal voltage of actuator output is constant；
About described ramp generator, including operational amplifier, feedback transistor NMOS1, the current mirror of current-limiting resistance R2, PMOS1 and PMOS2 composition, integrating capacitor C2 and reset switch S3；
Described operational amplifier OP2 is for keeping positive input terminal and negative input end voltage equal by negative feedback；
Described feedback transistor NMOS1 is for regulating the electric current flowing through current mirror；
Described current-limiting resistance R2 is for being converted into electric current by input voltage measurement signal；
Described current mirror is for replicating the electric current flowing through R2 in proportion；
Described integrating capacitor C2 is for current integration, producing oblique wave rising signals；
Described reset switch S3 is for resetting to ramp signal during turning off at power nmos switch；
Wherein, described operational amplifier positive input terminal connects detection resistance Rcs non-ground-end, and negative input end connects current-limiting resistance R2 non-ground-end and feedback transistor NMOS1 source, and outfan connects feedback transistor NMOS1 grid end；
Described feedback transistor NMOS1 source concatenation operation amplifier OP2 negative input end, and current-limiting resistance R2 non-ground-end, drain terminal connects current mirror input, grid end concatenation operation amplifier OP2 outfan；
Described current-limiting resistance R2 one end concatenation operation amplifier OP2 negative input end, and feedback transistor NMOS1 source, the other end connects ground GND；
Described current mirror one end connects feedback transistor NMOS1 drain terminal, and the other end connects integrating capacitor C2 non-ground-end and reset switch S3 non-ground-end；
Described integrating capacitor C2 one end connects reset switch S3 non-ground-end and current mirror outputs, and the other end connects ground GND；
Described reset switch S3 one end connects ground, and the other end connects integrating capacitor C2 non-ground-end；
The workflow of described ramp generator is specific as follows:
When power switch NMOS turns on, voltage detection signal input on detection resistance Rcs, by the negative feedback of operational amplifier, the voltage of the negative input end of operational amplifier is equal to voltage detection signal, by resistance R2, it is converted into electric current, size of current is that voltage detection signal is divided by resistance R2, because breadth length ratio (W2/L2)/(the W1/L1)=n of PMOS2 and PMOS1 in current mirror, therefore the voltage detection signal that image current is n times is divided by resistance R2, this electric current is proportional to voltage detection signal, load capacitance C2 is charged, voltage detection signal is more big, ramp slopes is more big, the moment that ramp signal reaches the control signal voltage that rheonome exports is made to shift to an earlier date, reduce dutycycle, load current signal is made to reduce；Voltage detection signal is more little, ramp slopes is more little, ramp signal is made to reach moment of control signal voltage of rheonome output delayed, increase dutycycle, load current signal is made to increase, until the meansigma methods of load current signal is stablized at reference voltage signal divided by detection resistance Rcs, system stability works；
When power switch NMOS turns off, reset switch S3 turns on, then ramp signal resets, output low level；
As it is shown on figure 3, waveform diagram during Average Current Control circuit stability designed by the present invention:
Logical AND drive circuit output signal controls the switch of power NMOS tube, and during NMOS conducting, the detection electric current that flows through of resistance Rcs is inductive current, and due to the inductance integral action to voltage, electric current constantly rises, and voltage detection signal constantly increases；When NMOS turns off, the electric current flowing through detection resistance Rcs is 0, and voltage detection signal is 0；The voltage electromotive signal that voltage transmission signal is detection resistance Rcs sampling of average current detection module output and the switching of reference voltage signal；The ramp signal Ramp that the control signal that input signal is rheonome output of comparator produces with ramp generator, in its equal moment, power switch NMOS tube turns off；Load current signal is the electric current flowing through load, and when steady operation, load current signal fluctuates divided by the detection upper and lower little scope of resistance Rcs at average current reference voltage signal.
The above is only the preferred embodiment of the present invention; it should be pointed out that, for those skilled in the art, under the premise without departing from the technology of the present invention principle; can also making some improvement and deformation, these improve and deformation also should be regarded as protection scope of the present invention.
Claims (9)
1. an Average Current Control circuit, it is characterised in that include band gap reference, comparator, agitator, logical AND drive circuit, average current detection module, rheonome and ramp generator；Wherein, one input of this average current detection module is connected with the reference voltage signal outfan of this band gap reference, another input is connected with the source of power switch, and the voltage transmission signal output part of this average current detection module is connected with an input of this rheonome；Another input of this rheonome is connected with the reference voltage signal outfan of this band gap reference, and outfan is connected with the negative input end of this comparator；The input of this ramp generator is connected with the source of this power switch, and outfan is connected with the positive input terminal of this comparator；One input of this logical AND drive circuit is connected with the outfan of this comparator, and another input is connected with the switch open pulse output end of this agitator, and outfan is connected with the grid end of this power switch；The source of this power switch detects resistance through one and is connected with earth terminal, and drain electrode is connected with switch power module.
2. circuit as claimed in claim 1, it is characterised in that described average current detection module includes the first switch, second switch；Wherein, this voltage detection signal and this rheonome, for controlling to reflect on this detection resistance that the voltage detection signal of switching current size send this rheonome to during this power switch turns on, are isolated by described first switch when this power switch turns off；Described second switch is for controlling to send the reference voltage signal that band gap reference produces to this rheonome during this power switch turns off, when this power switch turns on by this reference voltage signal and the isolation of this rheonome.
3. circuit as claimed in claim 1 or 2, it is characterised in that described rheonome includes resistance, integrating capacitor, operational amplifier；Described resistance one end is connected with the outfan of this average current detection module, and the other end is connected with the negative input end of this operational amplifier, integrating capacitor one end respectively；This operational amplifier positive input terminal is connected with the reference voltage signal outfan of this band gap reference, and outfan is connected with this integrating capacitor other end.
4. circuit as claimed in claim 1, it is characterised in that described ramp generator includes operational amplifier, feedback transistor, current-limiting resistance, current mirror, integrating capacitor and reset switch；Wherein, this operational amplifier positive input terminal connects the non-ground-end of this detection resistance, and negative input end connects the source of this current-limiting resistance non-ground-end, this feedback transistor respectively, and outfan connects the grid end of this feedback transistor；The drain terminal of this feedback transistor connects this current mirror input；The outfan of this current mirror connects integrating capacitor non-ground-end, this reset switch non-ground-end respectively；This integrating capacitor other end, this reset switch other end and this current-limiting resistance other end connect earth terminal.
5. circuit as claimed in claim 4, it is characterised in that described current mirror is for replicating electric current in proportion, and proportionate relationship sets according to current-limiting resistance, the capacitance of integrating capacitor and circuit work frequency.
6., based on an Average Current Control method for Average Current Control circuit described in claim 1, the steps include:
1) logical AND drive circuit produces according to agitator power switch start signal and the switch OFF signal of comparator output control shutoff and the conducting of power switch；
2) when power switch turns on, the electric current of power switch is flow through in the detection of average current current detection module, and the voltage detection signal of reflection size of current is sent to rheonome input；Ramp generator will flow through the electric current integration in proportion of power switch, and oblique wave rising signals is sent to comparator positive input terminal；When power switch turns off, the reference voltage signal that average current detection module input band gap reference produces, reference voltage signal is sent to rheonome input；Ramp generator resets, and low level signal is sent to comparator positive input terminal；
3) reference voltage signal that the voltage signal that average current detection module is inputted by rheonome and band gap reference produce does after the recovery integration, produces control signal and is sent to comparator negative input end；
4) signal of input positive input terminal and negative input end is compared by comparator, when ramp signal voltage is higher than control signal voltage, and comparator upset output high level, produce power switch and turn off pulse signal, be sent to logical AND drive circuit.
7. method as claimed in claim 6, it is characterised in that described average current detection module includes the first switch S1, second switch S2；When power switch turns on, first switch S1 conducting, average current detection module input for detect resistance detection to flow through the voltage detection signal that power switch electric current converts；When power switch turns off, second switch S2 turns on, the reference voltage signal that the input of average current detection module produces for band gap reference.
8. method as claimed in claim 6, it is characterised in that described rheonome includes resistance, integrating capacitor, operational amplifier；Described resistance one end is connected with the outfan of this average current detection module, and the other end is connected with the negative input end of this operational amplifier, integrating capacitor one end respectively；This operational amplifier positive input terminal is connected with the reference voltage signal outfan of this band gap reference, and outfan is connected with this integrating capacitor other end；Wherein, described operational amplifier is for making positive and negative input terminal voltage consistent by negative feedback control.
9. method as claimed in claim 6, it is characterised in that described ramp generator includes operational amplifier, feedback transistor, current-limiting resistance, current mirror, integrating capacitor and reset switch；Wherein, this operational amplifier positive input terminal connects the non-ground-end of this detection resistance, and negative input end connects the source of this current-limiting resistance non-ground-end, this feedback transistor respectively, and outfan connects the grid end of this feedback transistor；The drain terminal of this feedback transistor connects this current mirror input；The outfan of this current mirror connects integrating capacitor non-ground-end, this reset switch non-ground-end respectively；This integrating capacitor other end, this reset switch other end and this current-limiting resistance other end connect earth terminal.
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| CN106961216A (en) * | 2017-05-15 | 2017-07-18 | 无锡猎金半导体有限公司 | Novel constant output current BUCK circuits |
| CN107124094A (en) * | 2017-06-23 | 2017-09-01 | 南京理工大学 | A kind of Average Current Control circuit and method for reducing control voltage ripple |
| CN109768703A (en) * | 2019-03-07 | 2019-05-17 | 常州大学 | A kind of frequency conversion Average Current Control device and method based on output voltage feedback |
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| CN112014616B (en) * | 2019-05-30 | 2023-03-21 | 伏达半导体(合肥)股份有限公司 | Current detection apparatus and method |
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