CN104297553A - Output voltage detection circuit, control circuit and switch-type converter - Google Patents
Output voltage detection circuit, control circuit and switch-type converter Download PDFInfo
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- CN104297553A CN104297553A CN201410588498.8A CN201410588498A CN104297553A CN 104297553 A CN104297553 A CN 104297553A CN 201410588498 A CN201410588498 A CN 201410588498A CN 104297553 A CN104297553 A CN 104297553A
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Abstract
The invention discloses an output voltage detection circuit, a control circuit and a switch-type converter. The output voltage detection circuit is used for detecting the output voltage of the switch-type converter; the output voltage is rectified and filtered through a rectifier diode and a filter capacitor, and discharging circuits connected to the two ends of the filter capacitor in parallel preset discharging time for the filter capacitor in each switch period, so that the output voltage is accurately detected. Meanwhile, voltage at the two ends of the filter capacitor is rapidly changed along with changes of the output voltage, and therefore the switch-type converter with the voltage detection circuit or an integrated circuit has the good voltage regulation factor.
Description
Technical field
The present invention relates to Power Electronic Technique, be specifically related to output voltage detecting circuit, control circuit and switched mode converter.
Background technology
In switched mode converter, usually its output voltage is needed to feed back in control circuit, be used for comparing with the reference voltage characterizing Switching Power Supply desired output voltage and producing switch control rule control signal, with the switch motion of the switching tube in gauge tap power supply, thus the output voltage of Switching Power Supply is made to be maintained its desired output voltage.Therefore, one is needed for detecting the testing circuit of output voltage.
Existing switched mode converter carries out output voltage detection by the divider resistance being arranged at control circuit chip exterior usually.Fig. 1 is the circuit diagram of existing switched mode converter, and switched mode converter is used for input voltage v
iNbe converted to stable output voltage v
o.Wherein, the resistor voltage divider circuit be made up of the first resistance R1 and the second resistance R2 is connected between the negative pole of voltage output end and sustained diode 1, thus, and output voltage v
obranch pressure voltage v is exported by after resistor voltage divider circuit dividing potential drop
d, branch pressure voltage v
dfeedback voltage v is converted to after sampling hold circuit sampling
fBoutput to comparator circuit, and and then comparative result is input to driving circuit, feedback voltage v
fBactual is output voltage v
odetected value.Thus, can realize output voltage v
odetection.
But, because resistor voltage divider circuit is placed in the outside of control circuit chip, when being in the larger environment of humidity, easily leak electricity between the feedback pin of control circuit chip and other pin, this can cause the change of each ohmically voltage drop in resistor voltage divider circuit, affect the degree of accuracy that output voltage detects, cause the voltage regulation factor of switched mode converter poor.
Summary of the invention
In view of this, a kind of switched mode converter output voltage detecting circuit, control circuit and switched mode converter are provided, switched mode converter can not be affected by the external environment, accurately detect and obtain output voltage, meanwhile, switched mode converter is made to have good voltage regulation factor.
First aspect, provides a kind of output voltage detecting circuit, and for detecting the output voltage of switched mode converter, described output voltage detecting circuit comprises:
Commutation diode, between the voltage output end being connected to described switched mode converter and first end;
Filter capacitor, is connected between described first end and testing circuit reference edge;
Discharge circuit, in parallel with described filter capacitor, for discharging the schedule time to described filter capacitor in each switch periods;
Sampling hold circuit, for sampling to first end voltage or branch pressure voltage, and according to the magnitude of voltage output detections voltage that sampling obtains;
Described branch pressure voltage is obtained after dividing potential drop by described first end voltage.
Preferably, described sampling hold circuit is used for sampling to described first end voltage or branch pressure voltage after described discharge circuit electric discharge terminates delay scheduled time again.
Preferably, described testing circuit reference edge is held with being connected to the control circuit reference of switched mode converter.
Preferably, the power stage circuit of described switched mode converter is voltage-dropping type topology, and described control circuit is connected with the negative pole of the fly-wheel diode of described power stage circuit with reference to ground end.
Preferably, described discharge circuit discharges the schedule time to described filter capacitor when each switch periods starts.
Preferably, described sampling hold circuit switches to shutoff at the power switch of described power stage circuit by conducting, and samples to described first end voltage or branch pressure voltage after the predetermined lead-edge-blanking time again.
Preferably, described output voltage detecting circuit also comprises:
Compensating circuit, in parallel with described filter capacitor, for by flowing through the freewheel current negative feedback of described fly-wheel diode to first end, compensate described first end voltage.
Preferably, described output voltage detecting circuit also comprises:
Resistor voltage divider circuit, in parallel with described filter capacitor, for exporting described branch pressure voltage to after described first end voltage at the second end.
Preferably, described output voltage detecting circuit also comprises:
Compensating circuit, is connected between described second end and described testing circuit reference edge, for by flowing through the freewheel current negative feedback of described fly-wheel diode to described second end, compensates described branch pressure voltage.
Second aspect, provides a kind of control circuit, and for switched mode converter, described integrated circuit comprises:
Output voltage detecting circuit as above;
Comparator circuit, exports comparative result for more described detection voltage and reference voltage;
Driving circuit, for generating switch controlling signal according to described comparative result, described switch controlling signal is for controlling the power stage circuit of described switched mode converter.
Preferably, the discharge circuit of described output voltage detecting circuit, sampling hold circuit and described comparator circuit and driving circuit are integrated into integrated circuit.
The third aspect, provides a kind of switched mode converter, comprises control circuit and power stage circuit;
Described control circuit comprises:
Output voltage detecting circuit as above;
Comparator circuit, exports comparative result for more described detection voltage and reference voltage;
Driving circuit, for generating switch controlling signal according to described comparative result, described switch controlling signal is for controlling described power stage circuit.
Preferably, the discharge circuit of described output voltage detecting circuit, sampling hold circuit and described comparator circuit and driving circuit are integrated into integrated circuit.
By commutation diode and filter capacitor, rectifying and wave-filtering is carried out to output voltage, discharge circuit simultaneously by being connected in parallel on filter capacitor two ends discharges the schedule time to filter capacitor in each switch periods, thus accurately can detect output voltage, and filter capacitor both end voltage is made to follow output voltage change Rapid Variable Design.The switched mode converter applying this voltage detecting circuit or integrated circuit has good voltage regulation factor.
Accompanying drawing explanation
By referring to the description of accompanying drawing to the embodiment of the present invention, above-mentioned and other objects, features and advantages of the present invention will be more clear, in the accompanying drawings:
Fig. 1 is the circuit diagram of existing switched mode converter;
Fig. 2 A is the circuit diagram of the switched mode converter of first embodiment of the invention;
Fig. 2 B is the schematic diagram of discharge circuit in a preferred implementation;
Fig. 3 is the circuit diagram of the switched mode converter of second embodiment of the invention;
Fig. 4 is the working waveform figure of the switched mode converter of second embodiment of the invention.
Embodiment
Based on embodiment, present invention is described below, but the present invention is not restricted to these embodiments.In hereafter details of the present invention being described, detailedly describe some specific detail sections.Do not have the description of these detail sections can understand the present invention completely for a person skilled in the art yet.In order to avoid obscuring essence of the present invention, known method, process, flow process, element and circuit do not describe in detail.
In addition, it should be understood by one skilled in the art that the accompanying drawing provided at this is all for illustrative purposes, and accompanying drawing is not necessarily drawn in proportion.
Meanwhile, should be appreciated that in the following description, " circuit " refers to the galvanic circle connected and composed by electrical connection or electromagnetism by least one element or electronic circuit.When " being connected to " another element when claiming element or circuit or claiming element/circuit " to be connected to " between two nodes, it can be directly couple or be connected to another element or can there is intermediary element, the connection between element can be physically, in logic or its combine.On the contrary, " be directly coupled to " when claiming element or " being directly connected to " another element time, mean that both do not exist intermediary element.
Unless the context clearly requires otherwise, similar words such as " comprising ", " comprising " otherwise in whole instructions and claims should be interpreted as the implication that comprises instead of exclusive or exhaustive implication; That is, be the implication of " including but not limited to ".
In describing the invention, it is to be appreciated that term " first ", " second " etc. are only for describing object, and instruction or hint relative importance can not be interpreted as.In addition, in describing the invention, except as otherwise noted, the implication of " multiple " is two or more.
Fig. 2 A is the circuit diagram of the switched mode converter of first embodiment of the invention.As shown in Figure 2 A, switched mode converter comprises control circuit 21 and power stage circuit 22.
Control circuit 21 is for the output voltage v of detection power level circuit 22
o, generate switch controlling signal Q, control the power switch S1 turn-on and turn-off of power stage circuit, make the voltage of power stage circuit 22 stable output.
Control circuit 21 comprises output voltage detecting circuit 211, comparator circuit 212 and driving circuit 213.
Output voltage detecting circuit 211 connects, for detecting output voltage v with the voltage output end o (also namely, the output terminal of switched mode converter) of power stage circuit 22
ooutput detections voltage v
fB.
Comparator circuit 212 detects voltage v for comparing
fBwith reference voltage v
rEFexport comparative result v
cMP.Reference voltage v
rEFfor characterizing desired output voltage.
Driving circuit 213 is for according to comparative result v
cMPgenerate switch controlling signal Q.
Power stage circuit 22 comprises at least one power switch S1, and power switch S1 is according to switch controlling signal Q turn-on and turn-off.By the turn-on and turn-off of power switch, can regulating power level circuit 22 output voltage, make it keep stable.In the present embodiment, power stage circuit 22 can adopt voltage-dropping type topology, booster type is topological, buck-boost type is topological or the topology of other type.
Load R
lbe connected with the voltage output end o of power stage circuit 22, to obtain stable voltage v
o.
In control circuit 21, output voltage detecting circuit 211 is connected between voltage output end o and testing circuit reference edge g.In the present embodiment, as shown in Figure 2, testing circuit reference edge g holds with being connected to the control circuit reference of switched mode converter.
Output voltage detecting circuit 211 comprises commutation diode D2, filter capacitor C2, resistor voltage divider circuit DIV, discharge circuit DIS and sampling hold circuit SAM.
Wherein, commutation diode D2 is connected between the voltage output end o of switched mode converter and first end f.Particularly, the positive pole of commutation diode D2 is connected with voltage output end o, and negative pole is connected with first end f.
Filter capacitor C2 is connected between first end f and testing circuit reference edge g (in the present embodiment, it is held with the control circuit reference ground of switched mode converter and is connected).
Commutation diode D2 and filter capacitor C2 can carry out rectification and filtering to output voltage, makes the both end voltage of filter capacitor C2 can keep relative consistent with the output voltage of power stage circuit 22, again can the burr of filtering noise wherein.Filtering noise and burr are conducive to protective resistance bleeder circuit DIV, prevent from causing damage to it.The unwanted signals damaged owing to easily causing integrated circuit is by filtering, and resistor voltage divider circuit DIV can be integrated in integrated circuit (IC) chip inside.
Resistor voltage divider circuit DIV is in parallel with filter capacitor C2, for exporting branch pressure voltage v to after filter capacitor both end voltage (also namely, first end voltage) dividing potential drop
d.
In the present embodiment, resistor voltage divider circuit DIV is made up of the first resistance R1 connected and the second resistance R2, exports branch pressure voltage v from the first resistance R1 with the end that is connected (also namely, the second end s) of the second resistance R2
d.
As mentioned above, introducing filter capacitor C2, can to make to be input to the voltage of resistor voltage divider circuit DIV more level and smooth, thus make resistor voltage divider circuit be suitable for being integrated in integrated circuit (IC) chip, and need not use volume greatly, external circuit easily affected by environment.But, filter capacitor C2 can make resistor voltage divider circuit DIV both end voltage can not with output voltage v
okeep completely the same, at output voltage v
ohave when changing by a relatively large margin, especially when load switches, the voltage at filter capacitor C2 two ends can not respond this change in time, this branch pressure voltage v that resistor voltage divider circuit DIV can be caused to export
dthe change of output voltage can not be reflected, and then the stability of influential system and the regulation of switched mode converter.
Thus, the present embodiment overcomes the problems referred to above by increasing the discharge circuit DIS in parallel with filter capacitor C2.
Discharge circuit DIS is in parallel with filter capacitor C2, in each switch periods to filter capacitor C2 discharge schedule time T1.Schedule time T1 is the shorter time.
When power stage circuit 22 adopts voltage-dropping type topology, discharge circuit DIS carries out discharge operation in power switch S1 conduction period.
Preferably, discharge circuit DIS when each switch periods starts when conducting (also, power switch S1 firm) to filter capacitor electric discharge schedule time T1.
The control signal that controlled discharge circuit DIS discharges can be generated by control circuit according to switch controlling signal Q.
In the present embodiment, switch periods refers to that switch controlling signal Q controls power switch S1 ON/OFF once the experienced cycle, and according to the difference of control circuit, it can be the set time, also can be change.
In a preferred embodiment, as shown in Figure 2 A, discharge circuit DIS comprises current source I1 and switch S 2.Current source I1 and switch S 2 are connected in series, and switch S 2 is conducting schedule time T1 in each switch periods, make to form current path within this time period, and the electric current that current source I1 generates can flow through, thus discharges to filter capacitor C2, reduces its both end voltage v
c2.
In a preferred embodiment, as shown in Figure 2 B, discharge circuit DIS also can control current source for pulse-width signal, and it is based on the control of a pulse-width signal, exports predetermined electric current in the schedule time T1 in each switch periods.
In the present embodiment, in each switch periods, filter capacitor C2 both end voltage can reduce due to the electric discharge of discharge circuit DIS, then when power switch S1 turns off, charged by the output voltage of voltage output end, be changed to consistent with output voltage, thus, filter capacitor C2 both end voltage v can be ensured
c2quick response output voltage v
ochange, improves the accuracy of voltage detecting, ensures that switched mode converter has good voltage regulation factor simultaneously.
Sampling hold circuit SAM inputs branch pressure voltage v
d, for branch pressure voltage v
dsample, and according to the magnitude of voltage output detections voltage v that sampling obtains
fB.In the present embodiment, sampling hold circuit SAM can after discharge circuit electric discharge terminates after delay scheduled time to branch pressure voltage v
dsample.Within this schedule time, filter capacitor C2 both end voltage is risen to basically identical and stable with output voltage by charging.
Preferably, sampling hold circuit SAM power switch S1 turn off after after a lead-edge-blanking time again to branch pressure voltage v
dsample.
Detect voltage v
fBbe imported in control circuit 21 as feedback parameters, thus control circuit 21 can generate switch controlling signal Q.
Should be understood that resistor voltage divider circuit DIV is non-essential, at output voltage v
otime less, output voltage detecting circuit 211 can not comprise resistor voltage divider circuit DIV.Now, directly first end voltage is input to sampling hold circuit SAM, samples, and according to the magnitude of voltage output detections voltage v that sampling obtains
fB.
Wherein, in a preferred embodiment, the resistor voltage divider circuit DIV in voltage detecting circuit 211, discharge circuit DIS and sampling hold circuit SAM together can be integrated in same integrated circuit with comparator circuit 212 and driving circuit 213.This integrated circuit has voltage sense pin, and it is connected to the first end f of voltage detecting circuit 211.
In another preferred embodiment, can also further the power switch S1 of power stage circuit be also integrated in this integrated circuit.
Thus, can level of integrated system be improved, and avoid the adverse effect that environment detects for output voltage.
The present embodiment carries out rectifying and wave-filtering by commutation diode and filter capacitor to output voltage, discharge circuit simultaneously by being connected in parallel on filter capacitor two ends discharges the schedule time to filter capacitor in each switch periods, thus accurately can detect output voltage, make filter capacitor both end voltage follow output voltage change Rapid Variable Design simultaneously, make the switched mode converter applying this voltage detecting circuit or integrated circuit have good voltage regulation factor.
Fig. 3 is the circuit diagram of the switched mode converter of second embodiment of the invention.As shown in Figure 3, switched mode converter comprises control circuit 31, power stage circuit 32.
Control circuit 31 is for the output voltage v of detection power level circuit 22
o, generate switch controlling signal Q, control the device for power switching S1 turn-on and turn-off of power stage circuit, make the voltage v of power stage circuit 32 stable output
o.
Control circuit 31 can by detection voltage v
fBcompare with the reference voltage of output voltage desired by characterizing, and and then the dutycycle of result adjustment switch controlling signal Q based on the comparison.
Control circuit 31 comprises output voltage detecting circuit 321, comparator circuit 312 and driving circuit 313.
Output voltage detecting circuit 311 connects, for detecting output voltage v with the voltage output end o (also namely, the output terminal of switched mode converter) of power stage circuit 32
oand output detections voltage v
fB.
Comparator circuit 312 detects voltage v for comparing
fBwith reference voltage v
rEFexport comparative result v
cMP.Reference voltage v
rEFfor characterizing desired output voltage.
Driving circuit 313 is for according to comparative result v
cMPgenerate switch controlling signal Q.
In figure 3, power stage circuit 32 adopts voltage-dropping type topology, and it can comprise device for power switching S1, sustained diode 1, energy-storage travelling wave tube L1 and output capacitance C1.Between the input end that device for power switching S1 is connected to power stage circuit 32 and intermediate ends m.Sustained diode 1 is connected between intermediate ends m and earth terminal, and wherein, its positive pole is connected with earth terminal, and negative pole is connected with intermediate ends m.Energy-storage travelling wave tube L1 is connected between intermediate ends and voltage output end, and it can be inductance.Output capacitance C1 is connected between voltage output end and earth terminal.
Load R
lbe connected with the voltage output end of power stage circuit 32, to obtain stable input voltage.
In control circuit 31, output voltage detecting circuit 311 is connected between voltage output end o and testing circuit reference edge g.In the present embodiment, the control circuit that described testing circuit reference edge g is connected to switched mode converter with reference to hold, also, with control circuit altogether.Under power stage circuit 32 is the prerequisite of voltage-dropping type topology, control circuit is connected with the intermediate ends m of power stage circuit 32 usually with reference to ground end, also, is connected with the negative pole of sustained diode 1.
Output voltage detecting circuit 311 comprises commutation diode D2, filter capacitor C2, resistor voltage divider circuit DIV, discharge circuit DIS and sampling hold circuit SAM.
Wherein, commutation diode D2 is connected between the voltage output end o of switched mode converter and first end f.Particularly, the positive pole of commutation diode D2 is connected with voltage output end, and negative pole is connected with first end f.
Filter capacitor C2 is connected between first end f and testing circuit reference edge g (being connected to the negative pole of sustained diode 1 in the present embodiment).
For voltage-dropping type topology, sustained diode 1 is in the conducting of power switch S1 blocking interval.During this period, filter capacitor C2 is equivalent to be connected between voltage output end and earth terminal, the output voltage v of its both end voltage and power stage circuit 32
okeep relatively consistent.
Similar with a upper embodiment, commutation diode D2 and filter capacitor C2 can carry out rectification and filtering to output voltage, make the both end voltage of filter capacitor C2 can keep relative consistent with the output voltage of power stage circuit 22, again can the burr of filtering noise wherein.Filtering noise and burr are conducive to protective resistance bleeder circuit DIV, prevent from causing damage to it.This makes resistor voltage divider circuit DIV can be integrated in integrated circuit (IC) chip inside, and need not worry that the noise of output voltage and burr can damage integrated circuit (IC) chip.
Resistor voltage divider circuit DIV is in parallel with filter capacitor C2, for exporting branch pressure voltage v to after filter capacitor both end voltage dividing potential drop
d.
Similar with the first embodiment, introducing filter capacitor C2 can make the voltage being input to resistor voltage divider circuit DIV more level and smooth, thus make resistor voltage divider circuit be suitable for being integrated in integrated circuit (IC) chip, and need not use volume greatly, external circuit easily affected by environment.But, filter capacitor C2 can make resistor voltage divider circuit both end voltage can not keep completely the same with output voltage, output voltage have change by a relatively large margin time, especially when load switches, the voltage at filter capacitor C2 two ends can not respond this change in time, this branch pressure voltage v that resistor voltage divider circuit DIV can be caused to export
dthe change of output voltage can not be reflected, and then the stability of influential system and the regulation of switched mode converter.
Thus, the present embodiment overcomes the problems referred to above by increasing the discharge circuit DIS in parallel with filter capacitor C2.
Discharge circuit DIS is in parallel with filter capacitor C2, in each switch periods to filter capacitor C2 discharge schedule time T1.Schedule time T1 is the shorter time.
Preferably, discharge circuit DIS when each switch periods starts to filter capacitor C2 discharge schedule time T1.
In the present embodiment, switch periods refers to that switch controlling signal Q controls power switch S1 ON/OFF once the experienced cycle, and according to the difference of control circuit, it can be the set time, also can be change.
Preferably, discharge circuit DIS comprises current source I1 and switch S 2.Current source I1 and switch S 2 are connected in series, and switch S 2 is conducting schedule time T1 in each switch periods, make to form current path within this time period, and the electric current that current source I1 generates can flow through, thus discharges to filter capacitor C2, reduces its both end voltage.
Preferably, discharge circuit DIS also can be pulse-width signal control current source as shown in Figure 2 B, and it is based on the control of a pulse-width signal PWM, exports predetermined electric current in the schedule time T1 in each switch periods.
In each switch periods, filter capacitor C2 both end voltage can reduce due to the electric discharge of discharge circuit DIS, is then charged by the voltage of voltage output end, is changed to consistent with output voltage, thus, can ensure filter capacitor C2 both end voltage v
c2output voltage v can be responded fast
ochange, improves the accuracy of voltage detecting, ensures that switched mode converter has good voltage regulation factor simultaneously.
Fig. 4 is the working waveform figure of the present embodiment.As shown in Figure 4, switch controlling signal Q controls power switch S1 turn-on and turn-off once in each switch periods, and wherein, when switch controlling signal Q is high level, power switch S1 conducting, when switch controlling signal Q is low level, power switch S1 turns off.When each switch periods starts, according to T
on1signal, discharge circuit DIS conducting to be discharged a schedule time T1 to filter capacitor C2 both end voltage, makes the both end voltage v of filter capacitor C1
c2decline.When discharge circuit DIS is made up of current source I1 and the switch S 2 of connecting with it, control signal T
on1act on switch S 2, make its conducting schedule time T1 in switch periods, thus filter capacitor C2 is discharged.
Close at power switch and have no progeny (preferably through a lead-edge-blanking time T
blkafterwards), filter capacitor C2 both end voltage is charged to output voltage and keeps stable, now based on sampled signal v
samplecarry out sampling to filter capacitor C2 both end voltage or the dividing potential drop proportional with it and keep obtaining the detected value v of output voltage
fB.
In a preferred embodiment, resistor voltage divider circuit DIV is made up of the first resistance R1 connected and the second resistance R2, exports branch pressure voltage v from the link of the first resistance R1 and the second resistance R2
d.
In another preferred embodiment, as shown in Figure 3, because sustained diode 1 and commutation diode D2 have positive pressure drop when conducting, therefore, in order to eliminate the impact of this positive pressure drop, a controlled current source I2 can be added in resistor voltage divider circuit DIV, controlled current source I2 is exported and power stage circuit output current i
oproportional electric current, and in parallel with the second resistance R2.Thus, resistor voltage divider circuit DIV comprises the first resistance R1, the second resistance R2 and controlled current source I2.
For the switched mode converter shown in Fig. 3, the both end voltage v of filter capacitor C2
c2meet v
c2=v
o+ v
d1-v
d2, wherein, v
d1and v
d2be respectively the forward voltage drop of sustained diode 1 and commutation diode D2.Due to forward voltage drop and the current in proportion flowing through diode of diode.When the power stage circuit 32 of voltage-dropping type topology is operated in continuous current mode pattern (CCM), flow through electric current and the output current i of sustained diode 1
orelevant, the electric current flowing through commutation diode D2 is very little, therefore, and the forward voltage drop v in sustained diode 1
d1non-vanishing, the forward voltage drop V of commutation diode D2
d2be close to zero.Thus, the both end voltage v of filter capacitor C2
c2≈ v
d1+ v
d1.And, the forward voltage drop v of sustained diode 1
d1with output current i
oproportional.The detection voltage v obtained is detected in order to make the output voltage detecting circuit when different loads
fBidentical, the present embodiment is compensated branch pressure voltage by compensating circuit (being a controlled current source I2 shown in Fig. 3), make freewheel current by negative feedback to the second end s, the component that the forward voltage drop of sustained diode 1 in branch pressure voltage is relevant can be removed, thus compensate branch pressure voltage v
d, make branch pressure voltage v
daccurate characterization output voltage v
o.。Described freewheel current i
d1for flowing through the electric current of the sustained diode 1 of the power stage circuit 31 of switched mode converter.
Particularly, in figure 3, compensating circuit is set to controlled current source I2.The size of current of controlled current source I2 is with output current i
o(output current i
othe change of freewheel current can be characterized) change and change, thus the forward voltage drop v of commutation diode D2 can be compensated
d1on the impact that output voltage detects, realize voltage compensation during different loads electric current, thus obtain good load regulation.Should be understood that compensating circuit also can be set to by characterizing the current source of other state modulator of freewheel current or other device to realize compensate function.
Sampling hold circuit SAM inputs branch pressure voltage v
d, for sampling to branch pressure voltage, and according to the magnitude of voltage output detections voltage v that sampling obtains
fB.
Detect voltage v
fBbe imported in control circuit 31 as feedback parameters, thus control circuit 31 can generate switch controlling signal Q.
Should be understood that resistor voltage divider circuit DIV is non-essential, at output voltage v
otime less, output voltage detecting circuit 211 can not comprise resistor voltage divider circuit DIV.Now, directly first end voltage is input to sampling hold circuit SAM, samples, and according to the magnitude of voltage output detections voltage v that sampling obtains
fB.Meanwhile, compensating circuit is in parallel with filter capacitor C1, for the freewheel current i by flowing through sustained diode 1
d1negative feedback, to first end, removes component relevant to the forward voltage drop of sustained diode 1 in first end voltage, thus compensates first end voltage, makes first end voltage accurate characterization output voltage v
o.
In a preferred embodiment, the resistor voltage divider circuit DIV in voltage detecting circuit 311, discharge circuit DIS and sampling hold circuit SAM can with comparator circuit 312 and driving circuit 313 together in integrated circuits integrated.This integrated circuit has voltage sense pin, and it is connected to the first end f of voltage detecting circuit 211.
In another preferred embodiment, can also further the power switch S1 of power stage circuit be also integrated in this integrated circuit.
Thus, can level of integrated system be improved, and avoid the adverse effect that environment detects for output voltage.
The present embodiment carries out rectifying and wave-filtering by commutation diode and filter capacitor to output voltage, discharge circuit simultaneously by being connected in parallel on filter capacitor two ends discharges the schedule time to filter capacitor in each switch periods, thus accurately can detect output voltage, make filter capacitor both end voltage follow output voltage change Rapid Variable Design simultaneously, make the switched mode converter applying this voltage detecting circuit or integrated circuit have good voltage regulation factor.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, to those skilled in the art, the present invention can have various change and change.All do within spirit of the present invention and principle any amendment, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (13)
1. an output voltage detecting circuit, for detecting the output voltage of switched mode converter, described output voltage detecting circuit comprises:
Commutation diode, between the voltage output end being connected to described switched mode converter and first end;
Filter capacitor, is connected between described first end and testing circuit reference edge;
Discharge circuit, in parallel with described filter capacitor, for discharging the schedule time to described filter capacitor in each switch periods;
Sampling hold circuit, for sampling to first end voltage or branch pressure voltage, and according to the magnitude of voltage output detections voltage that sampling obtains;
Described branch pressure voltage is obtained after dividing potential drop by described first end voltage.
2. output voltage detecting circuit according to claim 1, is characterized in that, described sampling hold circuit is used for sampling to described first end voltage or branch pressure voltage after described discharge circuit electric discharge terminates delay scheduled time again.
3. output voltage detecting circuit according to claim 1, is characterized in that, described testing circuit reference edge is held with being connected to the control circuit reference of switched mode converter.
4. output voltage detecting circuit according to claim 3, is characterized in that, the power stage circuit of described switched mode converter is voltage-dropping type topology, and described control circuit is connected with the negative pole of the fly-wheel diode of described power stage circuit with reference to ground end.
5. output voltage detecting circuit according to claim 4, is characterized in that, described discharge circuit discharges the schedule time to described filter capacitor when each switch periods starts.
6. output voltage detecting circuit according to claim 5, it is characterized in that, described sampling hold circuit switches to shutoff at the power switch of described power stage circuit by conducting, and samples to described first end voltage or branch pressure voltage after the predetermined lead-edge-blanking time again.
7. output voltage detecting circuit according to claim 4, is characterized in that, described output voltage detecting circuit also comprises:
Compensating circuit, in parallel with described filter capacitor, for by flowing through the freewheel current negative feedback of described fly-wheel diode to first end, compensate described first end voltage.
8. output voltage detecting circuit according to claim 4, is characterized in that, described output voltage detecting circuit also comprises:
Resistor voltage divider circuit, in parallel with described filter capacitor, for exporting described branch pressure voltage to after described first end voltage at the second end.
9. output voltage detecting circuit according to claim 8, is characterized in that, described output voltage detecting circuit also comprises:
Compensating circuit, is connected between described second end and described testing circuit reference edge, for by flowing through the freewheel current negative feedback of described fly-wheel diode to described second end, compensates described branch pressure voltage.
10. a control circuit, for switched mode converter, described integrated circuit comprises:
Output voltage detecting circuit as claimed in any one of claims 1-9 wherein;
Comparator circuit, exports comparative result for more described detection voltage and reference voltage;
Driving circuit, for generating switch controlling signal according to described comparative result, described switch controlling signal is for controlling the power stage circuit of described switched mode converter.
11. control circuits according to claim 10, is characterized in that, the discharge circuit of described output voltage detecting circuit, sampling hold circuit and described comparator circuit and driving circuit are integrated into integrated circuit.
12. 1 kinds of switched mode converters, comprise control circuit and power stage circuit;
Described control circuit comprises:
Output voltage detecting circuit as claimed in any one of claims 1-9 wherein;
Comparator circuit, exports comparative result for more described detection voltage and reference voltage;
Driving circuit, for generating switch controlling signal according to described comparative result, described switch controlling signal is for controlling described power stage circuit.
13. switched mode converters according to claim 12, is characterized in that, the discharge circuit of described output voltage detecting circuit, sampling hold circuit and described comparator circuit and driving circuit are integrated into integrated circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410588498.8A CN104297553B (en) | 2014-10-28 | 2014-10-28 | Output voltage detecting circuit, control circuit and switched mode converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410588498.8A CN104297553B (en) | 2014-10-28 | 2014-10-28 | Output voltage detecting circuit, control circuit and switched mode converter |
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| Publication Number | Publication Date |
|---|---|
| CN104297553A true CN104297553A (en) | 2015-01-21 |
| CN104297553B CN104297553B (en) | 2017-09-15 |
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| CN201410588498.8A Active CN104297553B (en) | 2014-10-28 | 2014-10-28 | Output voltage detecting circuit, control circuit and switched mode converter |
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| CN104991548A (en) * | 2015-05-21 | 2015-10-21 | 西安航空动力股份有限公司 | Detection method of control system in ground measurement and control instrument |
| CN105101576A (en) * | 2015-09-09 | 2015-11-25 | 无锡华润矽科微电子有限公司 | Load voltage compensation circuit for light-emitting diode (LED) driving |
| CN105204602A (en) * | 2015-09-02 | 2015-12-30 | 上海兆芯集成电路有限公司 | Power control device |
| CN106771934A (en) * | 2017-02-10 | 2017-05-31 | 汽-大众汽车有限公司 | A kind of motor in electric automobile tests high-low pressure cable connecting device |
| CN106940988A (en) * | 2016-01-05 | 2017-07-11 | 奇景光电股份有限公司 | The display of this power control method of power control method with application |
| CN109936347A (en) * | 2017-12-18 | 2019-06-25 | 中国科学院大连化学物理研究所 | Pulse-modulator high-pressure compensating device |
| CN109936345A (en) * | 2017-12-18 | 2019-06-25 | 中国科学院大连化学物理研究所 | Pulse-modulator high-pressure compensating device and method |
| CN111146960A (en) * | 2020-01-19 | 2020-05-12 | 矽力杰半导体技术(杭州)有限公司 | Detection circuit and switching converter using same |
| CN113391113A (en) * | 2021-06-18 | 2021-09-14 | 矽力杰半导体技术(杭州)有限公司 | Voltage detection circuit, switch converter and integrated circuit |
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| CN104991548B (en) * | 2015-05-21 | 2017-09-26 | 西安航空动力股份有限公司 | The detection method of control system in a kind of ground observing and controlling instrument |
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| CN111146960A (en) * | 2020-01-19 | 2020-05-12 | 矽力杰半导体技术(杭州)有限公司 | Detection circuit and switching converter using same |
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| CN113391113A (en) * | 2021-06-18 | 2021-09-14 | 矽力杰半导体技术(杭州)有限公司 | Voltage detection circuit, switch converter and integrated circuit |
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