CN102594151A - Switching mode power supply and control method of switching tube thereof - Google Patents
Switching mode power supply and control method of switching tube thereof Download PDFInfo
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- CN102594151A CN102594151A CN2012100282795A CN201210028279A CN102594151A CN 102594151 A CN102594151 A CN 102594151A CN 2012100282795 A CN2012100282795 A CN 2012100282795A CN 201210028279 A CN201210028279 A CN 201210028279A CN 102594151 A CN102594151 A CN 102594151A
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Abstract
The invention discloses a switching mode power supply and a control method of a switching tube thereof. The switching mode power supply comprises a transformer, a switching tube, a sampling resistor and a pulse-width modulation (PWM) control chip. The PWM control chip is used for controlling the switching of the switching tube, and comprises a detection unit and a leading edge blanking (LEB) time determining unit. The detection unit is used for detecting turn-on time of the switching tube in a current period, and the LEB time determining unit is used for determining LEB time in a next period according to the detected turn-on time of the switching tube in the current period; wherein the determined LEB time in the next period is larger than maximum duration of a spike voltage generated on the sampling resistor at a turn-on moment of the switching tube, and smaller than the turn-on time of the switching tube. According to the technical scheme of the switching mode power supply and the control method of the switching tube thereof, the turn-on time of the switching tube in the current period is used for determining the LEB time in the next period, therefore the LEB time is incapable of exceeding the turn-on time of the switching tube during a turn-on period of a switch; and logical errors, damage or even explosion risks of the switching tube in the turn-on time of the switching tube can be decreased or prevented.
Description
Technical field
The present invention relates to switch power technology, relate in particular to the control method of a kind of Switching Power Supply and switching tube thereof.
Background technology
Switching Power Supply can change into one or more direct current output to a power supply expeditiously, and the voltage of these out-put supplies can be greater than or less than former supply voltage.Fig. 1 shows existing a kind of Switching Power Supply.In this Switching Power Supply, select for use NPN type switching tube Q1 as switching tube, the base stage of this switching tube Q1 connects the base stage control end (Vbase) of pwm chip U1, and the emitter of switching tube Q1 is through sampling resistor R
CsGround connection, simultaneously, the emitter of switching tube Q1 also connects the sampling end (CS) of pwm chip U1, and the collector electrode of switching tube Q1 also connects the end of the same name of the former limit winding of transformer T1, and the different name end of the former limit winding of transformer T1 connects DC input voitage.When this Switching Power Supply is worked, the break-make of the base stage control end control switch pipe Q1 of pwm chip U1, still; Because switching tube Q1 is not desirable switching tube, owing to there is stored charge, switching tube Q1 can not turn-off immediately in the moment of turn-offing; Therefore the designer can add preparatory breaking circuit usually; Just before normal logic is turn-offed, reduce the base current of switching tube Q1 as much as possible, this time base stage electrorheological very little; The electric charge of accumulation also can reduce, and when normal logic is turn-offed, has just turn-offed easily.
Fig. 2 is the ideal waveform figure of Switching Power Supply shown in Figure 1 corresponding node voltage and electric current when work.In the beginning of each cycle T, pwm chip U1 opens switching tube Q1, the emitter current I of switching tube Q1
pBeginning increases with a certain fixedly rate of rise, works as I
pIncrease to and make sampling resistor R
CsOn voltage V
CsVoltage surpasses the first reference voltage V of the internal comparator of pwm chip U1
Ref1The time, switching tube Q1 is turn-offed the base current I of switching tube Q1 at this time in advance
bWhen becoming normally 1/10th of electric current even littler electric current I
B_pre, I
pElectric current continues to increase, and works as V
CsVoltage surpasses the second reference voltage V of the internal comparator of pwm chip U1
Ref2The time, switching tube Q1 can thoroughly be turn-offed.The conducting of switching tube Q1 will be controlled by inner constant current of pwm chip U1 or constant voltage logic control circuit.In addition, in the moment of switching tube Q1 conducting, since the influence of parasitic capacitance, stray inductance, transformer leakage inductance, the electric current I of switching tube Q1 emitter
pThe spike that the short time can occur is when this electric current flows through sampling resistor R
CsThe time can produce bigger peak voltage, if this peak voltage is greater than the first reference voltage V of the internal comparator of pwm chip U1
Ref1Or the second reference voltage V
Ref2Logic control circuit will turn-off or on-off switching tube Q1 in advance; This switch motion obviously is not designer's a original idea, and therefore existing general technology is exactly LEB (leading edge blanking, the lead-edge-blanking) time that after switching tube Q1 conducting, postpones to fix to detect sampling resistor R again
CsOn voltage V
Cs,, will avoid like this because switching tube Q1 conducting moment V like Fig. 2
CsThe logic error that the peak voltage that occurs causes.
Can avoid or reduce the problem of above-mentioned existence to a certain extent although add the fixed L EB time.But the fixing LEB time is not perfect design, because at switching tube Q1 ON time in the long cycle, if switching tube Q1 conducting LEB after the time, V
CsVoltage does not also reach and turn-offs or shutoff voltage in advance, this time V
CsVoltage receives spike and disturbs, and makes V
CsThe peak voltage V of short time appears in voltage
SpIn one case, like Fig. 3 A, work as V
SpGreater than V
Ref2The time, circuit can directly be skipped the direct on-off switching tube Q1 of preparatory shutdown mode, can cause tangible logic error like this, even can damage switching tube Q1, and this situation is shown in the fault time among Fig. 3 A.The switching tube Q1 base control signal V of this moment
Base, the voltage signal V on the sampling resistor
Cs, switching tube Q1 base current I
b, switching tube Q1 collector voltage V
cWaveform is shown in Fig. 3 A.Under another kind of situation, work as V
SpGreater than V
Ref1Less than V
Ref2The time, at this moment can cause preparatory shutoff, if this moment range switch pipe Q1 normal turn-off also has longer a period of time, will cause the preparatory off state of long period, the base current of switching tube Q1 is very little owing to this time, so the collector voltage V of switching tube Q1
cWill constantly rise, when this voltage rise to maximum voltage that switching tube Q1 can bear the time, switching tube Q1 will burn even occur the danger of blast, this situation is shown in danger time among Fig. 3 B.Switching tube Q1 base stage control in this time voltage V
Base, the voltage V on the sampling resistor
Cs, switching tube Q1 base current I
b, collector voltage V
cShown in Fig. 3 B.
Summary of the invention
The technical problem that the present invention will solve is; To prior art above-mentioned because the LEB time defective that fixedly makes switching tube logic error, damage even blast; A kind of Switching Power Supply is provided, can avoids taking place the situation of switching tube logic error, damage even blast.
The technical solution adopted for the present invention to solve the technical problems is: construct a kind of Switching Power Supply; Comprise transformer, switching tube, sampling resistor and be used for the pwm chip of control switch pipe break-make; Wherein, The different name end of the former limit winding of said transformer connects DC input voitage, and the end of the same name of the former limit winding of said transformer connects the collector electrode of said switching tube, and the base stage of said switching tube connects the base stage control end of pwm chip; The emitter of said switching tube is through sampling resistor ground connection, and the emitter of said switching tube also connects the sampling end of pwm chip; Said pwm chip comprises:
Probe unit is used to survey the switching tube ON time of current period;
The LEB time is confirmed the unit; Be used for confirming the LEB time of following one-period according to the switching tube ON time of the current period of being surveyed; Wherein, The LEB time of determined following one-period is greater than the maximum duration of the peak voltage that is produced on the switching tube conducting instantaneous sampling resistance, and less than the switching tube ON time.
In Switching Power Supply of the present invention, said probe unit comprises:
Oscillator is used to produce the clock cycle;
Counter is used for according to the clock cycle that oscillator produces the high level of the base control signal of the current period of switching tube being counted;
Decoder is used for count value is deciphered, to confirm the switching tube ON time of current period.
In Switching Power Supply of the present invention, said pwm chip comprises register, and said register store in advance switching tube a plurality of ON times and with the pairing LEB time of each ON time;
The said LEB time confirms that the unit is used for the switching tube ON time according to the current period of being surveyed; From register, select the corresponding LEB time of switching tube ON time with said current period, and confirmed as the LEB time of following one-period the selected LEB time.
In Switching Power Supply of the present invention, the said LEB time confirms that the unit is used for the switching tube ON time of the current period of being surveyed is deducted the preset set time, and the difference of gained is confirmed as the LEB time of following one-period.
In Switching Power Supply of the present invention, said probe unit is used for confirming through the DC input voitage of the transformer of surveying current period and the second inner reference voltage of pwm chip the switching tube ON time of current period.
In Switching Power Supply of the present invention; The said LEB time confirm the unit comprise reverser, first switch, second switch, charging capacitor, current source, reference voltage source, comparator, with door, wherein, first switch is connected between the inverting input and ground of comparator; The first end ground connection of current source; Through second switch, charging capacitor ground connection, the tie point of second switch and charging capacitor connects the inverting input of comparator to second end of current source, the in-phase input end of the first termination comparator of reference voltage source successively; The second end ground connection of reference voltage source; The base stage control end connects the control end of second switch and the input of reverser respectively, and the output of reverser connects the control end of first switch, the first input end of the output termination of comparator and door; With the second input termination base stage control end of door, be LEB time of following one-period with time of door output high level.
The present invention also constructs a kind of control method of switching tube of Switching Power Supply, it is characterized in that, comprising:
S1. survey the switching tube ON time of current period;
S2. confirm the LEB time of following one-period according to the switching tube ON time of the current period of being surveyed; Wherein, The LEB time of determined following one-period is greater than the maximum duration of the peak voltage that is produced on the switching tube conducting instantaneous sampling resistance, and less than the switching tube ON time.
In the control method of the switching tube of Switching Power Supply of the present invention, said step S1 is:
The clock cycle that produces according to oscillator, the high level of the base control signal of the current period of switching tube is counted, and count value is deciphered, to confirm the switching tube ON time of current period.
In the control method of the switching tube of Switching Power Supply of the present invention, said step S2 is:
Switching tube ON time according to the current period of being surveyed; From register, select the corresponding LEB time of switching tube ON time with said current period; And confirmed as LEB time of following one-period the selected LEB time; Wherein, said register stores a plurality of ON times and and the pairing LEB time of each ON time of switching tube in advance.
In the control method of the switching tube of Switching Power Supply of the present invention, said step S2 is:
The switching tube ON time of the current period of being surveyed is deducted the preset set time, and the difference of gained confirmed as the LEB time of following one-period.
In the control method of the switching tube of Switching Power Supply of the present invention, in step S1, the DC input voitage of the transformer through surveying current period and the switching tube ON time that the second inner reference voltage of pwm chip is confirmed current period.
In the control method of the switching tube of Switching Power Supply of the present invention; In said step S2; In the charging interval that changes charging capacitor according to the DC input voitage or the second inner reference voltage of pwm chip of the transformer of the current period of being surveyed, the time that the voltage that begins to be charged to charging capacitor from charging capacitor rises to preset reference voltage is the LEB time of following one-period.
The technical scheme of embodiment of the present invention; During the work of this Switching Power Supply, the pwm chip through this embodiment comes the control switch pipe, because the switching tube ON time of current period and the switching tube ON time of following one-period are more or less the same; So; Confirm LEB time of following one-period according to the switching tube ON time of current period, when the switching tube ON time of current period was long, the LEB time of following one-period was also long; At the switching tube ON time of current period in short-term, the LEB time of following one-period is also short.Thereby the moment that has guaranteed peak interference is dropped on LEB in the time; And then guaranteed that the LEB time can not reduce or avoid the danger of switching tube logic error, damage even the blast of appearance in the switching tube ON time again above the ON time of switching tube in the switching tube turn-on cycle.
Description of drawings
To combine accompanying drawing and embodiment that the present invention is described further below, in the accompanying drawing:
Fig. 1 is the circuit diagram of existing a kind of Switching Power Supply;
Fig. 2 is the voltage of Switching Power Supply shown in Figure 1 respective nodes when work, the ideal waveform figure of electric current;
The oscillogram of the voltage of Fig. 3 A respective nodes that is Switching Power Supply shown in Figure 1 when receiving spike and disturb, a kind of situation of electric current;
The oscillogram of the voltage of Fig. 3 B respective nodes that is Switching Power Supply shown in Figure 1 when receiving spike and disturb, the another kind of situation of electric current;
Fig. 4 is the building-block of logic of the pwm chip embodiment one of Switching Power Supply of the present invention;
The oscillogram of the voltage of Fig. 5 A respective nodes that is Switching Power Supply shown in Figure 4 when receiving spike and disturb, a kind of situation of electric current;
The oscillogram of the voltage of Fig. 5 B respective nodes that is Switching Power Supply shown in Figure 4 when receiving spike and disturb, the another kind of situation of electric current;
Fig. 6 is the building-block of logic of an embodiment of probe unit among Fig. 4;
Fig. 7 A is the circuit diagram that the LEB time is confirmed an embodiment of unit among Fig. 4;
Fig. 7 B confirms the voltage of unit respective nodes, the oscillogram of electric current the LEB time shown in Fig. 7 A;
Fig. 8 is the flow chart of control method embodiment one of the switching tube of Switching Power Supply of the present invention.
Embodiment
Fig. 4 is the building-block of logic of the pwm chip embodiment one of Switching Power Supply of the present invention, at first should be noted that combination Fig. 1, and this Switching Power Supply comprises transformer T1, switching tube Q1, sampling resistor R
CsWith the pwm chip U1 that is used for control switch pipe break-make, wherein, the different name end of the former limit winding of transformer T1 connects DC input voitage V
IN, the end of the same name of the former limit winding of transformer T1 connects the collector electrode of switching tube Q1, and the base stage of switching tube Q1 connects the base stage control end (Vbase) of pwm chip U1, and the emitter of switching tube Q1 is through sampling resistor R
CsGround connection, the emitter of switching tube Q1 also connect the sampling end (CS) of pwm chip U1.Stress pwm chip U1 below, as shown in Figure 4, pwm chip U1 comprises that probe unit 11 and LEB time confirms unit 12, and wherein, probe unit 11 is used to survey the switching tube ON time of current period; The LEB time confirms that unit 12 is used for confirming according to the switching tube ON time of the current period of being surveyed the LEB time of following one-period; Wherein, The LEB time of determined following one-period is greater than the maximum duration of the peak voltage that produces on the switching tube Q1 conducting instantaneous sampling resistance, and less than the switching tube ON time.When this Switching Power Supply work; Pwm chip U1 through this embodiment comes control switch pipe Q1; Because the switching tube ON time of current period and the switching tube ON time of following one-period are more or less the same, so, confirm LEB time of following one-period according to the switching tube ON time of current period; When the switching tube ON time of current period was long, the LEB time of following one-period was also long; At the switching tube ON time of current period in short-term, the LEB time of following one-period is also short.Shown in Fig. 5 A and Fig. 5 B, wherein, the oscillogram of the voltage of Fig. 5 A respective nodes that is Switching Power Supply shown in Figure 4 when receiving spike and disturb, a kind of situation of electric current than Fig. 3 A, has been adjusted the LEB time; The oscillogram of the voltage of Fig. 5 B respective nodes that is Switching Power Supply shown in Figure 4 when receiving spike and disturb, the another kind of situation of electric current; Than Fig. 3 B; Adjusted the LEB time; Thereby the moment that has guaranteed peak interference is dropped on LEB in the time, so guaranteed switch conduction in the cycle LEB time can not surpass the ON time of switching tube, can reduce or avoid the danger of the switching tube logic error, damage even the blast that occur in the switching tube ON time again.
Fig. 6 shows the logical construction of an embodiment of probe unit among Fig. 4, and in this embodiment, probe unit comprises continuous oscillator 111, counter 112 and decoder 113, and wherein, oscillator 111 is used to produce the clock cycle; Counter 112 is used for according to the clock cycle that oscillator produces the high level of the base control signal of the current period of switching tube being counted; Decoder 113 is used for count value is deciphered, to confirm the switching tube ON time of current period.
After having confirmed the switching tube ON time of current period, the LEB time confirms that the unit just can confirm the LEB time of following one-period according to the switching tube ON time in this current cycle.In one embodiment, pwm chip comprises register, and register stores a plurality of ON times and and the pairing LEB time of each ON time of switching tube in advance.After having confirmed the switching tube ON time of current period; The LEB time confirms that the unit is used for the switching tube ON time according to the current period of being surveyed; From register, select the corresponding LEB time T of switching tube ON time (n) with said current period, and confirmed as the LEB time of following one-period the selected LEB time.Then, in the switching tube conducting of following one-period, T (n) is done subtraction, each clock cycle subtracts 1, up to reducing to till 0, do subtraction during this period of time just as LEB time of following one-period.In another embodiment, after having confirmed the switching tube ON time of current period, the switching tube ON time of determined current period is deducted preset set time Tc, and the difference T (n) of gained confirmed as the LEB time of following one-period.Then, in the switching tube conducting of following one-period, T (n) is done subtraction, each clock cycle subtracts 1, up to reducing to till 0, do subtraction during this period of time just as LEB time of following one-period.
Certainly, in another embodiment, probe unit also can be confirmed the ON time of switching tube according to alternate manner, for example, because
Wherein, T
OnpBe the switching tube ON time; V
Cs_ref2Second reference voltage for the comparator of pwm chip inside; V
InFor the input AC signal through over commutation and filtered DC input voitage value, the i.e. DC input voitage of transformer; L
pInductance value for the former limit of transformer T1 winding.So, also can be through surveying current period V
Cs_ref2, V
InSignal obtains the information of current period switch conduction time, and then confirms the LEB time of following one-period.
Specify below how according to the current period V that is surveyed
Cs_ref2, V
InConfirm the LEB time of following one-period: combine Fig. 7 A and Fig. 7 B; At first, Fig. 7 A show the LEB time confirm the circuit diagram of an embodiment of unit, this LEB time confirm the unit comprise reverser U121, first K switch 1, second switch K2, charging capacitor C, current source Ich, reference voltage source Vref, comparator U122, with a door U123; Wherein, First K switch 1 is connected between the inverting input and ground of comparator U122, the first end ground connection of current source Ich, and second end of current source Ich is successively through second switch K2, charging capacitor C ground connection; The tie point of second switch K2 and charging capacitor C connects the inverting input of comparator U122; The in-phase input end of the first termination comparator U122 of reference voltage source Vref, the second end ground connection of reference voltage source Vref, base stage control end (Vbase) connects the control end of second switch K2 and the input of reverser U121 respectively; The output of reverser U121 connects the control end of first K switch 1; The first input end of the output termination of comparator U122 and door U123, with the second input termination base stage control end of door U123, the time of exporting high level with door U123 is the LEB time of following one-period.In conjunction with Fig. 7 B; When base stage control end (Vbase) was high level, first K switch 1 was broken off, second switch K2 is closed, and current source Ich begins the charging for charging capacitor C; The voltage Vc of charging capacitor C begins to rise with certain slope; As the voltage Vc of charging capacitor C during less than the voltage of reference voltage source Vref, comparator U122 exports high level, with door U123 output high level; As the voltage Vc of charging capacitor C during greater than the voltage of reference voltage source Vref, comparator U122 output low level is with door U123 output low level.Therefore, can be with confirming as LEB time of following one-period with the time of door U123 output high level.For avoiding next cycle switch pipe the danger of logic error, infringement even blast to occur; In the charging interval that can change charging capacitor according to the DC input voitage or the second inner reference voltage of pwm chip of the transformer of the current period of being surveyed, the method that changes the charging interval of charging capacitor C for example be at least one in following: (1) change current source Ich; (2) capacitance of change charging capacitor C; (3) change reference voltage source Vref.Because it is the LEB time of following one-period that the voltage that begins to be charged to charging capacitor from charging capacitor rises to the time of preset reference voltage; So; According to the charging interval that the DC input voitage or the second inner reference voltage of pwm chip of the transformer of the current period of being surveyed changed charging capacitor, just correspondingly changed the LEB time of following one-period.
Fig. 8 is the flow chart of control method embodiment one of the switching tube of Switching Power Supply of the present invention, and the control method of the switching tube of this Switching Power Supply comprises:
S1. survey the switching tube ON time of current period;
S2. confirm the LEB time of following one-period according to the switching tube ON time of the current period of being surveyed; Wherein, The LEB time of determined following one-period is greater than the maximum duration of the peak voltage that is produced on the switching tube conducting instantaneous sampling resistance, and less than the switching tube ON time.
In one embodiment, step S1 is: the clock cycle that produces according to oscillator, the high level of the base control signal of the current period of switching tube is counted, and count value is deciphered, to confirm the switching tube ON time of current period.Correspondingly; Step S2 is: according to the switching tube ON time of the current period of being surveyed; From register, select the corresponding LEB time of switching tube ON time with said current period; And the selected LEB time confirmed as LEB time of following one-period, wherein, said register store in advance switching tube a plurality of ON times and with the pairing LEB time of each ON time.Certainly, step S2 also can be: the switching tube ON time of the current period of being surveyed is deducted the preset set time, and the difference of gained confirmed as the LEB time of following one-period.
In another embodiment, step S1 is: the DC input voitage of the transformer through surveying current period and the switching tube ON time that the second inner reference voltage of pwm chip is confirmed current period.Correspondingly; Step S2 is: in the charging interval that changes charging capacitor according to the DC input voitage or the second inner reference voltage of pwm chip of the transformer of the current period of being surveyed, the time that the voltage that begins to be charged to charging capacitor from charging capacitor rises to preset reference voltage is the LEB time of following one-period.
The above is merely the preferred embodiments of the present invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within the claim scope of the present invention.
Claims (12)
1. Switching Power Supply; Comprise transformer, switching tube, sampling resistor and be used for the pwm chip of control switch pipe break-make; Wherein, The different name end of the former limit winding of said transformer connects DC input voitage, and the end of the same name of the former limit winding of said transformer connects the collector electrode of said switching tube, and the base stage of said switching tube connects the base stage control end of pwm chip; The emitter of said switching tube is through sampling resistor ground connection, and the emitter of said switching tube also connects the sampling end of pwm chip; It is characterized in that said pwm chip comprises:
Probe unit is used to survey the switching tube ON time of current period;
The LEB time is confirmed the unit; Be used for confirming the LEB time of following one-period according to the switching tube ON time of the current period of being surveyed; Wherein, The LEB time of determined following one-period is greater than the maximum duration of the peak voltage that is produced on the switching tube conducting instantaneous sampling resistance, and less than the switching tube ON time.
2. Switching Power Supply according to claim 1 is characterized in that, said probe unit comprises:
Oscillator is used to produce the clock cycle;
Counter is used for according to the clock cycle that oscillator produces the high level of the base control signal of the current period of switching tube being counted;
Decoder is used for count value is deciphered, to confirm the switching tube ON time of current period.
3. Switching Power Supply according to claim 2 is characterized in that said pwm chip comprises register, and said register store in advance switching tube a plurality of ON times and with the pairing LEB time of each ON time;
The said LEB time confirms that the unit is used for the switching tube ON time according to the current period of being surveyed; From register, select the corresponding LEB time of switching tube ON time with said current period, and confirmed as the LEB time of following one-period the selected LEB time.
4. Switching Power Supply according to claim 2 is characterized in that, the said LEB time confirms that the unit is used for the switching tube ON time of the current period of being surveyed is deducted the preset set time, and the difference of gained is confirmed as the LEB time of following one-period.
5. Switching Power Supply according to claim 1 is characterized in that, said probe unit is used for confirming through the DC input voitage of the transformer of surveying current period and the second inner reference voltage of pwm chip the switching tube ON time of current period.
6. Switching Power Supply according to claim 5 is characterized in that, the said LEB time confirm the unit comprise reverser, first switch, second switch, charging capacitor, current source, reference voltage source, comparator, with door; Wherein, First switch is connected between the inverting input and ground of comparator, the first end ground connection of current source, and second end of current source is successively through second switch, charging capacitor ground connection; The tie point of second switch and charging capacitor connects the inverting input of comparator; The in-phase input end of the first termination comparator of reference voltage source, the second end ground connection of reference voltage source, the base stage control end connects the control end of second switch and the input of reverser respectively; The output of reverser connects the control end of first switch; The first input end of the output termination of comparator and door with the second input termination base stage control end of door, is LEB time of following one-period with time of door output high level.
7. the control method of the switching tube of the described Switching Power Supply of claim 1 is characterized in that, comprising:
S1. survey the switching tube ON time of current period;
S2. confirm the LEB time of following one-period according to the switching tube ON time of the current period of being surveyed; Wherein, The LEB time of determined following one-period is greater than the maximum duration of the peak voltage that is produced on the switching tube conducting instantaneous sampling resistance, and less than the switching tube ON time.
8. the control method of the switching tube of Switching Power Supply according to claim 7 is characterized in that, said step S1 is:
The clock cycle that produces according to oscillator, the high level of the base control signal of the current period of switching tube is counted, and count value is deciphered, to confirm the switching tube ON time of current period.
9. the control method of the switching tube of Switching Power Supply according to claim 8 is characterized in that, said step S2 is:
Switching tube ON time according to the current period of being surveyed; From register, select the corresponding LEB time of switching tube ON time with said current period; And confirmed as LEB time of following one-period the selected LEB time; Wherein, said register stores a plurality of ON times and and the pairing LEB time of each ON time of switching tube in advance.
10. the control method of the switching tube of Switching Power Supply according to claim 8 is characterized in that, said step S2 is:
The switching tube ON time of the current period of being surveyed is deducted the preset set time, and the difference of gained confirmed as the LEB time of following one-period.
11. the control method of the switching tube of Switching Power Supply according to claim 7; It is characterized in that; In step S1, the DC input voitage of the transformer through surveying current period and the switching tube ON time that the second inner reference voltage of pwm chip is confirmed current period.
12. the control method of the switching tube of Switching Power Supply according to claim 11; It is characterized in that; In said step S2; In the charging interval that changes charging capacitor according to the DC input voitage or the second inner reference voltage of pwm chip of the transformer of the current period of being surveyed, the time that the voltage that begins to be charged to charging capacitor from charging capacitor rises to preset reference voltage is the LEB time of following one-period.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104009616A (en) * | 2013-02-23 | 2014-08-27 | 德州仪器公司 | Apparatus and methods to control peak current mode controlled power converters using selective noise blanking |
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| EP0626755A1 (en) * | 1993-05-25 | 1994-11-30 | Motorola, Inc. | Leading edge blanking circuit |
| US20090091353A1 (en) * | 2007-10-04 | 2009-04-09 | Chui-Hua Chiu | Method for detecting leading edge blanking parameter of power management chip |
| CN102340253A (en) * | 2010-07-19 | 2012-02-01 | 力林科技股份有限公司 | Power supply converting device with regulatable lead-edge-blanking time and overcurrent protection method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104009616A (en) * | 2013-02-23 | 2014-08-27 | 德州仪器公司 | Apparatus and methods to control peak current mode controlled power converters using selective noise blanking |
| CN104009616B (en) * | 2013-02-23 | 2018-11-13 | 德州仪器公司 | To use selective noise blanking control peak-current mode control power converter device and method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102594151B (en) | 2014-07-16 |
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Address after: 518057, room 10, building 5-8, Changhong science and technology building, twelve South tech Road, Nanshan District Science Park, Shenzhen, Guangdong Patentee after: Huimang Microelectronics (Shenzhen) Co.,Ltd. Address before: 518057, building 10, building 5-8, Changhong technology building, twelve South tech Road, Nanshan District science and Technology Park, Shenzhen, Guangdong Patentee before: FREMONT MICRO DEVICES (SZ) Ltd. |