CN106533411B - A kind of adaptive turn-off time generation circuit suitable for booster converter - Google Patents

A kind of adaptive turn-off time generation circuit suitable for booster converter Download PDF

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Publication number
CN106533411B
CN106533411B CN201710010095.9A CN201710010095A CN106533411B CN 106533411 B CN106533411 B CN 106533411B CN 201710010095 A CN201710010095 A CN 201710010095A CN 106533411 B CN106533411 B CN 106533411B
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China
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pmos tube
tube
comparator
grid
pmos
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CN201710010095.9A
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CN106533411A (en
Inventor
明鑫
唐韵扬
高笛
魏秀凌
王卓
张波
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University of Electronic Science and Technology of China
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University of Electronic Science and Technology of China
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/16—Modifications for eliminating interference voltages or currents
    • H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches

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  • Dc-Dc Converters (AREA)

Abstract

A kind of adaptive turn-off time generation circuit suitable for booster converter, belongs to electronic circuit technology field.Voltage value at comparator positive input introduces true duty cycle information, avoids influence of the load current to frequency；The negative input of comparator connects a fixed clock generator, when the voltage of the voltage of comparator negative input touching comparator positive input, the output signal of adaptive turn-off time generation circuit can export a upward pulse and change switching signal, to control booster converter unlatching.Present invention introduces true duty cycle informations, avoid influence of the load current to frequency, stablize switching frequency, are conducive to the processing of electromagnetic interference, reduce design cost.

Description

A kind of adaptive turn-off time generation circuit suitable for booster converter
Technical field
The invention belongs to electronic circuit technology fields, and in particular to be suitable for oneself of booster converter (boost) to one kind Adapt to the generation circuit of turn-off time (ACOT:adaptive constant-off-time).
Background technique
In recent years, with the fast development of power electronics and electronic technology, booster converter is in computer, communication, industry The fields such as automation, electronics or electric instrument are more widely applied.
Traditional booster converter has two kinds of current-mode, voltage-mode loop control models, and the advantage of current-mode is have Simpler loop compensation and higher line regulation and load regulation.But on the other hand, since current-mode is to making an uproar Sound is very sensitive, subharmonic concussion is especially likely to occur when duty ratio is greater than 50%, so generally requiring slope compensation.Phase For the Peak Current Mode booster converter of general constant frequency, the Peak Current Mode boosting inverter with constant off-time Device does not need to do slope compensation, can guarantee its stability yet.However the turn-off time of booster converter and its working frequency meet Relational expression TOFF=(1-D)/f, wherein TOFFThe turn-off time is represented, D represents duty ratio, f representation switch frequency.Therefore general perseverance Determining the turn-off time will lead to the variation of different duty application lower frequency, and the difficulty for causing electromagnetic interference (EMI) to handle increases.
General adaptive constant turn-off time generator passes through the information of sampled input voltage and output voltage, to simulate The information of duty ratio obtains the frequency of an approximately constant.It is limited due to power tube but when load current changes Conducting resistance and inductance on dead resistance influence, the relationship between output voltage and input voltage has been more than by accounting for Sky also suffers from the influence of load current, so true duty cycle information cannot be represented, so by this method than determining Obtained constant frequency is still less desirable.
Summary of the invention
The problem of the deficiency of stability brought by variation for boost converter systems working frequency, the present invention provide one Generation circuit of the kind for the adaptive constant turn-off time of booster converter, directly samples the information of duty ratio, guarantees different Frequency-invariant under duty ratio reduces design cost conducive to the processing of electromagnetic interference EMI, and avoids load current to frequency Influence.
The technical solution of the present invention is as follows:
A kind of adaptive turn-off time generation circuit suitable for booster converter, including comparator A0, the first PMOS tube M1, the second PMOS tube M2, the first NMOS tube M3, first resistor R1, second resistance R2, first capacitor C1, the second capacitor C2, third electricity Hold C3, the first current source IC1, the second current source IC2And phase inverter,
Second PMOS tube M2With the first NMOS tube M3Grid input switch signal PWM, the first NMOS tube M3Drain electrode connect One current source IC1, third capacitor C3One end and comparator A0Negative input, source electrode meets third capacitor C3The other end simultaneously Ground connection；
Second current source IC2Meet the first PMOS tube M1With the second PMOS tube M2Source electrode, the first PMOS tube M1Grid connect base Quasi- voltage Vref, grounded drain, the second PMOS tube M2Drain electrode pass through first resistor R1With first capacitor C1Parallel-connection structure after Ground connection；
Second resistance R2It connects in comparator A0Positive input and the second PMOS tube M2Drain electrode between, the second capacitor C2 It connects in comparator A0Between positive input and ground；
The input of phase inverter terminates comparator A0Output end, output end output adaptive turn-off time generates electricity The output signal TOFF-FLAG on road.
Specifically, the comparator A0Including third PMOS tube M4, the 4th PMOS tube M5, the 5th PMOS tube M6, the 6th PMOS Pipe M7, the 7th PMOS tube M8, the 8th PMOS tube M9, the second NMOS tube M10, third NMOS tube M11With the 4th NMOS tube M12,
Third PMOS tube M4With the 5th PMOS tube M6Grid meet first grid signal vtb1, source electrode all connects supply voltage AVDD, third PMOS tube M4Drain electrode meet the 4th PMOS tube M5Source electrode, the 5th PMOS tube M6Drain electrode meet the 6th PMOS tube M7's Source electrode, the 4th PMOS tube M5With the 6th PMOS tube M7Grid meet second grid signal vtb2；
7th PMOS tube M8With the 8th PMOS tube M9Source electrode interconnect and connect the 4th PMOS tube M5Drain electrode, the 7th PMOS Pipe M8Grid be the comparator A0Negative input, the 8th PMOS tube M9Grid be the comparator A0Forward direction it is defeated Enter end；
Third NMOS tube M11Grid connect the second NMOS tube M10Grid and drain electrode and the 7th PMOS tube M8Drain electrode, Its 8th PMOS tube M of connection that drains9Drain electrode and the 4th NMOS tube M12Grid, the 4th NMOS tube M12Drain electrode and the 6th PMOS Pipe M7Drain interconnection and as the comparator A0Output end；
Second NMOS tube M10, third NMOS tube M11With the 4th NMOS tube M12Source electrode ground connection.
The invention has the benefit that the present invention passes through to current source IC2Apply switch control signal, is directly accessed switch Signal PWM introduces true duty cycle information in the voltage value of comparator A0 positive input Vr point, avoids load current pair The influence of frequency avoids boost converter systems switching frequency from changing with the variation of duty ratio, stablizes switching frequency, favorably In the processing of electromagnetic interference EMI, design cost is reduced.
Detailed description of the invention
Fig. 1 is a kind of system frame of the adaptive turn-off time generation circuit suitable for booster converter provided by the invention Frame figure.
Fig. 2 is a kind of comparator of the adaptive turn-off time generation circuit suitable for booster converter provided by the invention A0Circuit diagram.
Fig. 3 is a kind of applicable boost converter systems frame diagram of the present invention.
Fig. 4 is LX point signal square wave figure in Fig. 3.
Fig. 5 is V in Fig. 1aPoint signal square wave figure.
Fig. 6 is comparator A in Fig. 10Positive input Vr and negative input Vc voltage oscillogram.
Specific embodiment
With reference to the accompanying drawing, the technical schemes of the invention are described in detail:
As shown in figure 3, a kind of boost converter circuit frame that the present invention is applicable in is by input voltage VIN, inductance, two Power tube MN and MP, capacitor and load are constituted, and input voltage is connected in one end of inductance and the source electrode of power tube MN, inductance it is another End connection power tube MN drain electrode and power tube MP source electrode, capacitor be connected in power tube MP drain electrode and power tube MN source electrode it Between, the inversion signal of the grid connection switch signal PWM of grid connection switch the signal PWM, power tube MP of power tube MNIt is the charging stage of inductance when MN is opened, and MP is turned off, the voltage of time Ton, LX point is low；As MN shutdown, MP It is inductance to capacitor discharge regime, the voltage of time Toff, LX point is the output voltage of booster converter, waveform when unlatching For figure as shown in figure 4, wherein D indicates the duty ratio of boost converter circuit, T indicates switch periods.
As shown in Figure 1, adaptive turn-off time generation circuit proposed by the present invention includes comparator A0, the first PMOS tube M1、 Second PMOS tube M2, the first NMOS tube M3, first resistor R1, second resistance R2, first capacitor C1, the second capacitor C2, third capacitor C3, the first current source IC1, the second current source IC2And phase inverter, the second PMOS tube M2With the first NMOS tube M3Grid input switch Signal PWM, the first NMOS tube M3Drain electrode meet third capacitor C3One end and comparator A0Negative input, source electrode ground connection, First current source IC1Pass through third capacitor C3After be grounded；Second current source IC2Meet the first PMOS tube M1With the second PMOS tube M2Source Pole, the first PMOS tube M1Grid meet reference voltage Vref, grounded drain, the second PMOS tube M2Drain electrode pass through first resistor It is grounded after the parallel-connection structure of R1 and first capacitor C1, the second PMOS tube M2Drain electrode be VaPoint；Second resistance connects in comparator A0's Positive input and the second PMOS tube M2Drain electrode between, the second capacitor C2It connects in comparator A0Between positive input and ground；Instead The input of phase device terminates comparator A0Output end, the output signal of output end output adaptive turn-off time generation circuit TOFF-FLAG, comparator A0Positive input be comparison point Vr, negative input be Vc point.
As shown in Fig. 2, comparator A0Including third PMOS tube M4, the 4th PMOS tube M5, the 5th PMOS tube M6, the 6th PMOS Pipe M7, the 7th PMOS tube M8, the 8th PMOS tube M9, the second NMOS tube M10, third NMOS tube M11With the 4th NMOS tube M12, third PMOS tube M4With the 5th PMOS tube M6Grid meet first grid signal vtb1, source electrode all meets supply voltage AVDD, the 3rd PMOS Pipe M4Drain electrode meet the 4th PMOS tube M5Source electrode, the 5th PMOS tube M6Drain electrode meet the 6th PMOS tube M7Source electrode, the 4th PMOS Pipe M5With the 6th PMOS tube M7Grid meet second grid signal vtb2；7th PMOS tube M8With the 8th PMOS tube M9Source electrode it is mutual Connect and connects the 4th PMOS tube M5Drain electrode, the 7th PMOS tube M8Grid be the comparator A0Negative input, the 8th PMOS tube M9Grid be the comparator A0Positive input；Third NMOS tube M11Grid connect the second NMOS tube M10's Grid and drain electrode and the 7th PMOS tube M8Drain electrode, drain electrode connection the 8th PMOS tube M9Drain electrode and the 4th NMOS tube M12's Grid, the 4th NMOS tube M12Drain electrode and the 6th PMOS tube M7Drain interconnection and as the comparator A0Output end；The Two NMOS tube M10, third NMOS tube M11With the 4th NMOS tube M12Source electrode ground connection.Wherein first grid signal vtb1 is that control is inclined The voltage signal of electric current is set, is generally obtained by a current mirror mirror；Second grid fresh flower vtb2 is common-source common-gate current mirror The grid signal of grid grade altogether guarantees that the mos pipe of common gate works in saturation region.
When circuit is run in Fig. 1, comparator A0The design of associated branch of positive input Vr point be skill of the invention Art bright spot.In the Ton stage, switching signal PWM is height, the second PMOS tube M2Shutdown, the second current source IC2From the first PMOS tube M1 Afterflow, first capacitor C1No charge accumulation is gone up, Va point voltage is low in Fig. 1；In the Toff stage, switching signal PWM be it is low, the One PMOS tube M1Pipe is opened, and the first PMOS tube M is flowed through1With the second PMOS tube M2Electric current are as follows:
First PMOS tube M1Gate source voltage | Vgs1-Vth| it is far longer than the second PMOS tube M2Gate source voltage | Vgs2-Vth|, then Second current source IC2Electric current flow through the first PMOS tube M1Can be ignored, be approximately considered the first PMOS tube M1Shutdown, the Two current source IC2Electric current all from the second PMOS tube M2Pass through, to small capacitances first capacitor C1Charging, charging rate quickly, Va The voltage of point is elevated quickly, and to small resistance first resistor R1Charging, when flowing through first resistor R1Electric current be equal to charging current IC2When, reach stable, at this time the voltage of Va point are as follows:
Va=R1·IC2
So with the operation of system charge and discharge, in the Ton stage, the voltage of Va point be it is low, in the Toff stage, Va point Voltage is height, and the waveform of the voltage of Va point is as shown in figure 5, be approximately a square wave.When specific implementation, R herein1·IC2With In the voltage setting of control Va point high level, the size of comparison point Vr is also controlled, value need to consider resistor area and power consumption Compromise, first capacitor C1It should take as far as possible small, be more favorable for the approximation of square wave, but first capacitor C simultaneously1Value lower limit should ensure that Node Va is not in voltage glitch, under normal circumstances R1*C1It should be less than 0.1TS。
Second resistance R2, the second capacitor C2It is big resistance, bulky capacitor, plays a RC filtering, the side of Va point voltage Wave is filtered into a DC voltage, and the voltage value of Vr point is the average value of Va:
Vr=(1-D) R1·IC2
Comparator A0The V of positive inputrThe voltage value of point introduces the information of true duty ratio, avoids load electricity Flow the influence to frequency.
When specific implementation, R2*C2It should be greater than 10TS, can be only achieved enough filter effects, while being considered as domain again Area, here and the compromise of precision and area.
Comparator negative input branch i.e. the first current source IC1, the first NMOS tube M3With third capacitor C3The electricity of composition Road, it is consistent with the generally fixed negative end branch of clock generator.When the Ton stage, i.e. switching signal PWM is high, and first NMOS tube M3When unlatching, the first current source IC1From the first NMOS tube M3Electric discharge, third capacitor C3No stored charge is gone up, at this time Vc Voltage be it is low, comparator output for height；When the Toff stage, i.e. switching signal PWM is low, the first NMOS tube M3When shutdown, first Current source IC1To third capacitor C3Charging, VcThe voltage lifting of point:
When the voltage of Vc point is raised to the voltage of touching Vr point, the output signal of adaptive turn-off time generation circuit TOFF_FLAG can export a upward pulse and change switching signal PWM, and original switching signal PWM is low level, output letter After number TOFF_FLAG comes, it is low level that switching signal PWM, which is jumped, terminates the Toff stage of booster converter, starts Ton In the stage, waveform is as shown in fig. 6, then have:
Vc=Vr
Both members have (1-D), offset:
It can solve:
Then switching frequency f are as follows:
The present invention passes through to current source IC2Apply switch control signal, that is, passes through the second PMOS tube M2Switch control, directly Switching signal PWM is accessed, switching signal PWM represents true duty cycle information, not will receive the influence of load current.And Tradition is by sampling the method for input and output voltage come simulation dutycycle information, when load current changes, input and output The relationship of voltage cannot be indicated only by duty ratio, can introduce the influence of load current, even if adding elimination load electricity again The interlock circuit of the information of stream can not precisely eliminate load current since the conducting resistance of power tube can not be estimated accurately It influences, increases design complexities instead.Present invention introduces information be PWM information, be not by traditional sampling input and output Voltage carrys out simulation dutycycle information, and PWM information is true duty cycle information, can accurately realize in this way one really The generation circuit of adaptive constant turn-off time, is not influenced by load current.Avoid boost converter systems switching frequency with The variation of duty ratio and change, stablize switching frequency, be conducive to the processing of electromagnetic interference EMI, reduce design cost.
Those skilled in the art disclosed the technical disclosures can make various do not depart from originally according to the present invention Various other specific variations and combinations of essence are invented, these variations and combinations are still within the scope of the present invention.

Claims (2)

1. a kind of adaptive turn-off time generation circuit suitable for booster converter, which is characterized in that including comparator (A0)、 First PMOS tube (M1), the second PMOS tube (M2), the first NMOS tube (M3), first resistor (R1), second resistance (R2), first capacitor (C1), the second capacitor (C2), third capacitor (C3), the first current source (IC1), the second current source (IC2) and phase inverter,
Second PMOS tube (M2) grid and the first NMOS tube (M3) grid input switch signal (PWM), the first NMOS tube (M3) Drain electrode meet the first current source (IC1), third capacitor (C3) one end and comparator (A0) negative input, the first NMOS tube (M3) source electrode meet third capacitor (C3) the other end and ground connection；
Second current source (IC2) meet the first PMOS tube (M1) and the second PMOS tube (M2) source electrode, the first PMOS tube (M1) grid It connects reference voltage (Vref), the first PMOS tube (M1) grounded drain, the second PMOS tube (M2) drain electrode pass through first resistor (R1) With first capacitor (C1) parallel-connection structure after be grounded；
Second resistance (R2) connect in comparator (A0) positive input and the second PMOS tube (M2) drain electrode between, the second capacitor (C2) connect in comparator (A0) between positive input and ground；
The input of phase inverter terminates comparator (A0) output end, output end output adaptive turn-off time of phase inverter produces The output signal (TOFF-FLAG) of raw circuit.
2. the adaptive turn-off time generation circuit according to claim 1 suitable for booster converter, which is characterized in that Comparator (the A0) it include third PMOS tube (M4), the 4th PMOS tube (M5), the 5th PMOS tube (M6), the 6th PMOS tube (M7)、 7th PMOS tube (M8), the 8th PMOS tube (M9), the second NMOS tube (M10), third NMOS tube (M11) and the 4th NMOS tube (M12),
Third PMOS tube (M4) and the 5th PMOS tube (M6) grid connect first grid signal (vtb1), source electrode all connect power supply electricity It presses (AVDD), third PMOS tube (M4) drain electrode meet the 4th PMOS tube (M5) source electrode, the 5th PMOS tube (M6) drain electrode connect the 6th PMOS tube (M7) source electrode, the 4th PMOS tube (M5) and the 6th PMOS tube (M7) grid meet second grid signal (vtb2)；
7th PMOS tube (M8) and the 8th PMOS tube (M9) source electrode interconnect and connect the 4th PMOS tube (M5) drain electrode, the 7th PMOS tube (M8) grid be the comparator (A0) negative input, the 8th PMOS tube (M9) grid be the comparator (A0) positive input；
Third NMOS tube (M11) grid connect the second NMOS tube (M10) grid and drain electrode and the 7th PMOS tube (M8) leakage Pole, the 8th PMOS tube (M of drain electrode connection9) drain electrode and the 4th NMOS tube (M12) grid, the 4th NMOS tube (M12) drain electrode With the 6th PMOS tube (M7) drain interconnection and as the comparator (A0) output end；
Second NMOS tube (M10), third NMOS tube (M11) and the 4th NMOS tube (M12) source electrode ground connection.
CN201710010095.9A 2017-01-06 2017-01-06 A kind of adaptive turn-off time generation circuit suitable for booster converter Expired - Fee Related CN106533411B (en)

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CN109980935A (en) * 2019-04-25 2019-07-05 西安电子科技大学 Self-adaptive turn-off time timer with adjustable switching frequency

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US7265606B1 (en) * 2004-09-02 2007-09-04 National Semiconductor Corporation Apparatus and method for a boot strap circuit for a boost voltage converter
CN201674212U (en) * 2010-04-30 2010-12-15 深圳市博源电子有限公司 Overvoltage protection circuit of a switch power supply and its corresponding switch power supply

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