CN201230276Y - Synchronous peak value current control mode impulse-width modulation DC/DC converter - Google Patents

Abstract

The utility model relates to a sync peak current control model pulse-width modulation DC/DC converter. The difference value between a reference voltage and a load voltage component is compared and amplified by an error amplifier, and the obtained control signals are transmitted to the inverting input terminal of a pulse-width modulation comparator; an oblique wave oscillator, an oblique wave compensating circuit and an adder are additionally arranged, the oblique wave signals produced by the oblique wave oscillator are transmitted into the input terminal of the oblique wave compensating circuit; the output terminals of the oblique wave compensating circuit and a current detection amplifier are respectively transmitted into the two input terminals of the adder; the output terminal of the adder is transmitted into the non inverting input terminal of the pulse-width modulation comparator; the output signal of the pulse-width modulation comparator and the positive narrow pulse signal produced by a pulse oscillator are respectively transmitted into the R terminal and the S terminal of a RS trigger, and the RS trigger is triggered to produce an on-off signal to control the on-off of a synchronous rectifier tube, a synchronous switch tube and a current detecting tube; and a DC voltage with small fluctuation can be obtained on a load after current is filtered by an inductor and a capacitor after passing through the energy storage and the release of the inductor.

Description

A kind of sync peaks current control mode pulse-width modulation DC/DC transducer

Technical field

The utility model relates to the power supply of portable type electronic product, and particularly a kind of sync peaks current control mode pulse-width modulation DC/DC transducer belongs to the switch power technology field.

Background technology

Power supply is an important component part of electronic product, and power quality directly influences the performance of electronic equipment.Portable type electronic product adopts powered battery usually, and along with the carrying out of discharge, cell voltage reduces gradually, and the internal resistance of cell increases gradually; On the one hand, when battery was brought into use, terminal voltage was higher and the internal resistance of cell is less, easily causes output current to cause waste of electric energy greater than the load actual electric current, especially is unfavorable for the prolongation of System production time and stand-by time; On the other hand, after use a period of time, terminal voltage reduces and internal resistance of cell increase, causes load variations to cause and the variation of bigger supply power voltage is unfavorable for the high performance work of system held again.For prolonging battery useful life and obtaining the little direct voltage that fluctuates, need high efficiency, little, the lightweight low voltage DC of volume/DC transducer.

The DC/DC transducer has three types: linear voltage regulator, charge pump and Switching Power Supply.Wherein Switching Power Supply is because of having efficient height, extremely people's the favor of characteristics of positive-negative polarity and buck mode flexibly, and it is widely used among mancarried device such as notebook computer, mobile phone, beep-pager, the PDA.

Switch power technology belongs to power electronic technology, it becomes another kind of form to power supply from a kind of modality conversion, satisfy various electricity consumption requirements,, therefore caused the attention of social each side and promoted rapidly because it energy-efficiently brings huge economic benefit.Recently along with the continuous development of mobile devices such as notebook computer, mobile phone, PDA, MP3, MP4, the kind of its power supply IC is also day by day various because of the cause of pursuing the equipment high performance.CPU, microcontroller, DSP etc. need the operating voltage of fixing separately, make that the operating voltage in the equipment has reached 5 kinds more than at least, and can change with the difference of used device version.In addition, for the light in a small amount and longer battery useful life of body of realizing mobile device, the power consumption of minority IC can increase.In this case, adopt standardized power supply IC or customization power supply to be the gesture of falling behind, having high flexibility and high performance Small Universal power supply IC has then become the developing direction of mobile device with power supply IC.

Prior art shown in Figure 2, sync peaks current control mode pulse-width modulation DC/DC transducer comprises error amplifier A1, pulse-width modulation comparator A2, current sense amplifier A3, pulse oscillator, rest-set flip-flop, synchronous rectifier M0, synchro switch pipe M1, current detecting pipe M2, current sense resistor R2, divider resistance R0, R1, inductance L 0, filter capacitor C0, frequency compensation resistance capacitance R3, C1, C2.By error amplifier A1 the difference between reference voltage V ref and the load voltage component Vout (R1/ (R0+R1)) is compared, amplifies, controlled signal Vc.Because a switch periods in the time, the variable quantity of load voltage is very little, can be similar to think same switch periods in the time Vc value constant.Vc is sent to the inverting input of pulse-width modulation comparator A2; Compare, amplify the back by current sense resistor R2 and the detected inductor current signal of current detecting pipe M2 through current sense amplifier A3 and produce the voltage Vsens that is proportional to the inductive current instantaneous value, Vsens is sent to the in-phase input end of pulse-width modulation comparator A2; The signal that pulse-width modulation comparator A2 produces is sent into the R end of rest-set flip-flop; The positive narrow pulse signal that pulse oscillator produces is delivered to the S end of rest-set flip-flop.When the oscillator in the circuit begins to send synchronously positive narrow pulse signal, be exactly the beginning of each switch periods.This moment S=1, R=0, rest-set flip-flop output QN=0, synchronous rectifier M0 begin to turn-off, synchro switch pipe M1 begins conducting.Electric current is flowed through synchro switch pipe M1, inductance L 0 to capacitor C 0 and load by battery, and inductive current continues to rise, and inductive energy storage is increasing, and energy is sent to inductance by battery and is stored in the inductance.After the positive very fast disappearance of narrow pulse signal, S=0, R=0, rest-set flip-flop output is in hold mode, and synchronous rectifier M0 maintains off state, and synchro switch pipe M1 maintains conducting state.After this, because synchro switch pipe M1 is in conducting state, inductive current begins linear the increase, Vsens also increases and increases along with inductive current, generally before this cycle finished, signal rose to and satisfies Vsens〉Vc, make pulse-width modulation comparator A2 produce upset, so R=1, S=0, rest-set flip-flop output QN=1, synchronous rectifier M0 begins conducting, synchro switch pipe M1 begins to turn-off, cutting off being connected of battery and inductance element, is that electric current is kept original direction so inductance produces induced electromotive force, and electric current flows to capacitor C 0 and load by inductance L 0, inductive current descends in time, and energy flows to load by inductance.Through inductance L 0, capacitor C 0 filtering, in load, can obtain the direct voltage Vout of pulsing very little.The relation of derivation output voltage and input voltage, the waveform at investigation switching node X place: when synchro switch pipe M1 conducting, synchronous rectifier M0 shutoff, ignore the conducting resistance of synchro switch pipe M1, have:

Vx＝Vin (1)

When synchro switch pipe (M1) shutoff, synchronous rectifier (M0) conducting, ignore the conducting resistance of synchronous rectifier (M0), have:

Vx＝0 (2)

The dead resistance of ignoring inductance L 0, capacitor C 0, the output voltage values that obtains in the load equates with the mean value of Vx, so have:

Vout＝D*Vin (3)

Wherein D is the duty ratio of synchro switch pipe (M1) ON time.

Oscillator is sent new pulse, begins next switch periods.

Said process has been realized following control law: when inductive current rises to the Vsens that satisfies condition〉during Vc, synchronous rectifier M0 promptly is switched on, synchro switch pipe M1 promptly is turned off, so inductance was disconnected with being connected of battery, inductive current is just linear subsequently to descend, up to next switch periods begin synchro switch pipe M1 again after the conducting inductive current just can increase.And in this cycle, synchro switch pipe M1 disconnects current instantaneous value constantly and is inductive current peak.Consider Vsens=i _LRsAs can reach a conclusion: in each cycle, be that the maximum that the inductive current instantaneous value in this cycle has been set is Vc/RsAs by the control voltage Vc of voltage control outer shroud output.

As seen, above-mentioned circuit has a defective, is exactly that system is unstable easily.

Summary of the invention

The purpose of this utility model is the defective that overcomes prior art, a kind of sync peaks current control mode pulse-width modulation DC/DC transducer is provided, it can improve conversion efficiency, obtain stable output, when can solve the portable type electronic product powered battery, reduce that the power consumption meaning extends the life of a cell or twice charging between the problem in the time interval.

Above-mentioned purpose of the present utility model is realized by following technical scheme:

A kind of sync peaks current control mode pulse-width modulation DC/DC transducer, be provided with and comprise error amplifier, the pulse-width modulation comparator, current sense amplifier, pulse oscillator, rest-set flip-flop, synchronous rectifier, the synchro switch pipe, the current detecting pipe, current sense resistor, divider resistance, inductance, filter capacitor and frequency compensation resistance capacitance, error amplifier compares reference voltage and the difference between the load voltage component of divider resistance dividing potential drop, amplify, controlled signal is also delivered to the inverting input of pulse-width modulation comparator, it is characterized in that: set up the oblique wave oscillator, oblique wave compensation circuit and adder, the ramp signal that the oblique wave oscillator produces is sent into the input of oblique wave compensation circuit, and the output of oblique wave compensation circuit is sent into an input of adder; Produce another input that the voltage signal that is proportional to the inductive current instantaneous value exports adder to by current sense resistor and the detected inductor current signal of current detecting pipe through current sense amplifier comparison, amplification back; The output of adder is sent into the in-phase input end of pulse-width modulation comparator; The positive narrow pulse signal that the output signal of pulse-width modulation comparator and pulse oscillator produce is delivered to R, the S end of rest-set flip-flop, triggering for generating switching signal, the Kai Heguan of control synchronous rectifier, synchro switch pipe and current detecting pipe respectively; Energy storage and the release characteristics and through inductance, capacitor filtering after of the result of said process by inductance obtains the very little direct voltage of pulsing in load.

Described oblique wave compensation circuit adopts the way of segmented compensation slope, and the slope of second portion is 4 times of slope of first;

Described reference voltage is 0.6V;

The open-loop gain of described error amplifier is more than or equal to 50dB, and phase margin is more than or equal to 60 °;

The open-loop gain of described pulse-width modulation comparator is more than or equal to 50dB;

The open-loop gain of described current sense amplifier is more than or equal to 20dB;

Positive narrow pulse signal and linear ramp signal that described oscillator produces are 1.5MHz;

Described synchronous rectifier is the NMOS pipe, and its conducting resistance is less than 0.4 Ω, and the synchro switch pipe is the PMOS pipe, and its conducting resistance is less than 0.5 Ω;

Described current sense resistor is 6 Ω.

Advantage of the present utility model and beneficial effect: inventive point of the present utility model is to utilize load voltage to be fed back to outer shroud, the inductive current instantaneous values feedback is as the internal control ring, introduce the oblique wave compensation technology and improve the stability of system, be implemented in the interior control of switch periods one by one inductive current peak.The utility model is as synchronous commutation type DC/DC transducer, can provide have high efficiency, big electric current, input voltage range are wide, the direct voltage output of output voltage stabilization, have very strong exploitativeness.

Description of drawings

Fig. 1 is an electric principle schematic of the present utility model;

Fig. 2 is the principle schematic of existing sync peaks current control mode pulse-width modulation DC/DC transducer;

Fig. 3 is a system simplification schematic diagram of the present utility model;

Fig. 4 is the current waveform figure of inductance of the present utility model;

Fig. 5 is the principle schematic of the another kind of embodiment of the utility model.

Embodiment

Referring to Fig. 1, compare with Fig. 2 prior art circuits, all the other are identical to have increased oblique wave oscillator, oblique wave compensation circuit and adder (being known circuits, so the physical circuit that no longer draws).The pulse signal Vosc that pulse oscillator produces sends into the S end of rest-set flip-flop; The ramp signal Vra that the oblique wave oscillator produces sends into the input of oblique wave compensation circuit; The output Vramp of oblique wave compensation circuit sends into an input of adder; The output Vsens of current sense amplifier A3 sends into another input of adder; The output Vp of adder sends into the in-phase input end of pulse-width modulation comparator; Feedback resistance R0 is connected between output voltage V out and the feedback voltage V FB, and feedback resistance R0 is connected between feedback voltage V FB and the ground; Inductance L 0 is connected between the drain terminal X of output voltage V out and synchronous rectifier M0, and filter capacitor C0 is connected between output voltage V out and the ground; The drain terminal of synchronous rectifier M0, the drain terminal of the drain terminal of synchro switch pipe M1 and current detecting pipe M2 is connected together, be X, the grid end of synchronous rectifier M0, the grid of the grid end of synchro switch pipe M1 and current detecting pipe M2 terminate at together, be Vswitch, the source end ground connection of synchronous rectifier M0, the source termination power of synchro switch pipe M1, the end Vse of the source termination current sampling resistor R2 of current detecting pipe M2, insert the inverting input of current sense amplifier A3 simultaneously, the substrate ground connection of synchronous rectifier M0, the substrate of the substrate of synchro switch pipe M1 and current detecting pipe M2 connects power supply; The other end of current sampling resistor R2 is connected on power supply, and the in-phase input end of current sense amplifier A3 also is connected on power supply; The inverting input of feedback voltage V FB put-into error amplifier A1, the in-phase input end of reference voltage Vref put-into error amplifier A1, the output Vc of error amplifier A1 inserts the inverting input of pulse-width modulation comparator; Frequency compensation capacitor C 2 is connected between the output Vc of feedback voltage V FB and error amplifier A1, also is connected between the output Vc of feedback voltage V FB and error amplifier A1 after frequency compensation resistance R 3 and 1 series connection of frequency compensation capacitor C; The output R of pulse-width modulation comparator inserts the R end of rest-set flip-flop, and the QN end Vswitch of rest-set flip-flop inserts grid end, the grid end of synchro switch pipe M1 and the grid end of current detecting pipe M2 of synchronous rectifier M0.

Wherein:

Inductance L 0 is used for receiving a supply voltage with accumulation energy therein from supply unit, produces induced voltage, and the energy that discharges accumulation;

Synchronous rectifier M0 and synchro switch pipe M1 by switch, power to the load-side output from power supply, and make the load-side output remain on the voltage that output is set;

Divider resistance (R0, R1) is used for output loading voltage is sampled, and obtains load voltage component Vout (R1/ (R0+R1));

Error amplifier A1 is used for comparison, amplifies from the error between load voltage component Vout (R1/ (R0+R1)) and the reference voltage V ref, controlled signal Vc;

Frequency compensation resistance capacitance (R3, C1, C2) is used to adjust zero point and the limit of error amplifier A1, thereby increases the phase margin of error amplifier A1, makes error amplifier A1 working stability;

Current detecting pipe M2 is used to detect the electric current that flows through synchro switch pipe M1, current sense resistor R2, and being used for current conversion is voltage, thereby obtains flowing through the current signal of inductance;

Current sense amplifier A3 is used for the inductor current signal that obtains from current detecting pipe M2 and current sense resistor R2 is compared, amplifies, thereby obtains being proportional to the voltage Vsens of inductive current instantaneous value;

Pulse oscillator and oblique wave oscillator are used to produce the linear ramp signal of positive narrow pulse signal and same frequency;

The oblique wave compensation circuit is used to produce oblique wave compensation signal Vramp, thereby improves the stability of total system;

Adder is used for voltage signal Vsens that is proportional to the inductive current instantaneous value that produces from current sense amplifier A3 and the oblique wave compensation signal Vramp that produces from the oblique wave compensation circuit are carried out addition, obtains integrated signal Vsens+Vramp;

Pulse-width modulation comparator A2 is used for control signal that produces from error amplifier A1 and the integrated signal Vsens+Vramp that produces from adder are compared, amplify, thereby produces the control signal of pulse-width modulation;

Rest-set flip-flop, to the control signal of the pulse-width modulation that produces from pulse-width modulation comparator A2 with carry out RS from the positive narrow pulse signal that oscillator produces and trigger, thereby produce the switching signal Vswith of control synchronous rectifier M0, synchro switch pipe M1 and current detecting pipe M2, the Kai Heguan of control synchronous rectifier M0, synchro switch pipe M1 and current detecting pipe M2;

Filter capacitor C0 and inductance L 0 constitute low pass filter together, thereby guarantee that output is stable.

Operation principle and process:

(difference between the R1/ (R0+R1) compares, amplifies to reference voltage V ref and load voltage component Vout by error amplifier A1, controlled signal Vc, frequency compensation resistance capacitance R3, C1, C2 are for zero point that changes error amplifier A1 and limit, thereby increase the phase margin of error amplifier A1, make error amplifier A1 working stability.The open-loop gain of error amplifier A1 is more than or equal to 50dB, and the phase margin of error amplifier A1 is more than or equal to 60 °.The detected inductor current signal of current sense resistor R2 and current detecting pipe M2 compares, amplifies the back through current sense amplifier A3 and produces the voltage Vsens that is proportional to the inductive current instantaneous value.The open-loop gain of current sense amplifier A3 is more than or equal to 20dB.Current sense resistor R2 is 6 Ω.

Vsens and the oblique wave compensation signal Vramp that produces by the oblique wave compensation circuit obtain integrated signal Vsens+Vramp after by the adder addition.The oblique wave compensation circuit adopts the way of segmented compensation slope, and the slope of second portion is 4 times of slope of first.Vc is sent to the inverting input of pulse-width modulation comparator A2, and integrated signal Vsens+Vramp is sent to the in-phase input end of pulse-width modulation comparator A2.Pulse-width modulation comparator A2 is the size of these two signals relatively.The open-loop gain of pulse-width modulation comparator A2 is more than or equal to 50dB.The signal that pulse-width modulation comparator A2 produces is sent into the R end of rest-set flip-flop; The positive narrow pulse signal of 1.5MHz that pulse oscillator produces is delivered to rest-set flip-flop S end.The oblique wave oscillator produces the linear ramp signal of same frequency, and this linear ramp signal is sent into the oblique wave compensation circuit.Output Vswith signal controlling synchronous rectifier M0, the synchro switch pipe M1 of rest-set flip-flop and the turn-on and turn-off of current detecting pipe M2.When pulse and oblique wave oscillator begin to send synchronously the positive narrow pulse signal of 1.5MHz and linear ramp compensating signal, be exactly the beginning of each switch periods.This moment S=1, R=0, rest-set flip-flop output QN=0, synchronous rectifier M0 begin to turn-off, synchro switch pipe M1 begins conducting.Electric current is flowed through synchro switch pipe M1, inductance L 0 to capacitor C 0 and load by battery, and inductive current continues to rise, and inductive energy storage is increasing, and energy is sent to inductance by battery and is stored in the inductance.After the positive very fast disappearance of narrow pulse signal, S=0, R=0, rest-set flip-flop output is in hold mode, and synchronous rectifier M0 maintains off state, and synchro switch pipe M1 maintains conducting state.After this, oblique wave compensation signal Vramp begins linear the increase from 0V, and because synchro switch pipe M1 is in conducting state, inductive current begins linear the increase, Vsens also increases and increases along with inductive current, generally before this cycle finishes, two signals rise to and satisfy Vsens+Vramp〉Vc, make pulse-width modulation comparator A2 produce upset, then R=1, S=0, rest-set flip-flop output QN=1, synchronous rectifier M0 begins conducting, and synchro switch pipe M1 begins to turn-off, and cuts off being connected of battery and inductance element, so it is that electric current is kept original direction that inductance produces induced electromotive force, electric current flows to capacitor C 0 and load by inductance L 0, and inductive current descends in time, and energy flows to load by inductance.Through inductance L 0, capacitor C 0 filtering, in load, can obtain the direct voltage Vout of pulsing very little.The relation of derivation output voltage and input voltage, the waveform at investigation switching node X place: when synchro switch pipe M1 conducting, synchronous rectifier M0 shutoff, ignore the conducting resistance of synchro switch pipe M1, have: Vx=Vin; When synchro switch pipe M1 shutoff, synchronous rectifier M0 conducting, ignore the conducting resistance of synchronous rectifier M0, have: Vx=0; The dead resistance of ignoring inductance L 0, capacitor C 0, the output voltage values that obtains in the load equates with the mean value of Vx, so have: Vout=D*Vin (wherein D is the duty ratio of synchro switch pipe M1 ON time).The voltage of Vout is fed to the negative terminal of error amplifier A1 through behind the electric resistance partial pressure, so in the open-loop gain of error amplifier A1 enough under the situation of height (more than or equal to 50dB): Vout=(1+R0/R1) * Vref.Oscillator 1 is sent new pulse, begins next switch periods.

As shown in Figure 3, from t=nT to t=in the one-period of (n+1) T (T is the cycle), the inductive current linearity rise to I _Ref, beginning then to descend, the inductive current when establishing t=nT is i _n, the inductive current during t=(n+1) T is i _N+1, output voltage is V.Can obtain following equation by above hypothesis:

$\frac{I_{\mathrm{ref}}-i_{n+1}}{(1-D)T}=\frac{v-V_{\mathrm{in}}}{L}---\left(4\right)$

$\frac{I_{\mathrm{ref}}-i_n}{\mathrm{DT}}=\frac{V_{\mathrm{in}}}{L}---\left(5\right)$

$i_{n+1}-i_n=\frac{V_{\mathrm{in}}}{L}\mathrm{DT}-\frac{v-V_{\mathrm{in}}}{L}(1-D)T---\left(6\right)$

$i_{n+1}=(1-\frac{v}{V_{\mathrm{in}}})i_n+\frac{I_{\mathrm{ref}}v}{V_{\mathrm{in}}}-\frac{(v-V_{\mathrm{in}})T}{L}---\left(7\right)$

Consider current i under the stable situation _nSmall sample perturbations, by $\frac{v}{V_{\mathrm{in}}}=\frac{1}{1-D}$ Can get according to formula (7) that (two of back all are i _nHigh-order in a small amount): ${\mathrm{\δi}}_{n+1}=\left(\frac{-D}{1-D}\right){\mathrm{\δi}}_n$

Order $\mathrm{\λ}=\frac{-D}{1-D},$ As seen want to make the work of system stability, must make-1＜λ＜1, be i.e. D＜0.5.But directly do not control duty ratio from the error signal of output voltage in actual applications, but be directly changed into electric current I _Ref, therefore be necessary to study in order to make system stability work to I _RefAny requirement is arranged.

Order $\mathrm{\Δi}=\frac{{\mathrm{DTV}}_{\mathrm{in}}}{L},$ The variable quantity of one-period internal inductance electric current from the minimum to the maximum just, like this

Be exactly the average current of one-period inductance, so the energy of battery consumption is exactly:

$(I_{\mathrm{ref}}-\frac{\mathrm{\Δi}}{2})V_{\mathrm{in}}T---\left(8\right)$

And the energy that consumes on the one-period load resistance is: $\frac{v^2}{R}=\frac{{V_{\mathrm{in}}}^{2}T}{{(1-D)}^{2}R}---\left(9\right)$

Consider the conservation of energy, under the situation of the loss of not considering energy, have following formula to exist:

$(I_{\mathrm{ref}}-\frac{\mathrm{\Δi}}{2})V_{\mathrm{in}}T=\frac{{V_{\mathrm{in}}}^{2}T}{{(1-D)}^{2}R}---\left(10\right)$

Can solve by (10) formula: $I_{\mathrm{ref}}=\frac{V_{\mathrm{in}}}{R}(\frac{\mathrm{DRT}}{2L}+\frac{1}{{(1-D)}^2})<{\frac{V_{\mathrm{in}}}{R}(\frac{\mathrm{DRT}}{2L}+\frac{1}{{(1-D)}^2})}_{D=0.5}---\left(11\right)$

That is: $I_{\mathrm{ref}}<\frac{V_{\mathrm{in}}}{R}(\frac{\mathrm{RT}}{4L}+4)---\left(12\right)$

System stability work that Here it is is to I _RefRequirement.

More than be the situation of not considering oblique wave compensation, if added the compensation oblique wave, shown in current waveform Fig. 4 of inductance: by Tu Kede: $i_n=\frac{V_{\mathrm{in}}}{L}\mathrm{DT}+m_c\mathrm{DT}=I_{\mathrm{ref}}---\left(13\right)$

As seen because the existence of oblique wave makes inductive current maximum and I _RefBetween a difference m has been arranged _cDT, thus reduced the peak value of inductive current, reduced owing to disturbance cause unsettled may.

Be necessary to illustrate why will compensate, and do not adopt a fixing electric current to compensate with oblique wave.As seen from Figure 4, if adopt fixed current to compensate, so for the inductive current waveform of Different Slope, peak current all is the same, employing oblique wave compensation then inductance peak current then changes along with slope, in the interval of 0＜D＜0.5, can find, D is more little just stable more, the corresponding peaks electric current is just big more, the dynamic response of the big then system of peak current is fast more within the specific limits, this shows adopt oblique wave compensation be system between stability and dynamic response, done one compromise.

Derive below system under the oblique wave compensation situation is arranged if can steady operation to D and I _RefRequirement, similar with the situation of no oblique wave compensation, can obtain:

$\frac{I_{\mathrm{ref}}-m_c\mathrm{DT}-i_{n+1}}{(1-D)T}=\frac{v-V_{\mathrm{in}}}{L}---\left(14\right)$

$\frac{I_{\mathrm{ref}}-m_c\mathrm{DT}-i_n}{\mathrm{DT}}=\frac{V_{\mathrm{in}}}{L}---\left(15\right)$

According to obtaining with top similar derivation:

${\mathrm{\&delta;i}}_{n+1}=(\frac{M_c}{1+M_c}-\frac{D}{(1-D)(1+M_c)}){\mathrm{\&delta;i}}_n---\left(16\right)$

Here $M_c=\frac{m_{c}L}{V_{\mathrm{in}}}$

Order $\mathrm{\&lambda;}=\frac{M_c}{1+M_c}-\frac{D}{(1-D)(1+M_c)}$

By-1＜λ＜1, can get: $D=\frac{M_c+0.5}{M_c+1}$

6

According to the conservation of energy, can obtain equally: $(I_{\mathrm{ref}}-m_c\mathrm{DT}-\frac{\mathrm{\&Delta;i}}{2})V_{\mathrm{in}}T=\frac{{V_{\mathrm{in}}}^{2}T}{{(1-D)}^{2}R}---\left(17\right)$

Have: $I_{\mathrm{ref}}<\frac{V_{\mathrm{in}}}{R}(\frac{\mathrm{RT}(M_c+0.5)}{4L(M_c+1)}+4{(M_c+1)}^2)---\left(18\right)$

Formula $\frac{V_{\mathrm{in}}}{R}(\frac{\mathrm{RT}(M_c+0.5)}{4L(M_c+1)}+4{(M_c+1)}^2)$ Be along with M _cIncrease and monotonically increasing this shows and adopts oblique wave compensation to increase I _RefHigher limit, that is to say the stability margin that has increased system.

Shown in another embodiment of Fig. 5, its basic principle is consistent with Fig. 1, and the position that just inductance connect is inconsistent, and Fig. 1 is the function that realizes step-down, and Fig. 5 is the function that realization is boosted.Oscillator block has comprised pulse oscillator and the oblique wave oscillator of Fig. 1 among Fig. 5.

Claims (3)

1, a kind of sync peaks current control mode pulse-width modulation DC/DC transducer, be provided with and comprise error amplifier, the pulse-width modulation comparator, current sense amplifier, pulse oscillator, rest-set flip-flop, synchronous rectifier, the synchro switch pipe, the current detecting pipe, current sense resistor, divider resistance, inductance, filter capacitor and frequency compensation resistance capacitance, error amplifier compares reference voltage and the difference between the load voltage component of divider resistance dividing potential drop, amplify, controlled signal is also delivered to the inverting input of pulse-width modulation comparator, it is characterized in that: set up the oblique wave oscillator, oblique wave compensation circuit and adder, the ramp signal that the oblique wave oscillator produces is sent into the input of oblique wave compensation circuit, and the output of oblique wave compensation circuit is sent into an input of adder; Produce another input that the voltage signal that is proportional to the inductive current instantaneous value exports adder to by current sense resistor and the detected inductor current signal of current detecting pipe through current sense amplifier comparison, amplification back; The output of adder is sent into the in-phase input end of pulse-width modulation comparator; The positive narrow pulse signal that the output signal of pulse-width modulation comparator and pulse oscillator produce is delivered to R, the S end of rest-set flip-flop, triggering for generating switching signal, the Kai Heguan of control synchronous rectifier, synchro switch pipe and current detecting pipe respectively; Energy storage and the release characteristics and through inductance, capacitor filtering after of the result of said process by inductance obtains the very little direct voltage of pulsing in load.

2, sync peaks current control mode pulse-width modulation DC/DC transducer according to claim 1 is characterized in that: described oblique wave compensation circuit adopts the segmented compensation slope, and the slope of second portion is 4 times of slope of first.

3, sync peaks current control mode pulse-width modulation DC/DC transducer according to claim 1 and 2 is characterized in that:

Described reference voltage is 0.6V;

The open-loop gain of described error amplifier is more than or equal to 50dB, and phase margin is more than or equal to 60 °;

The open-loop gain of described pulse-width modulation comparator is more than or equal to 50dB;

The open-loop gain of described current sense amplifier is more than or equal to 20dB;

Positive narrow pulse signal and linear ramp signal that described oscillator produces are 1.5MHz;

Described synchronous rectifier is the NMOS pipe, and its conducting resistance is less than 0.4 Ω, and the synchro switch pipe is the PMOS pipe, and its conducting resistance is less than 0.5 Ω;

Described current sense resistor is 6 Ω.

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