CN100481695C - DC-DC inverter and electronic device therewith - Google Patents

Abstract

A small-sized, low-cost dc-to-dc converter, and an electronic apparatus using it are provided. The DC-DC converter 10 is provided with an stable multivibrator 12, having a first time-constant circuit 13 for setting the on-time of its output and a second time-constant circuit 14 for setting the off-time of the output, and a switching element Q1 to be controlled by the output of the astable multivibrator 12. The duty radio of the astable multivibrator 12 is changed, in accordance with the output voltage, and consequently the output voltage is controlled. Accordingly, it is possible to reduce the size and cost of the dc-to-dc converter, since it is possible to form the converter having a simple circuit.

Description

DC-DC transducer and the electronic installation that adopts this transducer

Technical field

The electronic installation that the present invention relates to a kind of DC-DC (DC-to-DC) transducer and adopt this transducer.

Background technology

Figure 10 is the circuit diagram of the existing DC-DC transducer of expression.In Figure 10, the DC-DC transducer is made of diode D1, the triode Q1 of switch element, resistance R 1, R2, capacitor C 1, C2, drive circuit 2, reference voltage generating circuit 3, error amplifying circuit 4, circuit for generating triangular wave 5, PWM comparator 6, the lead-out terminal Pout of DC power supply Vcc, inductance component L 1, rectifier cell.

At this, DC power supply Vcc is connected with an end of inductance component L 1, and the other end of inductance component L 1 is connected with the collector electrode of triode Q1 and the anode of diode D1 respectively.The negative electrode of diode D1 is connected with lead-out terminal Pout.The grounded emitter of triode Q1.Capacitor C 1 is connected in parallel on DC power supply Vcc.Lead-out terminal Pout is by capacitor C 2 ground connection.Lead-out terminal Pout is successively by resistance R 1, R2 ground connection.The tie point of resistance R 1 and R2 is connected with a side's of error amplifying circuit 4 input.The opposing party's of error amplifying circuit 4 input is connected with reference voltage generating circuit.The output of error amplifying circuit 4 is connected with a side's of PWM comparator 6 input.The opposing party's input of PWM comparator 6 is connected with circuit for generating triangular wave 5.The output of PWM comparator 6 is connected with drive circuit 2, and the output of drive circuit 2 is connected with the base stage of triode Q1.

The DC-DC transducer 1 of Gou Chenging is step-up DC-DC transducer like this, and triode Q1 is opened and closed by drive circuit 2 controls.The electric current that flows in the inductance component L 1 is controlled by triode Q1.That is, during triode Q1 conducting, the energy of DC power supply Vcc is inductance component L 1 charging, discharges by diode D1 when triode Q1 turn-offs, and exports from lead-out terminal Pout.ON time and turn-off time by control triode Q1 are determined the output voltage values that lead-out terminal Pout is exported.

Then, the control for output voltage describes with reference to Figure 11.If the conducting of triode Q1, turn-off than for certain, the output voltage of DC-DC transducer 1 changes owing to the variation in voltage of DC power supply Vcc and the variation that is connected the load on the lead-out terminal Pout.For this reason, do not change such control even need carry out voltage and the load change output voltage of DC power supply Vcc yet.Like this, at first detect output voltage, be input to error amplifying circuit 4 by resistance R 1 and R2.On error amplifying circuit 4, also imported the reference voltage that is produced by reference voltage generating circuit 3, the error output a of its difference of output reflection.Output voltage is high more, and a is high more in error output.Error output a is input to PWM comparator 6.Also import the triangular wave output b that circuit for generating triangular wave 5 is exported on the PWM comparator 6, PWM comparator 6 compares both, and output is L (low) level when error output a is bigger than triangular wave output b, is the relatively output c of H (height) level when triangular wave output b is big.Error output a, triangular wave are exported b, are relatively exported c over time as shown in figure 11.Its pass is, a is big more in error output, and the time that triangular wave output b ratio error output a is big is short more, and the duty ratio of relatively exporting c is more little.On the contrary, a is more little in error output, and the time that triangular wave output b ratio error output a is big is long more, and the duty ratio of relatively exporting c is big more.Relatively export c and be input in the drive circuit 2, determine the conducting of control triode Q1, the duty ratio of shutoff by drive circuit 2.Duty ratio is big more, and the ON time of triode Q1 is long more, and output voltage raises, if ON time is short more, output voltage reduces.When output voltage is high, make the duty ratio of conducting, shutoff of control triode Q1 little, reduce output voltage, on the contrary, when output voltage is low, allow output voltage raise, by like this output voltage being controlled at set-point.

Summary of the invention

Yet in DC-DC transducer 1 shown in Figure 10, because error amplifying circuit 4, circuit for generating triangular wave 5 and PWM comparator 6 etc. are arranged, the scale of circuit increases, and exists the problem of cost degradation difficulty.Again, because circuit scale is big, though many by the situation of ICization, its shape is big, and the price height, except that the cost degradation difficulty, also exists the problem of miniaturization difficulty.

The present invention is the invention that addresses the above problem just, and its purpose is to provide a kind of miniaturization, DC-DC transducer and the electronic installation that adopts this transducer cheaply.

In order to achieve the above object, DC-DC transducer of the present invention, it is characterized in that: comprise having the 1st timing circuit of setting the output turn-off time and the astable multivibrator of setting the 2nd timing circuit of ON time, switch element by the output of described astable multivibrator control, and rectifier cell, the magnitude of voltage that makes input voltage changes and as output voltage, comprise that the time constant by making at least one side in the described the 1st and the 2nd timing circuit changes according to described output voltage, the ON time of described switch element and at least one side in the turn-off time are changed, control the output voltage controlling circuit of described output voltage with this, at least one of the described the 1st and the 2nd timing circuit is equipped with the impedance variable circuit that is used to change time constant, and this impedance variable circuit is connected to described output voltage controlling circuit.

Again, the feature of DC-DC transducer of the present invention is to be provided with described switch element to be connected in series, and carries out the inductance element that discharges and recharges of energy.

Again, the feature of DC-DC transducer of the present invention is the impedance variable circuit that comprises the time constant variation that makes at least one side in the described the 1st and the 2nd timing circuit.

Again, the feature of DC-DC transducer of the present invention is to be provided with push-pull output circuit between the output of described astable multivibrator and described switch element.

Again, the feature of DC-DC transducer of the present invention is that described rectifier cell is made of with switch element rectification, described astable multivibrator comprise control described switch element conducting and shutoff the 1st output, when described switch element turn-offs, control described rectification with the 1st anti-phase while of output and export with the 2nd of switch element conducting.

Again, the feature of DC-DC transducer of the present invention for make described switch element and described rectification with switch element during inserting both between the mutual conducting and turn-offing simultaneously, on the rising edge waveform of the described the 1st and the 2nd output, be provided with inclination.

Again, the feature of DC-DC transducer of the present invention is to be provided with push-pull output circuit between the output of described astable multivibrator and described rectification are with switch element.

Again, the feature of DC-DC transducer of the present invention is that described rectification is adopted MOSFET with switch element.

Again, the feature of DC-DC transducer of the present invention is that described switch element adopts MOSFET.

Again, the feature of electronic installation of the present invention is to adopt described any one DC-DC transducer.

According to such formation, in DC-DC transducer of the present invention, can realize that circuit is simple, miniaturization and cost degradation.

In electronic installation of the present invention, can realize miniaturization and cost degradation again.

Description of drawings

Fig. 1 is the circuit diagram of an embodiment of expression DC-DC transducer of the present invention.

Fig. 2 is collector voltage and the time dependent performance plot of base voltage that is illustrated in 2 triodes of employed astable multivibrator in the DC-DC transducer shown in Figure 1.

Fig. 3 is the circuit diagram of the concrete example of expression output voltage controlling circuit of DC-DC transducer shown in Figure 1 and impedance variable circuit.

Fig. 4 is the circuit diagram of another embodiment of expression DC-DC transducer of the present invention.

Fig. 5 is the circuit diagram of the another embodiment of expression DC-DC transducer of the present invention.

Fig. 6 is the circuit diagram of the another embodiment of expression DC-DC transducer of the present invention.

Fig. 7 is the time dependent performance plot of each several part signal of expression DC-DC transducer shown in Figure 6.

Fig. 8 is the circuit diagram of the another embodiment of expression DC-DC transducer of the present invention.

Fig. 9 is the stereogram of an embodiment of expression electronic installation of the present invention.

Figure 10 is the circuit diagram of the existing DC-DC transducer of expression.

Figure 11 is the time dependent performance plot of each several part signal of expression DC-DC transducer shown in Figure 10.

Symbol description

10,20,30,40,50-DC-DC transducer; 11-output voltage controlling circuit; 12,21-astable multivibrator; 13,22-the 1 timing circuit; 14,23-the 2 timing circuit; 15,24-impedance variable circuit; 31,42-push-pull output circuit; 41-boostrap circuit; 51-logic inverting circuit; 60-printer; Q1-triode (switch element); Q2, Q3, Q4, Q5-triode; Q6, Q8-FET (switch element); Q7-FET (rectification switch element); D1-diode (rectifier cell); L1-inductance element.

Embodiment

Fig. 1 is the circuit diagram of an embodiment of expression DC-DC transducer of the present invention.In Fig. 1, the part identical or suitable with Figure 10 adopts identical mark, omits its explanation at this.

In Fig. 1, DC-DC transducer 10, comprise output voltage controlling circuit 11 and astable multivibrator 12, substitute above-mentioned existing drive circuit 2, reference voltage generating circuit 3, error amplifying circuit 4, circuit for generating triangular wave 5, PWM comparator 6, resistance R 1, R2.The 2nd timing circuit 14 of the turn-off time of the 1st timing circuit 13 of the turn-off time of definite triode Q2 that multivibrator 12 constitutes by triode Q2, by resistance and electric capacity, triode Q3, definite triode Q3 of being made of impedance variable circuit 15 and electric capacity is constituted.The collector electrode of triode Q3 is connected with base stage as the triode Q1 of switch element, becomes the lead-out terminal of astable multivibrator 12.Output voltage controlling circuit 11 is connected with impedance variable circuit 15.

In the DC-DC transducer 10 that constitutes like this, astable multivibrator 12 is according to the 1st and the 2nd timing circuit 13 and 14 frequencies of determining and duty ratio vibration.Fig. 2 is the collector voltage v2c of the triode Q2 of expression astable multivibrator 12 and collector voltage v3c and the time dependent sequential chart of base voltage v3b of base voltage v2b, triode Q3.In addition, the collector voltage of the triode Q3 base voltage v1b of triode Q1 just.As shown in Figure 2, triode Q2 and Q3 are respectively according to the 1st and the 2nd timing circuit 13 and 14 mutual conducting of turn-off time, the shutoffs of determining.The current collection of triode Q3 is the output of astable multivibrator 12 very, and (when triode Q2 turn-offs) is L (low) level when triode Q3 conducting, and (during triode Q2 conducting) is H (height) level when triode Q3 turn-offs.Therefore, astable multivibrator 12 vibrates by turn-off time and the 2nd timing circuit 14 definite ON time that the 1st timing circuit 13 is determined, drives triode Q1.Like this, conducting, the shutoff of control triode Q1 allow DC-DC transducer 10 move.

Below, the output voltage control of DC-DC transducer 10 is described.In DC-DC transducer 10, output voltage controlling circuit 11 detects output voltage and built-in reference voltage compares, and output expression output voltage is wanted high or low signal with respect to given voltage, and is input to impedance variable circuit 15.Impedance variable circuit 15 is according to its impedance of signal change from output voltage controlling circuit 11.Specifically, when for example the output voltage of DC-DC transducer 10 was higher than given output voltage, output voltage controlling circuit 11 actions made the impedance of impedance variable circuit 15 little.Because impedance variable circuit 15 is inscapes of timing circuit 14 of determining the turn-off time of triode Q3, the time constant of timing circuit 14 is more little, the turn-off time of triode Q3 is short more, and the turn-off time of the triode Q3 ON time of short more expression triode Q1 is short more.At this moment since turn-off time of triode Q2 without any variation, so the turn-off time of triode Q1 do not change yet.Its result, triode Q1 with respect to the ratio of the total ascent time ON time of ON time and turn-off time, be that duty ratio diminishes, output voltage descends.On the contrary, when output voltage is low, increase the duty ratio of triode Q1, allow output voltage raise.Like this, in DC-DC transducer 10, output voltage is controlled on the given voltage.

At this, Fig. 3 is the circuit diagram of the concrete example of expression output voltage controlling circuit 11 and impedance variable circuit 15.In Fig. 3, output voltage controlling circuit 11 is made of resistance R 3, R4, R5, triode Q4, Zener diode D2, capacitor C 3.At this, resistance R 3 and R4 are connected in series between the lead-out terminal Pout of DC-DC transducer 10 and ground.And resistance R 5 and triode Q4 and Zener diode D2 also are connected in series between lead-out terminal Pout and ground.The tie point of resistance R 3 and R4 is connected with the base stage of triode Q4.Then, between the collector electrode of the tie point of resistance R 3 and R4 and triode Q4, be connected capacitor C 3.Wherein, the collector electrode of triode Q4 is as the output of output voltage controlling circuit 11.Again, impedance variable circuit 15 is made of resistance R 6, the series circuit of being made up of resistance R 7 and triode Q5 that is connected in parallel with it.Wherein, the base stage of triode Q5 becomes the control end of impedance variable circuit 15, is connected with the output of output voltage controlling circuit 11.

In the output voltage controlling circuit 11 and impedance variable circuit 15 that constitute like this, the output voltage of DC-DC transducer 10 is detected by resistance R 3 and R4 dividing potential drop, is input to the base stage of triode Q4.The emitter of triode Q4 remains on certain voltage by Zener diode D2, when output voltage rises, increases the electric current of triode Q4 base stage, reduces the collector voltage of triode Q4, promptly reduces the base voltage of the triode Q5 of impedance variable circuit 15.If reduce the base voltage of triode Q5, with the resistance value between emitter-collector electrode of reduction triode Q5.Its result, the resistance value of reduction impedance variable circuit 15 integral body, i.e. impedance.Output voltage controlling circuit 11 and impedance variable circuit 15 move in such a way.

In addition, the formation of output voltage controlling circuit and impedance variable circuit 15 is not limited thereto, as long as have same function, what kind of circuit constitutes can.

Fig. 4 is the circuit diagram of another embodiment of expression DC-DC transducer of the present invention.In the DC-DC of Fig. 4 transducer 20, adopt identical mark with the part that Fig. 1 equates, omit its explanation at this.

In Fig. 4, DC-DC transducer 20 comprises that astable multivibrator 21 is in order to substitute the astable multivibrator 12 in the DC-DC transducer 10.The 2nd timing circuit 23 of the turn-off time of the 1st timing circuit 22 of the turn-off time of definite triode Q2 that astable multivibrator 21 constitutes by triode Q2, by impedance variable circuit 24 and electric capacity, triode Q3, definite triode Q3 of being made of resistance and electric capacity is constituted.Output voltage controlling circuit 11 is connected with impedance variable circuit 24.

The DC-DC transducer 20 of Gou Chenging so just becomes on the inscape this point of the 1st timing circuit 22 of the turn-off time of determining triode Q2 different with DC-DC transducer 10 at impedance variable circuit 24.For this reason, in DC-DC transducer 20, according to the variation of output voltage, the turn-off time of triode Q1 changes, and ON time does not change.For this reason, change ON time and the ratio of the turn-off time of the total ascent time of turn-off time, be duty ratio, output voltage is controlled on the given voltage with respect to triode Q1.Opposite with DC-DC transducer 10 at this, 24 patterns of wants of impedance variable circuit are big for resistance value when output voltage is high.

Fig. 5 is the circuit diagram of another embodiment of expression DC-DC transducer of the present invention.In the DC-DC of Fig. 5 transducer 30, adopt identical mark with the part that Fig. 1 equates, omit its explanation at this.

In Fig. 5, DC-DC transducer 30 is on the basis of the formation of the DC-DC of Fig. 1 transducer 10, output at astable multivibrator 12, be between the collector electrode and base stage of triode Q3, comprise the push-pull output circuit 31 and the accelerating circuit 32 that are connected in series as the triode Q1 of switch element.

In the DC-DC transducer 30 that constitutes like this, the output of astable multivibrator 12 is imported in the push-pull output circuit 31, and push-pull output circuit 31 strengthens the output of astable multivibrator 12.Then, the output of push-pull output circuit 31 is input on the base stage as the triode Q1 of switch element by accelerating circuit 32.Like this, improve the switching speed of triode Q1.At this moment switching speed is meant triode Q1 from the conducting state to the off state, perhaps the speed that changes from the off state to the conducting state.By improving the switching speed of triode Q1, reduce the switching losses among the triode Q1.Because the switching losses among the triode Q1 is the major part in the loss of DC-DC transducer 30, by reducing the switching losses among the triode Q1, can improve the efficient of DC-DC transducer 30.

Fig. 6 is the circuit diagram of another embodiment of expression DC-DC transducer of the present invention.In the DC-DC of Fig. 6 transducer 40, adopt identical mark with the part that Fig. 5 equates, omit its explanation at this.

In Fig. 6, DC-DC transducer 40 is buck DC-DC transducers, in the formation of the DC-DC of Fig. 5 transducer 30, remove triode Q1, diode D1 and accelerating circuit 32, comprise FETQ6, as FETQ7, boostrap circuit 41 and the push-pull output circuit 42 of rectification with switch element as switch element.

At this FETQ6 and FETQ7 is N-channel MOS FET.FETQ6 connects between DC power supply Vcc and inductance component L 1.The output of push-pull output circuit 31 is connected with the grid of FETQ6.The boostrap circuit 41 that diode D3 and capacitor C 4 constitute connects between drain electrode-source electrode of FETQ6.The collector electrode of the NPN type triode Q2 of the power supply connecting portion of push-pull output circuit 31 is connected on the boostrap circuit 41, specifically is the tie point that is connected to diode D3 and capacitor C 4.The tie point of FETQ6 and inductance component L 1 is by FETQ7 ground connection.The collector electrode of the triode Q2 of astable multivibrator 12 is connected with the grid of FETQ7 by push-pull output circuit 42.Its result is from the 1st output that the collector electrode of triode Q3 is exported astable multivibrator 12, the 2nd output of exporting astable multivibrator 12 from the collector electrode of triode Q2.

Fig. 7 for the grid voltage v6g of the collector voltage v3c of the grid voltage v7g of the collector voltage v2c of triode Q2 of expression astable multivibrator 12 and base voltage v2b, FETQ7 and drain voltage v7d, triode Q3 and base voltage v3b and FETQ6 over time, be used for illustrating the action of DC-DC transducer 40 at this.

At first, in DC- DC transducer 40,2 triode Q2 of astable multivibrator 12 and the mutual conducting of Q3, shutoff.At this moment, the collector voltage v3c of the collector voltage v2c of triode Q2 and base voltage v2b and triode Q3 and base voltage v3b are as shown in Figure 7.Compare with DC-DC transducer 10 shown in Figure 2, the rising edge waveform of collector voltage v2c, v3c is provided with on the inclination this point different.The slope of this inclination is determined by the resistance that is connected with the collector electrode of triode Q2 and Q3 respectively and the time constant of electric capacity.Be that the time constant is big more, slope is big more.In addition, DC-DC transducer 10 shown in Figure 2 is not have slope fully, and just slope is very steep, almost vertical lifting.

Collector voltage v3c as the 1st triode Q3 that exports is input to push-pull output circuit 31.Because the power supply connecting portion of push-pull output circuit 31 is to be connected on the boostrap circuit 41, therefore than DC power supply Vcc voltage height.Be applied on the grid of FETQ6 from push-pull output circuit 31 with respect to the abundant big voltage of the source voltage of FETQ6.Conducting, the shutoff of control FETQ6 are moved as switch element like this.At this moment, owing to be provided with inclination on the rising edge waveform of the collector voltage v3c of triode Q3, as shown in Figure 7, the rising edge waveform that is applied to the voltage v6g on the grid of FETQ6 also has inclination.For this reason, the grid voltage v6g of FETQ6 will reach the threshold values of FETQ6 conducting, will spend some time a little.Its result as shown in Figure 7, from triode Q7 conducting, produces t1 idle time till the FETQ6 conducting.

On the other hand, the collector voltage v2c as the 2nd triode Q2 that exports is input in the push-pull output circuit 42.The 2nd output that strengthens at push-pull output circuit 42 is applied on the grid of FETQ7.Conducting, the shutoff of control FETQ7 like this.At this moment, owing to be provided with inclination on the rising edge waveform of the collector voltage v2c of triode Q2, as shown in Figure 7, the rising edge waveform that is applied to the voltage v7g on the grid of FETQ7 also has inclination.For this reason, the grid voltage v7g of FETQ7 will reach the threshold values of FETQ7 conducting, will spend some time a little.Its result as shown in Figure 7, turn-offs from triode Q6, produces t2 idle time till the FETQ7 conducting.

Like this, insert t1 idle time, t2 that FETQ6 and FETQ7 all turn-off, the mutual conducting of FETQ6 and FETQ7, shutoff.At this, tilt to be provided with t1 idle time, t2 by on the rising edge waveform of collector voltage v2c, the v3c of triode Q2, Q3, being provided with, be in order to prevent if both equal conductings of moment make DC power supply Vcc take place by the situation of FETQ6 and FETQ7 shorted to earth.

Like this, FETQ7 turn-offs when the FETQ6 conducting, flows out electric current by FETQ6 and inductance component L 1 to lead-out terminal Pout from DC power supply Vcc.For this reason, as shown in Figure 7, when the FETQ6 conducting, the drain voltage v7d of FETQ7, be that the source voltage of FETQ6 is identical with DC power supply Vcc basically.

On the other hand, FETQ7 conducting when FETQ6 turn-offs, the magnetization energy of savings on inductance L 1 flows out electric current by FETQ7 and inductance component L 1 to lead-out terminal Pout.That is, the switch of FETQ7 and FETQ6 is synchronous, as synchronous rectification element action from electric current a to direction that flow through.For this reason, as shown in Figure 7, when FETQ6 turn-offs, the source voltage of FETQ6, be that the drain voltage v7d of FETQ7 is for than low a little any the negative value of earthed voltage.

In addition, at the t1 and turn-off idle time between the FETQ6 conducting from FETQ7 t2 idle time that turn-offs from FETQ6 between the FETQ7 conducting, dull also the needs by FETQ7 to inductance L 1 inflow current, because the FETQ7 of MOSFET itself has body diode, by this diode from ground connection to the lead-out terminal Pout electric current of flowing through.During the FETQ7 conducting and idle time when t1, t2, the value of the drain voltage v7d of FETQ7 changes, and this is that big cause is wanted in the voltage drop during by body diode because compare with the situation of the FETQ7 of electric current by being in conducting state.

In the DC-DC transducer 40 of the present application that constitutes like this, one side of 2 outputs that astable multivibrator 12 had originally exports the switch that is used to control as the FETQ6 of switch element as the 1st, and the opposing party is used to control as the switch of rectification with the FETQ7 of switch element as the 2nd output, constitutes circuit of synchronous rectification.For this reason, there is no need to be adopted as the control IC that controls the rectifier switch element and adopt high price, can realize the DC-DC transducer of synchronous rectification mode.Again, owing to do not need to carry the space of control with IC, to such an extent as to can realize the miniaturization of printed circuit board (PCB) DC-DC transducer itself.Certainly, also can realize it being the low lossization of circuit of synchronous rectification characteristics.

Fig. 8 is the circuit diagram of another embodiment of expression DC-DC transducer of the present invention.In the DC-DC of Fig. 8 transducer 50, adopt identical mark with the part that Fig. 6 equates, omit its explanation at this.

In Fig. 8, DC-DC transducer 50 is in the DC-DC of Fig. 6 transducer 40, remove boostrap circuit 41, substitute FETQ6, between the 1st output of astable multivibrator 12 and push-pull output circuit 31, also comprise logic inverting circuit 51 simultaneously with the FETQ8 of P channel mosfet.Again, the collector electrode of the NPN type triode of the power supply connecting portion of push-pull output circuit 31 is connected with DC power supply Vcc.

In DC-DC transducer 50, because the FETQ8 that adopts the P channel mosfet as switch element, there is no need to allow the grid voltage of FETQ8 than source voltage height, so do not need boostrap circuit 41.On the contrary, because FETQ8 is opposite with respect to the logical AND FETQ6 that is applied to its conducting of signal, shutoff on the grid, for this reason, need be with the logic inverting circuit 51 of the 1st logical inversion of exporting.

The situation of DC-DC transducer 50 of Gou Chenging and DC-DC transducer 40 is basic identical like this, also brings into play same action effect.

In addition, in the various embodiments described above, though what adopt is by allowing the time constant of the either party in the 1st timing circuit and the 2nd timing circuit change the formation of coming control output voltage, also can adopt and allow the time constant of the 1st and the 2nd timing circuit all change, for example when the time constant of the 1st timing circuit increases, allow the time constant minimizing of the 2nd timing circuit wait the formation of control output voltage, also can bring into play same action effect.Again, when allowing both time constant change, it is certain basically to get out of the way the ON time and the total ascent time of turn-off time of closing element, and promptly the switching frequency of switch element is certain basically, comes control output voltage.

Again, in the various embodiments described above, though in the DC-DC of booster type and voltage-dropping type converter circuit, be that the formation of astable multivibrator is illustrated to what adopt, as the formation of DC-DC transducer, be not limited to booster type and voltage-dropping type, so long as input direct voltage, output dc voltage, anti-phase type etc., what kind of circuit constitute can, can the performance action effect identical with voltage-dropping type with booster type.

Again, in the various embodiments described above,, also can be the formation that charge pump circuit etc. does not comprise the DC-DC converter circuit of inductance element though explanation is the DC-DC converter circuit that comprises inductance element, can bring into play identical action effect.

Fig. 9 is the stereogram of an embodiment of expression electronic installation of the present invention.In Fig. 9, be that the printer 60 of one of electronic installation adopts DC-DC transducer 10 of the present invention as the part of power circuit.

Like this, by adopting DC-DC transducer 10 of the present invention, owing to can realize the miniaturization and the cost degradation of switching power circuit, can realize the miniaturization and the low price of printer 60 itself.

In addition,, also can adopt Fig. 4, Fig. 5, Fig. 6, DC- DC transducer 20,30,40,50 shown in Figure 8 in printer shown in Figure 9 60, can bring into play identical action effect though what adopt is DC-DC transducer 10 shown in Figure 1.

Again, electronic instrument of the present invention is not limited to printer, can comprise that notebook computer, portable electronic instrument etc. need all electronic instruments of the DC power supply of burning voltage.

According to DC-DC transducer of the present invention, employing comprises the 1st timing circuit of setting the turn-off time and the astable multivibrator control switch element of setting the 2nd timing circuit of ON time, allow at least simultaneously either party's time constant changes in the 1st and the 2nd timing circuit according to output voltage, control output voltage can realize that circuit constitutes simple, miniaturization, cost degradation.

Again, by constituting the 1st and the 2nd mutual anti-phase output of adopting astable multivibrator, control switch element and rectification can realize miniaturization, cost degradation, low lossization with the circuit of synchronous rectification of switch element respectively.

According to electronic installation of the present invention,, can realize miniaturization, cost degradation by adopting DC-DC transducer of the present invention again.

Claims (9)

1. DC-DC transducer is characterized in that:

Comprise have the 1st timing circuit of setting the output turn-off time and the astable multivibrator of setting the 2nd timing circuit of ON time, by the switch element and the rectifier cell of the output control of described astable multivibrator,

The magnitude of voltage that makes input voltage changes and as output voltage,

Comprise that the time constant by making at least one side in the described the 1st and the 2nd timing circuit changes, makes the ON time of described switch element and at least one side in the turn-off time to change, control the output voltage controlling circuit of described output voltage with this according to described output voltage

At least one of the described the 1st and the 2nd timing circuit is equipped with the impedance variable circuit that is used to change time constant, and this impedance variable circuit is connected to described output voltage controlling circuit.

2. DC-DC transducer according to claim 1 is characterized in that:

Be provided with the inductance element that discharges and recharges that is connected in series, carries out energy with described switch element.

3. according to each described DC-DC transducer in the claim 1 to 2, it is characterized in that:

Between the output of described astable multivibrator and described switch element, be provided with push-pull output circuit.

4. DC-DC transducer according to claim 3 is characterized in that:

Described rectifier cell is made of with switch element rectification,

Described astable multivibrator comprise control described switch element conducting and shutoff the 1st output, when described switch element turn-offs, control described rectification with the 1st anti-phase while of output and export with the 2nd of switch element conducting.

5. DC-DC transducer according to claim 4 is characterized in that:

For make described switch element and described rectification with switch element during inserting between the mutual conducting that both turn-off simultaneously, the rising edge waveform of the described the 1st and the 2nd output is provided with inclination.

6. DC-DC transducer according to claim 5 is characterized in that:

Between the output of described astable multivibrator and described rectification are with switch element, be provided with push-pull output circuit.

7. DC-DC transducer according to claim 6 is characterized in that:

Described rectification is adopted MOSFET with switch element.

8. DC-DC transducer according to claim 7 is characterized in that:

Described switch element adopts MOSFET.

9. an electronic installation is characterized in that;

Adopt each described DC-DC transducer in the claim 1 to 8.

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