CN102957314B - A kind of voltage-reference replacement method and Switching Power Supply - Google Patents

Abstract

The invention discloses a kind of voltage-reference replacement method, comprise the 4th resistance in use first resistance unit and the second resistance unit replacement output voltage working range regulating circuit, use the second voltage-reference to replace the first voltage-reference; The first end of the first resistance unit connects the second voltage-reference, and the first end of the second resistance unit connects ground, and the second end of the first resistance unit is connected the positive input of error calculation circuit after being connected with the second end of the second resistance unit; The equivalent resistance of the first resistance unit and the second resistance unit and the resistance of the 4th resistance, replace before and after voltage source meet certain relation.Replacement method of the present invention, can realize using new voltage-reference to replace necessary corresponding changeless primary voltage a reference source when working in external outside Circuit tuning, the problem that a reference source Vref flexibility that the working method solving circuit causes is not high, also can guarantee external outside Circuit tuning still according to the TRIM function works of its correspondence simultaneously.

Description

A kind of voltage-reference replacement method and Switching Power Supply

Technical field

The present invention relates to Switching Power Supply, particularly relate to for the voltage-reference replacement method in Switching Power Supply.

Background technology

In Switching Power Supply, for guaranteeing the stable of output voltage, often use negative feed back control system.As shown in Figure 1, for the structure chart of the negative feed back control system in existing common Switching Power Supply, negative feed back control system 10 comprises sample circuit 1, error calculation circuit 2, adjuster 3 and PWM (PulseWidthModulation, pulse width modulation) controller 4.The output voltage Vout of sample circuit 1 pair of Switching Power Supply samples, by the reverse input end of sampled voltage error originated from input counting circuit 2, the positive input of error calculation circuit 2 receives set-point, i.e. a reference source Vref, the error amount of both calculating, by errors value input regulator 3, adjuster 3 carries out computing to it, as PID arithmetic, PI computing etc., obtain control voltage Verr.After PWM controller 4 receives this control voltage Verr, export the pulse drive signal of corresponding duty ratio, this pulse drive signal drives the switching tube in main loop of power circuit 100, thus the output voltage Vout controlling main loop of power circuit tends towards stability.

In Switching Power Supply, for making output voltage Vout can regulate in certain working range, often set up output voltage working range regulating circuit.As shown in Figure 2, for the negative feed back control system shown in Fig. 1 increases the structure chart after output voltage working range regulating circuit, output voltage working range regulating circuit comprises the second resistance R2 and the 4th resistance R4, a reference source Vref is by the positive input of error originated from input counting circuit 2 after the 4th resistance R4, the first end of the second resistance R2 connects the positive input of error calculation circuit 2, and second end of the second resistance R2 is as adjusting port C for connecting outside Circuit tuning 30.Change the value of output voltage Vout by the adjustment of device parameters in outside Circuit tuning 30, make output voltage Vout adjustable in certain working range.Also be the corresponding TRIM function of outside Circuit tuning 30 of each implementation, TRIM function defines the one-to-one relationship in outside Circuit tuning 30 between parameter and the value of output voltage Vout.When user needs the value of output voltage Vout of by-pass cock power supply, the relevant parameter of outside Circuit tuning 30 is calculated according to TRIM function, thus will determine the outside Circuit tuning 30 after parameter and adjust port C in output voltage working range regulating circuit and be connected, and then regulation output voltage Vout be the value expected.

The implementation of outside Circuit tuning has multiple, for ensureing the compatibility of output voltage working range regulating circuit and multiple outside Circuit tuning, therefore the second resistance R2 in output voltage working range regulating circuit is required, the value of the 4th resistance R4 and a reference source Vref immobilizes, namely user only needs the value of parameter according to the corresponding outside Circuit tuning of the TRIM function setup of each outside Circuit tuning and adjustable output voltage Vout, does not need the parameter adjusting device in Switching Power Supply more further.But the value as above-mentioned three devices keeps immobilizing, although can meet the requirement of compatible aspect, directly causes the flexibility of circuit working not high.Particularly the value of a reference source Vref requires to immobilize, and is sometimes difficult to meet.Such as, require in current most Switching Power Supply that a reference source Vref of corresponding input is that 1.225V immobilizes, if the signal source that the front stage circuits of user produces is 2V, then this signal source just cannot be applied in the Switching Power Supply of above-mentioned band output voltage working range regulating circuit as a reference source.For this problem, the solution that industry often uses is: set up a bleeder circuit and operational amplifier again, by bleeder circuit, dividing potential drop is carried out to the signal source of 2V, dividing potential drop obtains the voltage of 1.225V, operational amplifier composition voltage follower circuit, the 1.225V making a reference source follow bleeder circuit dividing potential drop to obtain, and then can be applicable in circuit.On the other hand, operational amplifier plays buffer action, and the work of the output voltage working range regulating circuit that bleeder circuit and the second resistance R2 and the 4th resistance R4 etc. are formed is independent of each other.For this solution, have two defects, one is, needs operational amplifier, can increase the cost of Switching Power Supply and the wiring space of pcb board like this; Two are, during Switching Power Supply starting up, a reference source Vref rise time is excessively slow, easily occur the phenomenon that start waveform is not good.In sum, need a kind of brand-new solution, the problem that a reference source Vref flexibility that the working method that can solve output voltage working range regulating circuit causes is not high, the cost of the Switching Power Supply caused in existing solution and the wiring space of pcb board can be avoided again to increase, the defect that start waveform is not good.

Summary of the invention

Technical problem to be solved by this invention is: make up above-mentioned the deficiencies in the prior art, a kind of voltage-reference replacement method is proposed, the problem that a reference source Vref flexibility is not high can be solved, the wiring space of Switching Power Supply cost and pcb board can be increased again, and guarantee that start waveform is good.

The further technical problem to be solved of the present invention is: propose a kind of Switching Power Supply, its a reference source can be arranged flexibly, can increase again the wiring space of Switching Power Supply cost and pcb board simultaneously, and guarantees that start waveform is good.

Technical problem of the present invention is solved by following technical scheme:

A kind of voltage-reference replacement method, in Switching Power Supply, described Switching Power Supply comprises negative feed back control system, and described negative feed back control system comprises sample circuit, error calculation circuit, adjuster and PWM controller, the positive input of described error calculation circuit receives a reference source, and reverse input end receives the output voltage of the described Switching Power Supply of described sampling circuit samples, described Switching Power Supply also comprises output voltage working range regulating circuit, described output voltage working range regulating circuit comprises the second resistance and the 4th resistance, described a reference source is by inputting the positive input of described error calculation circuit after described 4th resistance, the first end of described second resistance connects the positive input of described error calculation circuit, second end of described second resistance is as adjusting port for connecting outside Circuit tuning, described outside Circuit tuning carries out work to adjust the output voltage of described Switching Power Supply when described a reference source is the first voltage-reference according to the TRIM function of its correspondence, described replacement method comprises use first resistance unit and the second resistance unit and replaces the 4th resistance in described output voltage working range regulating circuit, the second voltage-reference is used to replace described first voltage-reference, the first end of described first resistance unit connects described second voltage-reference, the first end of described second resistance unit connects ground, is connected the positive input of described error calculation circuit after the second end of described first resistance unit is connected with the second end of described second resistance unit, the equivalent resistance of described first resistance unit and described second resistance unit is respectively: $\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1},$ Wherein, Vref2 is the magnitude of voltage of described second voltage-reference, and Vref1 is the magnitude of voltage of described first voltage-reference be replaced, and R4 is the resistance of described 4th resistance be replaced.

Technical problem of the present invention is solved by following further technical scheme:

A kind of Switching Power Supply, comprise negative feed back control system, described negative feed back control system comprises sample circuit, error calculation circuit, adjuster and PWM controller; Described Switching Power Supply also comprises output voltage working range regulating circuit; The a reference source that the positive input of described error calculation circuit receives is the second above-mentioned voltage-reference, described output voltage working range regulating circuit is obtain after replacing according to above-mentioned voltage-reference replacement method, comprise the second resistance, the first resistance unit and the second resistance unit; The equivalent resistance of described first resistance unit and described second resistance unit is respectively: $\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1},$ Wherein, Vref2 is the magnitude of voltage of described second voltage-reference, and Vref1 is the magnitude of voltage of described first voltage-reference be replaced, and R4 is the resistance of described 4th resistance be replaced; The first end of described first resistance unit connects described second voltage-reference, the first end of described second resistance unit connects ground, is connected the positive input of described error calculation circuit after the second end of described first resistance unit is connected with the second end of described second resistance unit; The first end of described second resistance connects the positive input of described error calculation circuit, second end of described second resistance is as adjustment port for connecting outside Circuit tuning, and described outside Circuit tuning carries out work to adjust the output voltage of described Switching Power Supply when described a reference source is the first voltage-reference according to the TRIM function of its correspondence.

The beneficial effect that the present invention is compared with the prior art is:

Voltage-reference replacement method of the present invention, use the 4th resistance in the first resistance unit and the second resistance unit replacement output voltage working range regulating circuit, first resistance unit simultaneously, the resistance of the second resistance unit and the resistance of the 4th resistance, the value of the voltage source before and after replacing meets certain relation, thus can realize using new voltage-reference to replace necessary corresponding changeless primary voltage a reference source when working in external outside Circuit tuning, the problem that a reference source Vref flexibility that the working method solving circuit causes is not high, also can guarantee external outside Circuit tuning still according to the TRIM function works of himself correspondence simultaneously.On the other hand, do not need in replacement method to use operational amplifier, therefore can not increase the wiring space of Switching Power Supply cost and pcb board, be only applied in solution by the first resistance unit, the second resistance unit simultaneously, can not cause postponing, thus guarantee that start waveform is good.Switching Power Supply of the present invention is replaced according to voltage-reference replacement method of the present invention and is obtained, and therefore in Switching Power Supply, a reference source can be arranged flexibly, can guarantee external outside Circuit tuning all the time according to the TRIM function works of himself correspondence simultaneously.

Accompanying drawing explanation

Fig. 1 is the structure chart of the negative feed back control system in Switching Power Supply of the prior art;

Fig. 2 is the structure chart after negative feed back control system shown in Fig. 1 increases output voltage working range regulating circuit;

Fig. 3 is the Switching Power Supply structure chart obtained after replacing according to voltage-reference replacement method of the present invention in this embodiment one;

Fig. 4 is the physical circuit figure of the Switching Power Supply medial error counting circuit shown in Fig. 3, sample circuit, adjuster and output voltage working range regulating circuit;

Fig. 5 is the physical circuit figure of Switching Power Supply medial error counting circuit, sample circuit, adjuster and output voltage working range regulating circuit after replacing in the specific embodiment of the invention two;

Fig. 6 is the physical circuit figure of Switching Power Supply medial error counting circuit, sample circuit, adjuster and output voltage working range regulating circuit after replacing in the specific embodiment of the invention three;

Fig. 7 is the physical circuit figure of Switching Power Supply medial error counting circuit, sample circuit, adjuster and output voltage working range regulating circuit after replacing in the specific embodiment of the invention four;

Fig. 8 is the physical circuit figure of Switching Power Supply medial error counting circuit, sample circuit, adjuster and output voltage working range regulating circuit after replacing in the specific embodiment of the invention five;

Fig. 9 is the physical circuit figure of Switching Power Supply medial error counting circuit, sample circuit, adjuster and output voltage working range regulating circuit after replacing in the specific embodiment of the invention six.

Embodiment

Contrast accompanying drawing below in conjunction with embodiment the present invention is described in further details.

Embodiment one

Voltage-reference replacement method in this embodiment, in Switching Power Supply described in background technology, Switching Power Supply comprises negative feed back control system, and negative feed back control system comprises sample circuit, error calculation circuit, adjuster and PWM controller.Switching Power Supply also comprises output voltage working range regulating circuit, its circuit structure as shown in Figure 2, comprise the second resistance R2 and the 4th resistance R4, a reference source Vref is by the positive input of error originated from input counting circuit after the 4th resistance R4, the first end of the second resistance R2 connects the positive input of error calculation circuit, and second end of the second resistance R2 is as adjusting port C for connecting outside Circuit tuning 30.

As shown in Figure 3, be the Switching Power Supply structure chart that obtains after replacing according to replacement method in this embodiment.Switching Power Supply comprises negative feed back control system 10, and negative feed back control system 10 comprises sample circuit 1, error calculation circuit 2, adjuster 3 and PWM controller 4.Switching Power Supply also comprises output voltage working range regulating circuit 20.

The output voltage Vout of sample circuit 1 pair of Switching Power Supply samples, by the reverse input end of sampled voltage error originated from input counting circuit 2, the positive input of error calculation circuit 2 receives the error amount of set-point (the second voltage-reference Vref2 after output voltage working range regulating circuit 20 from the magnitude of voltage that the first end of the second resistance R2 exports) both calculating, by in errors value input regulator 3, adjuster 3 carries out computing to it, as PID arithmetic, PI computings etc., obtain control voltage Verr.After control PWM controller 4 receives this control voltage Verr, export the pulse drive signal of corresponding duty ratio, this pulse drive signal drives the switching tube in main loop of power circuit 100, thus the output voltage Vout controlling main loop of power circuit 100 tends towards stability.After adjustment port C in output voltage working range regulating circuit 20 connects outside Circuit tuning 30, can adjust in a working range according to the output voltage of the TRIM function adjustment Switching Power Supply of outside Circuit tuning 30.

Particularly, as shown in Figure 4, be the physical circuit figure of the Switching Power Supply medial error counting circuit 2 shown in Fig. 3, sample circuit 1, adjuster 3, output voltage working range regulating circuit 20 and the outside Circuit tuning 30 be connected.

Sample circuit 1 comprises the 3rd resistance R3,5th resistance R5 and the 6th resistance R6, the output voltage Vout of the first end connecting valve power supply of the 5th resistance R5, second end of the 5th resistance R5 connects the first end of the 3rd resistance R3 and the first end of the 6th resistance R6 respectively, the reverse input end of the second end concatenation operation amplifier U1 of the 3rd resistance R3, the second end ground connection of the 6th resistance R6.In circuit, adjuster 3 comprises operational amplifier U1, the first resistance R1 and the first electric capacity C1, the reverse input end of the first end concatenation operation amplifier U1 of the first resistance R1, second end of the first resistance R1 connects the first end of the first electric capacity C1, the output of the second end concatenation operation amplifier U1 of the first electric capacity C1.Operational amplifier U1 also plays the effect of error calculation circuit 2 for error calculation, the positive input of operational amplifier U1 receives the second voltage-reference Vref2, and reverse input end receives the output voltage Vout of the Switching Power Supply that sample circuit 1 is sampled.

Output voltage working range regulating circuit 20 comprises the second resistance R2, the first resistance unit RD1 and the second resistance unit RD2.Wherein, the first resistance unit RD1 is made up of the 7th resistance R7, and the second resistance unit RD2 is made up of the 8th resistance R8, the resistance of the 7th resistance R7 $R7=\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},$ The resistance of the 8th resistance R8 $R8=\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1}.$ In formula, Vref2 is the magnitude of voltage replacing power supply second voltage-reference Vref2, and Vref1 is the magnitude of voltage of the first voltage-reference Vref1 be replaced, and R4 is the resistance of the 4th resistance R4 be replaced.The first end of the 7th resistance R7 connects the second voltage-reference Vref2, and the first end of the 8th resistance R8 connects ground, the positive input of concatenation operation amplifier U1 after the 7th resistance R7 second end is connected with second end of the 8th resistance R8.The first end of the second resistance R2 connects the positive input of error calculation circuit 2, and second end of the second resistance R2 is as adjustment port C.

The outside Circuit tuning 30 adjusting port C connection in this embodiment comprises rise resistance Rup and lowers resistance Rdown, the first end A raising resistance Rup or the first end B lowering resistance Rdown is connected with adjustment port C as the output port of outside Circuit tuning, raise the output voltage Vout of the second end connecting valve power supply of resistance Rup, the second end lowering resistance Rdown connects ground.Wherein, when a reference source Vref in switching power circuit gets the first voltage-reference Vref1, this outside Circuit tuning 30 carries out work to adjust the output voltage of Switching Power Supply according to the TRIM function of himself correspondence, and the TRIM function of this outside Circuit tuning 30 correspondence is specially:

$\mathrm{Rdown}=\frac{R4}{\mathrm{\Δ}}-R2-R4---1-1$

$\mathrm{Rup}=\frac{R4\×\mathrm{Vnom}\×(1+\mathrm{\Δ})}{\mathrm{Vref}1\×\mathrm{\Δ}}-\frac{R4}{\mathrm{\Δ}}-R2-R4---1-2$

In formula, vnom is the output voltage values of Switching Power Supply before adjustment port connects outside Circuit tuning 30, Vo is the output voltage values of Switching Power Supply after adjustment port connects outside Circuit tuning, Vref1 is the magnitude of voltage of the first voltage-reference Vref1, R4 is the resistance of the 4th resistance R4, and R2 is the resistance of the second resistance R2.Namely above-mentioned TRIM function defines in outside Circuit tuning 30 one-to-one relationship raising resistance Rup and lower between the value of resistance Rdown and the value of output voltage Vout, user is according to this TRIM function, adjustment is raised resistance Rup and is lowered the value of resistance Rdown, thus the output voltage of adjustment Switching Power Supply.In detail, switching power circuit output voltage Vout shown in Fig. 1 is Vnom under stable situation, after user buys Switching Power Supply product, as wished that output voltage Vout is adjusted to Vo, the TRIM function that what the user of product needed to do is exactly according to formula 1-2 calculates the value of rise resistance Rup, the first end A of the rise resistance Rup of respective resistance values is connected with adjustment port C, raise the output voltage Vout of the second end connecting valve power supply of resistance Rup, thus by the rise resistance Rup place in circuit of respective resistance values.As wished, output voltage Vout is adjusted downward to Vo, the TRIM function that what the user of product needed to do is exactly according to formula 1-1 calculates the value of downward resistance Rdown, by the downward resistance Rdown of respective resistance values first end B be connected with adjustment port C, the second end lowering resistance Rdown connects ground, thus by the downward resistance Rdown place in circuit of respective resistance values.

Comparison diagram 2 and Fig. 3 known, in this embodiment, voltage-reference replacement method comprises: use the 4th resistance R4 in the first resistance unit RD1 and the second resistance unit RD2 replacement output voltage working range regulating circuit, use the second voltage-reference Vref2 to replace the first voltage-reference Vref1.Concrete connection is: the first end of the first resistance unit RD1 connects the second voltage-reference Vref2, the first end of the second resistance unit RD2 connects ground, is connected the positive input of error calculation circuit 2 after second end of the first resistance unit RD1 is connected with second end of the second resistance unit RD2; The equivalent resistance of the first resistance unit RD1 and the second resistance unit RD2 is respectively: $\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1},$ Wherein, Vref2 is the magnitude of voltage of the second voltage-reference Vref2, and Vref1 is the magnitude of voltage of the first voltage-reference Vref1 be replaced, and R4 is the resistance of the 4th resistance R4 be replaced.

As previously mentioned, the outside Circuit tuning 30 in this embodiment carries out work when a reference source Vref is the first voltage-reference Vref1 according to aforementioned TRIM function.Therefore will describe in detail as follows, another voltage-reference is used according to the voltage-reference replacement method in this embodiment, i.e. the second voltage-reference Vref2, after replacing the first voltage-reference Vref1, outside Circuit tuning 30 still carries out work according to TRIM function.

After replacing according to the replacement method of this embodiment, because the equivalent resistance of the first resistance unit RD1 and the second resistance unit RD2 is respectively $\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1},$ The first resistance unit RD1 and the second resistance unit RD2 is made to meet following formula 1-3 and 1-4,

$\frac{1}{\mathrm{RD}1}+\frac{1}{\mathrm{RD}2}=\frac{1}{R4}---1-3$

$\frac{\mathrm{RD}2}{\mathrm{RD}1+\mathrm{RD}2}\×\mathrm{Vref}2=\mathrm{Vref}1---1-4$

Formula 1-4 shows the impedances such as the circuit network in the dotted line frame 20 be connected to form of the first resistance unit RD1 and the second resistance unit RD2 and the 4th resistance R4 in Fig. 2, formula 1-5 then shows point compression functions of circuit realiration to the second voltage-reference Vref2, makes the magnitude of voltage at the positive input place of error calculation circuit 2 still be the first voltage-reference Vref1.Meet above-mentioned two formulas simultaneously, show that circuit network in dotted line frame 20 is for the course of work of output voltage working range regulating circuit, it achieves the dual-use function of dividing potential drop to the second voltage-reference Vref2 and the impedance matching of TRIM function simultaneously, therefore the output voltage working range regulating circuit equivalence be made up of the first voltage-reference Vref1 and the 4th resistance R4 in the output voltage working range regulating circuit be made up of the circuit network in the second voltage-reference Vref2 and dotted line frame 20 in Fig. 3 and Fig. 2, based on output voltage working range regulating circuit replacement before and after be equivalent, so the work of outside Circuit tuning 30 after replacing still is carried out according to constant TRIM function.

In sum, the replacement method in this embodiment achieves use second voltage-reference Vref2 and replaces the first voltage-reference Vref1, and outside Circuit tuning 30 still carries out work according to TRIM function simultaneously.This also shows, any voltage-reference that user's front stage circuits produces, as long as according to the replacement method of this embodiment, first resistance unit RD1 of respective resistance values and the second resistance unit RD2 being connected into circuit replacement the 4th resistance R4 can be applied in switching power circuit by any voltage-reference, outside Circuit tuning 30 is still suitable for TRIM function simultaneously, brings convenience to the use of user.Simultaneously, do not need in the replacement method of this embodiment to use operational amplifier, therefore the wiring space of Switching Power Supply cost and pcb board can not be increased, only be applied in solution by the first resistance unit RD1, the second resistance unit RD2 simultaneously, can not cause postponing, thus guarantee that start waveform is good.

Embodiment two

This embodiment is with the difference of execution mode one: in this embodiment, during replacement, the first resistance unit is made up of two resistant series.

As shown in Figure 5, be the physical circuit figure of the outside Circuit tuning of the Switching Power Supply medial error counting circuit after replacing in this embodiment, sample circuit, adjuster, output voltage working range regulating circuit and connection.Wherein, error calculation circuit, sample circuit, adjuster are identical with execution mode one with the physical circuit of the outside Circuit tuning of connection, the implementation of the first resistance unit RD1 only in output voltage working range regulating circuit is different from execution mode one: the first resistance unit RD1 in output voltage working range regulating circuit is composed in series by the 9th resistance R9 and the tenth resistance R10, and the resistance value R9 of the 9th resistance R9 and the resistance value R10 of the tenth resistance R10 meets: although the implementation of the first resistance unit is different from execution mode one in this embodiment, but use second voltage-reference Vref2 can be realized equally and replace former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Certainly, known when the first resistance unit RD1 is made up of the resistant series of three or more according to this embodiment, as long as series equivalent value is the equivalent resistance of the first resistance unit RD1, then can realize use second voltage-reference Vref2 equally and replace former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Embodiment three

This embodiment is with the difference of execution mode one: in this embodiment, during replacement, the first resistance unit is made up of two resistor coupled in parallel.

As shown in Figure 6, be the physical circuit figure of the outside Circuit tuning of the Switching Power Supply medial error counting circuit after replacing in this embodiment, sample circuit, adjuster, output voltage working range regulating circuit and connection.Wherein, error calculation circuit, sample circuit, adjuster are identical with execution mode one with the physical circuit of the outside Circuit tuning of connection, the implementation of the first resistance unit RD1 only in output voltage working range regulating circuit is different from execution mode one: the first resistance unit RD1 in output voltage working range regulating circuit is composed in parallel by the 11 resistance R11 and the 12 resistance R12, the resistance value R11 of the 11 resistance R11 and the resistance value R10 of the 12 resistance R12 meets the equivalent resistance that both parallel equivalent resistances are the first resistance unit RD1, namely although the implementation of the first resistance unit is different from execution mode one in this embodiment, but use second voltage-reference Vref2 can be realized equally and replace former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Certainly, known when the first resistance unit RD1 is made up of the resistor coupled in parallel of three or more according to this embodiment, as long as parallel equivalent value is the equivalent resistance of the first resistance unit RD1, the same use second voltage-reference Vref2 that can realize replaces former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Embodiment four

This embodiment is with the difference of execution mode one: in this embodiment, during replacement, the second resistance unit is made up of two resistant series.

As shown in Figure 7, be the physical circuit figure of the outside Circuit tuning of the Switching Power Supply medial error counting circuit after replacing in this embodiment, sample circuit, adjuster, output voltage working range regulating circuit and connection.Wherein, error calculation circuit, sample circuit, adjuster are identical with execution mode one with the physical circuit of the outside Circuit tuning of connection, the implementation of the second resistance unit RD2 only in output voltage working range regulating circuit is different from execution mode one: the second resistance unit RD2 in output voltage working range regulating circuit is composed in series by the 13 resistance R13 and the 14 resistance R14, and the resistance value R13 of the 13 resistance R13 and the resistance value R14 of the 14 resistance R14 meets: although the implementation of the second resistance unit is different from execution mode one in this embodiment, but use second voltage-reference Vref2 can be realized equally and replace former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Certainly, known when the second resistance unit RD2 is made up of the resistant series of three or more according to this embodiment, as long as series equivalent value is the equivalent resistance of the second resistance unit RD2, the same use second voltage-reference Vref2 that can realize replaces former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Embodiment five

This embodiment is with the difference of execution mode one: in this embodiment, during replacement, the second resistance unit is made up of two resistor coupled in parallel.

As shown in Figure 8, be the physical circuit figure of the outside Circuit tuning of the Switching Power Supply medial error counting circuit after replacing in this embodiment, sample circuit, adjuster, output voltage working range regulating circuit and connection.Wherein, error calculation circuit, sample circuit, adjuster are identical with execution mode one with the physical circuit of the outside Circuit tuning of connection, the implementation of the second resistance unit RD2 only in output voltage working range regulating circuit is different from execution mode one: the second resistance unit RD2 in output voltage working range regulating circuit is composed in parallel by the 15 resistance R15 and the 16 resistance R17, the resistance value R15 of the 15 resistance R15 and the resistance value R16 of the 16 resistance R16 meets the equivalent resistance that both parallel equivalent resistances are the second resistance unit RD2, namely although the implementation of the second resistance unit is different from execution mode one in this embodiment, but use second voltage-reference Vref2 can be realized equally and replace former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Certainly, known when the second resistance unit RD2 is made up of the resistor coupled in parallel of three or more according to this embodiment, as long as parallel equivalent value is the equivalent resistance of the second resistance unit RD2, the same use second voltage-reference Vref2 that can realize replaces former first voltage-reference Vref1, and after replacing, outside Circuit tuning still carries out work according to the TRIM function of its correspondence.

Embodiment six

This embodiment is with the difference of execution mode one: in this embodiment, and the outside Circuit tuning that adjustment port C connects is realized by the mode of outer filling voltage.

As shown in Figure 9, be the physical circuit figure of the outside Circuit tuning of the Switching Power Supply medial error counting circuit after replacing in this embodiment, sample circuit, adjuster, output voltage working range regulating circuit and connection.Wherein, error calculation circuit, sample circuit, adjuster are identical with execution mode one with the physical circuit of output voltage working range regulating circuit, the implementation of only external outside Circuit tuning is different from execution mode one: external outside Circuit tuning 40 comprises voltage source V trim, the positive output end of voltage source V trim holds C to be connected as the output port of outside Circuit tuning 40 with adjustment, and the negative output terminal of voltage source V trim connects ground.This outside Circuit tuning 40 carries out work to adjust the output voltage of Switching Power Supply according to the TRIM function of himself correspondence when a reference source Vref is the first voltage-reference Vref1 in switching power circuit, and the TRIM function of this outside Circuit tuning 40 correspondence is specially:

$\mathrm{Vtrim}=[1+(1+\frac{R2}{R4})\mathrm{\Δ}]\×\mathrm{Vref}1---1-5$

In formula, vnom is the output voltage values of Switching Power Supply before adjustment port connects outside Circuit tuning, Vo is the output voltage values of Switching Power Supply after adjustment port connects outside Circuit tuning, Vref1 is the magnitude of voltage of the first voltage-reference Vref1, R4 is the resistance of the 4th resistance R4, and R2 is the resistance of the second resistance R2.Namely this TRIM function defines the one-to-one relationship between the value of voltage source V trim in outside Circuit tuning 40 and the value of output voltage Vout, and user, according to this TRIM function, adjusts the value of voltage source V trim, thus the output voltage of adjustment Switching Power Supply.In detail, switching power circuit output voltage Vout shown in Fig. 1 is Vnom under stable situation, after user buys Switching Power Supply product, as wished, output voltage Vout is adjusted to Vo, the value of the TRIM function calculating voltage source Vtrim that what the user of product needed to do is exactly according to formula 1-5, hold C to be connected with adjustment the positive output end of the voltage source V trim of corresponding value, the negative output terminal of voltage source V trim connects ground, thus by the voltage source V trim place in circuit of respective resistance values.Only adjusting the external outside Circuit tuning of port C in this embodiment is different from execution mode one, but replace according to replacement method, the second voltage-reference Vref2 is used to replace former first voltage-reference Vref1, the Switching Power Supply that first resistance unit RD1 and the second resistance unit RD2 obtains after replacing former 4th resistance, still formula 1-3 and 1-4 two equivalences are met in circuit, then output voltage working range regulating circuit 20 remains equivalence before and after replacing, then outside Circuit tuning 30 still carries out work according to the TRIM function of its correspondence.

Above content is in conjunction with concrete preferred implementation further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, make some substituting or obvious modification without departing from the inventive concept of the premise, and performance or purposes identical, all should be considered as belonging to protection scope of the present invention.

Claims (10)

1. a voltage-reference replacement method, in Switching Power Supply, described Switching Power Supply comprises negative feed back control system, and described negative feed back control system comprises sample circuit, error calculation circuit, adjuster and PWM controller, the positive input of described error calculation circuit receives a reference source, and reverse input end receives the output voltage (Vout) of the described Switching Power Supply of described sampling circuit samples, described Switching Power Supply also comprises output voltage working range regulating circuit, described output voltage working range regulating circuit comprises the second resistance (R2) and the 4th resistance (R4), described a reference source inputs the positive input of described error calculation circuit afterwards by described 4th resistance (R4), the first end of described second resistance (R2) connects the positive input of described error calculation circuit, second end of described second resistance (R2) is as adjusting port for connecting outside Circuit tuning, described outside Circuit tuning carries out work to adjust the output voltage of described Switching Power Supply when described a reference source is the first voltage-reference (Vref1) according to the TRIM function of its correspondence, it is characterized in that:

Described replacement method comprises use first resistance unit (RD1) and the second resistance unit (RD2) and replaces the 4th resistance (R4) in described output voltage working range regulating circuit, uses the second voltage-reference (Vref2) to replace described first voltage-reference (Vref1); The first end of described first resistance unit (RD1) connects described second voltage-reference (Vref2), the first end of described second resistance unit (RD2) connects ground, is connected the positive input of described error calculation circuit after the second end of described first resistance unit (RD1) is connected with the second end of described second resistance unit (RD2); The equivalent resistance of described first resistance unit (RD1) and described second resistance unit (RD2) is respectively: $\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1},$ Wherein, Vref2 is the magnitude of voltage of described second voltage-reference (Vref2), and Vref1 is the magnitude of voltage of described first voltage-reference (Vref1) be replaced, and R4 is the resistance of described 4th resistance (R4) be replaced.

2. voltage-reference replacement method according to claim 1, it is characterized in that: described first resistance unit (RD1) is made up of the 7th resistance (R7), described second resistance unit (RD2) is made up of the 8th resistance (R8); The first end of described 7th resistance (R7) connects described second voltage-reference (Vref2), the first end of described 8th resistance (R8) connects ground, is connected the positive input of described error calculation circuit after the second end of described 7th resistance (R7) is connected with the second end of described 8th resistance (R8); The resistance of described 7th resistance (R7) and described 8th resistance (R8) is respectively the equivalent resistance of described first resistance unit (RD1) and described second resistance unit (RD2).

3. voltage-reference replacement method according to claim 1, it is characterized in that: described first resistance unit (RD1) is made up of at least two resistant series, after the resistance value of resistance described in each meets each resistant series, equivalent resistance is the equivalent resistance of described first resistance unit, or, described first resistance unit is made up of at least two resistor coupled in parallel, and after the resistance value of resistance described in each meets each resistor coupled in parallel, equivalent resistance is the equivalent resistance of described first resistance unit.

4. voltage-reference replacement method according to claim 1, it is characterized in that: described second resistance unit (RD2) is made up of at least two resistant series, after the resistance value of resistance described in each meets each resistant series, equivalent resistance is the equivalent resistance of described second resistance unit, or, described second resistance unit is made up of at least two resistor coupled in parallel, and after the resistance value of resistance described in each meets each resistor coupled in parallel, equivalent resistance is the equivalent resistance of described second resistance unit.

5. a Switching Power Supply, comprises negative feed back control system, and described negative feed back control system comprises sample circuit, error calculation circuit, adjuster and PWM controller; Described Switching Power Supply also comprises output voltage working range regulating circuit; It is characterized in that: a reference source voltage-reference according to claim 1 replacement method accessory rights that the positive input of described error calculation circuit receives requires that the first voltage-reference (Vref1) described in 1 replaces with the second voltage-reference (Vref2) according to claim 1, described output voltage working range regulating circuit is obtain after voltage-reference replacement method according to claim 1 is replaced, comprise the second resistance (R2), the first resistance unit (RD1) and the second resistance unit (RD2); The equivalent resistance of described first resistance unit (RD1) and described second resistance unit (RD2) is respectively: $\mathrm{RD}1=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}1},\mathrm{RD}2=\frac{\mathrm{Vref}2\×R4}{\mathrm{Vref}2-\mathrm{Vref}1},$ Wherein, Vref2 is the magnitude of voltage of described second voltage-reference (Vref2), Vref1 is the magnitude of voltage of described first voltage-reference (Vref1) be replaced, and R4 is the resistance of the 4th resistance (R4) that voltage-reference replacement method according to claim 1 is replaced by the first resistance unit (RD1) and the second resistance unit (RD2); The first end of described first resistance unit (RD1) connects described second voltage-reference (Vref2), the first end of described second resistance unit (RD2) connects ground, is connected the positive input of described error calculation circuit after the second end of described first resistance unit (RD1) is connected with the second end of described second resistance unit (RD2); The first end of described second resistance (R2) connects the positive input of described error calculation circuit, second end of described second resistance (R2) is as adjustment port for connecting outside Circuit tuning, and described outside Circuit tuning carries out work to adjust the output voltage of described Switching Power Supply when described a reference source is the first voltage-reference (Vref1) according to the TRIM function of its correspondence.

6. Switching Power Supply according to claim 5, is characterized in that: described first resistance unit (RD1) is made up of the 7th resistance (R7), and described second resistance unit (RD2) is made up of the 8th resistance (R8); The first end of described 7th resistance connects described second voltage-reference (Vref2), the first end of described 8th resistance (R8) connects ground, is connected the positive input of described error calculation circuit after described 7th resistance (R7) second end is connected with the second end of described 8th resistance (R8); The resistance of described 7th resistance (R7) and described 8th resistance (R8) is respectively the equivalent resistance of described first resistance unit (RD1) and described second resistance unit (RD2).

7. Switching Power Supply according to claim 5, it is characterized in that: described outside Circuit tuning comprises rise resistance (Rup) and lowers resistance (Rdown), the first end of described rise resistance (Rup) or the first end of described downward resistance (Rdown) are connected with described adjustment port as the output port of described outside Circuit tuning, second end of described rise resistance (Rup) connects the output voltage (Vout) of described Switching Power Supply, and the second end of described downward resistance (Rdown) connects ground; The TRIM function that described outside Circuit tuning is corresponding is: $\mathrm{Rdown}=\frac{R4}{\mathrm{\Δ}}-R2-R4,$ In formula, $\mathrm{\Δ}=\left|\frac{\mathrm{Vo}-\mathrm{Vnom}}{\mathrm{Vnom}}\right|,$ Vnom is the output voltage values of described Switching Power Supply before described adjustment port connects described outside Circuit tuning, Vo is the output voltage values of described Switching Power Supply after described adjustment port connects described outside Circuit tuning, Vref1 is the magnitude of voltage of described first voltage-reference (Vref1), R4 is the resistance of described 4th resistance (R4), and R2 is the resistance of described second resistance (R2).

8. Switching Power Supply according to claim 5, it is characterized in that: described outside Circuit tuning comprises voltage source, the positive output end of described voltage source is connected with described adjustment port as the output port of described outside Circuit tuning, and the negative output terminal of described voltage source connects ground; The TRIM function that described outside Circuit tuning is corresponding is: $\mathrm{Vtrim}=[1+(1+\frac{R2}{R4})\mathrm{\Δ}]\×\mathrm{Vref}1,$ In formula, $\mathrm{\Δ}=\left|\frac{\mathrm{Vo}-\mathrm{Vnom}}{\mathrm{Vnom}}\right|,$ Vnom is the output voltage values of described Switching Power Supply before described adjustment port connects described outside Circuit tuning, Vo is the output voltage values of described Switching Power Supply after described adjustment port connects described outside Circuit tuning, Vref1 is the magnitude of voltage of described first voltage-reference (Vref1), R4 is the resistance of described 4th resistance (R4), and R2 is the resistance of described second resistance (R2).

9. Switching Power Supply according to claim 5, it is characterized in that: described sample circuit comprises the 3rd resistance (R3), 5th resistance (R5) and the 6th resistance (R6), the first end of described 5th resistance (R5) connects the output voltage (Vout) of described Switching Power Supply, second end of described 5th resistance (R5) connects the first end of described 3rd resistance (R3) and the first end of described 6th resistance (R6) respectively, second end of described 3rd resistance (R3) connects the reverse input end of described error calculation circuit, second end ground connection of described 6th resistance (R6).

10. Switching Power Supply according to claim 5, it is characterized in that: described adjuster comprises operational amplifier (U1), the first resistance (R1) and the first electric capacity (C1), the first end of described first resistance (R1) connects the reverse input end of described operational amplifier (U1), second end of described first resistance (R1) connects the first end of described first electric capacity (C1), and the second end of described first electric capacity (C1) connects the output of described operational amplifier (U1); Described operational amplifier (U1) is also for error calculation, the positive input of described operational amplifier (U1) receives described second voltage-reference (Vref2), and reverse input end receives the output voltage (Vout) of the described Switching Power Supply of described sampling circuit samples.