CN102437735A - Switch power supply and divider therefor - Google Patents

Abstract

The invention discloses a divider for a switch power supply, which comprises four groups of bipolar transistor sets, wherein an output current and an input current of the divider have the following relationship, wherein if I1 is a current signal corresponding a sampling signal of a linear voltage peak value signal, a formula of Iout_min=(n*I3/beta)m is obtained according to the relationship among a base current, a collector current and an emitter current of the bipolar transistor, wherein beta is an amplification factor of the bipolar transistor sets, and m is the cascade quantity of bipolar transistors in the bipolar transistor sets. Known from the expression of Iout_min and Iout_max, the higher the linear voltage is, the lower the n is, and the smaller the Iout_min and the Iout_max are, thus the divider for the switch power supply has a function of online compensation. Therefore, a linear voltage compensation circuit does not need to be additionally arranged in the switch power supply, circuit structure is simplified and cost is reduced.

Description

A kind of Switching Power Supply is with divider and Switching Power Supply

Technical field

The application relates to the switch power technology field, and particularly relating to a kind of Switching Power Supply is Switching Power Supply with divider.

Background technology

In Switching Power Supply; Because the existence of power switch pipe, there is turn off delay time in power switch pipe, and there is error in the output voltage of Switching Power Supply; And the line voltage of this error and input is big or small proportional; Usually meeting increases by a line voltage compensation circuit in the periphery of the control circuit of Switching Power Supply, and when making Switching Power Supply import different line voltage, output current is consistent.

Traditional Switching Power Supply needs line voltage compensation circuit of extra increase, and circuit structure is complicated, and cost is high, and compensate function is unstable.

Summary of the invention

For solving the problems of the technologies described above; The application embodiment provides a kind of Switching Power Supply with divider and Switching Power Supply, and this divider also has the line voltage compensation function except that the basic function with divider; With the purpose that realizes simplifying circuit, practices thrift cost, technical scheme is following:

The present invention provides a kind of Switching Power Supply to use divider, comprising: the set of first bipolar transistor, the set of second bipolar transistor, the set of the 3rd bipolar transistor and the set of the 4th bipolar transistor, wherein:

The control end of said first bipolar transistor set links to each other with the control end of said the 3rd bipolar transistor set; And the control end of this first bipolar transistor set links to each other with first end of said the 4th bipolar transistor set; First end of said first bipolar transistor set links to each other with DC power supply, and second end has first input current as the first input end input of this divider;

The control end of said second bipolar transistor set links to each other with second end of said first bipolar transistor set; First end of said second bipolar transistor set connects said DC power supply; Second end of said second bipolar transistor set connects second end of said the 4th bipolar transistor set, and the electric current that flows through on this second bipolar transistor is the output current of this divider;

First end of said the 3rd bipolar transistor set connects said DC power supply, and second end connects the control end of said the 4th bipolar transistor set, and this second end has second input current as second input input of this divider;

First end of said the 4th bipolar transistor set has the 3rd input current as the 3rd input input of this divider.

Preferably; Above-mentioned Switching Power Supply is with also comprising in the divider; Be connected said DC power supply and said second bipolar transistor set first end between switching tube; And first end of this switching tube links to each other with said DC power supply, and second end of this switching tube links to each other with first end of said second bipolar transistor set, and control end links to each other with second end of this switching tube.

Preferably, said switching tube is a PMOS pipe, and first end of said switching tube, second end, control end are respectively source electrode, drain electrode, the grid of PMOS pipe.

Preferably, said first bipolar transistor set is first bipolar transistor, and control end, first end, second end of said first bipolar transistor set are respectively base stage, collector electrode, the emitter of said first bipolar transistor;

Said second bipolar transistor set is base stage, collector electrode, the emitter that control end, first end, second end of said second bipolar transistor set of second bipolar transistor is respectively said second bipolar transistor;

Said the 3rd bipolar transistor set is base stage, collector electrode, the emitter that control end, first end, second end of said the 3rd bipolar transistor set of the 3rd bipolar transistor is respectively said the 3rd bipolar transistor;

Said the 4th bipolar transistor set is base stage, collector electrode, the emitter that control end, first end, second end of said the 4th bipolar transistor set of the 4th bipolar transistor is respectively said the 4th bipolar transistor.

Preferably, said first, second, third bipolar transistor is NPN transistor.

Preferably; Said first bipolar transistor set comprises the 5th bipolar transistor and the 6th bipolar transistor of cascade; The base stage of said the 5th bipolar transistor is the control end of this first bipolar transistor set; The collector electrode of the 5th bipolar transistor links to each other with the collector electrode of said the 6th bipolar transistor as first end of this first bipolar transistor set; The emitter of the 5th bipolar transistor links to each other with the base stage of said the 6th bipolar transistor, and the emitter of said the 6th bipolar transistor is as second end of this first bipolar transistor set;

Said second bipolar transistor set comprises the 7th bipolar transistor and the 8th bipolar transistor of cascade; The base stage of said the 7th bipolar transistor is the control end of this second bipolar transistor set; The collector electrode of said the 7th bipolar transistor is as first end of said second bipolar transistor set, and the emitter of said the 7th bipolar transistor links to each other with the base stage of said the 8th bipolar transistor; The collector electrode of said the 8th bipolar transistor links to each other with the collector electrode of said the 7th bipolar transistor, second end of very said second bipolar transistor set of the emission of the collector electrode of the 8th bipolar transistor;

Said the 3rd bipolar transistor set comprises the 9th bipolar transistor and the tenth bipolar transistor of cascade; The base stage of said the 9th bipolar transistor is the control end of the 3rd bipolar transistor set; The emitter of said the 9th bipolar transistor links to each other with the base stage of said the tenth bipolar transistor, and the collector electrode of said the 9th bipolar transistor links to each other with the collector electrode of said the tenth bipolar transistor as first end of the 3rd bipolar transistor set; Second end of very said the 3rd bipolar transistor set of the emission of said the tenth bipolar transistor;

Said the 4th bipolar transistor set comprises the 11 bipolar transistor and the 12 bipolar transistor of cascade; The base stage of said the 11 bipolar transistor is the control end of the 4th bipolar transistor set; The current collection of the 11 bipolar transistor is first end of the 4th bipolar transistor set very; Emitter links to each other with the base stage of said the 12 bipolar transistor; The collector electrode of said the 12 bipolar transistor links to each other with the collector electrode of said the 11 bipolar transistor, and the emission of said the 12 bipolar transistor is second end of the 4th bipolar transistor set very.

Preferably, said the the the the 5th, the 6th, the 7th, the 8th, the 9th, the tenth, the 11, the 12 bipolar transistor is NPN transistor.

The present invention also provides a kind of Switching Power Supply to use controller; Comprise constant-current drive circuit; Be used to produce the predeterminated voltage of the variation tendency variation of the input voltage of following said Switching Power Supply; This predeterminated voltage offers the power switch pipe control circuit that is used to produce the power controlling switch tube working status in the said controller, so that switch power supply output current is constant, said constant-current drive circuit comprises that above-mentioned Switching Power Supply uses divider.

The present invention also provides a kind of Switching Power Supply; Comprise controller with constant-current drive circuit; This constant-current drive circuit is used to produce the predeterminated voltage of the variation tendency variation of the input voltage of following said Switching Power Supply; This predeterminated voltage offers the power switch pipe control circuit of the operating state that is used to produce the power controlling switching tube in the said controller, so that switch power supply output current keeps is constant, said constant-current drive circuit comprises that above-mentioned Switching Power Supply uses divider.

Technical scheme by above the application embodiment provides is visible, has following relation between the output current of this divider and the input current:

Wherein, suppose I1 is and line voltage peak signal sampling signal current corresponding signal can get according to relation between bipolar transistor base current, collector current and the emitter current three: I _{Out_min}=(n*I ₃/ β) ^m, Wherein, I _{Out_min}And I _{Out_max}β in the expression formula is the multiplication factor of bipolar transistor set, and m is a positive integer, equates with bipolar transistor cascade number in the bipolar transistor set.

By I _{Out_min}And I _{Out_max}Expression formula can know, when line voltage high more, I ₁Also just big more, but n is more little, the I that obtains _{Out_min}And I _{Out_max}Also just more little, so the divider that the application embodiment provides has the function of line compensation.Thereby Switching Power Supply need not and sets up the line voltage compensation circuit outward, simplifies circuit structure, has reduced cost.

Description of drawings

In order to be illustrated more clearly in the application embodiment or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiment that put down in writing among the application, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

The electrical block diagram of a kind of divider that Fig. 1 provides for the application embodiment;

Fig. 2 is the output current wave figure of divider shown in Figure 1;

The electrical block diagram of the another kind of divider that Fig. 3 provides for the application embodiment;

The structural representation of a kind of Switching Power Supply that Fig. 4 provides for the application embodiment;

The Switching Power Supply that Fig. 5 provides for the application embodiment is with the structural representation of controller;

The structural representation of the constant-current control circuit that Fig. 6 provides for the application embodiment.

Embodiment

The application embodiment provides a kind of Switching Power Supply to use divider; This divider comprises: the set of first bipolar transistor, the set of second bipolar transistor, the set of the 3rd bipolar transistor and the set of the 4th bipolar transistor; Wherein, The control end of said first bipolar transistor set links to each other with the control end of said the 3rd bipolar transistor set; And the control end of this first bipolar transistor set links to each other with first end of said the 4th bipolar transistor set, and first end of said first bipolar transistor set links to each other with DC power supply, and the electric current that second end flows through is the first input current I ₁The control end of said second bipolar transistor set links to each other with second end of said first bipolar transistor set; First end of said second bipolar transistor set connects said DC power supply; Second end of said second bipolar transistor set connects second end of said the 4th bipolar transistor set, and the electric current that flows through on this second bipolar transistor is the output current I of this divider _OutFirst end of said the 3rd bipolar transistor set connects said DC power supply, and second end connects the control end of said the 4th bipolar transistor set, and the electric current that this second end flows through is the second input current I ₂The electric current that first end of said the 4th bipolar transistor set flows through is the 3rd input current I ₃

There is following relation between the output current of the divider that the application embodiment provides and the input current:

Wherein suppose

And according between bipolar transistor base current, collector current and the emitter current three relation can get: I _{Out_min}=(n*I ₃/ β) ^m,

Wherein, I _{Out_min}And I _{Out_max}β in the expression formula is the multiplication factor of bipolar transistor set, and m is a positive integer, equates with bipolar transistor cascade number in the bipolar transistor set.

By I _{Out_min}And I _{Out_max}Expression formula can be known, I ₁Be line voltage peak sampled signal current corresponding signal, when line voltage high more, I ₁Also just big more, but n is more little, the I that obtains _{Out_min}And I _{Out_max}Also just more little, so the divider that the application embodiment provides has the function of line compensation.

In order to make those skilled in the art person understand the technical scheme among the application better; To combine the accompanying drawing among the application embodiment below; Technical scheme among the application embodiment is carried out clear, intactly description; Obviously, described embodiment only is the application's part embodiment, rather than whole embodiment.Based on the embodiment among the application, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all should belong to the scope of the application's protection.

See also Fig. 1, show a kind of electrical block diagram of divider, the first, second, third, fourth bipolar transistor set of this divider is respectively NPN transistor Q1, Q2, Q3, Q4, wherein:

The base stage of transistor Q1 links to each other with the base stage of transistor Q3, and the collector electrode of transistor Q1 links to each other with DC power supply VDD, the emitter of transistor Q1 and the first current source I ₁Link to each other; The base stage of transistor Q2 links to each other with the emitter of said transistor Q1, and the collector electrode of transistor Q2 links to each other with DC power supply VDD through switching tube P1, and the emitter of transistor Q2 links to each other with the emitter of transistor Q4; The collector electrode of transistor Q3 links to each other with DC power supply VDD, the emitter and the second current source I ₂Link to each other, the base stage of transistor Q4 links to each other with the emitter of transistor Q3, collector electrode and the 3rd current source I ₃Link to each other, and the collector electrode of transistor Q4 links to each other with the base stage of transistor Q3.

The electric current of first, second, third current source is the input current of this divider, flows through the output current of the electric current of switching tube P1 for this divider.

Transistorized annexation by shown in Figure 1 can be known, relation below the voltage difference between each transistorized base stage and the emitter exists:

Vbe1+Vbe2＝Vbe3+Vbe4 (1)

Wherein, Vbe1 in the formula (1) is the base stage of transistor Q1 and the voltage difference between the emitter; Vbe2 is the base stage of transistor Q2 and the voltage difference between the emitter, the base stage of Vbe3 transistor Q3 and the voltage difference between the emitter, the base stage of Vbe4 transistor Q4 and the voltage difference between the emitter.

Because the voltage difference between transistorized base stage and the emitter is following:

Vbe1＝V _T*ln(I ₁/Is) (2)

Vbe2＝V _T*ln(I _out/Is) (3)

Vbe3＝V _T*ln(I ₂/Is) (4)

Vbe4＝V _T*ln(I ₃/Is) (5)

Wherein, V _TBe temperature voltage equivalent, V _T=KT/q, wherein K is a Boltzmann constant, and T is a thermodynamic temperature, and q is the electric weight of electronics, under 27 ℃ of the normal temperature, V _T≈ 26mV, Is are reverse saturation current.

Therefore, can obtain by formula (1):

V _T* ln (I ₁/ Is)+V _T* ln (I _Out/ Is)=V _T* ln (I ₂/ Is)+V _T* ln (I ₃/ Is), can obtain:

I ₁*I _out＝I ₂*I ₃ (6)

Can know that by formula (6) output current of divider shown in Figure 2 is:

$I_{\mathrm{out}}=\frac{I_2\·I_3}{I_1}---\left(7\right)$

The multiplication factor of transistor Q1-Q4 is identical, and is β, so,

I _{C_Q1}＝I ₁+I _out/β-I ₁/β＝I ₁+(I _out-I ₁)/β (8)

I _{C_Q3}＝I ₂+I ₃/β-I ₂/β＝I ₂+(I ₃-I ₂)/β (9)

I _{C_Q4}＝I ₃-I ₁/β-I ₂/β＝I ₃-(I ₂+I ₁)/β (10)

Wherein, I in the above-mentioned formula _{C_Q1}Be the collector current of transistor Q1, I _{C_Q3}Be the collector current of transistor Q3, be the collector current of transistor Q4.

Because the output current of divider

Because I ₃=I _{C_Q4}, and transistorized base current very I ignore, so I _{C_Q1}≈ I ₁, I _{C_Q3}≈ I ₂, I _{C_Q3}≈ I ₂, therefore,

$I_{\mathrm{out}}=I_{C\_Q2}=\frac{(I_2+(I_3-I_2)/\mathrm{\β})\×(I_3-(I_2+I_1)/\mathrm{\β})}{I_1+(I_{\mathrm{out}}-I_1)/\mathrm{\β}}---\left(11\right)$

Suppose, $\frac{I_3}{I_1}=n---\left(12\right)$

Then $I_{\mathrm{Out}}=I_3\×\left(\frac{\frac{I_2}{I_1}+(n-\frac{I_2}{I_1})/\mathrm{\β}}{1+(n\·\frac{I_2}{I_1}-1)/\mathrm{\β}}\right)\×(1-\frac{\frac{I_2}{I_1}+1}{n\·\mathrm{\β}})---\left(13\right)$

Try to achieve the minimum value I of formula (12) _{Out_min}With maximum I _{Out_max}Be respectively:

I _{out_min}＝n·I ₃/β (14)

$I_{\mathrm{out}\_\max }=I_3\·(1-\frac{2}{n\·\mathrm{\β}})---\left(15\right)$

Can know by formula (12), if I ₁Big more, then n is more little, also I then _{Out_min}And I _{Out_max}Also just more little.Wherein, V ₁Be the line voltage peak sampled signal of Switching Power Supply input, I ₁Be V ₁Current corresponding, therefore, when line voltage high more, V ₁When also can the phase strain big, I ₁Also just big more, n is more little, the I that obtains _{Out_min}And I _{Out_max}Also just more little, so the divider that the application embodiment provides has the function of line compensation.

See also Fig. 2, show the output current wave figure of the divider that Fig. 2 provides, the abscissa of this figure is the second input current I ₂With the ratio of first input current, ordinate is the output current I of this divider _OutWherein, this oscillogram is at I ₃Record under the condition of=30uA, and dotted line is I ₁The oscillogram of the output current that=10uA is corresponding; Solid line is I ₁The oscillogram of the output current that=30uA is corresponding.Can know I by Fig. 3 ₁Big more, the electric current of this divider output is more little, plays the line voltage compensation effect, thereby makes the output current of Switching Power Supply be consistent.

Preferably, the switching tube P1 in the present embodiment can manage for PMOS, and the drain electrode of P1 links to each other with the collector electrode of transistor Q2; Source electrode links to each other with DC power supply VDD; Grid links to each other with drain electrode, and this PMOS pipe is used for the output current of this divider is offered the circuit module of back level, and is concrete; Need another switching tube of this switching tube P1 and extra increase is constituted mirror image circuit, the electric current on said another switching tube is the electric current I on the switching tube P1 _OutImage current, and this image current offered the late-class circuit module that links to each other with this another switching circuit.

The divider that present embodiment provides not only has the basic function of divider, also has the line voltage compensation function, makes Switching Power Supply need not extra increase line voltage compensation circuit, thereby has simplified circuit structure; Having practiced thrift cost, and, can know according to formula (14) and (15); The output current of divider is relevant with n, and line voltage is big more, and n is more little; Corresponding relation between line voltage and the n is stablized constant, therefore, and the line voltage compensation function-stable of this divider.

Present once relation between the input and output of the divider that the foregoing description provides, see also Fig. 4, show the electrical block diagram of another kind of divider, present quadratic relation between the output of this divider and the input.

As shown in Figure 3, this divider comprises: transistor Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, wherein:

Q5 and Q6 cascade constitute first bipolar transistor set of divider; The emitter of Q5 links to each other with the base stage of Q6; The collector electrode of Q5 links to each other with the collector electrode of Q6; And link to each other with DC power supply VDD as first end of first bipolar transistor set, the emission of Q6 is second end gathered of first bipolar transistor very, and the electric current that flows through the Q6 emitter is the first input current I ₁, this first input current I ₁Be Switching Power Supply line voltage peak sampled signal current corresponding signal, the base stage of Q5 is the control of first bipolar transistor set.

Q7 and Q8 cascade constitute second bipolar transistor set of divider; The base stage of Q7 links to each other with the emitter of Q6 as the control end of second bipolar transistor set; The collector electrode of Q7 links to each other with DC power supply VDD through switching tube P1 as first end of second bipolar transistor set; The emitter of Q7 links to each other with the base stage of Q8, and the collector electrode of Q8 links to each other with the collector electrode of Q7, and the emission of Q8 is second end of second bipolar transistor set very.

Q9 and Q10 cascade constitute the 3rd bipolar transistor set of divider; The base stage of Q9 links to each other with the base stage of said Q5 as the control end of the 3rd bipolar transistor set; The collector electrode of Q10 links to each other with the Q9 collector electrode and links to each other with DC power supply VDD, and the emitter input of Q10 has the second input current I ₂, the commutating voltage sampled signal current corresponding signal that this second input current is a Switching Power Supply.

Q11 and Q12 cascade constitute the 4th bipolar transistor set of divider, and the base stage of Q11 links to each other with the emitter of Q10 as the control end of the 4th bipolar transistor set, and the collector electrode input of Q11 has the 3rd input current I ₃, the emitter of Q11 links to each other with the base stage of Q12, and the collector electrode of Q12 links to each other with the collector electrode of Q11, and the emitter of Q12 links to each other with the emitter of Q8 as second end of said the 4th bipolar transistor set.

Can get by each transistorized annexation among Fig. 3:

Vbe5+Vbe6+Vbe7+Vbe8＝Vbe9+Vbe10+Vbe11+Vbe12 (16)

According to characteristics of transistor, the output current of present embodiment divider is:

$I_{\mathrm{out}}={\left(\frac{I_2\·I_3}{I_1}\right)}^2---\left(17\right)$

$I_{\mathrm{out}}={\left(\frac{(I_2+(I_3-I_2)/\mathrm{\β})\×(I_3-(I_2+I_1)/\mathrm{\β})}{I_1+(I_{\mathrm{out}}-I_1)/\mathrm{\β}}\right)}^2---\left(18\right)$

Suppose, $\frac{I_3}{I_1}=n$

Then,

$I_{\mathrm{out}}={\left(I_3\right)}^2\×{\left(\frac{\frac{I_2}{I_1}+(n-\frac{I_2}{I_1})/\mathrm{\β}}{1+(n\·\frac{I_2}{I_1}-1)/\mathrm{\β}}\right)}^2\×{(1-\frac{\frac{I_2}{I_1}+1}{n\·\mathrm{\β}})}^2---\left(19\right)$

The minimum value I of formula (19) _{Out_min1}With maximum I _{Out_max1}Be respectively:

I _{out_minl}＝(n·I ₃/β) ² (20)

$I_{\mathrm{out}\_\max 1}={\left(I_3\right)}^2\·{(1-\frac{2}{n\·\mathrm{\β}})}^2---\left(21\right)$

If I ₁Big more, n then ²More little, I _{Out_min1}And I _{Out_max1}Also just more little, because I ₁Be the line voltage peak sampled signal current corresponding signal of Switching Power Supply input, therefore, when line voltage is high more, I ₁Also just big more, the I that obtains _{Out_min1}And I _{Out_max1}Also just more little, so the divider that the application embodiment provides has the function of certain line compensation.

Preferably, as shown in Figure 3, said divider also comprises switching tube P1; Concrete, this switching tube P1 can realize that the drain electrode of PMOS pipe links to each other with the base stage of Q5 through the PMOS pipe; Source electrode links to each other with DC power supply VDD, and grid links to each other with drain electrode, and this PMOS pipe is used for the output current of this divider is offered the circuit module of back level; Concrete, needing another switching tube of this switching tube P1 and extra increase is constituted mirror image circuit, the electric current on said another switching tube is the electric current I on the switching tube P1 _OutImage current, and this image current offered the late-class circuit module that links to each other with this another switching circuit......

The divider that present embodiment provides makes output current and input current present the relation of quadratic power, and the embodiment of the divider corresponding with Fig. 2 compares, and works as I ₁The increase amplitude is identical, n ²Reduce with quadratic relation, i.e. n ²Less than n, i.e. I _{Out_min1}And I _{Out_max1}Respectively less than I _{Out_min}And I _{Out_max}So the output current of the divider that present embodiment provides is littler, therefore, the line voltage compensation performance of the divider that present embodiment provides is higher than the line voltage compensation function of the corresponding divider of Fig. 2.

Need to prove that the embodiment that the output that this specification provides and input appear once with the divider of quadratic relation only is a preferred embodiment, certainly through changing the progression of cascade, can obtain the repeatedly relation of side, the present invention does not limit this.

The embodiment of the invention also provides a kind of Switching Power Supply, sees also Fig. 4, shows the structural representation of Switching Power Supply, and this Switching Power Supply comprises: rectification circuit 100, transformer 200, controller 300, power switch pipe 400, wherein:

Rectification circuit 100 carries out alternating current input power supplying Vac to offer transformer 200 after the rectification.

Transformer 200 comprises former limit winding 201; Secondary winding 202 with 201 couplings of said former limit winding; And with the auxiliary winding 203 of said secondary winding 202 couplings; Auxiliary winding 203 is used to said controller 300 provides power supply, and the output current of secondary winding 202 drives the drive current of load through conduct behind the rectifying and wave-filtering.

Controller 300 is used for the operating state of the detection information Control power switch pipe 400 of each test side, is constant current thereby make the mean value of switch power supply output current.

See also the structural representation of controller shown in Figure 5, this controller comprises: secondary winding state signal generating circuit 301, power switch pipe switch off control circuit 302, constant-current control circuit 303 and drive circuit 304, wherein:

Said secondary winding state signal generating circuit 301 is used for producing and the corresponding logic level signal of secondary winding 202 states, and is concrete, and when the conducting of secondary winding, this secondary winding state signal generating circuit 301 produces logic-high signal; When the secondary winding ended, this secondary winding state signal generating circuit 301 produced logic lows.

Said power switch pipe switches off control circuit 302, is used for when the voltage signal that detects the said primary current of reflection reaches said predeterminated voltage, and the power output switching tube turn-offs control signal.

Said constant-current control circuit 303; Be used to produce the variation tendency of following said input voltage vin and the predeterminated voltage Vcs_ref that changes offers said power switch pipe and switch off control circuit 302, and; Be used to produce power switch pipe conducting control signal, offer said drive circuit 304;

Drive circuit 304 is used for after receiving said power switch pipe shutoff control signal, controlling said power switch pipe and turn-offing, and after receiving said power switch pipe conducting control signal, control said power switch pipe conducting.

See also Fig. 6, show the structural representation of the constant-current control circuit that the application embodiment provides, this circuit mainly comprises:

Input voltage peak value sampling circuit 310, the first voltage-current converter circuits 320, second voltage-current converter circuit 330, divider 340, predeterminated voltage produce circuit 350, and the power pipe Continuity signal that opens the light produces circuit 360, wherein:

Said input voltage peak value sampling circuit 310 is used to obtain reflecting the real peak signal of former limit winding input voltage.

Said first voltage-current converter circuit 320 is used for converting said input voltage sampled signal into the current corresponding sampled signal;

Said second voltage-current converter circuit 330 is used for said crest voltage sampled signal conversion current corresponding signal;

The first input end of said divider 340 links to each other with the output of said second voltage-current converter circuit 330; Second input links to each other with the output of said first voltage-current converter circuit 320; The 3rd input links to each other with constant-current source Ic; Output produces circuit 350 with said predeterminated voltage and links to each other, and simultaneously, the output of divider produces circuit 360 with said power switch pipe Continuity signal and links to each other.

The phase place that said divider 340 is used to produce phase place and said input voltage vin is consistent, and the current signal of amplitude between 0～Ic has the line voltage compensation function simultaneously.

Said predeterminated voltage produces circuit 350, and according to the electric current I divider generation predeterminated voltage Vcs_ref of divider 340 outputs, the phase place of this predeterminated voltage Vcs_ref is identical with the phase place of input voltage vin.

Said power switch pipe Continuity signal produces circuit 360; Electric current I divider according to divider 340 outputs produces power switch pipe conducting control signal; Be used for the when conducting of power controlling switching tube; Thereby making the ratio of switch periods of ON time and the power switch pipe of secondary winding is a particular expression formula, guarantees that the average current of led drive circuit output is a steady state value.

Divider in the Switching Power Supply that present embodiment provides in the constant-current control circuit not only has the basic function of divider; Also has the line voltage compensation function; Therefore make Switching Power Supply need not extra increase line voltage compensation circuit, thereby simplified circuit structure, practiced thrift cost.

Need to prove; In this article; Relational terms such as first and second grades only is used for an entity or operation are made a distinction with another entity or operation, and not necessarily requires or hint relation or the order that has any this reality between these entities or the operation.

The above only is the application's a embodiment; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the application's principle; Can also make some improvement and retouching, these improvement and retouching also should be regarded as the application's protection range.

Claims (9)

1. a Switching Power Supply is used divider, it is characterized in that, comprising: the set of first bipolar transistor, the set of second bipolar transistor, the set of the 3rd bipolar transistor and the set of the 4th bipolar transistor, wherein:

The control end of said first bipolar transistor set links to each other with the control end of said the 3rd bipolar transistor set; And the control end of this first bipolar transistor set links to each other with first end of said the 4th bipolar transistor set; First end of said first bipolar transistor set links to each other with DC power supply, and second end has first input current as the first input end input of this divider;

The control end of said second bipolar transistor set links to each other with second end of said first bipolar transistor set; First end of said second bipolar transistor set connects said DC power supply; Second end of said second bipolar transistor set connects second end of said the 4th bipolar transistor set, and the electric current that flows through on this second bipolar transistor is the output current of this divider;

First end of said the 3rd bipolar transistor set connects said DC power supply, and second end connects the control end of said the 4th bipolar transistor set, and this second end has second input current as second input input of this divider;

First end of said the 4th bipolar transistor set has the 3rd input current as the 3rd input input of this divider.

2. Switching Power Supply according to claim 1 is used divider; It is characterized in that; Comprise that also be connected the switching tube between first end of said DC power supply and said second bipolar transistor set, and first end of this switching tube links to each other with said DC power supply; Second end of this switching tube links to each other with first end of said second bipolar transistor set, and control end links to each other with second end of this switching tube.

3. Switching Power Supply according to claim 2 is used divider, it is characterized in that, said switching tube is a PMOS pipe, and first end of said switching tube, second end, control end are respectively source electrode, drain electrode, the grid of PMOS pipe.

4. use divider according to each described Switching Power Supply of claim 1-3, it is characterized in that,

Said first bipolar transistor set is first bipolar transistor, and control end, first end, second end of said first bipolar transistor set are respectively base stage, collector electrode, the emitter of said first bipolar transistor;

Said second bipolar transistor set is base stage, collector electrode, the emitter that control end, first end, second end of said second bipolar transistor set of second bipolar transistor is respectively said second bipolar transistor;

Said the 3rd bipolar transistor set is base stage, collector electrode, the emitter that control end, first end, second end of said the 3rd bipolar transistor set of the 3rd bipolar transistor is respectively said the 3rd bipolar transistor;

Said the 4th bipolar transistor set is base stage, collector electrode, the emitter that control end, first end, second end of said the 4th bipolar transistor set of the 4th bipolar transistor is respectively said the 4th bipolar transistor.

5. Switching Power Supply according to claim 4 is used divider, it is characterized in that, said first, second, third bipolar transistor is NPN transistor.

6. use divider according to each described Switching Power Supply of claim 1-3, it is characterized in that:

Said first bipolar transistor set comprises the 5th bipolar transistor and the 6th bipolar transistor of cascade; The base stage of said the 5th bipolar transistor is the control end of this first bipolar transistor set; The collector electrode of the 5th bipolar transistor links to each other with the collector electrode of said the 6th bipolar transistor as first end of this first bipolar transistor set; The emitter of the 5th bipolar transistor links to each other with the base stage of said the 6th bipolar transistor, and the emitter of said the 6th bipolar transistor is as second end of this first bipolar transistor set;

Said second bipolar transistor set comprises the 7th bipolar transistor and the 8th bipolar transistor of cascade; The base stage of said the 7th bipolar transistor is the control end of this second bipolar transistor set; The collector electrode of said the 7th bipolar transistor is as first end of said second bipolar transistor set, and the emitter of said the 7th bipolar transistor links to each other with the base stage of said the 8th bipolar transistor; The collector electrode of said the 8th bipolar transistor links to each other with the collector electrode of said the 7th bipolar transistor, second end of very said second bipolar transistor set of the emission of the collector electrode of the 8th bipolar transistor;

Said the 3rd bipolar transistor set comprises the 9th bipolar transistor and the tenth bipolar transistor of cascade; The base stage of said the 9th bipolar transistor is the control end of the 3rd bipolar transistor set; The emitter of said the 9th bipolar transistor links to each other with the base stage of said the tenth bipolar transistor, and the collector electrode of said the 9th bipolar transistor links to each other with the collector electrode of said the tenth bipolar transistor as first end of the 3rd bipolar transistor set; Second end of very said the 3rd bipolar transistor set of the emission of said the tenth bipolar transistor;

Said the 4th bipolar transistor set comprises the 11 bipolar transistor and the 12 bipolar transistor of cascade; The base stage of said the 11 bipolar transistor is the control end of the 4th bipolar transistor set; The current collection of the 11 bipolar transistor is first end of the 4th bipolar transistor set very; Emitter links to each other with the base stage of said the 12 bipolar transistor; The collector electrode of said the 12 bipolar transistor links to each other with the collector electrode of said the 11 bipolar transistor, and the emission of said the 12 bipolar transistor is second end of the 4th bipolar transistor set very.

7. Switching Power Supply according to claim 6 is used divider, it is characterized in that, said the the the the 5th, the 6th, the 7th, the 8th, the 9th, the tenth, the 11, the 12 bipolar transistor is NPN transistor.

8. a Switching Power Supply is used controller; Comprise constant-current drive circuit; Be used to produce the predeterminated voltage of the variation tendency variation of the input voltage of following said Switching Power Supply, this predeterminated voltage offers the power switch pipe control circuit that is used to produce the power controlling switch tube working status in the said controller, so that switch power supply output current is constant; It is characterized in that said constant-current drive circuit comprises that each described Switching Power Supply of claim 1-7 uses divider.

9. Switching Power Supply; Comprise controller with constant-current drive circuit; This constant-current drive circuit is used to produce the predeterminated voltage that the variation tendency of the input voltage of following said Switching Power Supply changes, and this predeterminated voltage offers the power switch pipe control circuit of the operating state that is used to produce the power controlling switching tube in the said controller, so that switch power supply output current keeps is constant; It is characterized in that said constant-current drive circuit comprises that each described Switching Power Supply of claim 1-7 uses divider.

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