CN103425167B - Constant voltage and constant current control circuit - Google Patents

Abstract

The invention discloses a constant voltage and constant current control circuit and a constant voltage and constant current switching compensation method. The method includes utilizing a constant current error amplifier (CCEA) to generate a constant current signal, utilizing a constant voltage error amplifier (CVEA) to generate a constant voltage signal, receiving the constant current signal and the constant voltage signal to control a controlled system, compensating current extracted by the CCEA from the CVEA in a period that the controlled system works in a constant voltage status and output current is approximate to a constant current value, and compensating current provided by the CVEA to the CCEA in a period that the controlled system works in a constant current status and output voltage is approximate to a constant voltage value. The constant voltage and constant current control circuit has the advantages that starting from basic reasons for interference in a switching period from the CCEA to the CVEA, output of the CCEA and the CVEA in a constant voltage and constant current switching period is compensated, so that a current range of non-constant voltage and non-constant current in the constant voltage and constant current switching period is eliminated, and the circuit can realize lossless switching between constant voltage and constant current.

Description

Constant voltage constant current control circuit

Technical field

The present invention relates to a kind of constant pressure and flow circuit, particularly relate to constant voltage constant current control circuit and constant pressure and flow switching compensation method.

Background technology

In the controls, constant pressure and flow controls to be by realizing the control of dutycycle.Figure 1 shows that existing a kind of concrete structure, only be described in this kind of concrete mode, as shown in Figure 1, the main modular of circuit comprises: constant-current amplifier 101 (constant current error amplifier, be called for short CCEA), constant-voltage amplifier 102 (constant voltage error amplifier is called for short CVEA) and state controller 103 etc.Wherein, CVEA102 works when controlled system is operated in pressure constant state, is used for controlling output voltage constant, and CCEA101 works when controlled system is operated in constant current state, is used for controlling exporting and input current constant.

As shown in Figure 1, wherein, two voltage input ends of CVEA102 are respectively reference voltage input terminal Vref_CV1 and feedback voltage input end VFB1; Two input ends of CCEA101 are respectively reference voltage input terminal Vref_CC1 and feedback voltage input end VCS1.The tail current size of CVEA102 and CCEA101 is 1: 1, and size is designated as i.

In the ideal case, the mutual conductance of CVEA102 and CCEA101 is infinitely great.When controlled system is operated in pressure constant state, when output (entering) electric current is less than constant current value, the VCS voltage ratio Vref_CC1 voltage of CCEA101 is low, because the mutual conductance of CCEA101 is infinitely great, the tail current of CCEA101 is all flowed away by metal-oxide-semiconductor N6 and metal-oxide-semiconductor N8, metal-oxide-semiconductor N7, metal-oxide-semiconductor N9 and metal-oxide-semiconductor N10 are all in off state, and such CCEA101 breaks from controlled system, now control controlled system by CVEA102 by loop and are in pressure constant state; When controlled system is operated in constant current state, the feedback voltage input end VFB1 input terminal voltage of CVEA102 is lower than the voltage of its reference voltage input terminal Vref_CV1, because the mutual conductance of CVEA102 is infinitely great, therefore, metal-oxide-semiconductor N1, metal-oxide-semiconductor N3 and metal-oxide-semiconductor N4 are all in off state, and the tail current of CVEA102 all flows into VC1 node from metal-oxide-semiconductor N2, serves as the current source load of CCEA101 output stage, now, CCEA101 controls controlled system by loop and is operated in constant current state.

But in practical situations both, the mutual conductance of CVEA102 and CVEA101 is all limited.Fig. 2 is the effect curve figure of existing constant voltage constant current control circuit.

1) when controlled system is operated in pressure constant state, i.e. V _fB1=V _{ref_CV1}, V _cS1> V _{ref_CC1}time:

A) when output current is much smaller than constant current value, corresponding time (g _n6for the mutual conductance of CVEA101 input to pipe metal-oxide-semiconductor N6 and metal-oxide-semiconductor N7), i _n6=i _n8=i, i _n7=i _n9=i _n10=0, now metal-oxide-semiconductor N10 is in off state, and CVEA101 does not affect CVEA102.The interval of horizontal ordinate i from 0 to ia in this state corresponding diagram 2;

B) when output current is comparatively close to constant current value, corresponding time, i _n10=i _n9=i _n7=g _n6(V _{ref_CC1}-V _cS1), this electric current is provided by metal-oxide-semiconductor N2, therefore i _n10=i _n2-i _n1=g _n1* (V _{ref_CC1}-V _fB1)=g _n6(V _{ref_CC1}-V _cS1), (wherein g _n1for the mutual conductance of CVEA1 input to pipe metal-oxide-semiconductor N1 and metal-oxide-semiconductor N2),

$V_{\mathrm{ref}\_\mathrm{CC}1}-V_{\mathrm{FB}1}=\frac{g_{n6}(V_{\mathrm{ref}\_\mathrm{CC}1}-V_{\mathrm{CS}1})}{g_{n1}},$ The variable quantity of corresponding output voltage is

$K*(V_{\mathrm{ref}\_\mathrm{CC}1}-V_{\mathrm{FB}1})=K*\frac{g_{n6}(V_{\mathrm{ref}\_\mathrm{CC}1}-V_{\mathrm{CS}1})}{g_{n1}},$ Wherein K is the feedback factor of output voltage to the feedback voltage end VFB1 voltage of CVEA102.Therefore the constant voltage effect of controlled system is subject to the impact of CVEA101.In this state corresponding diagram 2, horizontal ordinate i is from ia to ilmt, the interval of ordinate V from Va to Vc.

2) when controlled system be operated in be constant voltage and constant current state time (output voltage equals constant voltage value, and output current equals constant current value), must corresponding V _fB1=V _{ref_CV1}, V _cS1=V _{ref_CC1}if: V _cS1=V _{ref_CC1}, then and the electric current of metal-oxide-semiconductor N10 is provided by metal-oxide-semiconductor N2, like this, therefore V _fB1≠ V _{ref_CC1}, controlled system is operated in and is constant voltage and the situation of constant current state does not exist;

3) when controlled system is operated in constant current state, i.e. V _fB1< V _{ref_CV1}, V _cS1=V _{ref_CC1}time:

A) when output voltage is close to constant voltage value, corresponding $\left(V_{\mathrm{ref}\_\mathrm{CV}1}\right)>V_{\mathrm{FB}1}>(V_{\mathrm{ref}\_\mathrm{CV}1}-\frac{1}{g_{n1}})$ Time,

i _N10＝i _N2-i _N4＝g _n1*(V _{ref_CV1}-V _FB1)，

$V_{\mathrm{ref}\_\mathrm{CC}1}-V_{\mathrm{CS}1}=\frac{\frac{1}{2}*i-i_{N7}}{g_{n6}}=\frac{\frac{1}{2}*i-g_{n1}*(V_{\mathrm{ref}\_\mathrm{CV}1}-V_{\mathrm{FB}1})}{g_{n6}}\&NotEqual;0,$ Therefore the constant current effect of controlled system is subject to the impact of CVEA102.In this state corresponding diagram 2, horizontal ordinate i is from ia to ilmt, the interval of ordinate V from Vc to Va;

B) when output voltage is far below constant voltage value, corresponding i _n2=i _n4=i _n5=i _n11=0, metal-oxide-semiconductor N11 is in off state, and CVEA102 breaks from controlled system, so namely the constant current effect of controlled system is not subject to the impact of CVEA102.In this state corresponding diagram 2, horizontal ordinate equals ilmt, the interval of ordinate V from 0 to Va.

Analysis above comprehensive obtains constant pressure and flow effect curve as shown in Figure 2, and when exporting (entering) electric current close to constant current value, output voltage starts to reduce, and when output voltage is close to constant voltage value, exports (entering) electric current and also starts to reduce.Namely, in constant voltage and constant current handoff procedure, one section of interval is had to be the also non-constant current of non-constant voltage, and not required constant voltage or constant current.

Summary of the invention

A kind of constant voltage constant current control circuit and constant pressure and flow is the object of the present invention is to provide to switch compensation method, in order to solve the constant voltage constant current control circuit of prior art, in constant voltage and constant current handoff procedure, in one section of Current Zone, the problem of the non-constant voltage of electric current also non-constant current.

To achieve these goals, the invention provides a kind of constant voltage constant current control circuit, it comprises: the first variable module, and described first variable module exports the first constant signal, and described first constant signal can increase or reduce within the first stage; Second variable module, described second variable module exports the second constant signal, and described second constant signal can increase or reduction in subordinate phase; Compensating module, be connected with described first variable module and described second variable module respectively, described compensating module was used within the described first stage, compensates, make described first constant signal constant within the described first stage to the value of described first constant signal increase or reduction; Described compensating module is used in described subordinate phase, compensates, make described second constant signal constant in described subordinate phase to the value of described second constant signal increase or reduction.

The present invention also provides a kind of constant pressure and flow to switch compensation method, comprises,

Constant-current amplifier is utilized to produce constant current signal;

Constant-voltage amplifier is utilized to produce constant voltage signal;

Receive described constant current signal and described constant voltage signal, to control controlled system;

Described controlled system be operated in pressure constant state and output current close to the stage of constant current value, the electric current that described constant-current amplifier extracts from described constant-voltage amplifier is compensated;

Described controlled system be operated in constant current state and output voltage close to stage of constant voltage value, the electric current described constant-voltage amplifier being supplied to described constant-current amplifier compensates.

Constant voltage constant current control circuit, the basic reason producing interference from constant-voltage amplifier and constant-current amplifier switch step is set about, by compensating in the output of constant pressure and flow switch step CCEA and CVEA of circuit, between the one section of Current Zone eliminating the also non-constant current of non-constant voltage in constant voltage and constant current handoff procedure, make circuit can realize harmless switching in constant voltage and constant current.

Accompanying drawing explanation

Fig. 1 is existing constant voltage constant current control circuit figure;

Fig. 2 is the effect curve figure of existing constant voltage constant current control circuit;

Fig. 3 is the module map of constant voltage constant current control circuit of the present invention;

Fig. 4 is the circuit diagram of an embodiment of constant voltage constant current control circuit of the present invention;

Fig. 5 is the effect curve figure of constant voltage constant current control circuit of the present invention.

Embodiment

Fig. 3 is the module map of constant voltage constant current control circuit of the present invention, and as shown in Figure 3, to achieve these goals, the invention provides a kind of constant voltage constant current control circuit, wherein, comprise, constant-voltage amplifier 305, constant-voltage amplifier 305 can export a constant voltage signal; Constant-current amplifier 306, constant-current amplifier 306 can export a constant current signal; Current compensation module 307, be connected with constant-voltage amplifier 305 and constant-current amplifier 306 respectively, and be operated in pressure constant state process in the controlled system (being all called for short controlled system below) that constant voltage constant current control circuit controls, and the output current of controlled system is close to the stage of constant current value, the electric current that constant-current amplifier 306 extracts from constant-voltage amplifier 305 is compensated, be operated in constant current state process in controlled system, the output voltage of controlled system is close to the stage of constant voltage, and electric current constant-voltage amplifier 305 being supplied to constant-current amplifier 306 compensates; Constant-voltage amplifier 305 and constant-current amplifier 306, the two is by current compensation module 307, is connected to a common signal output node 308.Wherein, this constant voltage constant current control circuit by the output signal of state controller 309 according to constant-voltage amplifier 305 and constant-current amplifier 306, can also control output voltage or the output current of controlled system.

Fig. 4 is the circuit diagram of an embodiment of constant voltage constant current control circuit of the present invention, as shown in Figure 4, in a wherein embodiment of constant voltage constant current control circuit of the present invention, constant-voltage amplifier 305 specifically comprises the first current source i1, and it is connected with the source electrode of the first PMOS M1 and the second PMOS M2; The grid of described first PMOS M1 connects the first feedback voltage V FB, the grid of drain electrode connection first NMOS tube M3 and drain electrode; The grid of described second PMOS M2 connects the first reference voltage Vref _ CV, the grid of drain electrode connection second NMOS tube M4 and drain electrode; Described first NMOS tube M3 source electrode is connected with the source electrode of described second NMOS tube M4, and equal ground connection.

Compensating module 307 comprises tail current source i3, and the size of current of its input is 1/2nd of the first current source i1 input current size; 3rd NMOS tube M5, its grid is connected with the grid of described second NMOS tube M2, and the source electrode of the 3rd NMOS tube M5 is connected with the source electrode of the 3rd NMOS tube M6 simultaneously; 4th NMOS tube M11, its source electrode is connected with the source electrode of the 3rd NMOS tube M5, the grid of the 4th NMOS tube M11 connects the source electrode of the 3rd NMOS tube M5, the drain electrode of the 4th NMOS tube M11 connects the input node VC of tail current source i3 and state controller 309, and this input node is signal output node 308 common in above-described embodiment.

Constant-current amplifier 306 specifically comprises: the second current source i2, it is connected with the source electrode of the 3rd PMOS M6 and the 4th PMOS M7, the grid of described 3rd PMOS M6 connects the second feedback voltage V CS, the drain electrode of the 3rd PMOS M6 connects grid and the drain electrode of the 5th NMOS tube M8, the grid of described 4th PMOS M7 connects the second reference voltage Vref _ CC, the drain electrode of described 4th PMOS M7 connects grid and the drain electrode of the 6th NMOS tube M9, the source electrode of described 5th NMOS tube M8 is connected with the source electrode of the 6th NMOS tube M9, and equal ground connection, the drain electrode of described 4th PMOS M7 connects the drain electrode of the 3rd NMOS tube M5, 7th NMOS tube M10, its grid connects the grid of the 6th NMOS tube M9, the source electrode of described 7th NMOS tube M10 connects the source electrode of described 5th NMOS tube M8 and described 6th NMOS tube M9, and the drain electrode of described 7th NMOS tube M10 connects the input node VC of described state controller 309.

As shown in Figure 4, state controller 309 specifically comprises: PWM comparer 11, and one input end connects comparative voltage, and another input end connects described input node; Logic and driver module 10, its input end connects the output terminal of comparer; On-off element 12, its control end connects the output terminal of described logic and driver module 10, and the output signal of described PWM comparer 11 can be amplified by described logic and driver module 10, and drives the folding of described on-off element 12, in the present embodiment, on-off element 12 is chosen as MOS type on-off element; Voltage stabilizing diode 15, one end of its negative electrode connecting valve element 12 and one end of inductance 13 connect, the plus earth of voltage stabilizing diode 15; Electric capacity 14, it is connected with the other end of inductance 13 and the output terminal of state controller 309.

According to the circuit in above-mentioned specific embodiment, what be described in further detail constant voltage constant current control circuit of the present invention below realizes principle.

In conjunction with reference to shown in figure 1 and Fig. 4, in the present embodiment, change the first NMOS tube M3 of former control circuit and the second NMOS tube M4 into diode connected mode by current mirror connected mode.In FIG, the grid of the first NMOS tube M3 is connected with the grid of the second NMOS tube M4, and the source electrode of the first NMOS tube M3 is connected with the source electrode of the second NMOS tube M4.In the present embodiment, increase the 3rd NMOS tube M5 and the 4th NMOS tube M11, the grid of the second NMOS tube M4 is connected to the grid of the 3rd NMOS tube M5, the electric current of mirror image second NMOS tube M4 is carried out by the 4th NMOS tube M5 and the 5th NMOS tube M11, and the drain terminal of the 4th NMOS tube M5 being connect the drain terminal of the 4th PMOS M7, the drain terminal of the 5th NMOS tube M11 connects VC node.3rd NMOS tube M5 is for compensating constant-voltage amplifier 305 impact on constant-current amplifier 306 under controlled system is operated in pressure constant state, and the 4th NMOS tube M11 is for compensating constant-current amplifier 306 impact on constant-voltage amplifier 305 under controlled system is operated in constant current state; Increase a tail current i3 and be connected to VC node, its size of current is to realize constant-voltage amplifier 305 and constant-current amplifier 306, the compensation of the impact of the tail current when exporting conversion.

The process that lower surface analysis controlled system switches between constant voltage duty and constant current operation state, Fig. 5 is the effect curve figure (wherein dotted line is the effect curve figure of existing constant voltage constant current control circuit) of constant voltage constant current control circuit of the present invention, as shown in FIG. 4 and 5:

When controlled system is operated in pressure constant state, i.e. V _fB=V _{ref_CV}, V _cS> V _{ref_CC}time:

When the output current of controlled system is much smaller than constant current value, corresponding time, i _m6=i _m8=i, i _m7=i _m9=i _m10=0, wherein, g _m1be the mutual conductance of the first PMOS M1 and the first NMOS tube pair of pipes, i _m6be the electric current of the 3rd PMOS M6, i _m8be the electric current of the 5th NMOS tube M8, i _m7be the electric current of the 4th PMOS M7, i _m9the electric current of the 6th NMOS tube M9, i _m10it is the electric current of the 7th NMOS tube M10; And now the 7th NMOS tube M10 is in off state, constant-current amplifier 306 does not affect constant-voltage amplifier 305, and namely the constant voltage effect of controlled system is unaffected.The interval of horizontal ordinate i from 0 to ia in this state corresponding diagram 5;

When the output current of controlled system is comparatively close to constant current value, corresponding time, $i_{M7}=\frac{1}{2}*(i-g_{m2}(V_{\mathrm{CS}}-V_{\mathrm{ref}\_\mathrm{CC}})).$ 3rd NMOS tube M5 and the second NMOS tube M4 is mirror, and according to current mirror principle, M4 needs the electric current with M5 equivalent, namely because V under constant voltage duty _cS> V _{ref_CC}, so then the 6th NMOS tube M9 and the 7th NMOS tube M10 is in off state, and constant-current amplifier 306 does not affect constant-voltage amplifier 305, and namely the constant voltage effect of controlled system is unaffected.In this state corresponding diagram 5, horizontal ordinate i is from ia to ilmt, the bold portion in the interval of ordinate V from Va to Vc.

When controlled system be operated in be constant voltage and constant current state time (output voltage equals constant voltage value, and output current equals constant current value), corresponding V _fB=V _{ref_CV}, V _cS=V _{ref_CC}:

$i_{M1}=i_{M2}=i_{M4}=i_{M5}=i_{M11}=i_{M6}=i_{M7}=\frac{1}{2}*i,$ Wherein, i _m1be the electric current of the first PMOS M1, i _m2be the electric current of the second PMOS M2, i _m4be the electric current of the second NMOS tube M4, i _m5be the electric current of the 3rd NMOS tube M5, i _m11be the electric current of the 4th NOMS pipe M11, according to Fig. 4 and above-mentioned current value, easily obtain i _m9=i _m10=0, now the 6th NMOS tube M9 and the 7th NMOS tube M10 is in critical conduction mode, and constant-current amplifier 306 does not affect constant-voltage amplifier 305, namely the constant voltage effect of controlled system and constant current effect all unaffected.In this state corresponding diagram 5, horizontal ordinate i is ilmt, and ordinate is the point of Vc, the point (ilmt, Vc) namely in Fig. 5;

When controlled system is operated in constant current state, i.e. V _fB< V _{ref_CV}, V _cS=V _{ref_CC}time:

When output voltage is close to constant voltage value, corresponding $\left(V_{\mathrm{ref}\_\mathrm{CV}}\right)>V_{\mathrm{FB}}>(V_{\mathrm{ref}\_\mathrm{CV}}-\frac{i}{g_{m1}})$ Time,

$i_{M2}=i_{M4}=i_{M5}=i_{M11}<\frac{1}{2}*i,$ $i_{M6}=i_{M7}=\frac{1}{2}*i,$

$i_{M10}=i_{M9}=i_{M7}-i_{M4}=\frac{1}{2}*i-i_{M4}>0,$ The electric current now flowing out VC node is

$i_{M11}+i_{M10}=i_{M4}+(\frac{1}{2}*i-i_{M4})=\frac{1}{2}*i=i_{M7}=i_{M6},$ Therefore, the constant current effect of controlled system is not by the impact of constant-voltage amplifier 305.In this state respective figure figure tetra-, horizontal ordinate i is from ia to ilmt, the interval of ordinate V from Va to Vc (solid line);

When output voltage is far below constant voltage value, corresponding time, i _m2=i _m4=i _m5=i _m11=0, M11 is in off state, and constant-voltage amplifier 305 breaks from controlled system, and namely the constant current effect of controlled system is not subject to the impact of constant-voltage amplifier 305.In this state corresponding diagram 5, horizontal ordinate equals ilmt, the interval of ordinate V from 0 to Va.

Therefore, the present invention can full remuneration due to non-ideality when constant pressure and flow that constant-current amplifier 306 and the limited mutual conductance of constant-voltage amplifier 305 cause switches, the perfection realizing constant pressure and flow switches.

Meanwhile, present invention provides a kind of constant pressure and flow and switch compensation method, wherein, comprise,

A constant-current amplifier is utilized to produce constant current signal;

A constant-voltage amplifier is utilized to produce constant voltage signal;

Utilize a state controller to receive described constant current signal and described constant voltage signal, control controlled system;

Described controlled system be operated in pressure constant state and output current close to the stage of constant current value, the electric current that described constant-current amplifier extracts from described constant-voltage amplifier is compensated;

Described controlled system be operated in constant current state and output voltage close to stage of constant voltage value, the electric current described constant-voltage amplifier being supplied to described constant-current amplifier compensates.

Wherein, above-mentioned constant pressure and flow switches compensation method, specifically can adopt circuit realiration as shown in Figure 4.

In sum, constant voltage constant current control circuit of the present invention, the basic reason producing interference from constant-voltage amplifier and constant-current amplifier switch step is set about, by mending, CCEA and CVEA of circuit is compensated in the output of constant pressure and flow switch step, eliminate in constant voltage and constant current handoff procedure, between one section of Current Zone of the non-constant voltage of electric current also non-constant current, make circuit can realize harmless switching in constant voltage and constant current.

Will be appreciated that, the above embodiments are only as exemplifying and propose preferred embodiment of the present invention, and the present invention is also not only confined to this, and the various simple modifications that those skilled in the art can implement also should fall within the scope of protection of the present invention.

Claims (3)

1. a constant voltage constant current control circuit, is characterized in that, comprising:

First variable module, described first variable module exports the first constant signal, and described first constant signal can increase or reduce within the first stage;

Second variable module, described second variable module exports the second constant signal, and described second constant signal can increase or reduction in subordinate phase;

Compensating module, be connected with described first variable module and described second variable module respectively, described compensating module was used within the described first stage, compensates, make described first constant signal constant within the described first stage to the value of described first constant signal increase or reduction; Described compensating module is used in described subordinate phase, compensates, make described second constant signal constant in described subordinate phase to the value of described second constant signal increase or reduction;

Wherein: described first variable module is constant-voltage amplifier, described second variable module is constant-current amplifier, described first constant signal is constant voltage signal, the described first stage be controlled system that described control circuit controls to be operated in pressure constant state process and the output current of described controlled system close to stage of constant current value; Described second constant signal is constant current signal, described subordinate phase be described controlled system to be operated in constant current state process and the output voltage of described controlled system close to stage of constant voltage; Described in the described first stage, constant-current amplifier extracts electric current from described constant-voltage amplifier, and in described subordinate phase, described constant-voltage amplifier is supplied to described constant-current amplifier electric current;

Termination first reference voltage in two input ends of described constant-voltage amplifier, the first feedback voltage of another termination output current; Described constant-current amplifier two input ends in termination second reference voltage, the second feedback voltage of output current described in another termination;

Described constant-voltage amplifier comprises: the first current source, is connected with the source electrode of the first PMOS and the second PMOS; The grid of described first PMOS connects described first feedback voltage, the grid of drain electrode connection first NMOS tube and drain electrode; The grid of described second PMOS connects described first reference voltage, the grid of drain electrode connection second NMOS tube and drain electrode; Described first NMOS tube source electrode is connected with the source electrode of described second NMOS tube, and equal ground connection;

Described compensating module comprises: tail current source, and its input current is 1/2nd of described first current source input current; 3rd NMOS tube, its grid is connected with the grid of described second NMOS tube, and the source electrode of described 3rd NMOS tube is connected with the source electrode of described second NMOS tube; 4th NMOS tube, its source electrode is connected with the source electrode of described 3rd NMOS tube, and the grid of described 4th NMOS tube connects the grid of described 3rd NMOS tube, and the drain electrode of described 4th NMOS tube connects the input node of described tail current source and described state controller;

Described constant-current amplifier comprises: the second current source, is connected with the source electrode of the 3rd PMOS and the 4th PMOS; The grid of described 3rd PMOS connects described second feedback voltage, and the drain electrode of described 3rd PMOS connects grid and the drain electrode of the 5th NMOS tube; The grid of described 4th PMOS connects described second reference voltage, and the drain electrode of described 4th PMOS connects grid and the drain electrode of the 6th NMOS tube; The source electrode of described 5th NMOS tube is connected with the source electrode of described 6th NMOS tube, and equal ground connection; The drain electrode of described 4th PMOS connects the drain electrode of described 6th NMOS tube; 7th NMOS tube, its grid connects the grid of the 6th NMOS tube, and the source electrode of described 7th NMOS tube connects the source electrode of described 5th NMOS tube and described 6th NMOS tube, and the drain electrode of described 7th NMOS tube connects the input node of described state controller.

2. constant voltage constant current control circuit according to claim 1, is characterized in that, also comprises state controller, for the output signal according to described constant-voltage amplifier or constant-current amplifier, controls described controlled system output voltage or output current.

3. circuit according to claim 2, is characterized in that, described state controller comprises: PWM comparer, and one input end connects comparative voltage, and another input end connects described input node; Logic and driver module, its input end connects the output terminal of comparer; On-off element, its control end connects the output terminal of described logic and driver module, and the output signal of described PWM comparer can be amplified by described logic and driver module, and drives the folding of described on-off element; Voltage stabilizing diode, one end that its negative electrode connects described on-off element and inductance connects, the plus earth of voltage stabilizing diode; Electric capacity, is connected with the other end of described inductance and the output terminal of described state controller.