CN100394200C - Current detection circuit - Google Patents

Abstract

The present invention provides a current detection circuit which comprises a voltage detection unit, a reference current generation unit and a conversion unit, wherein the voltage detection unit is used for generating a detection voltage signal which represents an electric potential difference caused by current to be detected; the reference current generation unit is used for generating a first reference current and a second reference current, so that a first liner relationship is formed between the first reference current and the second reference current; the conversion unit is coupled between the voltage detection unit and the reference current generation unit and is used for responding the detection voltage signal and the first reference current to determine a first operation voltage and responding to the first operation voltage and the second reference current to determine a second operation voltage and a conversion current, so that the second operation voltage equals to the first operation voltage substantially; at least the second reference current is removed by means of the conversion unit to generate a detection current signal, wherein a second linear relationship is formed between the detection current signal and the current to be detected.

Description

Current detection circuit

Technical field

The present invention relates to a kind of current detection circuit, relate in particular to a kind of current detection circuit of electric current of high-voltage circuit breaker or big current power switch of flowing through that is used to detect.

Background technology

In synchronous suitching type (Synchronous Switching) DC/DC electric pressure converter,, then must detect the size and the variation of inductive current (Inductor Current) if use the mechanism of current-mode (Current Mode) as FEEDBACK CONTROL.Usually, as long as utilize a resistance string to be coupled to inductance, the potential difference (PD) that is caused in the time of can flowing through this resistance in series by means of inductive current and obtain the size of desired inductive current and the information that changes.Yet this method must be used resistance in series, causes I ²* R power consumption.In the sizable circuit application situation of inductive current,,, hindered the development of integrated circuit chip microminiaturization so that enough current flowing abilities to be provided because the restriction of semiconductor fabrication process and material must be used large-area resistance in series.In addition, must use the potential difference (PD) on operational amplifier (Operational Amplifier) the extraction resistance in series two ends, additionally cause circuit complicated and cause the shortcoming that circuit operation speed reduces.

Fig. 1 shows the circuit block diagram of the synchronous suitching type DC/DC electric pressure converter that is provided with current detection circuit commonly used.As shown in Figure 1, side switch HS and side switch LS are coupled in series with input voltage source V _InAnd between ground potential.One end of inductance L is coupled in the tie point A between side switch HS and the side switch LS, and its other end is then as output terminal, in order to supply an output voltage V of regulating _OutOutput terminal also is provided with an output capacitance C _o, in order to for output voltage V _OutCarry out Filtering Processing.Side switch HS and side switch LS are controlled by upside drive signal HD and the downside drive signal LD that the synchronous switch controller 11 of current-mode is exported respectively.In synchronous suitching type DC/DC electric pressure converter, the operation of side switch HS and side switch LS is inverting each other.When side switch HS conducting and not conducting of side switch LS, input voltage source V _InSupplying energy makes inductive current I to inductance L _LThereby increase gradually.On the other hand, when side switch not conducting of HS and side switch LS conducting, the energy that before had been stored in the inductance L is released into output terminal, as output voltage V _OutSo, inductive current I _LThereby reduce gradually.

Therefore, implemented by the PMOS transistor and in the situation that side switch LS is implemented by nmos pass transistor, upside drive signal HD belongs to the identical pulse signal of phase place with downside drive signal LD at side switch HS.In the situation that side switch HS and side switch LS implement by nmos pass transistor, upside drive signal HD and downside drive signal LD belong to the pulse signal of 180 degree of phasic difference mutually.In addition, for preventing that side switch HS and side switch LS conducting simultaneously from causing output voltage source V _InAnd the short circuit between ground potential, upside drive signal HD and downside drive signal LD are designed to the to have on-delay pulse signal of non-overlapping of (Turn-On Delay).

In using the situation of current-mode, in order to detect inductive current I as feedback control mechanism _LSize and change, resistance in series R is set _sBe coupled in series with inductance L.Extract resistance in series R by means of operational amplifier 12 _sTwo ends are because of inductive current I _LFlow through the potential difference (PD) that is caused, so produce one can be in order to represent inductive current I _LDetection voltage V _sSubsequently, the detection voltage V that is produced by operational amplifier 12 _sFeed back to the synchronous switch controller 11 of current-mode, so that carry out Controlled in Current Mode and Based smoothly.

Aforementioned prior art skill must be used resistance in series R _sWith, to detect inductive current I _L, cause I _L ²* R _sPower consumption.At inductive current I _LIn sizable circuit application situation, because the restriction of semiconductor fabrication process and material must be used large-area resistance in series R _s,, hindered the development of integrated circuit chip microminiaturization so that enough current flowing abilities to be provided.In addition, must use operational amplifier 12 acquisition resistance in series R _sPotential difference (PD) on the two ends additionally causes circuit complicated and causes the shortcoming that circuit operation speed reduces.

Summary of the invention

Because foregoing problems, one of the object of the invention is to provide a kind of current detection circuit, can reduce the power consumption of current detecting.

Another purpose of the present invention is to provide a kind of current detection circuit, can be made of the small circuit unit of size.

Another object of the present invention is to provide a kind of current detection circuit, can improve the operating speed of current detecting.

The invention provides a kind of current detection circuit, replace resistance in series and operational amplifier commonly used.The inventor at first observes when the side switch conducting, the electric current of the side switch of flowing through equal the to flow through electric current of inductance, and the electric current of this side switch of flowing through (is conducting resistance R between drain-source for the side switch channel resistance _{Ds (ON)}) two ends cause a potential difference (PD).Therefore, directly detect the potential difference (PD) at this side switch channel resistance two ends according to current detection circuit of the present invention, can obtain the detection current value linear by means of the voltage/current conversion subsequently, to be effectively applied to the FEEDBACK CONTROL of current-mode with inductive current.Owing to need not use resistance in series and complex calculations amplifier according to current detection circuit of the present invention, so avoid huge, and operating speed reduction or the like the shortcoming of the caused power consumption of common technology, size.In addition, the operation and the side switch of foundation current detection circuit of the present invention start or stop simultaneously, further save the power consumption of current detecting.

According to one aspect of the present invention, a kind of current detection circuit is provided, comprise a voltage detection unit, a reference current generation unit and a converting unit.Voltage detection unit produces a detectable voltage signals, the potential difference (PD) that electric current caused that on behalf of a desire, it detect.The reference current generation unit produces one first reference current and one second reference current.This first with this second reference current between become one first linear relationship.Converting unit is coupled between this voltage detection unit and this reference current generation unit.In response to this detectable voltage signals and this first reference current, converting unit is determined one first operating voltage.In response to this first operating voltage and this second reference current, converting unit is determined one second operating voltage and a switching current.This second operating voltage equals this first operating voltage in fact.Deduct at least this second reference current by means of this switching current and produce a sensed current signal.Become one second linear relationship between this sensed current signal and the electric current that this desire detects.

Preferably, this current detection circuit also comprises a Voltage Feedback control module, is coupled in this converting unit, and the variation of this first operating voltage is reflected on this second operating voltage.

Preferably, this current detection circuit also comprises the accurate adjustment unit in an electric current position, is coupled in this converting unit or this Voltage Feedback control module, in order to adjust a direct current electric current position standard of this sensed current signal.

According to another aspect of the present invention, a kind of electric current detecting method is provided, comprise the following step: produce a detectable voltage signals, the potential difference (PD) that electric current caused that on behalf of a desire, it detect.Produce one first reference current.Produce one second reference current, make this first with this second reference current between become one first linear relationship.In response to this detectable voltage signals and this first reference current and determine one first operating voltage.Corresponding to this first operating voltage and this second reference current and determine one second operating voltage and a switching current, make this second operating voltage equal this first operating voltage in fact.Produce a sensed current signal by means of this switching current deducts at least this second reference current, make to become one second linear relationship between this sensed current signal and electric current that this desire detects.

Preferably, this electric current detecting method also comprises a step: by means of a Voltage Feedback control variation of this first operating voltage is reflected on this second operating voltage.

Preferably, this electric current detecting method also comprises a step: a direct current electric current position standard of adjusting this sensed current signal.

Description of drawings

Fig. 1 shows the circuit block diagram of the synchronous suitching type DC/DC electric pressure converter that is provided with current detection circuit commonly used.

Fig. 2 shows the circuit block diagram that is provided with according to the synchronous suitching type DC/DC electric pressure converter of current detection circuit of the present invention.

Fig. 3 shows the detailed circuit diagram according to the current detection circuit of first embodiment of the invention.

Fig. 4 shows the detailed circuit diagram according to the current detection circuit of second embodiment of the invention.

Fig. 5 shows the detailed circuit diagram according to the current detection circuit of third embodiment of the invention.

Fig. 6 shows the detailed circuit diagram according to the current detection circuit of fourth embodiment of the invention.

The primary clustering symbol description

Synchronous switch controller 12 operational amplifiers of 11 current-modes

13,13-1～13-4 current detection circuit

A～E node C _oOutput capacitance

L inductance R _sResistance in series

HD upside drive signal LD downside drive signal

HS side switch LS side switch

I _A1, I _A2Adjust electric current I _BiasBias current

I _HSSide switch channel current I _LInductive current

I _R1, I _R2Reference current I _SenSensed current signal

I _tSwitching current V _InInput voltage source

V _OutOutput voltage V _sDetectable voltage signals

V _SenDetect voltage N1～N5 nmos pass transistor

P1～P7 PMOS transistor

Embodiment

Explanation hereinafter and accompanying drawing will make aforementioned and other purpose of the present invention, feature, more obvious with advantage.Now describe the preferred embodiment of the present invention of bright foundation with reference to the accompanying drawings in detail.

Fig. 2 shows the circuit block diagram that is provided with according to the synchronous suitching type DC/DC electric pressure converter of current detection circuit 13 of the present invention.Side switch HS is connected in input voltage source V _InAnd between node A, side switch LS then is connected between node A and ground potential.Inductance L is connected between node A and exit point.The inventor at first observes when side switch HS conducting, the channel current I of the side switch of flowing through HS _HSAlso equal to be supplied to the electric current I of inductance L _L, and this side switch channel current I _HSFor side switch channel resistance R _HSTwo ends cause a potential difference (PD):

V _in-V _sen＝I _HS·R _HS

Therefore, directly detect this side switch channel resistance R according to current detection circuit 13 of the present invention _HSPotential difference (PD) (the V at two ends _In-V _Sen), by means of converting thereof into relevant treatment such as voltage/current, can obtain and inductive current I subsequently _LLinear detection electric current I _SenBecause foundation current detection circuit 13 of the present invention need not use the resistance in series R in the common technology _sWith complex calculations amplifier 12, so can realize reducing power consumption, dwindle overall dimensions and improve the advantage of operating speed.In addition, the detecting operation and the side switch HS of foundation current detection circuit 13 of the present invention start or stop simultaneously, further save the power consumption of current detecting.

Fig. 3 shows the detailed circuit diagram according to the current detection circuit 13-1 of first embodiment of the invention.Current detection circuit 13-1 comprises a voltage detection unit (P1, P2), a reference current generation unit (I _Bias, N1, N2, N3) an and converting unit (P3, P4, P5, P6).

Particularly, voltage detection unit is in order to detect side switch channel resistance R _HSThe potential difference (PD) at two ends.Suppose that the side switch channel resistance is R _HSAnd the channel current of the side switch of flowing through HS is I _HS, potential difference (PD) V between the drain electrode of side switch HS and source electrode then _DsCan be expressed as:

V _ds＝V _in-v _sen＝I _HS·R _HS

In the embodiment shown in fig. 3, voltage detection unit is formed by PMOS transistor P1 and P2.The source electrode of transistor P1 is connected in input voltage source V _In, its grid is connected to the source electrode (being Node B) that ground potential and its drain electrode are connected in transistor P2.The grid of transistor P2 is connected to the grid of side switch HS, and its drain electrode is connected to the drain electrode of side switch HS.When upside drive signal HD made side switch HS conducting, transistor P1 and P2 all operated in three polar regions (TriodeRegion), therefore were equivalent to a channel resistance respectively.The channel resistance of supposing transistor P1 is R _P1And the channel resistance of transistor P2 is R _P2, because transistor P1 and P2 are as the resitstance voltage divider of connecting, so the voltage V that Node B (being dividing point) is located _BCan be expressed as:

$V_B=\frac{R_{P2}\&CenterDot;V_{\mathrm{in}}+{\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P\&CenterDot;V_{\mathrm{<figure-callout\; id="1"\; label="sen\; R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">sen</figure-callout>}}}{R_P}$

In order to prevent the operation of original circuit that current detection circuit 13-1 influence of the present invention is detected, voltage detection unit is designed to have high-impedance behavior.Therefore, the channel resistance R of transistor P1 and P2 _P1With R _P2Be designed to much larger than the channel resistance R of side switch HS _HS, that is:

R _P1+R _P2＞＞R _HS

In the case, flow through the electric current of transistor P1 and P2 compared to side switch channel current I _HSAlmost can ignore.So, at side switch HS in conduction period, inductive current I _LStill can be suitably by side switch channel current I _HSRepresentative is not subjected to influencing of current detection circuit 13-1, that is:

I _L≈I _HS

In other words, though in fact detect side switch channel current I according to current detection circuit 13-1 of the present invention _HSBut, but on circuit application substantial equivalence in detecting inductive current I _L

The reference current generation unit is in order to supply the first reference current I _R1With the second reference current I _R2, the first reference current I wherein _R1With the second reference current I _R2Between the being aligned sexual intercourse, that is:

I _r1＝K·I _r2

K is the proportionality constant more than or equal to 1 herein.In the embodiment shown in fig. 3, the reference current generation unit comprises a bias current source I _BiasAnd nmos pass transistor N1, N2 and N3.The leakage drain of transistor N1 is connected in bias current source I _Bias, its grid drain electrode and its source electrode of being connected in self be connected in ground potential.Grid, its source electrode that the grid of transistor N2 is connected in transistor N1 is connected in ground potential and its drain electrode in order to allow the first reference current I _R1Discharging (Sinking) or circulation (Flowing).Grid, its source electrode that the grid of transistor N3 is connected in transistor N1 is connected in ground potential and its drain electrode in order to allow the second reference current I _R2Discharging or circulation.Transistor N1, N2, with N3 form a multiple output stage current-mirror structure, wherein transistor N2 and N3 are respectively independently electric current output stage.If it is mutually the same that the structure of transistor N2 and N3 and made become, only its grid breadth length ratio (W/L) is designed to satisfy following relational expression:

(W/L) _N2＝K·(W/L) _N3

Reference current I then _R1With the second reference current I _R2Between can to obtain desired linear relationship as follows:

$\frac{I_{r1}}{I_{r2}}=\frac{{(W/L)}_{N2}}{{(W/L)}_{N3}}=K$

Converting unit system is coupled between voltage detection unit and reference current generation unit, in order to based on first and second reference current I _R1With I _R2And with detectable voltage signals V that voltage detection unit produced _BConvert desired sensed current signal I to _SenIn the embodiment shown in fig. 3, converting unit comprises PMOS transistor P3, P4, P5 and P6.The source electrode of transistor P3 is connected in Node B, and its grid is connected in ground potential, and its drain electrode is connected in node C.Therefore, transistor P3 operates in three polar regions, and its effect is equivalent to a channel resistance R _P3The source electrode of transistor P4 is connected in input voltage source V _In, its grid is connected in ground potential, and its drain electrode is connected in node D.Therefore, transistor P4 operates in three polar regions, and its effect is equivalent to a channel resistance R _P4In addition, the source electrode of transistor P5 is connected in node C, and the source electrode of transistor P6 then is connected in node D.The grid of transistor P5 and P6 interconnects, and the grid of transistor P6 more is connected to the drain electrode of itself.Therefore, transistor P5 and P6 constitute a current-mirror structure.The drain electrode of transistor P5 is connected in the drain electrode of transistor N2, in order to allow the first reference current I _R1Transistor P3 and P5 flow through.The drain electrode of transistor P6 is connected in the drain electrode of transistor N3, in order to allow the second reference current I _R2Transistor P6 flows through.

Because first and second reference current I _R1With I _R2Between have the linear relationship of proportionality constant K, so the grid breadth length ratio (W/L) of transistor P5 and P6 must be designed to satisfy following relational expression (supposing that the structure of transistor P5 and P6 and made become mutually the same) accordingly, to allow first and second reference current I _R1With I _R2Circulation smoothly:

(W/L) _P5＝K·(W/L) _P6

Because the first reference current I _R1So the transistor P3 that flows through is the current potential V of node C _CCan be expressed as:

$V_C=V_B-{\mathrm{<figure-callout\; id="1"\; label="I\; r"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">I</figure-callout>}}_r\&CenterDot;R_{P3}$

$=V_{\mathrm{in}}-(V_{\mathrm{in}}-V_B)-I_{r1}\&CenterDot;R_{P3}$

$=V_{\mathrm{in}}-\frac{R_{P1}}{{\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P+R_{P2}}\&CenterDot;(V_{\mathrm{in}}-V_{\mathrm{sen}})-I_{r1}\&CenterDot;R_{P3}$

$=V_{\mathrm{in}}-\frac{R_{P1}}{{\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P+R_{P2}}\&CenterDot;I_{\mathrm{HS}}\&CenterDot;R_{\mathrm{HS}}-I_{r1}\&CenterDot;R_{P3}$

Now suppose a switching current I _tTransistor P4, then the current potential V of node D flow through _DCan be expressed as:

V _D＝V _in-I _t·R _P4

As previously mentioned, because transistor P5 and P6 are coupled into current-mirror structure, and first and second reference current I that is supplied from transistor N2 and N3 _R1With I _R2The breadth length ratio (W/L) that also cooperates transistor P5 and P6 accordingly _P5With (W/L) _P6So, the gate source voltage across poles V of transistor P5 _{GS (P5)}Gate source voltage across poles V with transistor P6 _{GS (P6)}Operate in the state that is equal to each other.In the case, because the grid of transistor P5 and P6 intercouples, so the source voltage of transistor P5 (is the voltage V of node C _C) with the source voltage of transistor P6 (be the voltage V of node D _D) state locating to be equal to each other:

$V_C=V_D\&DoubleRightArrow;$

$V_{\mathrm{in}}-\frac{R_{P1}}{{\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P+R_{P2}}\&CenterDot;I_{\mathrm{HS}}\&CenterDot;R_{\mathrm{HS}}-I_{r1}\&CenterDot;R_{P3}=V_{\mathrm{in}}-I_t\&CenterDot;R_{P4}\&DoubleRightArrow;$

$I_t=\frac{R_{P1}}{R_{P4}\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P+R_{P2})}\&CenterDot;I_{\mathrm{HS}}\&CenterDot;R_{\mathrm{HS}}+\frac{R_{P3}}{R_{P4}}\&CenterDot;I_{r1}$

$=\frac{R_{P1}}{R_{P4}\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P+R_{P2})}\&CenterDot;I_{\mathrm{HS}}\&CenterDot;R_{\mathrm{HS}}+\frac{R_{P3}}{R_{P4}}\&CenterDot;K\&CenterDot;I_{r2}$

$\&equiv;\mathrm{\&Omega;}\&CenterDot;I_{\mathrm{HS}}+\mathrm{\&Phi;}\&CenterDot;I_{r2}$

$\mathrm{\&Omega;}\&equiv;\frac{{\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P\&CenterDot;R_{\mathrm{HS}}}{R_{P4}\&CenterDot;({\mathrm{<figure-callout\; id="1"\; label="R\; P"\; filenames="C20041008998500231.png"\; state="\{\{state\}\}">R</figure-callout>}}_P+R_{P2})}$

$\mathrm{\&Phi;}\&equiv;\frac{R_{P3}}{R_{P4}}\&CenterDot;K$

Therefore, the sensed current signal I that is exported from node D _SenPromptly as follows:

I _sen＝I _t-I _r2

＝Ω·I _HS+(Ф-1)·I _r2

Because proportionality constant Ω and the Ф and the second reference current I _R2All belong to predefined circuit characteristic parameter when circuit design, its value can obtain via simple calculating, so can export sensed current signal I according to current detection circuit 13-1 of the present invention effectively based on aforesaid equation _Sen, itself and side switch channel current I _HSBetween present a linear relationship.Because side switch channel current I _HSInductive current I no better than _LSo, realize accurately measuring inductive current I according to current detection circuit 13-1 of the present invention _LPurpose.

In one embodiment of this invention, the channel resistance R of transistor P3 and P4 _P3With R _P4Can be set at and be equal to each other, and set transistor P5 and P6 and have identical breadth length ratio and make K=1, then the value of proportionality constant Ф promptly becomes 1.In the case, sensed current signal I _SenFurther be simplified to and directly be proportional to side switch channel current I _HS:

I _sen＝Ω·I _HS

Fig. 4 shows the detailed circuit diagram according to the current detection circuit 13-2 of second embodiment of the invention.Comparison diagram 3 and 4 as can be known, second embodiment is different from the first embodiment part and is that the current detection circuit 13-2 according to second embodiment also is provided with a Voltage Feedback control module (P7), in order to rapid reflection detectable voltage signals V _BVariation, and then guarantee the stable operation of integrated circuit and the sensed current signal I that is produced _SenCorrectness.

In second embodiment shown in Figure 4, the Voltage Feedback control module comprises a PMOS transistor P7, and its grid is connected in the drain electrode of transistor P5, and its source electrode is connected in the source electrode of transistor P6, and it drains in order to export desired sensed current signal I _SenAs side switch channel current I _HSWhen increasing (or minimizing), the voltage V of node A _SenDecrease (or rising), and then be reflected in detectable voltage signals V _BReduction (or raise).As a result, the source voltage of transistor P5 (is the voltage V of node C _C) reduce (or rising) with drain voltage synchronously with the identical change degree.By means of the FEEDBACK CONTROL that transistor P7 is provided, the variable quantity of the drain voltage of transistor P5 causes that rapidly the source voltage of transistor P6 (is the voltage V of node D _D) variation of identical size takes place.Therefore, the voltage V of node D _DThe voltage V that can reflect node C rapidly _CVariation, by means of keeping the relation that both equate, guarantee the stable operation of integrated circuit and the sensed current signal I that is produced _SenCorrectness.

Fig. 5 shows the detailed circuit diagram according to the current detection circuit 13-3 of third embodiment of the invention.Comparison diagram 4 and 5 as can be known, the 3rd embodiment is different from the second embodiment part and is that the current detection circuit 13-3 according to the 3rd embodiment also is provided with the accurate adjustment unit in an electric current position (N4), in order to adjust sensed current signal I _SenDC current position standard, thereby predetermined current compensation (Offset), the elasticity that can promote circuit design and application are provided.

In the 3rd embodiment shown in Figure 5, the accurate adjustment unit in electric current position comprises a nmos pass transistor N4, and its grid is connected in the grid of transistor N1, and its source electrode is connected in ground potential, and its drain electrode is connected in the drain electrode (being node E) of transistor P7, adjusts electric current I in order to allow one _A1Discharging or circulation.Therefore, the sensed current signal I that is exported from node E _SenThe DC current position accurate according to adjusting electric current I _A1And change:

I _sen＝I _t-I _r2-I _a1

＝Ω·I _HS+(Ф-1)·I _r2-I _a1

If adjustment electric current I _A1Set for and equal (Ф-1) * I _R2, sensed current signal I then _SenBe simplified to and directly be proportional to side switch channel current I _HS:

I _sen＝Ω·I _HS

Fig. 6 shows the detailed circuit diagram according to the current detection circuit 13-4 of fourth embodiment of the invention.Comparison diagram 4 and 6 as can be known, the 4th embodiment is different from the second embodiment part and is that the current detection circuit 13-4 according to the 4th embodiment also is provided with the accurate adjustment unit in an electric current position (N5), in order to adjust sensed current signal I _SenDC current position standard, thereby provide predetermined current compensation, the elasticity that can promote circuit design and application.

In the 4th embodiment shown in Figure 6, the accurate adjustment unit in electric current position comprises a nmos pass transistor N5, and its grid is connected in the grid of transistor N1, and its source electrode is connected in ground potential, and its drain electrode is connected in the source electrode (being node D) of transistor P7, adjusts electric current I in order to allow one _A2Discharging or circulation.Therefore, the sensed current signal I that exports from the drain electrode of transistor P7 _SenThe DC current position will definitely be according to adjusting electric current I _A2And change:

I _sen＝I _t-I _r2-I _a2

＝Ω·I _HS+(Ф-1)·I _r2-I _a2

If adjustment electric current I _A2Set for and equal (Ф-1) I _R2, sensed current signal I then _SenBe simplified to and directly be proportional to side switch channel current I _HS:

I _sen＝Ω·I _HS

In sum, directly detect the potential difference (PD) of side switch channel resistance, can obtain the sensed current signal linear by means of the voltage/current conversion subsequently with inductive current according to the present invention's current detection circuit.Owing to need not use resistance in series and complex calculations amplifier according to current detection circuit of the present invention, the existing size of historical facts or anecdotes is dwindled the advantage that improves with operating speed.In addition, the detecting operation system of foundation current detection circuit of the present invention starts or stops simultaneously with side switch, further saves the power consumption of current detecting.

Though the present invention is illustrated as illustration by means of preferred embodiment, should be appreciated that: the present invention does not limit the embodiment disclosed herein.On the contrary, this invention is intended to contain tangible to those skilled in the art various modifications and similar configuration.Therefore, the scope of application claim should be according to the widest annotation, and this type of is revised and similar configuration to contain all.

Claims (10)

1. current detection circuit comprises:

One voltage detection unit is in order to produce a detectable voltage signals, the potential difference (PD) that electric current caused that on behalf of a desire, it detect;

One reference current generation unit, in order to produce one first reference current and one second reference current, make this first with this second reference current between become one first linear relationship; And

One converting unit, be coupled between this voltage detection unit and this reference current generation unit, in order to determine one first operating voltage in response to this detectable voltage signals and this first reference current, and determine one second operating voltage and a switching current in response to this first operating voltage and this second reference current, make this second operating voltage equal this first operating voltage, and deduct at least this second reference current by means of this switching current and produce a sensed current signal

Wherein, become one second linear relationship between this sensed current signal and electric current that this desire detects.

2. according to the current detection circuit of claim 1, wherein:

The electric current that this potential difference (PD) is detected by this desire switch module of flowing through is caused, and

This voltage detection unit starts when this switch module conducting producing this detectable voltage signals, and stops to produce this detectable voltage signals when this not conducting of switch module.

3. according to the current detection circuit of claim 2, wherein:

This voltage detection unit comprises:

One the first transistor is operable to one first equivalent resistance, and

One transistor seconds is operable to one second equivalent resistance and forms when this not conducting of switch module and opens circuit when this switch module conducting, wherein:

This first with this transistor seconds be coupled in this switch module, make that this detectable voltage signals is a dividing potential drop of this potential difference (PD).

4. according to the current detection circuit of claim 1, wherein:

This converting unit comprises:

One first resistive device has one first end points and one second end points, and this first end points is in order to receive this detectable voltage signals;

One the first transistor, be coupled between this second end points and this reference current generation unit, make this first reference current this first transistor of flowing through, wherein: this first reference current this first resistive device of more flowing through makes this first operating voltage be determined by a gate source voltage across poles of this first transistor;

One second resistive device has one first end points and one second end points, and this first end points is in order to receive an input voltage source; And

One transistor seconds, be coupled between this second end points and this reference current generation unit, make this second reference current this transistor seconds of flowing through, wherein: this second operating voltage system determined by a gate source voltage across poles of this transistor seconds, and this switching current this second resistive device of flowing through.

5. according to the current detection circuit of claim 4, also comprise:

One Voltage Feedback control module is coupled between this first transistor and this transistor seconds, and the variation of this first operating voltage is reflected on this second operating voltage, wherein:

This Voltage Feedback control module is implemented by one the 3rd transistor, the 3rd transistor have a grid, one source pole, with a drain electrode, this grid is controlled by this first transistor, and this source-coupled is in this transistor seconds, and this sensed current signal is exported via this drain electrode.

6. according to the current detection circuit of claim 1, also comprise:

One Voltage Feedback control module is coupled in this converting unit, and the variation of this first operating voltage is reflected on this second operating voltage.

7. according to the current detection circuit of claim 1, also comprise:

The accurate adjustment unit in one electric current position is coupled in this converting unit, in order to adjust a direct current electric current position standard of this sensed current signal.

8. electric current detecting method comprises:

Produce a detectable voltage signals, in order to the potential difference (PD) that electric current caused of representing a desire to detect;

Produce one first reference current;

Produce one second reference current, make this first with this second reference current between become one first linear relationship;

Determine one first operating voltage in response to this detectable voltage signals and this first reference current;

Determine one second operating voltage and a switching current to make this second operating voltage equal this first operating voltage in response to this first operating voltage and this second reference current; And

Produce a sensed current signal by means of this switching current deducts at least this second reference current, make to become one second linear relationship between this sensed current signal and the electric current that this desire detects.

9. electric current detecting method according to Claim 8 also comprises:

By means of Voltage Feedback control, the variation of this first operating voltage is reflected on this second operating voltage.

10. electric current detecting method according to Claim 8 also comprises:

Adjust a direct current electric current position standard of this sensed current signal.

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