CN102299627A

CN102299627A - DC-DC converters having improved current sensing and related methods

Info

Publication number: CN102299627A
Application number: CN2011101287537A
Authority: CN
Inventors: R·H·艾沙姆
Original assignee: Intersil Inc
Current assignee: Intersil Corp
Priority date: 2006-05-24
Filing date: 2006-10-23
Publication date: 2011-12-28
Anticipated expiration: 2026-10-23
Also published as: TW200744293A; CN101079575B; CN102299627B; TWI404316B; CN103986328A; CN101079575A

Abstract

Provided is a power converter with a set resistor having a resistance RSET. Each of the channels of the power converter include an error amplifier for comparing reference voltage with adjusted output voltage; a pulse width modulator (PWM) for adjusting the output voltage, a current sensing element for sensing a first current, a sense resistor having resistance RSENSE coupled to the current sensing element such that the first current flows through the sense resistor, a reference resistor having a resistance RREFERENCE which is a fixed multiple of RSENSE, and a circuit coupled to a set resistor, the reference resistor and the sense resistor; the circuit is configured to output current; the value of the output current with the RSET is proportional to the RSENSE with the RREFERENCE, wherein the circuit provides output current to the error amplifier.

Description

Have the DC-DC converter and the correlation technique that improve induction by current

The application be the applicant on October 23rd, 2006 submit to, application number for " 200610136584.0 ", denomination of invention divides an application for the application for a patent for invention of " having the DC-DC converter and the correlation technique that improve induction by current ".

Related application the present invention requires in the priority of the provisional application No.60/808197 that is entitled as " METHOD OF IMPROVED CURRENT SENSING IN DC-DC CONVERTERS " of submission on May 24th, 2006, and the full content of this application is incorporated herein by reference.

Technical field

The present invention relates to the accurate measurement of inductive current, be particularly useful for controlling the switch in voltage regulator circuit and the related power circuit.

Background technology

Accurately the sensing lead electric current is so that realization comprises the control of the various device of current motor, DC-DC converter circuit and voltage regulator circuit.A kind of well-known circuit 100 of the inductive current sensing lead electric current by flowing into the DC-DC converter that is used for is shown in Fig. 1 (a).Pin in the circuit 100

With

Between the part on vertical dotted line right side usually in the inside of IC chip, and contain inductor L 110 and C usually in comprising of IC chip exterior _FILTERThe part of the low pass filter of (output capacitor) exists

With

Between the left side of dotted line.Have inductance L and have external inductance L 110 and the C of DC resistance DCR _FILTERConstitute the part of low-pass filter network, this C _FILTERThe input signal of the apply pulse width modulated that will be provided by pulse-width modulator (PWM, not shown) converts load R to _LOADOn steady state voltage output V _OUTThe part of voltage drop is to be caused by its DC resistance that is shown DCR on the L 110.Resistance R with capacitors in series _INDWith capacitor C _INDBe illustrated as placing on the inductor 110, thus R _IND/ C _INDThe time constant of closely mating with the time constant of L/DCR is provided.

C _INDOn stride voltage, in Fig. 1 (a), be shown V _IND, the voltage drop on the coupling DCR, and thereby as inductive current I _INDEffective indication.Operational amplifier A 1 places circuit 100, and with the grid of driving N mos transistor Q1, the source electrode of transistor Q1 is at pin I

The place connects back the inverting input of A1.Inductive reactance R _SENSE120 place pin

With V _OUTBetween.

Be connected in pin

The homophase input of A1 be connected to R _INDWith C _INDBetween node.In this configuration, the high-gain of A1 is with pin

Driven to equaling pin in fact

Voltage, thereby capacitor C _INDOn equal V _INDVoltage will place R _SENSEOn.Q1 equals transmission to V then _IND/ R _SENSE, or I _IND* DCR/R _SENSEElectric current.This electric current I _SENSECan obtain in the drain electrode of Q1, and follow I _OUTCan handle and be used for overcurrent release or be used to be provided with through adjusting output impedance.

Although Q1 is illustrated as the Nmos transistor in Fig. 1, in optional embodiment also its drain current make up the Nmos that forms the bidirectional current induction and the combination of Pmos.Also can be only being that bias current exists

Increase and at I _OUTReduce back initial value to allow the Nmos or the Pmos of bidirectional current induction.

R _SENSEResistance with

Pin also can connect on synchronous rectifier FET.In the case, the RDS of FET _ONIt can be the current sensing elements that substitutes inductor DCR.By MOSFET r under the sampling when PWM drives synchronous rectifier _{DS (ON)}On the load current induction of voltage shown in the circuit 140 shown in Fig. 1 (b).PWM 150 driving grid drivers 152, (synchronous rectifier) two drove the

Nmos

156 and 157 of inductor 160 in turn about this gate drivers 152 drove.Amplifier A1 is by ISEN-output being connected to the ground connection benchmark of the source electrode of MOSFET 157.When FET 156 conductings, inductive current I _LFrom V _INFlow through 156, and during FET 157 conductings instantly, then flow out from earth terminal.Inductive current (I _L) therefore make the pressure drop on the FET 157 equal RD _SONWith the product of inductive current, the resistance of this inductive current and inductive reactance 170 multiply by sensed electric current (I _SEN) relevant.Particularly, enter I _SEN+The electric current as a result of pin and channel current I _LProportional.I then _SENElectric current is sampled after abundant setting time and keeps, as well known in the field in this technique.Sample rate current can be used for comprising in the application of channel current balance, loaded line adjustment and overcurrent protection.

R in the

circuit

100 and 140 _SENSEBeing provided in chip is outward because R _SENSENeed be adjustable, thereby obtain to be used for the expectation I of circuit 100 _OUTValue is to be used for DCR and I _INDVarious combination.For example, if I _OUTCompare with the generation overcurrent release with the fixed current value that integrated circuit (IC) is inner, and inductor DCR and desired I _INDCurrent-release point is provided with by system restriction, then R _SENSEValue must be adjusted to expect I _INDLast acquisition expectation I _OUTBecause need the cause of adjustability, so R _SENSEUsually be arranged on the outside of IC as shown in Figure 1.R _SENSEUsually second reason that is arranged on the IC outside is that most of integrated circuit technologies do not support accurately to reach stable internal resistor.

Use outside R _SENSEA problem be I _SENSE+Pin is to the susceptibility of the noise jamming as shown in Fig. 1 (a) and 1 (b), and this noise jamming is the noise by capacitor parasitics 130 couplings.Refer again to Fig. 1 (a), be capacitively coupled to pin I _SENSE+Noise current be revealed as the drain current of the Q1 that comprises noise component(s) shown in Figure 1, be I _OUT+NoiseKnown this coupling noise can have a negative impact to performance, and has required very fine printed circuit board wiring to minimize pin I _SENSE+On capacitive coupling.Usually attempt I _SENSE+It is infeasible being set as bypass, dispose into a limit in the feedback of amplifier A1 because this understands, thereby may make the A1 instability.

Thereby, need be through improved switch regulating circuit, particularly be used in the current measurement circuit of accurate sensing lead electric current in switch regulating circuit, the circuit for controlling motor etc., they need not have outside accurate R on the inverting input of the A1 with additional noise susceptibility _SENSE

Summary of the invention

The DC-DC converter comprises: the chip that includes the pulse-width modulator (PWM) that error amplifier and input be connected to the error amplifier output; By with the output node (V of this converter _OUT) inductor that the described PWM of series connection drives, wherein load current flows through inductor.V _OUTArrive the inverting input of error amplifier by the network-feedback that comprises feedback resistance (RFB).The circuit that is used for inductive load current comprises: first operational amplifier; Has resistance R on the chip _SENSEThe inductive reactance that is coupled to first amplifier's inverting input; The induced current that wherein is relevant to load current flows through inductive reactance, and the correlated current source provides output current with the supply induced current.Reference resistance is arranged on the chip and has the R of being _SENSEThe fixing resistance R of multiple _REFERENCESet resistance and be arranged to have resistance R _SETTracking circuit is arranged to equal to set ohmically voltage with the voltage on the reference resistance.Functional block is coupled so that receive by the electric current of setting resistance and the ratio that obtains them by the electric current of reference resistance.The electric current multiplier is configured to the wherein output of functional block and is connected to this electric current multiplier.The electric current multiplier provide with load current divided by R _SETProportional measurement electric current.

The present invention can utilize the various circuit arrangement that are used for inductive load current.In one embodiment, use inductor DCR induction, wherein converter also comprises and the resistance of the capacitors in series of crossing over the inductor placement, and this resistance has the DC resistance (DCR) that is designed to the time constant that is complementary with the time constant of inductor and is associated.In another embodiment, use MOSFET r _{DS (ON)}Induction, wherein converter also comprises the output that is connected in PWM and the synchronous rectifier between the inductor.

Inductive reactance and described reference resistance preferably are manufactured from the same material.In one embodiment, converter comprises current mirror, it has the output that is connected to the error amplifier end of oppisite phase and is used for the input of measurement of inductance electric current, described current mirror becomes the source electric current to flow through RFB described measurement current conversion, controls output impedance with the electromotive force that improves the inverting input of described error amplifier along with the increase of measuring electric current.In another embodiment, converter also comprises and makes comparisons and produce and apply a reset signal and enter the structure of overcurrent condition to PWM to prevent PWM measuring electric current and fixed reference electric current.In this embodiment, the structure that is used for comparison can comprise converter, and the output of this converter is coupled to the replacement pin of converter, if wherein measure electric current greater than reference current, then PWM will be forbidden.

The method of induction by current may further comprise the steps in the DC-DC converter: DC-DC is provided converter chip, it comprises the error amplifier that is coupled to the pulse-width modulator (PWM) that drives inductor, this inductor and the output node (V that is suitable for by the converter of load ground connection _OUT) series connection, wherein load current flows through described inductor.V _OUTReturn the inverting input of error amplifier via the network-feedback that comprises feedback resistance (RFB).The circuit that comprises inductive reactance that is used for inductive load current is at chip, and this inductive reactance has and is used to produce the faradic resistance value (R that is relevant to load current _SENSE).The correlated current source provides output current (I _OUT) so that induced current to be provided.Reference resistance is arranged on the chip and has the R of being _SENSEThe fixing resistance R of multiple _REFERENCEBe provided with and have resistance R _SETSetting resistance, also be provided with the tracking circuit that is used for the voltage on the reference resistance is arranged to equal to set ohmically voltage.

The ratio of the electric current of setting resistance and the electric current of the reference resistance of flowing through of flowing through is determined.Then with described R _SENSEThe irrelevant measurement electric current of actual value use this ratio to determine, this measures electric current and load current divided by R _SETProportional.

The circuit that is used to respond to described load current can be realized inductor DCR induction.In another embodiment, be used to respond to the circuit realization MOSFET r of described load current _{DS (ON)}Induction.

This method also can comprise utilizing measures electric current so that the step of fixedly output impedance to be provided.In this embodiment, this utilizes step to comprise measurement electric current (normally absorption current) is transformed into the source electric current, and the source electric current of making flows through feedback resistance so that increase on the inverting input with respect to V along with the increase of inductive current _OUTVoltage.

In another embodiment of the present invention, this method is further comprising the steps of: exceed scheduled volume if load current increases to, then utilize the measurement electric current to close PWM and enter overcurrent condition to avoid PWM.In this embodiment, this utilizes step to comprise: will measure electric current and predetermined reference current is made comparisons, and if measure electric current greater than reference current, then be cut to the power supply of described PWM.In one embodiment, measure electric current and reference current and all be configured to input inverter, the output of this inverter is coupled to the replacement pin of adjuster, if wherein measure electric current greater than reference current, then PWM is forbidden.

Description of drawings

By consulting following detail specifications and accompanying drawing, the present invention with and the complete understanding of feature and advantage can be accomplished, wherein

Fig. 1 (a) is a schematic diagram of realizing the known load induction by current of inductor DCR induction in the DC-DC converter.

Fig. 1 (b) is when PWM drives synchronous rectifier, realizes r in the DC-DC converter _{DS (ON)}The schematic diagram of the known circuit of the load current induction of induction.

Fig. 2 illustrates the circuit of the induced inside resistance that has the inductive current that is used for measuring the DC-DC converter according to an embodiment of the invention.

Fig. 3 illustrate comprise use inductor DCR according to another embodiment of the present invention to respond to come the sensing lead electric current, with the schematic diagram of the exemplary DC-DC converter of the circuit of the output impedance of control change device.

Fig. 4 illustrate comprise the inductor DCR that reuses according to further embodiment of this invention respond to come the sensing lead electric current, with the schematic diagram of the exemplary DC-DC converter of the circuit of the PWM power supply of overcurrent release action protection converter.

Embodiment

The circuit that has the induced inside resistance that is used for the load current induction in the DC-DC converter of realizing inductor DCR induction or other switch regulating circuit according to an embodiment of the invention is shown in Figure 2.Circuit 200 comprise with circuit 100 shown in Fig. 1 (a) in identical circuit element, but added the adjunct circuit 250 (in dotted line, illustrating) that comprises benchmark and tracking circuit, this benchmark and tracking circuit can have nothing to do in R the inductive current of the inductor 110 of flowing through _SENSE120 actual value is measured.The same with circuit 100, circuit 200 comprises common part and common part (inductor L 110 and C in the IC outside in IC inside _FILTERUsually in the IC outside).Yet different with circuit shown in Figure 1 100 is R _SENSEIn IC inside.

Circuit 200 is included in I _OUTElectric current multiplier 215 on the path is I so that form _OUTMultiple, equal M*I _OUTOutput current I _OUT2 Circuit 200 is provided with second resistance R in IC inside _REFERENCE220.R _REFERENCE220 owing to place R on chip _SENSENear 120 and by with R _SENSE120 identical electric conducting materials are made, so can be manufactured with accurate control and R _SENSEResistance ratio K.That is R, _REFERENCE=K*R _SENSEK can be independent of process reform or temperature change obtains, and can be to be greater than or less than 1 convenient value arbitrarily.Circuit 200 also comprises non-essential resistance R _SET235.R _SETThe voltage of 235 high potential sides is shown to be coupled to V _CC, and R _SET235 low potential side is driven into any reference voltage.As shown in Figure 2, R _SETAny reference voltage of 235 low potential sides is provided with by the exemplary circuit that comprises voltage source V 1, and this voltage source V 1 is coupled to Pmos source follower Q2.

In common knowledge as those skilled in the art, the source electrode of MOS transistor can exchange the role at the transistor duration of work with drain electrode.Therefore, the term " source electrode " that is used to identify the current-carrying electrode of MOS transistor in this paper and claim is not to be intended to limit the performed function of current-carrying electrode with respect to serving as source electrode or drain in the special time of circuit working with " drain electrode ".

Operational amplifier A

₂250 link together to drive R with Pmos Q3 255 _REFERENCE220 low potential end, thereby R _REFERENCE220 have in fact and R _SET235 identical voltages.R _REFERENCE220 can be by other drives such as NPN/PNP mixing follower, but in application-specific, system accuracy requires to get rid of the method.From R _REFERENCE220 electric current with from R _SET235 electric current is fed to functional block F1 260.F1 can enlarge a multiplier multiple M by well-known analog or digital circuit, and this multiple M equals to pass through R _SETElectric current with pass through R _REFERENCEThe ratio of electric current.Because electric current and each resistance value of the resistance by having same potential on it are inversely proportional to, so M equals R _REFERENCE/ R _SETBecause R _REFERENCEEqual K*R _SENSESo, M=K*R _SENSE/ R _SET

As mentioned above for circuit 100 shown in Figure 1, output current I _OUTEqual I _IND* DCR/R _SENSEI _OUT2＝M*I _OUT＝M*I _IND*DCR/R _SENSE。Use K*R _SENSE/ R _SETSubstitute M, then:

I _OUT2＝K*DCR/R _SET (1)

Importantly, there is not R in the equation (1) _SET, and I _OUT2Only depend on external circuit elements (L and R _SET, and the DC resistance (DCR) of L) value.Therefore, do not require R _SENSEBe accurate.R _SENSE120 relative R of needs _REFERENCEFixed ratio (K) is arranged, and this fixed ratio is easy to be provided with by circuit design.Because resistance is proportional, so be used for R _SENSEWith R _REFERENCEThe resistivity of electric conducting material in the change of technology (or temperature) precision of the current measurement that provides by circuit 200 can be provided.

Pmos follower (Q2 and Q3) is illustrated as driving R _SENSE235 and R _REFERENCE220, and R _SENSEWith R _REFERENCEBe illustrated as termination positive supply VCC.Although what illustrate is the Pmos follower, driver also may be selected to be the bipolar transistor of NMOS or arbitrary polarity, but and termination ground connection or other power supply.If be presented as nmos drive transistor, the voltage reference V1 that then drives the Q2 grid incites somebody to action the suitably reverse of polarity and termination.

Although not shown in Figure 2, R _REFERENCE220 can drive by reference voltage V 1 and follower, and R _SETCan drive effectively by A2 and Q3.This normally is lower than desired, because R _SETParasitic capacitance can in the feedback of A2250, produce a limit, this can cause the A2 instability.

Circuit 200 can be used for providing through the improved accurately switch regulating circuit of the inductive current of measurement that benefits from, such as DC-DC converter, circuit for controlling motor etc.

Fig. 3 and Fig. 4 show induced current I _OUT2Exemplary use with respect to the DC-DC converter of pulse width modulation.Fig. 3 has illustrated the output impedance of control change device, and Fig. 4 illustrates use overcurrent release action protection PWM power supply.Yet, notice that the present invention is not limited to the DC-DC converter of pulse width modulation, because it may be used on Other related equipment.In addition, as mentioned above, the load current sensor circuit that is different from the circuit of responding to based on inductor DCR can be applicable to the present invention.For example, realize MOSFET r shown in Fig. 1 (b) _{DS (ON)}The replaceable use of the device of induction by current, wherein induction connection ( With

) be connected to down source electrode and the drain electrode thereof of FET (ground connection).Other suitable load current sensor circuit also can be used for the present invention.

Referring now to Fig. 3, the schematic diagram of exemplary PWM DC-DC converter 300 is shown, this converter 300 comprises: the pin that is used for measuring according to the present invention leap inductor 110

With

The circuit 310 of inductive current, this capacitor CF is formed for the low pass filter of load RL with inductor 110.Converter 300 comprises error amplifier 350, and this error amplifier 350 is with the reference voltage V that is applied _REFWith through regulating output voltage V _OUTMake comparisons.V _OUTProcess resistance R FB feeds back to the inverting input of amplifier 350, node FB.Other is coupling in the output node COMP of error amplifier 350 and the compensating element, RC1 between the node FB and CC1 is for suitable system responses is provided.Node COMP driving pulse width modulator PWM 360, this pulse-width modulator PWM 360 are provided with some relations between its COMP voltage input and the duty cycle output.Input to PWM 360 provides the conventional oscillator of clock signal (for example sawtooth waveforms) not to be illustrated.PWM output signal PWM _OUTBecome output voltage V by inductor LF 110 with capacitor CF low-pass filter _OUTIt is that adjuster has appointment output impedance that the typical case of DC-DC converter requires.Be V _OUTMust be with respect to the load current I that increases _LOADReduce so that fixing appointment output impedance is provided with fixed ratio.

The circuit 310 that is used for the inductance measuring electric current is used in converter shown in Figure 3 300, with the electric current of induction by LF 110, should be essentially identical electric current with above-mentioned electric current by load RL on average by the electric current of LF 110.The circuit 310 that is used to measure electric current can be presented as circuit 200, and this circuit 200 comprises the R that crosses over LF 110 _INDWith C _IND, V on the chip _OUTWith

R between the pin _SENSE, and shown in the R shown in the circuit 200 _SETAdd pin together to

With

Other exemplary circuit on right side.

Electric current I by circuit 310 generations that are used for the inductance measuring electric current _OUT2Be applied in, and used current mirror and have suitable polarity.The output of current mirror 330 is to be expressed as I _OUT2The source electric current, its RFB that flows through, thus along with I _LOADIncrease and with respect to V _OUTIncrease the voltage on the node FB.Error amplifier 350 reduces V then _OUTVoltage, thereby node FB keeps equaling V _REF, thereby desired fixedly output impedance is provided.

Fig. 4 shows second exemplary application that is used for according to inductive current induction circuit of the present invention.Fig. 4 shows the schematic diagram of exemplary PWM DC-DC converter 400, and this PWM DC-DC converter 400 comprises in a circuit according to the invention 310, and this circuit 310 is used for the inductance measuring electric current, is used for overcurrent release action protection PWM power supply.As described in respect to Fig. 3, the circuit 310 that is used to measure electric current can be presented as exemplary measuring circuit shown in Figure 2.

When work, if load current I _LOADIncrease to and surpass the scheduled current level, the power supply that the circuit 310 that is used for the inductance measuring electric current then according to the present invention can cut off PWM 360.In one embodiment, inverter 435 is coupled to the replacement pin of PWM 360.I _OUT2With the fixed reference electric current I that is provided _REFMake comparisons.Require the replacement pin for for the high converter, if I for normal running _OUT2Greater than I _REF, then the input of inverter 435 will be dragged down, and this will cause inverter to uprise and send reset signal making PWM 360 disabled to PWM 360, thereby prevent that PWM360 from entering overcurrent condition.

This invention provides some remarkable advantages.An advantage is exactly R _SENSEOn chip, be an inner node thereby cause the anti-phase input of A1, and therefore shield the capacitive coupling of noise.In the circuit 200

With

Node all is low-impedance, so more be not easy to be subjected to noise jamming.Another advantage is exactly from non-essential resistance R _SETInput can be DC or low frequency because it can not influence from I _SENSETo I _OUT2The bandwidth in path.So R _SETCan be set as bypass (by-pass capacitor is not shown) to prevent noise jamming.

Also having an advantage is exactly R _SETCan be used to control I _SENSETo I _OUT2Some passages.This with each passage is used separate outer R _SETCompare and to save element.Another advantage is exactly that thermistor can be used to temperature change R _SETValue, and with I _OUT2The conductive coefficient adjusted to inductor DCR of gain be complementary.Positive temperature coefficient thermistor (PTC) or PTC-resistor network can be used to replace R _SETPTC or PTC-resistor network may be selected to be has the temperature coefficient identical with the DCR of inductor, and will be placed with and be convenient to heat and follow the tracks of inductor.Along with the increase of inductor temperature and the therefore increase of its DCR value, the constant ratio of given induced current and actual inductive current, the similar resistance value increase of PTC or PTC-resistor network will reduce the gain amplifier of sensor circuit.Thermistor is set as bypass to prevent noise jamming near IC.

Be understandable that, described the present invention although combine preferred specific embodiment of the present invention, the description of front and the example of back all are intended to explanation but not limit the scope of the invention.Others in the scope of the invention, advantage and change are conspicuous for one of ordinary skill in the art of the present invention.

Claims

1. power inverter with a plurality of channels, described power inverter comprises:

Set resistance, its resistance value is R _SetAnd

Each channel for described a plurality of channels:

Error amplifier is configured to make comparisons with reference voltage and through regulating output voltage;

Pulse-width modulator is coupled to described error amplifier and is configured to based on the described output voltage through regulating of relatively changing in the described error amplifier; And

Current sensing elements is coupled to described pulse-width modulator and is configured to respond to first electric current;

Inductive reactance, its resistance value are R _Sense, described inductive reactance is coupled to described current sensing elements so that described first induced current flows through described inductive reactance;

Reference resistance has the R of being _SenseThe resistance value R of fixedly multiple _ReferenceAnd

Be coupled to the circuit of described setting resistance, described reference resistance and described inductive reactance, described circuit is configured to produce output current, the value of described output current and R _SetAnd R _SenseWith R _ReferenceFixed ratio proportional, wherein said which couple to described error amplifier to provide described output current to described error amplifier.

2. power inverter as claimed in claim 1 is characterized in that, the described current sensing elements of each respective channel is realized inductor D.C. resistance (DCR) induction.

3. power inverter as claimed in claim 1, it is characterized in that, each channel for described a plurality of channels, described circuit comprises tracking circuit, and described tracking circuit is configured to drive described reference resistance so that the voltage on the described reference resistance is substantially equal to the ohmically voltage of described setting.

4. power inverter as claimed in claim 3 is characterized in that, for each channel of described a plurality of channels, described circuit is configured to determine to pass through R _SetElectric current with pass through R _ReferenceThe ratio of electric current, and R is passed through in combination _SetElectric current with pass through R _ReferenceThe ratio and first of electric current measure electric current to produce described output current.

5. power inverter as claimed in claim 3 is characterized in that, described tracking circuit comprises:

Source follower is coupled to the low potential end of described reference resistance; And

Operational amplifier has the output of the grid that is coupled to described source follower.

6. power inverter as claimed in claim 1 is characterized in that, described setting resistance comprises a plurality of resistance that comprise one or more thermistors.

7. power inverter as claimed in claim 1 is characterized in that, described reference resistance and described inductive reactance are made of the material of same type.

8. power inverter as claimed in claim 1, it is characterized in that, the inverter that also comprises the replacement pin that is coupled to described pulse-width modulator, if wherein described output current greater than reference current, then described inverter sends reset signal to described pulse-width modulator.

9. power inverter as claimed in claim 1, it is characterized in that, each channel for described a plurality of channels, also comprise the current mirror between the input of the output that is coupling in described integrated circuit and described error amplifier, wherein said current mirror increases the voltage of input of described error amplifier so that described power inverter provides fixing output impedance based on described output current.

10. the equipment of the load current of each channel that is used for measuring a plurality of channels, described equipment comprises:

Set resistance, its resistance value is R _SetAnd

Be coupled to the integrated circuit of described setting resistance; Wherein for each channel of described a plurality of channels, described integrated circuit comprises:

Inductive reactance, its resistance value are R _Sense, described inductive reactance is coupled to corresponding current sensing elements so that flow through described inductive reactance from corresponding first induced current of described current sensing elements;

Be coupled to the circuit of described setting resistance, described reference resistance and described inductive reactance, described circuit is configured to produce output current, the value of described output current and R _SetAnd R _SenseWith R _ReferenceFixed ratio proportional.

11. equipment as claimed in claim 10 is characterized in that, for each channel of described a plurality of channels, described inductive reactance is coupled to the current sensing elements of realizing inductor D.C. resistance (DCR) induction.

12. equipment as claimed in claim 10, it is characterized in that, each channel for described a plurality of channels, described circuit in the described integrated circuit comprises tracking circuit, and described tracking circuit is configured to drive described reference resistance so that the voltage on the described reference resistance is substantially equal to the ohmically voltage of described setting.

13. equipment as claimed in claim 12 is characterized in that, described tracking circuit comprises:

14. equipment as claimed in claim 12 is characterized in that, for each channel of described a plurality of channels, the circuit in the described integrated circuit is configured to determine to pass through R _SetElectric current with pass through R _ReferenceThe ratio of electric current, and R is passed through in combination _SetElectric current with pass through R _ReferenceThe ratio and first of electric current measure electric current to produce described output current.

15. equipment as claimed in claim 10 is characterized in that, described setting resistance comprises a plurality of resistance that comprise one or more thermistors.

16. equipment as claimed in claim 10 is characterized in that, described reference resistance and described inductive reactance are made of the material of same type.

17. equipment as claimed in claim 10 is characterized in that, for each channel of described a plurality of channels, described inductive reactance is coupled to the current sensing elements of realizing mos field effect transistor (MOSFET) RDS (on) induction.

18. the method for the load current of each channel that is used for measuring a plurality of channels, described method is included as each channel of described a plurality of channels:

Receive corresponding induced current;

With the induced current received by having first resistance of first resistance value accordingly;

Generate indication based on described first resistance value and measure electric current from corresponding first of described corresponding faradic load current;

Set the corresponding second ohmically voltage and equal the 3rd ohmically voltage substantially, described the 3rd resistance has the 3rd resistance value, and each channel of wherein said a plurality of channels uses the 3rd identical resistance;

Determine to flow through the electric current and the ratio that flows through the electric current of described the 3rd resistance of described corresponding second resistance, wherein each corresponding second resistance has and is fixing second resistance value of multiple of described corresponding first resistance;

Make up described corresponding first measurement electric current and determined ratio and measure electric current to generate corresponding second of the described load current of indication, described corresponding second measures electric current is independent of described corresponding first resistance value; And

Export described corresponding second and measure electric current.

19. method as claimed in claim 18 is characterized in that, also comprises revising described corresponding second resistance value to regulate described corresponding second gain of measuring electric current.