CN103941795A - Multi-voltage output multiplexing structure unrelated to reference point - Google Patents

Abstract

The invention relates to the field of circuit analysis, and provides a structure for obtaining feedback voltages unrelated to a reference voltage, reducing devices as much as possible for a circuit where various different reference voltages are needed and accurately providing each feedback voltage. According to the technical scheme, the multi-voltage output multiplexing structure unrelated to a reference point is composed of two divider resistors and a P type transistor, wherein the emitting electrode voltage of the transistor is Ve, the collector electrode voltage of the transistor is Vc, the base electrode voltage of the transistor is Vb, the voltages at the two ends of a load are V1 and V2, a middle node of a potential-divider network formed by connecting the two divider resistors between V1 and V2 in series is connected with a base electrode of the transistor, the other end of the first divider resistor is connected with an emitting electrode of the transistor through an emitting electrode resistor, and a collector electrode of the transistor is connected to the reference level of the input end through N collector electrode resistors. The multi-voltage output multiplexing structure is mainly applied to circuit analysis.

Description

Export reusable structure with the multivoltage that reference point is irrelevant

Technical field

The present invention relates to circuit analysis field, relate in particular to the control loop that contains a plurality of different Voltage Feedback information, be applicable to extract a plurality of feedback voltages in the floating ground structure of output voltage, and a plurality of voltage reusable same structure.Specifically, relate to the multivoltage output reusable structure irrelevant with reference point.

Technical background

For two-port network, conventional basic structure has public datum between input and output, namely publicly.In comparatively complicated Circuits System, input end and output terminal often do not have public reference point, and center section element is divided into both sides by circuit, is called primary side and secondary side, and center section element is generally transformer.For example, the inverse-excitation type in switching power circuit (fly-back) transducer.Some voltage-dropping types (Buck) power factor converters (PFC) have also adopted the input structure separated with output.In such structure, the level reference point of input end level reference point and output terminal without any relation.In integrated circuit structure, the feedback voltage of control loop need to be taken from output terminal, and the reference point of importation of need to take while feeding back to importation is benchmark.At this moment in order to obtain load voltage accurately, the difference after calculating partial pressure and between input end reference point by the differential voltage value at load two ends of the best way is fed back.

In circuit for the different feedback voltages of a plurality of needs, circuit in the past is usually taken from the different position of output according to the not same-action of feedback voltage, or used the structure repeating, increased on the one hand the number of devices of circuit, increased on the one hand the power consumption of circuit.

Summary of the invention

For overcoming the deficiencies in the prior art, propose a kind of structure and obtain the feedback voltage irrelevant with reference voltage, and in the circuit of a plurality of different reference voltages of needs, reduce as much as possible the device that circuit is used, and each feedback voltage is accurately provided.For this reason, the technical scheme that the present invention takes is, with the irrelevant multivoltage output reusable structure of reference point, by two divider resistances, P transistor npn npn forms, and transistorized emitter voltage is V _e, collector voltage is V _c, base voltage is V _b, the voltage at load two ends is V ₁and V ₂, V ₁and V ₂between the intermediate node of the potential-divider network that forms of two divider resistances series connection connect transistorized base stage, the other end of the first divider resistance connects transistorized emitter through emitter resistance, transistorized collector is connected to the datum of input end through N collector resistance, namely with reference to ground, feedback voltage connects output resistance through transistorized collector and takes out, and the node between every two collector resistances connects respectively an output resistance and takes out a road feedback voltage.

N=1 wherein.

Technical characterstic of the present invention and effect:

Therefore the present invention utilizes transistorized characteristic, because collector current can not change along with the change of collector resistance, can realize the plurality of voltages irrelevant with reference voltage and exports by the absolute value of resistance and the ratio of each resistance are rationally set.

Accompanying drawing explanation

The Voltage-output that Fig. 1 and end-point voltage absolute value are irrelevant;

The multivoltage output multiplexing structure that Fig. 2 and end-point voltage absolute value are irrelevant.

Embodiment

With the irrelevant circuit structure of reference point as Fig. 1.Mainly, by divider resistance, P transistor npn npn forms, and realizes the Voltage-output irrelevant with reference point.Transistorized emitter voltage is V _e, collector voltage is V _c, base voltage is V _b, the voltage at load two ends is V ₁and V ₂, differential voltage is V _o.Two resistance R ₁and R ₂the intermediate node of the potential-divider network that series connection forms connects transistorized base stage, R ₁the other end through resistance R ₃connect transistorized emitter, transistorized collector is through resistance R ₄be connected to the datum of input end, namely, with reference to ground, feedback voltage is through transistorized collector contact resistance R ₅taking out, is V _fB.V _fBcomputation process as follows,

$V_b=V_1+\frac{R_2}{R_1+R_2}\·V_o;---1)$

$I_c=I_e=(V_2-V_e)\·\frac{1}{R_3};---2)$

V _FB=I _c·R ₄；3）

By 1), 2) substitution 3) obtain:

$V_{\mathrm{FB}}=(V_o-\frac{R_2}{R_1+R_2}\·V_o-0.7)\·\frac{R_4}{R_3};---4)$

Through abbreviation, obtain V _fBexpression formula as follows:

$V_{\mathrm{FB}}=\frac{R_1}{R_1+R_2}\·\frac{R_4}{R_3}\·V_o;---5)$

Can find out V _fBonly relevant with the difference value of output voltage.

The multiplexing structure of realizing many feedback voltages that the present invention is designed is as Fig. 2.Can adopt the different Voltage-output of realizing of transistor collector resistance in series, without other structure.Resistance is respectively R ₄₁, R ₄₂{ R _4x..., voltage output value is respectively V _fB1, V _fB2{ V _fBx? Partial pressure value is calculated as follows:

$V_{\mathrm{FB}1}=\frac{R_1}{R_1+R_2}\·\frac{R_{41}+R_{41}+\·\·\·}{R_3}\·V_o;---6)$

The general expression of feedback voltage is:

$V_{\mathrm{FBx}}=\frac{R_1}{R_1+R_2}\·\frac{R_{4x}+R_{4x+1}+\·\·\·}{R_3}\·V_o;---7)$

Below in conjunction with the drawings and specific embodiments, further describe the present invention.

Take load end differential voltage as 80V output, and it is example that feedback control loop needs the FEEDBACK CONTROL voltage of 2.5V and 5V.The resistance value of R1 and R2 is respectively 1.5M Ω, 510k Ω, and the resistance value of R3 is 1M Ω, the resistance value of R41 and R42 is 42.83k Ω.Output be respectively VFB1=5V, VFB2=2.5V with the irrelevant feedback voltage of end-point voltage.

This circuit can be used for input and output isolation and need to export in the circuit of feedback voltage and input does not have in the circuit of common reference point with exporting.

Claims (2)

1. with the irrelevant multivoltage of a reference point output reusable structure, it is characterized in that, by two divider resistances, P transistor npn npn forms, and transistorized emitter voltage is V _e, collector voltage is V _c, base voltage is V _b, the voltage at load two ends is V ₁and V ₂, V ₁and V ₂between the intermediate node of the potential-divider network that forms of two divider resistances series connection connect transistorized base stage, the other end of the first divider resistance connects transistorized emitter through emitter resistance, transistorized collector is connected to the datum of input end through N collector resistance, namely with reference to ground, feedback voltage connects output resistance through transistorized collector and takes out, and the node between every two collector resistances connects respectively an output resistance and takes out a road feedback voltage.

2. the irrelevant multivoltage output reusable structure of as claimed in claim 1 and reference point, is characterized in that, wherein N=1.