CN201374646Y - Duty cycle measurement circuit of switching power supply and switching power supply frequency detection circuit - Google Patents

Abstract

The utility model provides a duty cycle measurement circuit of a switching power supply, which consists of a switching control module, a charging voltage/current conversion module, a charging current mirroring module, a discharging voltage/current conversion module, a discharging current mirroring module and a capacitor C2. The charging voltage/current conversion module and the discharging voltage/current conversion module are utilized to convert the voltage of the capacitor C2 into charging current and discharging current which are then transmitted by the current mirroring modules, so that the transmitted charging current and discharging current can become low, thereby the charging and discharging currents for the capacitor can become low, consequently, the capacitor can be integrated in the duty cycle measurement circuit of the switching power supply, peripheral pins are reduced, the cost is reduced, and low ripple voltage can be obtained.

Description

The duty detection circuit of Switching Power Supply and Switching Power Supply frequency detection circuit

Technical field

The utility model relates to the duty ratio detection technique of Switching Power Supply and the application in frequency detecting thereof.

Background technology

In the Switching Power Supply voltage stabilizing circuit, need the duty ratio of sense switch signal, convert the numerical value of the duty ratio of switching signal to stable voltage or current value, as the part of switching power circuit control.

Fig. 1 is the Switching Power Supply duty detection circuit that generally adopts at present, and input square-wave signal Vi is to reverser NA, and the other end of reverser NA is connected to the grid of switch P MOS transistor P1 and switch nmos pass transistor N1, and the source electrode of P1 connects reference voltage V _DDThe source ground of N1, the drain electrode of P1 is connected resistance R 1 with the drain electrode of N1, and capacitor C 1 is connected between the source electrode of the other end of resistance R 1 and N1, switching controls capacitor C 1 by P1 and N1 discharges and recharges, in the duty ratio of the interface place of resistance R 1 and capacitor C 1 sense switch power supply.

Suppose input square-wave signal Vi, the cycle is T, and high level lasting time is Ton, and then the duty ratio D of Vi input is:

$D=\frac{\mathrm{Ton}}{T}---\left(1\right)$

When the Vi input high level, N1 turn-offs, the P1 conducting, and capacitor C 1 charging, charge circuit is power supply V _DD-PMOS pipe P1-resistance R 1-capacitor C 1; When Vi is input as low level, the N1 conducting, P1 turn-offs, capacitor C 1 discharge, discharge path is capacitor C 1-resistance R 1-NMOS pipe N1-ground.

When the duty ratio of input square-wave signal Vi is fixed, and the R1C1 time constant for charging and discharging is during much larger than switch periods, and the voltage on the electric capacity is finally constant, and this output voltage can represent to import the size of duty cycle square wave.

Because after output voltage stabilization, discharging and recharging of electric capacity reached balance, charging charge equals discharge charge, that is:

$\mathrm{Ton}\&CenterDot;\frac{V_{\mathrm{DD}}-{\mathrm{<figure-callout\; id="1"\; label="V\; O\; R"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">V</figure-callout>}}_O}{R}=(T-\mathrm{Ton})\&CenterDot;\frac{V_O}{R1}---\left(2\right)$

Obtain following result:

V _O＝D·V _DD

D＝T _on/T (3)

It is output voltage V _OBe directly proportional with the duty ratio of input square-wave signal.

The ripple of output voltage is:

${\mathrm{\&Delta;V}}_O=\frac{\mathrm{Ton}(V_{\mathrm{DD}}-V_O)}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">R</figure-callout>}1\&CenterDot;\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">C</figure-callout>}1}=\frac{D\&CenterDot;T\&CenterDot;V_{\mathrm{DD}}\&CenterDot;(1-D)}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">R</figure-callout>}1\&CenterDot;C1}---\left(4\right)$

Fig. 2 shows present Switching Power Supply duty detection circuit input Vi, output Vo and ripple Δ V _OOscillogram.

Ripple coefficient:

$\frac{\mathrm{\&Delta;}{V}_O}{V_O}=\frac{T\&CenterDot;(1-D)}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">R</figure-callout>}1\&CenterDot;C1}---\left(5\right)$

Under input square-wave signal Vi cycle permanence condition, output ripple and R1, C1 to discharge and recharge time constant relevant, strengthen the ripple that R1, C1 can reduce voltage effectively, the elimination ripple is to the influence of late-class circuit.

When D=1/2, output ripple numerical value maximum, for:

${\mathrm{\&Delta;V}}_O=\frac{T\&CenterDot;V_{\mathrm{DD}}}{4\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">R</figure-callout>}1\&CenterDot;C1}---\left(6\right)$

Suppose T=20ms, V _DDBe 5V, R1=100K Ω, C1=10uF obtains Δ V _O=25mV.Because electric capacity is too big, can't be integrated in the Switching Power Supply duty detection circuit, a pin need additionally be provided, be used for external capacitor, adjust output voltage, the current value of duty detection circuit if desired, the pin that also will increase an integrated circuit is provided with, and so just needs to use two pins that the numerical values recited that detects duty ratio is set.

Summary of the invention

The utility model is intended to solve the deficiencies in the prior art, a kind of inner integrated charge resistance capacitance is provided and can adjusts the Switching Power Supply duty detection circuit of duty ratio voltage, current value.

The utility model also provides the frequency detection circuit that utilizes the Switching Power Supply duty detection circuit to realize simultaneously.

The Switching Power Supply duty detection circuit, comprise switch control module, charging voltage/current conversion module, charging current mirror image module, discharge voltage/current conversion module, discharging current mirror image module, capacitor C 2, input signal Vi imports described switch control module, one end of capacitor C 2 connects charging voltage/current conversion module, discharge voltage/current conversion module, charging current mirror image module, discharging current mirror image module, the other end ground connection of capacitor C 2, charging voltage/current conversion module connects charging current mirror image module, discharge voltage/current conversion module connects discharging current mirror image module, charging voltage/current conversion module, charging current mirror image module, discharge voltage/current conversion module, discharging current mirror image module or capacitor C 2 outputs comprise the value of duty cycle information, and the output of switch control module connects and control:

(1) inputing or outputing of charging voltage/current conversion module and discharge voltage/current conversion module, or;

(2) inputing or outputing of charging voltage/current conversion module and discharging current mirror image module, or;

(3) inputing or outputing of charging current mirror image module and discharge voltage/current conversion module, or;

(4) charging current mirror image module and discharging current mirror image module inputs or outputs.

Described Switching Power Supply duty detection circuit also comprises the current/voltage-converted module, and described current/voltage-converted module is a voltage with the current conversion of discharging current mirror image module output.

Switching Power Supply duty ratio detection method, it is characterized in that switch control module input signal Vi, when input signal Vi is high level, charging voltage/current conversion module converts capacitance voltage Vc to electric current, charging current mirror image module is with the output current mirror image of charging voltage/current conversion module, and charging current mirror image module is to capacitor C 2 chargings; When input signal Vi is low level, discharge voltage/current conversion module converts capacitance voltage Vc to electric current, discharging current mirror image module is with the output current mirror image of discharge voltage/current conversion module, discharging current mirror image module is to capacitor C 2 discharges, charging voltage/current conversion module, charging current mirror image module, discharge voltage/current conversion module or the output of discharging current mirror image module comprise the value of duty cycle information, the output control of switch control module

(1) output of charging voltage/current conversion module and discharge voltage/current conversion module, or;

(2) output of charging voltage/current conversion module and discharging current mirror image module, or;

(3) output of charging current mirror image module and discharge voltage/current conversion module, or;

(4) output of charging current mirror image module and discharging current mirror image module.

Described Switching Power Supply duty ratio detection method also comprises described discharge voltage/current conversion module or switch control module output Switching Power Supply duty ratio measuring value.

A kind of Switching Power Supply frequency detection circuit, comprise that fixed pulse width produces circuit and Switching Power Supply duty detection circuit, the square-wave signal V1 of fixed frequency imports described fixed pulse width and produces circuit, fixed pulse width produces circuit and is connected to the Switching Power Supply duty detection circuit, by Switching Power Supply duty detection circuit output Switching Power Supply duty ratio measuring value.

Described fixed pulse width produces circuit and generates the fixed pulse width signal.

Wherein, described Switching Power Supply duty detection circuit adopts the aforesaid Switching Power Supply duty detection circuit of the utility model.

The beneficial effects of the utility model are: the utility model is charging current and discharging current by charging piezoelectric voltage/current conversion module, discharge voltage/current conversion module with the voltage transitions on the capacitor C 2, utilize the transmission of current mirror module again, make charging current and discharging current after transmitting diminish, thereby reduce size to the charging and discharging currents of electric capacity, therefore can adopt little electric capacity, integrated capacitance in the Switching Power Supply duty detection circuit, reduce peripheral pin, reduce cost, realize little ripple voltage; The utility model is by the control of switch control module control to voltage/current modular converter, current mirror module, realization is controlled discharging and recharging of electric capacity, by the image current ratio of adjusting in charging voltage/current conversion module, the discharge voltage/current conversion module duty ratio voltage, the electric current of output is adjusted; The utility model is adjusted the duty ratio magnitude of voltage of output by selecting different external resistor values simultaneously, helps the debugging of circuit.

The frequency detection circuit that the utility model provides, can be applied in the frequency conversion ON-OFF control circuit, because output voltage or power and frequency dependence, obtain representing the voltage of frequency by frequency detection circuit, realize compensation to ON-OFF control circuit output voltage or power.Suppose that output voltage or frequency uprise with incoming frequency and linear the increase, the output voltage that then can frequency of utilization detects comes the output frequency of control circuit, reaches the purpose of adjustment, regulated output voltage or power output.

Description of drawings

Fig. 1 is present Switching Power Supply duty detection circuit figure

Fig. 2 is the present input of Switching Power Supply duty detection circuit, output waveform figure

Fig. 3 A, 3B, 3C, 3D are the utility model Switching Power Supply duty detection circuit structure chart

Fig. 4 is for being the utility model Switching Power Supply duty detection circuit Fig. 1

Fig. 5 is the utility model Switching Power Supply duty detection circuit Fig. 2

Fig. 6 is for being the utility model Switching Power Supply duty detection circuit Fig. 3

Fig. 7 is switch handover module circuit diagram a kind of of Fig. 4

Fig. 8 is the utility model frequency detection circuit structure chart and oscillogram

Fig. 9 is a fixed pulse width generation circuit

Figure 10 is the input of fixed pulse width generation circuit, output waveform figure

Embodiment

Below in conjunction with accompanying drawing the utility model content is further specified.

As shown in Figure 3, the Switching Power Supply duty detection circuit, comprise switch control module 1, charging current mirror image module 2, charging voltage/current conversion module 3, discharge voltage/current conversion module 4, discharging current mirror image module 4, capacitor C 2, input signal Vi imports described switch control module 1, one end of capacitor C 2 connects charging voltage/current conversion module 3, discharge voltage/current conversion 4, the other end ground connection of capacitor C 2, charging voltage/current conversion module 3 connects charging current mirror image module 2, discharge voltage/current conversion module 5 connects discharging current mirror image module 4, charging current mirror image module 2, charging voltage/current conversion module 3, discharge voltage/current conversion module 4, discharging current mirror image module 4 or capacitor C 2 outputs comprise the value of duty cycle information, and a kind of connection and the control in the following connected mode is pressed in the output of described switch control module 1:

As shown in Figure 3A, the output of switch control module 1 connects inputing or outputing of charging current mirror image module 2 and discharging current mirror image module 4;

Shown in Fig. 3 B, the output of switch control module 1 connects inputing or outputing of charging voltage/current conversion module 3 and discharge voltage/current conversion module 5, or;

Shown in Fig. 3 C, the output of switch control module 1 connects inputing or outputing of charging current mirror image module 2 and discharge voltage/current conversion module 5, or;

Shown in Fig. 3 D, the output of switch control module 1 connects inputing or outputing of charging voltage/current conversion module 3 and discharging current mirror image module 4, or;

Shown in Fig. 4,5,6, described charging voltage/current conversion module 3 comprises operational amplifier A 1, PMOS transistor M9, resistance R _A, the input anode of described operational amplifier A 1 connects capacitor C 2, the input negative terminal connecting resistance R of operational amplifier A 1 _AAn end and the source electrode of M9, the grid of the output termination M9 of operational amplifier A 1, resistance R _AThe other end insert current potential V _A, the drain electrode of M9 connects charging current mirror image module.

Shown in Fig. 4,5,6, described discharge voltage/current conversion module 5 comprises operational amplifier A 2, nmos pass transistor pipe M12, resistance R _B, the input anode of described operational amplifier A 2 connects capacitor C 2, the input negative terminal connecting resistance R of operational amplifier A 2 _BAn end and the source electrode of M12, the output of operational amplifier A 2 connects the grid of M12, resistance R _BThe other end insert current potential V _B, the drain electrode of M12 connects discharging current mirror image module.

Shown in Fig. 4,5,6, described charging current mirror image module 2 comprises the first charging current mirror image circuit 21 and the second charging current mirror image circuit 22:

The described first charging current mirror image circuit 21 is made up of nmos pass transistor M10 and the nmos pass transistor M11 that common gate, common source connect, the grid of M10, drain electrode are connected to the drain electrode of charging voltage/current conversion module M9, and the drain electrode of M11 connects the second charging current mirror image circuit 22;

The described second charging current mirror image circuit 22 is made up of PMOS transistor M7 and the M8 that common gate, common source connect, and the source electrode of M7 and M8 meets power supply V _DD, the drain electrode of M8, grid connect the drain electrode of the M11 of the first charging current module, and the drain electrode of M7 connects switch control module 1.

Shown in Fig. 4,5,6, described discharging current mirror image module 4 comprises the first discharging current mirror image circuit 41 and the second discharging current mirror image circuit 42:

The described first discharging current mirror image circuit 41 is made up of nmos pass transistor M1 and the M2 that common gate, common source connect, and the drain electrode of M1 connects switch control module, and the drain electrode of M2, grid connect the second discharging current mirror image module 42;

The described second discharging current mirror image circuit 42 is made up of PMOS transistor M13, the M14 that common gate, common source connect, and the source electrode of M13 and M14 meets power supply V _DD, the drain electrode of M13, grid connect the M12 drain electrode of described discharge voltage/current conversion module, and the drain electrode of M14 connects the M2 drain electrode of the first discharging current mirror image module 41.

The charging current mirror image module 2, the discharging current mirror image module 4 that are adopted as Fig. 4,5,6 only are a kind of of the utility model embodiment, rather than to restriction of the present utility model, charging current mirror image module 2 or discharging current mirror image module 4 in the utility model can also be made up of a plurality of current mirror circuits, as four current mirror circuits, simultaneously the structure of current mirror module can also adopt other forms of current source structure, as various current sources such as collapsible, the inferior current sources of Weir.

The drain electrode of the drain electrode of described M9, the drain electrode of M11, M12, the drain electrode of M14 output comprise the value of duty cycle information.

As shown in Figure 4, the output of described switch control module 1 is used to switch the output of charging current mirror image module 2 and the output of discharging current mirror image module 4, described switch control module 1 comprises reverser NA1, nmos pass transistor M3, PMOS transistor M6, input signal Vi connects the reverser input, the output of reverser connects the grid of M3, M6, the drain electrode of M3 and M6 is connected to an end of capacitor C 2, the source electrode of M6 connects the drain electrode of the M7 of the second charging current mirror image circuit 22, and the source electrode of M3 connects the drain electrode of the M1 of the first discharging current mirror image circuit 41.

As shown in Figure 5, the output of described switch control module 1 is used to switch the input of charging current mirror image module 2 and the input of discharging current mirror image module 4, described switch control module 1 comprises nmos pass transistor M17, PMOS transistor M16, input signal Vi connects M16, the grid of M17, the drain electrode of M16 is connected to the drain electrode of the M8 of the second charging current mirror image circuit 22, the source electrode of M16 is connected to the source electrode of the M8 of the first charging current mirror image circuit 21, the drain electrode of M17 is connected to the drain electrode of the M2 of the first discharging current mirror image circuit 41, and the source electrode of M17 connects the source electrode of the M2 of the first discharging current mirror image circuit 41.

As shown in Figure 6, the output of described switch control module 1 is used to switch the input of charging voltage/current conversion module 3 and the input of discharge voltage/current conversion module 5, described switch control module 1 comprises nmos pass transistor M21, PMOS transistor M20, input signal Vi connects the grid of M20, M21, the drain electrode of M20 is connected to the grid of the M9 of charging voltage/current conversion module 3, and the source electrode of M20 is connected to the current potential V of charging voltage/current conversion module 3 _A, the drain electrode of M21 is connected to the grid of the M12 of discharge voltage/current conversion module 5, and the source electrode of M21 is connected to the current potential V of discharge voltage/current conversion module 5 _B

The embodiment of the connected mode of Fig. 4,5,6 described switch control module 1 outputs is just to explanation of the present utility model, rather than to restriction of the present utility model, other connected mode of the output of the switch control module 1 that the utility model is told a story and Fig. 4,5,6 connected mode are in like manner.

In addition, Fig. 4, Fig. 5, switch control module that Fig. 6 adopts 1 only are a kind of in the utility model embodiment, and described switch control module 1 can also carry out following any conversion:

Wherein, described M3, M6, M16, M17, M20, M21 use transmission gate to realize;

Wherein, described M3, M17, M21 adopt the NPN pipe, and M6, M16, M20 adopt the PNP pipe, and input signal is done corresponding the variation simultaneously;

Wherein, the grid of described M3, M6, M16, M17, M20, M21 is with connecting buffer circuit between the input signal Vi;

Wherein, the reverser of described Fig. 4 can be multistage reverser, perhaps input voltage this during as reverse voltage, omit reverser;

Wherein, increase increase nmos pass transistor M5 between nmos pass transistor M4 or described M6 and the capacitor C 2 between the M3 of described Fig. 4 and the capacitor C 2.

Fig. 7 shows a kind of embodiment in the conversion of above-mentioned possibility for example, rather than to restriction of the present utility model.

Described Switching Power Supply duty detection circuit can also comprise current/voltage-converted module 6, and described current/voltage-converted module 6 is with the electric current I of discharging current mirror image module 5 outputs _oBe converted to voltage V _o

Described current/voltage-converted module 6 is by the capacitor C of parallel connection _DC, resistance R _DCConstitute resistance R _DC, capacitor C _DCAn end connect the PMOS transistor M15 drain electrode of the second discharging current mirror image module, output Switching Power Supply duty ratio measuring current value, resistance R _DC, capacitor C _DCOther end ground connection, wherein said M15 is with the M13 of the described second discharging current mirror image circuit and the 14 common current mirror circuits of forming common gates, common source, described capacitor C _DCBe used to reduce change the voltage fluctuation that causes, resistance R because of electric current _DCBe used for determining the height of output voltage.

Described PMOS transistor M9, M7, M8, M13, M14, M15 can replace with the positive-negative-positive triode, and its corresponding connected mode in like manner.

Described nmos pass transistor M12, M10, M11, M1, M2 can replace with NPN type triode, and its corresponding connected mode in like manner.

Below be example with accompanying drawing 4, the beneficial effect that can reach the utility model describes.

Suppose that the voltage on the capacitor C 2 is Vc, then the drain electrode output current value of the M9 in charging current/voltage transformation module 3 is:

$I_{\mathrm{dM}9}=\frac{V_A-\mathrm{Vc}}{R_A}---\left(7\right)$

The breadth length ratio of supposing M10 is

The breadth length ratio of M11 is

The breadth length ratio of M8 is

The breadth length ratio of M7 is Then: the drain current of M7 is when the M6 conducting:

$I_{\mathrm{dM}7}=\frac{W_{M7}\&CenterDot;L_{M8}\&CenterDot;W_{M11}\&CenterDot;L_{M10}}{L_{M7}\&CenterDot;W_{M8}\&CenterDot;L_{M11}\&CenterDot;W_{M10}}\&CenterDot;I_{\mathrm{dM}9}=\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}1\&CenterDot;I_{\mathrm{dM}9}=\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}1\&CenterDot;\frac{V_A-\mathrm{Vc}}{R_A}---\left(8\right)$

In like manner:

The drain electrode output current value of M12 in discharging current/voltage transformation module 5 is:

$I_{\mathrm{dM}12}=\frac{\mathrm{Vc}-V_B}{R_B}---\left(9\right)$

The breadth length ratio of supposing M13 is

The breadth length ratio of M14 is

The breadth length ratio of M15 is

The breadth length ratio of M1 is

The breadth length ratio of M2 is Then: the drain current of M1 is when the M3 conducting:

${\mathrm{<figure-callout\; id="1"\; label="I\; dM"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">I</figure-callout>}}_{\mathrm{dM}}=\frac{{\mathrm{<figure-callout\; id="1"\; label="W\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">W</figure-callout>}}_M\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="L\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">L</figure-callout>}}_M\&CenterDot;W_{M14}\&CenterDot;L_{M13}}{{\mathrm{<figure-callout\; id="1"\; label="L\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">L</figure-callout>}}_M\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="W\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">W</figure-callout>}}_M\&CenterDot;L_{M14}\&CenterDot;W_{M13}}\&CenterDot;I_{\mathrm{dM}12}=\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2\&CenterDot;I_{\mathrm{dM}12}=\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2\&CenterDot;\frac{\mathrm{Vc}-V_B}{R_B}---\left(10\right)$

Wherein $\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2=\frac{{\mathrm{<figure-callout\; id="1"\; label="W\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">W</figure-callout>}}_M\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="L\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">L</figure-callout>}}_M\&CenterDot;W_{M14}\&CenterDot;L_{M13}}{{\mathrm{<figure-callout\; id="1"\; label="L\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">L</figure-callout>}}_M\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="W\; M"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">W</figure-callout>}}_M\&CenterDot;L_{M14}\&CenterDot;W_{M13}}$

Output current value:

$I_o=\frac{{\mathrm{<figure-callout\; id="15"\; label="W\; M"\; filenames="Y2008201690670019H3.png"\; state="\{\{state\}\}">W</figure-callout>}}_M\&CenterDot;L_{M13}}{{\mathrm{<figure-callout\; id="15"\; label="L\; M"\; filenames="Y2008201690670019H3.png"\; state="\{\{state\}\}">L</figure-callout>}}_M\&CenterDot;W_{M13}}\&CenterDot;I_{\mathrm{dM}12}=\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;I_{\mathrm{dM}12}=\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;\frac{\mathrm{Vc}-V_B}{R_B}---\left(11\right)$

Wherein $\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3=\frac{{\mathrm{<figure-callout\; id="15"\; label="W\; M"\; filenames="Y2008201690670019H3.png"\; state="\{\{state\}\}">W</figure-callout>}}_M\&CenterDot;L_{M13}}{{\mathrm{<figure-callout\; id="15"\; label="L\; M"\; filenames="Y2008201690670019H3.png"\; state="\{\{state\}\}">L</figure-callout>}}_M\&CenterDot;W_{M13}}$

Output voltage values:

$V_o=I_o\&CenterDot;R_{\mathrm{DC}}=\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;\frac{\mathrm{Vc}-V_B}{R_B}\&CenterDot;R_{\mathrm{DC}}---\left(12\right)$

Owing to after output Vc voltage is stable, discharging and recharging of electric capacity reached balance, charging charge=discharge charge arranged, that is:

T _on·I _dM7＝(T-T _on)·I _dM1 (13)

Substitution (8), (10) formula, and order $\frac{K}{}$ $\frac{1}{\mathrm{RA}}=\frac{\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2}{\mathrm{RB}},$ Can obtain:

T _on·(V _A-Vc)＝(T-T _on)·(Vc-V _B) (14)

(1) substitution, have: Vc-V _B=D (V _A-V _B) (15)

(15) substitution (11), (12), have:

$I_o=\frac{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;D\&CenterDot;(V_A-V_B)}{R_B}---\left(16\right)$

$V_o=\frac{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;D\&CenterDot;(V_A-V_B)\&CenterDot;R_{\mathrm{DC}}}{R_B}=K\&CenterDot;D---\left(17\right)$

Wherein: $K=\frac{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;(V_A-V_B)\&CenterDot;R_{\mathrm{DC}}}{R_B}$

At V _A, V _BUnder the constant condition, output voltage V o or electric current I o are directly proportional with duty ratio.

If make V _B=0, then have: Vc=DV _A(18)

The Vc point also can be used as direct output voltage, if regulate output, and can be by regulating V _AVoltage obtains.

Voltage ripple size on the capacitor C 2 is:

$\mathrm{\&Delta;Vc}=\frac{(T-\mathrm{Ton})\&CenterDot;I_{\mathrm{dM}1}}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">C</figure-callout>}2}=\frac{(1-D)\&CenterDot;T\&CenterDot;I_{\mathrm{dM}1}}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">C</figure-callout>}2}=\frac{(1-D)\&CenterDot;T\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2\&CenterDot;(\mathrm{Vc}-V_B)}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">C</figure-callout>}2\&CenterDot;R_B}---\left(19\right)$

(15) substitution, have: $\mathrm{\&Delta;Vc}=\frac{D\&CenterDot;(1-D)\&CenterDot;T\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2\&CenterDot;(V_A-V_B)}{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">C</figure-callout>}2\&CenterDot;R_B}$

When D=0.5, the voltage ripple maximum on the C2:

$\mathrm{\&Delta;}\mathrm{Vc}\max =\frac{T\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}2\&CenterDot;(V_A-V_B)}{4\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">C</figure-callout>}2\&CenterDot;R_B}---\left(20\right)$

In given period T scope, as long as the K2/R that gets _BNumerical value is enough little, and the voltage ripple on the C2 just can be accomplished very little.And this moment, capacitor C 2 can obtain and not be big especially, like this, just can be made in IC interior.

Suppose: C2=SpF, R _B=1M Ω, V _A-V _B=3V, T=20us, K2=0.001 obtains Δ Vcmax=3mV, and promptly the ripple voltage of this moment changes little.Above C2, R _BCan be made in IC interior.

For output voltage $V_o=\frac{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;D\&CenterDot;(V_A-V_B)\&CenterDot;R_{\mathrm{DC}}}{R_B},$ Do not add capacitor C _DCThe time, the voltage ripple of output is as follows:

$\mathrm{\&Delta;Vo}=\frac{\mathrm{<figure-callout\; id="3"\; label="K"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">K</figure-callout>}3\&CenterDot;\mathrm{\&Delta;Vc}\&CenterDot;R_{\mathrm{DC}}}{R_B}---\left(21\right)$

By adding external capacitor C _DC, can be so that the ripple of Vo becomes extremely low.In some occasion, when requirement is not high especially to ripple, external capacitor C _DCCan.

As a kind of Switching Power Supply frequency detection circuit of Fig. 8, comprise that fixed pulse width produces circuit and Switching Power Supply duty detection circuit, the input square-wave signal V1 of input fixed frequency imports described fixed pulse width and produces circuit, fixed pulse width produces circuit and is connected to the Switching Power Supply duty detection circuit, by Switching Power Supply duty detection circuit output Switching Power Supply duty ratio measuring value.

Wherein, described Switching Power Supply duty detection circuit adopts the utility model Switching Power Supply duty detection circuit.

Wherein, described fixed pulse width produces circuit and produces the fixed pulse width signal, the input square-wave signal V1 of different cycles, through fixed pulse width generation circuit as shown in Figure 9, the fixedly high level time of the V2 that produces is constant to be t1, then duty ratio is D=t1/T, is obtained by (3) or (17) formula:

$V_o=K\&CenterDot;D=\frac{K\&CenterDot;t1}{T}=K\&CenterDot;\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">t</figure-callout>}1\&CenterDot;f---\left(22\right)$

Wherein K, t1 are that constant, f=1/T are the frequencies of input signal, and promptly output voltage values is directly proportional with frequency.This circuit can detect the highest frequency value that obtains: $f_{\max }=\frac{1}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="Y2008201690670016H1.png,Y2008201690670016H2.png"\; state="\{\{state\}\}">t</figure-callout>}1}.$

The frequency detection circuit that the utility model provides, can be applied in the frequency conversion ON-OFF control circuit, because output voltage or power and frequency dependence, obtain representing the voltage of frequency by frequency detection circuit, realize compensation to ON-OFF control circuit output voltage or frequency.

The utility model discloses the duty detection circuit of Switching Power Supply and utilize this circuit to realize frequency detection circuit, and describe embodiment of the present utility model and effect with reference to the accompanying drawings.What should be understood that is that the foregoing description is just to explanation of the present utility model; rather than to restriction of the present utility model; any innovation and creation that do not exceed in the utility model connotation scope; include but not limited to the modification of the composition mode of modification, sample circuit and mirror image to switch control module, to the change of the local structure of circuit, to the replacement of the type or the model of components and parts; and the replacement of other unsubstantialities or modification, all fall within the utility model protection range.

Claims (12)

1. Switching Power Supply duty detection circuit, it is characterized in that comprising switch control module, charging voltage/current conversion module, charging current mirror image module, discharge voltage/current conversion module, discharging current mirror image module, capacitor C 2, input signal Vi imports described switch control module, one end of capacitor C 2 connects charging voltage/current conversion module, discharge voltage/current conversion module, charging current mirror image module, discharging current mirror image module, the other end ground connection of capacitor C 2, charging voltage/current conversion module connects charging current mirror image module, discharge voltage/current conversion module connects discharging current mirror image module, charging voltage/current conversion module, charging current mirror image module, discharge voltage/current conversion module, discharging current mirror image module or capacitor C 2 outputs comprise the value of duty cycle information, and the output of switch control module connects control

(1) inputing or outputing of charging voltage/current conversion module and discharge voltage/current conversion module, or;

(2) inputing or outputing of charging voltage/current conversion module and discharging current mirror image module, or;

(3) inputing or outputing of charging current mirror image module and discharge voltage/current conversion module, or;

(4) charging current mirror image module and discharging current mirror image module inputs or outputs.

2. Switching Power Supply duty detection circuit as claimed in claim 1, it is characterized in that when input signal Vi is high level, charging voltage/current conversion module converts capacitance voltage Vc to electric current, charging current mirror image module is with the output current mirror image of charging voltage/current conversion module, and charging current mirror image module is to capacitor C 2 chargings; When input signal Vi was low level, discharge voltage/current conversion module converted capacitance voltage Vc to electric current, and discharging current mirror image module is with the output current mirror image of discharge voltage/current conversion module, and discharging current mirror image module is to capacitor C 2 discharges.

3. Switching Power Supply duty detection circuit as claimed in claim 1 is characterized in that also comprising the current/voltage-converted module, and described current/voltage-converted module is a voltage with the current conversion of discharging current mirror image module output.

4. Switching Power Supply duty detection circuit as claimed in claim 1 is characterized in that described charging voltage/current conversion module comprises operational amplifier A 1, PMOS transistor M9, resistance R _A, the input anode of described operational amplifier A 1 connects capacitor C 2, the input negative terminal connecting resistance R of operational amplifier A 1 _AAn end and the source electrode of M9, the grid of the output termination M9 of operational amplifier A 1, resistance R _AThe other end insert current potential V _A, the drain electrode of M9 connects described charging current mirror image module.

5. Switching Power Supply duty detection circuit as claimed in claim 1 is characterized in that described discharge voltage/current conversion module comprises operational amplifier A 2, nmos pass transistor pipe M12, resistance R _B, the input anode of described operational amplifier A 2 connects capacitor C 2, the input negative terminal connecting resistance R of operational amplifier A 2 _BAn end and the source electrode of M12, the output of operational amplifier A 2 connects the grid of M12, resistance R _BThe other end insert current potential V _B, the drain electrode of M12 connects described discharging current mirror image module.

6. Switching Power Supply duty detection circuit as claimed in claim 1 is characterized in that described charging current mirror image module comprises the first charging current mirror image circuit and the second charging current mirror image circuit:

The described first charging current mirror image circuit is made up of nmos pass transistor M10 and the nmos pass transistor M11 that common gate, common source connect, the drain electrode of M10, grid are connected to the drain electrode of charging voltage/current conversion module M9, and the drain electrode of M11 connects the second charging current mirror image circuit;

The described second charging current mirror image circuit is made up of PMOS transistor M7 and the M8 that common gate, common source connect, and the source electrode of M7 and M8 meets power supply V _DD, the drain electrode of M8, grid connect the drain electrode of the M11 of the first charging current module, and the drain electrode of M7 connects described switch control module.

7. Switching Power Supply duty detection circuit as claimed in claim 1 is characterized in that described discharging current mirror image module comprises the first discharging current mirror image circuit and the second discharging current mirror image circuit:

The described first discharging current mirror image circuit is made up of nmos pass transistor M1 and the M2 that common gate, common source connect, and the drain electrode of M1, grid connect switch control module, and the drain electrode of M2, grid connect the second discharging current mirror image module;

The described second discharging current mirror image circuit is made up of PMOS transistor M13, the M14 that common gate, common source connect, and the source electrode of M13 and M14 meets power supply V _DD, the drain electrode of M13, grid connect the M12 drain electrode of described discharge voltage/current conversion module, and the drain electrode of M14 connects the M2 drain electrode of the first discharging current mirror image module.

8. Switching Power Supply duty detection circuit as claimed in claim 1, it is characterized in that described switch control module comprises reverser NA1, nmos pass transistor M3, PMOS transistor M6, input signal Vi connects the reverser input, the output of reverser connects the grid of M3, M6, the drain electrode of M3 and M6 is connected to an end of capacitor C 2, the source electrode of M6 connects the drain electrode of the M7 of the second charging current mirror image circuit, and the source electrode of M3 connects the drain electrode of the M1 of the first discharging current mirror image circuit.

9. Switching Power Supply duty detection circuit as claimed in claim 1, it is characterized in that described switch control module comprises nmos pass transistor M17, PMOS transistor M16, input signal Vi connects the grid of M16, M17, the drain electrode of M16 is connected to the drain electrode of the M8 of the second charging current mirror image circuit, the source electrode of M16 is connected to the source electrode of the M8 of the first charging current mirror image circuit, the drain electrode of M17 is connected to the drain electrode of the M2 of the first discharging current mirror image circuit, and the source electrode of M17 connects the source electrode of the M2 of the first discharging current mirror image circuit.

10. Switching Power Supply duty detection circuit as claimed in claim 1, it is characterized in that described switch control module comprises nmos pass transistor M21, PMOS transistor M20, input signal Vi connects the grid of M20, M21, the drain electrode of M20 is connected to the grid of the M9 of charging voltage/current conversion module 3, and the source electrode of M20 is connected to the current potential V of charging voltage/current conversion module _A, the drain electrode of M21 is connected to the grid of the M12 of discharge voltage/current conversion module, and the source electrode of M21 is connected to the current potential V of discharge voltage/current conversion module _B

11. Switching Power Supply duty detection circuit as claimed in claim 3 is characterized in that the capacitor C of described current/voltage-converted module by parallel connection _DC, resistance R _DCConstitute resistance R _DC, capacitor C _DCAn end connect the PMOS transistor M15 drain electrode of the second discharging current mirror image module, output Switching Power Supply duty ratio measuring current value, resistance R _DC, capacitor C _DCOther end ground connection, wherein said M15 is with the M13 of the described second discharging current mirror image circuit and the 14 common current mirror circuits of forming common gates, common source.

12. Switching Power Supply frequency detection circuit, it is characterized in that comprising that fixed pulse width produces circuit and Switching Power Supply duty detection circuit, the square-wave signal V1 of fixed frequency imports described fixed pulse width and produces circuit, fixed pulse width produces circuit and is connected to the Switching Power Supply duty detection circuit, by Switching Power Supply duty detection circuit output Switching Power Supply duty ratio measuring value, described fixed pulse width produces circuit and generates the fixed pulse width signal, and described Switching Power Supply duty detection circuit is described any one Switching Power Supply duty detection circuit of claim 1-11.

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