CN109378970B - Switching power supply control mode switching circuit and switching power supply chip - Google Patents
Switching power supply control mode switching circuit and switching power supply chip Download PDFInfo
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- CN109378970B CN109378970B CN201811580588.7A CN201811580588A CN109378970B CN 109378970 B CN109378970 B CN 109378970B CN 201811580588 A CN201811580588 A CN 201811580588A CN 109378970 B CN109378970 B CN 109378970B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/1566—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
Abstract
The application provides a switching power supply control mode switching circuit and a switching power supply chip, wherein the switching power supply control mode switching circuit is used for generating a driving signal for controlling a power driving tube in a switching power supply; the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module; the mode switching threshold generation module includes: a current source, an equivalent variable resistor and an operational amplifier; the resistance value of the equivalent variable resistor is inversely related to the input voltage of the switching power supply. The resistance of the equivalent variable resistor is in inverse proportion to the input voltage of the switching power supply, namely, the dynamic impedance mode switching circuit based on input voltage sampling is adopted, so that the input voltage can be detected in real time, the switching current of the switching power supply control mode switching circuit is about 0 along with the change rate of the input voltage of the switching power supply, and the purpose of stabilizing the control mode switching threshold is achieved.
Description
Technical Field
The present application relates to the field of integrated circuits, and in particular, to a high-precision switching power supply control mode switching circuit and a switching power supply chip.
Background
Among the switching power supply chips, a BOOST type switching power supply chip has an extremely important application, and is characterized in that the on/off of a power tube can be controlled to make the output voltage higher than the input voltage. The topological structure is shown in fig. 1, and the power tube driving signal DRVP is a square wave signal with a duty ratio of D and is used for controlling the on and off of a power tube; when the power tube driving signal DRVP is at a high level, the P-type power switch tube MP1 is turned off, the N-type power switch tube MN1 is turned on, the SW end is pulled to the ground potential, the input power supply VIN generates a current to the ground on the inductor L1 so that the inductor L1 stores energy, and at the moment, power is supplied to the output end VOUT through the C1; when the power transistor driving signal DRVP is at a low level, the P-type power switching transistor MP1 is turned on, the N-type power switching transistor MN1 is turned off, and the current on the inductor L1 cannot be suddenly changed, so that the SW terminal potential is raised, VSW > VOUT, and power is supplied to C1 and VOUT through the P-type power switching transistor MP 1. From the law of conservation of energy, when the circuit works stably, it is possible to obtain:
VOUT＝VIN/(1-D)；
wherein D is the duty cycle of the power transistor driving signal DRVP.
Whereas modulation schemes in BOOST circuits include PWM (Pulse Width Modulation ) and PFM (Pulse frequency modulation, pulse frequency modulation).
When the output load current is smaller, if the PWM mode modulation is still adopted, the system power consumption is larger, and the efficiency is reduced, so that in the existing design, the control mode of the circuit is usually converted from PWM to PFM when the output load current is smaller, namely, light load, and is converted back to the PWM mode when the load current is larger, namely, heavy load. Accordingly, in such circuits and applications, it is necessary to design corresponding mode detection and conversion circuits.
As shown in fig. 2, fig. 2 is a schematic structural diagram of a PWM-PFM mode switching module in the prior art; the mode switching module includes: for detecting the current flowing through the inductance L1 in FIG. 1, i.e. the load current
The device comprises a current sensing detection module DECT, a driving signal generation module Driver for generating driving signals, a PWM module and a PFM module; wherein, the PWM module passes through the reference voltage V REF And feedback signal V FB Generating a square wave signal with a duty ratio of D, and converting the square wave signal into a power tube driving signal DRVP through a driving signal generating module Driver; and the load current i detected by the inductor current detection module DECT L Can determine which modulation scheme is used to switch and modulate the drive signal (i.e., pulse signal) DRVP.
However, in the switching power supply mode switching circuit in the prior art, when switching between the PFM control mode in light load and the PWM control mode in heavy load, there is a problem that the switching threshold point is unstable.
Disclosure of Invention
In view of the above, the present application provides a switching power supply control mode switching circuit and a switching power supply chip, so as to solve the problem that in the switching power supply mode switching circuit in the prior art, when switching between the PFM control mode in light load and the PWM control mode in heavy load, the switching threshold point is unstable.
In order to achieve the above purpose, the present application provides the following technical solutions:
a switching power supply control mode switching circuit for generating a drive signal for controlling a power drive tube in the switching power supply;
the switching power supply control mode switching circuit includes:
the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module;
the mode switching threshold generating module is connected with the negative feedback loop control module, and the negative feedback loop control module is connected with the driving signal generating module;
the mode switching threshold generating module is used for generating a mode switching threshold voltage and inputting the mode switching threshold voltage into the negative feedback loop control module;
the negative feedback loop control module is used for generating a Pulse Width Modulation (PWM) square wave signal under the action of the mode switching threshold generation module;
the driving signal generating module receives the PWM square wave signal and converts the PWM square wave signal into the driving signal, and the driving signal is used for controlling the on or off of a power driving tube in the switching power supply;
wherein the mode switching threshold generation module includes:
a current source, an equivalent variable resistor and an operational amplifier;
the current source and the equivalent variable resistor are connected in series between an external power supply voltage and ground;
the common end of the current source and the equivalent variable resistor is connected with the non-inverting input end of the operational amplifier;
the inverting input end of the operational amplifier is connected with the output end of the operational amplifier, and the output end of the operational amplifier is used as the output end of the mode switching threshold generating module and is connected with the negative feedback loop control module;
the resistance value of the equivalent variable resistor is inversely related to the input voltage of the switching power supply.
Preferably, the equivalent variable resistor is a transistor.
Preferably, the transistor is an NMOS transistor.
Preferably, the grid electrode of the NMOS tube is connected with the input end of the switching power supply;
the source electrode of the NMOS tube is connected with the ground;
and the drain electrode of the NMOS tube is connected with the non-inverting input end of the operational amplifier.
Preferably, the transistor is a PMOS transistor.
Preferably, the grid electrode of the PMOS tube is connected with the input end of the switching power supply;
the source electrode of the PMOS tube is connected with the external power supply voltage;
and the drain electrode of the PMOS tube is connected with the non-inverting input end of the operational amplifier.
Preferably, the negative feedback loop control module includes:
the error amplifier, the comparator and the current acquisition and voltage conversion module;
the non-inverting input end of the error amplifier is connected with a base reference voltage;
the inverting input end of the error amplifier is connected with the sampling voltage of the output end of the switching power supply;
the output end of the error amplifier is connected with the inverting input end of the comparator and the output end of the mode switching threshold generating module;
the current collection and voltage conversion module is used for collecting the load current of the switching power supply and converting the load current into voltage; the output end of the current acquisition and voltage conversion module is connected with the non-inverting input end of the comparator;
the output end of the comparator is used as the output end of the negative feedback loop control module and is connected with the driving signal generation module.
Preferably, the driving signal generating module includes:
the driving logic generation module and the driving signal conversion module are connected;
the driving logic generating module is connected with the output end of the negative feedback loop control module and is used for receiving the PWM square wave signal and carrying out logic operation on the PWM square wave signal;
the driving signal conversion module converts the PWM square wave signal into a driving signal and outputs the driving signal.
The application also provides a switching power supply chip, comprising:
the switching power supply comprises at least a power driving tube, and the switching power supply mode switching circuit outputs a driving signal for driving the power driving tube.
Preferably, the switching power supply is a BOOST circuit, a BUCK circuit or a BOOST-BUCK combined circuit.
According to the technical scheme, the switching power supply control mode switching circuit is used for generating a driving signal for controlling a power driving tube in the switching power supply; the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module; the mode switching threshold generation module includes: a current source, an equivalent variable resistor and an operational amplifier; the resistance value of the equivalent variable resistor is inversely related to the input voltage of the switching power supply. The resistance of the equivalent variable resistor is in inverse proportion to the input voltage of the switching power supply, namely, the dynamic impedance mode switching circuit based on input voltage sampling is adopted, so that the input voltage can be detected in real time, the switching current of the switching power supply control mode switching circuit is about 0 along with the change rate of the input voltage of the switching power supply, and the purpose of stabilizing the control mode switching threshold is achieved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a BOOST topology in the prior art;
FIG. 2 is a schematic diagram of a PWM-PFM mode switching module in the prior art;
FIG. 3 is a schematic diagram of a PWM-PFM switching circuit in the prior art;
fig. 4 is a block diagram of a switching power supply control mode switching circuit according to an embodiment of the present application;
fig. 5 is a schematic diagram of a switching power supply control mode switching circuit according to an embodiment of the present application;
FIG. 6 is a schematic diagram of another switching power supply control mode switching circuit according to an embodiment of the present application;
fig. 7 is a schematic diagram of a switching power supply control mode switching circuit according to another embodiment of the present application.
Detailed Description
As described in the background art, in the switching power supply mode switching circuit in the prior art, when switching between the PFM control mode in light load and the PWM control mode in heavy load, there is a problem that the switching threshold point is unstable.
The inventors found that the cause of the above problems is as follows:
in the prior art, a specific PWM-PFM mode switching circuit structure is provided, please refer to fig. 3, fig. 3 is a specific embodiment of the block diagram of fig. 2; the PWM-PFM mode switching circuit includes: the device comprises a current source IB, a constant resistor RB, an operational amplifier OP, an error amplifier EA, a high-speed comparator HS_COMP, an inductance current acquisition and voltage conversion module V_SAMPLE, a driving LOGIC generation module LOGIC_GEN and a driving signal generation module Driver.
In FIG. 3, VREF is a reference voltage, VFB is a sampling voltage of the output terminal VOUT in FIG. 1, and V is known from the circuit structure in FIG. 1 FB =r2/(r1+r2), the error amplifier EA amplifies the difference between VREF and VFB and generates an error amplified signal V C ，V SLOPE Inductor current i collected for V_SAMPLE L Post-conversion to inductor current i L Is used for comparing V by a high-speed comparator HS_COMP C And V SLOPE Is larger than (1)Small, and produces a square wave signal that is passed through the LOGIC GEN and DRIVER modules to produce the power transistor drive signal DRVP.
The fixed current IB generates a switching threshold voltage V of PWM-PFM at a constant resistance RB CLP_L When the voltage at the VC terminal is too low, the operation amplifier OP clamps VC to make V C ＝V CLP_L . When the load current is relatively large, referring to fig. 1, the value of the output voltage VOUT is reduced, and correspondingly, the sampled voltage V of the output terminal VOUT FB Also decreases, thus, there is V in each period FB <V REF Amplifying the difference between the two by an error amplifier EA, i.e. the resulting V C In the high position, thus V C >V CLP_L At this time, every period has V SLOPE ≥V C Thereby generating a PWM pulse signal.
When the output load current gradually decreases, the energy of the output terminal VOUT is released slowly, so that V is present FB >V REF Then V is caused by the clamping action of the operational amplifier OP C ＝V CLP_L In this case, if V is present in one period SLOPE <V CLP_L The main power tube MP1 of the BOOST topology in fig. 1 is turned on in a skip cycle, and enters a PFM modulation mode. Thus, a PWM to PFM load current switching threshold I can be obtained O_TH The method comprises the following steps:
I B ×R B ＝i p ×R slp (1)
in the above, i p Is the inductance current value when the high-speed comparator HS_COMP is turned over, and is formed by V CLP_L ＝I B *R B Size determination of i 0 For slope compensation current, which is a fixed value in design, R slp Is electric powerThe equivalent sampling resistor of the current sensing acquisition and voltage conversion module V_SAMPLE is also a fixed value in design, and D is the duty ratio of the BOOST circuit in stable operation.
From the above formula, the switching current threshold I for switching the control mode from PFM to PWM O_TH (i.e. the switching current threshold for PWM to PFM) is proportional to the duty cycle (1-D), i.e. the input voltage V IN The larger the switching threshold current of the control mode, the larger, which is available through derivation,
as can be seen from equation (5), the derivatives of io_th and VIN are a number other than zero, i.e., the switching current threshold I in the switching power supply control circuit O_TH As the input voltage VIN changes. That is to say at the same output load current I B Under the condition that different input voltages VIN cause output ripples to be greatly different, the problem that the switching threshold point is unstable when a PFM control mode in light load and a PWM control mode in heavy load are switched is caused, and therefore great interference is caused to some applications with medium load.
Based on this, the application provides a switching power supply control mode switching circuit for generating a drive signal for controlling a power drive tube in the switching power supply;
the switching power supply control mode switching circuit includes:
the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module;
the mode switching threshold generating module is connected with the negative feedback loop control module, and the negative feedback loop control module is connected with the driving signal generating module;
the mode switching threshold generating module is used for generating a mode switching threshold voltage and inputting the mode switching threshold voltage into the negative feedback loop control module;
the negative feedback loop control module is used for generating a Pulse Width Modulation (PWM) square wave signal under the action of the mode switching threshold generation module;
the driving signal generating module receives the PWM square wave signal and converts the PWM square wave signal into the driving signal, and the driving signal is used for controlling the on or off of a power driving tube in the switching power supply;
wherein the mode switching threshold generation module includes:
a current source, an equivalent variable resistor and an operational amplifier;
the current source and the equivalent variable resistor are connected in series between an external power supply voltage and ground;
the common end of the current source and the equivalent variable resistor is connected with the non-inverting input end of the operational amplifier;
the inverting input end of the operational amplifier is connected with the output end of the operational amplifier, and the output end of the operational amplifier is used as the output end of the mode switching threshold generating module and is connected with the negative feedback loop control module;
the resistance value of the equivalent variable resistor is inversely related to the input voltage of the switching power supply.
The switching power supply control mode switching circuit is used for generating a driving signal for controlling a power driving tube in the switching power supply; the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module; the mode switching threshold generation module includes: a current source, an equivalent variable resistor and an operational amplifier; the resistance value of the equivalent variable resistor is inversely related to the input voltage of the switching power supply. The resistance of the equivalent variable resistor is in inverse proportion to the input voltage of the switching power supply, namely, the dynamic impedance mode switching circuit based on input voltage sampling is adopted, so that the input voltage can be detected in real time, the switching current of the switching power supply control mode switching circuit is about 0 along with the change rate of the input voltage of the switching power supply, and the purpose of stabilizing the control mode switching threshold is achieved.
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Referring to fig. 4, fig. 4 is a schematic diagram of a switching power supply control mode switching circuit according to an embodiment of the present application; the switching power supply control mode switching circuit includes: a mode switching threshold generating module 1, a negative feedback loop control module 2 and a driving signal generating module 3; the mode switching threshold generating module 1 is connected with the negative feedback loop control module 2, and the negative feedback loop control module 2 is connected with the driving signal generating module 3; the mode switching threshold generating module is used for generating a mode switching threshold voltage and inputting the mode switching threshold voltage into the negative feedback loop control module; the negative feedback loop control module is used for generating a Pulse Width Modulation (PWM) square wave signal under the action of the mode switching threshold generation module; the driving signal generating module receives the PWM square wave signal and converts the PWM square wave signal into the driving signal, and the driving signal is used for controlling the on or off of a power driving tube in the switching power supply.
Wherein the mode switching threshold generation module includes: a current source 11, an equivalent variable resistor 12 and an operational amplifier 13;
the current source 11 and the equivalent variable resistor 12 are connected in series between the external power supply voltage VDD and the ground, and it should be noted that, in this embodiment, the specific positional relationship between the current source 11 and the equivalent variable resistor 12 is not limited, in fig. 4, one end of the current source 11 is connected to the external power supply voltage VDD, and one end of the equivalent variable resistor 12 is grounded, in other embodiments of the present application, one end of the current source 11 may be grounded, and one end of the equivalent variable resistor 12 is connected to the external power supply voltage VDD;
the common end of the current source 11 and the equivalent variable resistor 12 is connected with the non-inverting input end of the operational amplifier 13;
the inverting input end of the operational amplifier 13 is connected with the output end of the operational amplifier 13, and the output end of the operational amplifier 13 is used as the output end of the mode switching threshold generating module 1 and is connected with the negative feedback loop control module 2;
the resistance of the equivalent variable resistor 12 is inversely related to the input voltage VIN of the switching power supply.
The specific structure of the switching power supply is not limited in this embodiment, and the switching power supply may be a BOOST circuit as shown in fig. 1, or may be a BOOST circuit that is conventional in the art, or a BOOST-BUCK circuit that combines a BOOST circuit with a BUCK circuit, which is not limited in this embodiment, and any switching power supply circuit that requires PWM and PFM modes may be suitable, which is not described in detail in this embodiment.
Note that, in this embodiment, the specific structures of the negative feedback loop control module 2 and the driving signal generating module 3 are not limited, and in one embodiment of the present application, the specific structures of the negative feedback loop control module 2 and the driving signal generating module 3 are shown in fig. 5, and are the same as those in fig. 3, and the same reference numerals are used to describe the same structures in this embodiment, which will not be described in detail in this embodiment.
Specifically, referring to fig. 5, the negative feedback loop control module 2 includes: error amplifier EA, comparator HS_COMP and current collection and voltage conversion module V_SAMPLE; the non-inverting input of the error amplifier EA is connected with a base reference voltage V REF The method comprises the steps of carrying out a first treatment on the surface of the The inverting input end of the error amplifier EA is connected with the sampling voltage V of the output end of the switching power supply FB The method comprises the steps of carrying out a first treatment on the surface of the The output end of the error amplifier EA is connected with the inverting input end of the comparator HS_COMP and the output end of the mode switching threshold generating module 1; the current acquisition and voltage conversion module V_SAMPLE is used for acquiring the load current i of the switching power supply L (see fig. 1), and apply the load current i L Converted into voltage V SLOPE The method comprises the steps of carrying out a first treatment on the surface of the The output end of the current acquisition and voltage conversion module V_SAMPLE is connected with the non-inverting input end of the comparator HS_COMP; the output end of the comparator HS_COMP is used as the output end of the negative feedback loop control module 2 and is connected with the output end of the negative feedback loop control moduleThe drive signal generation module 3 is connected.
The drive signal generation module 3 includes: the driving logic generation module and the driving signal conversion module are connected; the driving LOGIC generation module LOGIC_GEN is connected with the output end of the negative feedback loop control module 2 and is used for receiving the PWM square wave signal and carrying out LOGIC operation on the PWM square wave signal; the driving signal conversion module DRIVER converts the PWM square wave signal into a driving signal DRVP and outputs the driving signal DRVP.
In addition, the specific structure and the specific type of the equivalent variable resistor are not limited in this embodiment, and the resistance of the equivalent variable resistor 12 may be alternatively changed in inverse relation with the input voltage VIN of the switching power supply. That is, the equivalent variable resistor 12 generates an equivalent impedance that is linearly inversely related to VIN, thereby generating a clamping voltage that is linearly related to the 1/VIN variation in the mode switching threshold generation module.
The inventor has found that in one embodiment of the present application, the equivalent variable resistor 12 may be a transistor, specifically, in one embodiment of the present application, the equivalent variable resistor may be an NMOS transistor, and in another embodiment of the present application, the equivalent variable resistor may also be a PMOS transistor. This is not limiting in the embodiments of the present application.
As shown in fig. 6, when the equivalent variable resistor is an NMOS transistor, the gate of the NMOS transistor MN2 is connected to the input terminal VIN of the switching power supply; the source electrode of the NMOS tube MN2 is connected with the ground; the drain electrode of the NMOS tube MN2 is connected with the non-inverting input end of the operational amplifier 13.
As shown in fig. 7, when the equivalent variable resistor is a PMOS transistor, the gate of the PMOS transistor MP2 is connected to the input terminal of the switching power supply; the source electrode of the PMOS tube MP2 is connected with an external power supply voltage VDD; and the drain electrode MP2 of the PMOS tube is connected with the non-inverting input end of the operational amplifier.
In order to clearly illustrate the beneficial effects of the embodiment of the present application, the embodiment of the present application uses an NMOS transistor as an example for detailed description.
Based on the circuit principle shown in fig. 6, the following formula can be obtained from fig. 6:
∴
wherein W2/L2 is the width-to-length ratio of NMOS transistor MN2, u n C OX Is the channel conductivity of NMOS tube, V THN Is the threshold voltage of NMOS tube, V GSN2 Is the gate-source voltage of NMOS tube, and is usually V IN >>V THN Therefore, the method can be obtained by the above formula,
from this, it can be seen that, since the constant resistance is replaced by the equivalent variable resistance, NMOS transistor MN2, the resistance value thereof is inversely related to the input voltage VIN of the switching power supply, so that the switching current threshold I can be made O_TH2 The derivative with the input voltage VIN is approximately equal to 0, i.e. the switching current threshold I O_TH2 The switching current threshold value is irrelevant to the change of the input voltage VIN, so that the problem that the switching current threshold value is too large along with the change of the input voltage when the control mode in the switching power supply chip is switched between PFM and PWM is solved, and the switching point of the control mode is not changed along with the change of the input voltage.
That is, the switching power supply control mode switching circuit provided by the application is used for generating a driving signal for controlling a power driving tube in the switching power supply; the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module; the mode switching threshold generation module includes: a current source, an equivalent variable resistor and an operational amplifier; the resistance value of the equivalent variable resistor is inversely related to the input voltage of the switching power supply. Because the resistance value of the equivalent variable resistor and the input voltage of the switching power supply are in inverse proportion, namely a dynamic impedance mode switching circuit based on input voltage sampling is adopted, and a BOOST circuit is taken as an example, the magnitude of the input voltage VIN can be detected in real time, and the switching current of the switching power supply control mode switching circuit is about 0 along with the change rate of the input voltage of the switching power supply, so that the purpose of stabilizing the switching threshold value of the control mode is achieved.
Based on the same inventive concept, the present application also provides a switching power supply chip, comprising: the switching power supply and the switching power supply mode switching circuit described in the above embodiments, the switching power supply including at least a power driving tube, the switching power supply mode switching circuit outputting a driving signal for driving the power driving tube.
In this embodiment, the specific structure of the switching power supply is not limited, and the switching power supply may be a BOOST circuit as shown in fig. 1, or may be a conventional BUCK circuit in the art, or a BOOST-BUCK combined circuit in which the BOOST circuit and the BUCK circuit are combined, which is not limited in this embodiment, and any switching power supply circuit that requires PWM and PFM modes may be suitable, which is not described in detail in this embodiment.
The switching power supply control mode switching circuit provided by the embodiment of the application has the characteristics of strong anti-interference capability, stable threshold switching point and small change along with input voltage, and can be widely applied to a power supply management chip, so that the switching power supply control mode switching circuit can be kept stable when switching the mode.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.
It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in an article or apparatus that comprises such element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A switching power supply control mode switching circuit for generating a drive signal for controlling a power drive tube in the switching power supply;
the switching power supply control mode switching circuit includes:
the system comprises a mode switching threshold generating module, a negative feedback loop control module and a driving signal generating module;
the mode switching threshold generating module is connected with the negative feedback loop control module, and the negative feedback loop control module is connected with the driving signal generating module;
the mode switching threshold generating module is used for generating a mode switching threshold voltage and inputting the mode switching threshold voltage into the negative feedback loop control module;
the negative feedback loop control module is used for generating a Pulse Width Modulation (PWM) square wave signal under the action of the mode switching threshold generation module;
the driving signal generating module receives the PWM square wave signal and converts the PWM square wave signal into the driving signal, and the driving signal is used for controlling the on or off of a power driving tube in the switching power supply;
wherein the mode switching threshold generation module includes:
a current source, an equivalent variable resistor and an operational amplifier;
the current source and the equivalent variable resistor are connected in series between an external power supply voltage and ground;
the common end of the current source and the equivalent variable resistor is connected with the non-inverting input end of the operational amplifier;
the inverting input end of the operational amplifier is connected with the output end of the operational amplifier, and the output end of the operational amplifier is used as the output end of the mode switching threshold generating module and is connected with the negative feedback loop control module;
the resistance value of the equivalent variable resistor is in inverse relation with the input voltage of the switching power supply;
the negative feedback loop control module includes:
the error amplifier, the comparator and the current acquisition and voltage conversion module;
the non-inverting input end of the error amplifier is connected with a base reference voltage;
the inverting input end of the error amplifier is connected with the sampling voltage of the output end of the switching power supply;
the output end of the error amplifier is connected with the inverting input end of the comparator and the output end of the mode switching threshold generating module;
the current collection and voltage conversion module is used for collecting the load current of the switching power supply and converting the load current into voltage; the output end of the current acquisition and voltage conversion module is connected with the non-inverting input end of the comparator;
the output end of the comparator is used as the output end of the negative feedback loop control module and is connected with the driving signal generation module;
the driving signal generation module includes:
the driving logic generation module and the driving signal conversion module are connected;
the driving logic generating module is connected with the output end of the negative feedback loop control module and is used for receiving the PWM square wave signal and carrying out logic operation on the PWM square wave signal;
the driving signal conversion module converts the PWM square wave signal into a driving signal and outputs the driving signal.
2. The switching power supply control mode switching circuit according to claim 1, wherein the equivalent variable resistor is a transistor.
3. The switching power supply control mode switching circuit according to claim 2, wherein the transistor is an NMOS transistor.
4. A switching power supply control mode switching circuit according to claim 3, wherein the gate of the NMOS transistor is connected to the input of the switching power supply;
the source electrode of the NMOS tube is connected with the ground;
and the drain electrode of the NMOS tube is connected with the non-inverting input end of the operational amplifier.
5. The switching power supply control mode switching circuit according to claim 2, wherein the transistor is a PMOS transistor.
6. The switching power supply control mode switching circuit according to claim 5, wherein a gate of the PMOS transistor is connected to an input terminal of the switching power supply;
the source electrode of the PMOS tube is connected with the external power supply voltage;
and the drain electrode of the PMOS tube is connected with the non-inverting input end of the operational amplifier.
7. A switching power supply chip, comprising:
a switching power supply and a switching power supply mode switching circuit according to any one of claims 1 to 6, the switching power supply comprising at least a power drive tube, the switching power supply mode switching circuit outputting a drive signal for driving the power drive tube.
8. The switching power supply chip of claim 7 wherein said switching power supply is a BOOST circuit, a BUCK circuit, or a BOOST-BUCK combined circuit.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5600234A (en) * | 1995-03-01 | 1997-02-04 | Texas Instruments Incorporated | Switch mode power converter and method |
| CN102969894A (en) * | 2012-11-19 | 2013-03-13 | 西安三馀半导体有限公司 | Mode automatic converting circuit for DC-DC (Direct Current to Direct Current) converter |
| CN105356734A (en) * | 2015-11-18 | 2016-02-24 | 浙江大学 | COT-control-based ripple-compensation-based buck circuit power management chip |
| CN209184489U (en) * | 2018-12-24 | 2019-07-30 | 上海艾为电子技术股份有限公司 | A kind of Switching Power Supply control mode switch circuit and switching power source chip |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8427123B2 (en) * | 2009-07-08 | 2013-04-23 | Microchip Technology Incorporated | System, method and apparatus to transition between pulse width modulation and pulse-frequency modulation in a switch mode power supply |
| US9083237B2 (en) * | 2010-07-13 | 2015-07-14 | O2Micro, Inc. | Circuits and methods for controlling a DC/DC converter |
| TWI496402B (en) * | 2013-07-29 | 2015-08-11 | Anpec Electronics Corp | Current-mode buck converter and electronic system using the same |
| CN105337500B (en) * | 2014-06-27 | 2018-05-04 | 意法半导体研发(深圳)有限公司 | Power inverter and the method responded for adjusting the linear transient of power inverter |
-
2018
- 2018-12-24 CN CN201811580588.7A patent/CN109378970B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5600234A (en) * | 1995-03-01 | 1997-02-04 | Texas Instruments Incorporated | Switch mode power converter and method |
| CN102969894A (en) * | 2012-11-19 | 2013-03-13 | 西安三馀半导体有限公司 | Mode automatic converting circuit for DC-DC (Direct Current to Direct Current) converter |
| CN105356734A (en) * | 2015-11-18 | 2016-02-24 | 浙江大学 | COT-control-based ripple-compensation-based buck circuit power management chip |
| CN209184489U (en) * | 2018-12-24 | 2019-07-30 | 上海艾为电子技术股份有限公司 | A kind of Switching Power Supply control mode switch circuit and switching power source chip |
Non-Patent Citations (1)
| Title |
|---|
| 刘帘曦 ; 杨银堂 ; 朱樟明 ; .PWM/PFM双模调制的高效率DC/DC开关电源.固体电子学研究与进展.2006,(第02期),全文. * |
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