CN112636584A - Electronic equipment, DC-DC power supply and control circuit thereof - Google Patents

Electronic equipment, DC-DC power supply and control circuit thereof Download PDF

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CN112636584A
CN112636584A CN202011300802.6A CN202011300802A CN112636584A CN 112636584 A CN112636584 A CN 112636584A CN 202011300802 A CN202011300802 A CN 202011300802A CN 112636584 A CN112636584 A CN 112636584A
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voltage
resistor
control module
power supply
module
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CN112636584B (en
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刘欢
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Ifreecomm Technology Co ltd
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Ifreecomm Technology Co ltd
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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
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters

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  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to an electronic device, a DC-DC power supply and a control circuit thereof. The control circuit includes: the control circuit comprises an enabling control module and a switch control module, wherein the enabling control module outputs a first enabling signal for controlling the voltage conversion module to convert the input voltage into the output voltage when the input voltage of the voltage conversion module is not less than a first threshold voltage; the switch control module starts to work after detecting the output voltage, outputs a first switch signal when the input voltage is not less than a second threshold voltage, and outputs a second switch signal when the input voltage is less than the second threshold voltage; the enabling control module outputs a first enabling signal when receiving the first switching signal, and outputs a second enabling signal for controlling the voltage conversion module to stop working when receiving the second switching signal. The problem that the output voltage will fluctuate to influence a load circuit due to repeated starting and stopping of the DC-DC power supply in the process of stopping the load is solved.

Description

Electronic equipment, DC-DC power supply and control circuit thereof
Technical Field
The invention relates to the technical field of power supply equipment, in particular to a DC-DC power supply and a control circuit thereof, and also relates to electronic equipment.
Background
At present, electronic equipment requiring Direct Current power supply basically adopts a DC-DC power supply (Direct Current) to convert the voltage of the Direct Current power supply into an output voltage to supply power to a load circuit, and if the output voltage of the DC-DC power supply generates jitter, the load circuit works abnormally, even the load circuit is damaged.
When the input voltage Vin at the input end of the DC-DC power supply is not less than the lower limit working voltage of the DC-DC power supply, the load circuit works, at the moment, the input voltage Vin at the input end of the DC-DC power supply is less than the output voltage Vcc at the output end of the DC-DC power supply, when the input voltage Vin at the input end of the DC-DC power supply is less than the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is turned off, the load circuit stops working, at the moment, the input voltage Vin rebounds to be equal to the output voltage Vcc at the moment, when the input voltage Vin rebounds to the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is restarted to ensure that the input voltage Vin is lower than the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is turned off, after the DC-DC power supply, the DC-DC power supply restarts. In the process, as the DC-DC power supply is repeatedly started and shut down, the output voltage fluctuates, the influence on the load circuit is great, and the load circuit can be damaged in severe cases.
Disclosure of Invention
Therefore, there is a need for an electronic device, a DC-DC power supply and a control circuit thereof, which are intended to solve the problem that the output voltage fluctuates due to repeated start and stop of the current DC-DC power supply during the stop of the load circuit, thereby affecting the load circuit.
A control circuit for a DC-DC power supply, connected to a voltage conversion module in the DC-DC power supply, an input of the voltage conversion module being connected to an output of a direct current power supply, the control circuit comprising:
the first end of the enabling control module is connected with the input end of the voltage conversion module, the second end of the enabling control module is connected with the enabling end of the voltage conversion module, and the enabling control module is used for outputting a first enabling signal when the input voltage at the input end of the voltage conversion module is not less than a first threshold voltage, and the first enabling signal is used for controlling the voltage conversion module to convert the input voltage into the output voltage;
the first end of the switch control module is connected with the output end of the voltage conversion module, the second end of the switch control module is connected with the third end of the enable control module, the switch control module is used for starting to work after the output voltage is detected, outputting a first switch signal when the input voltage is not less than a second threshold voltage, and outputting a second switch signal when the input voltage is less than the second threshold voltage;
the enabling control module is further used for outputting a first enabling signal when receiving a first switching signal, and outputting a second enabling signal when receiving a second switching signal, wherein the second enabling signal is used for controlling the voltage conversion module to stop working; the first threshold voltage is greater than a second threshold voltage, and a difference between the first threshold voltage and the second threshold voltage is not less than a difference between the input voltage and an output voltage of an output end of the direct-current power supply.
In one embodiment, the switch control module comprises a resistor R1 and a switch tube Q1;
one end of the resistor R1 is a first end of the switch control module, and the input end of the switch tube Q1 is a second end of the switch control module;
the other end of the resistor R1 is connected with the control end of the switch tube Q1, and the output end of the switch tube Q1 is grounded.
In one embodiment, the switch control module further includes a capacitor C1, one end of the capacitor C1 is connected to the control end of the switching tube Q1, and the other end of the capacitor C1 is grounded.
In one embodiment, the switching transistor Q1 includes an NPN transistor and an NMOS transistor.
In one embodiment, the enable control module comprises: the resistor R2, the resistor R3, the resistor R4 and the switch tube Q2;
a common terminal of the resistor R2 and the resistor R3 is a first terminal of the enable control module, a common terminal of the resistor R3 and the resistor R4 is a second terminal of the enable control module, and a control terminal of the switch tube Q2 is a third terminal of the enable control module;
the other end of the resistor R2 is connected with the control end of the switch tube Q2, the other end of the resistor R4 is connected with the input end of the switch tube Q2, and the output end of the switch tube Q2 is grounded.
In one embodiment, the control circuit further comprises:
a capacitor C2, one end of the capacitor C2 is connected to the first end of the enable control module, and the other end of the capacitor C2 is connected to the second end of the enable control module.
In one embodiment, the control circuit further comprises:
and one end of the capacitor C3 is connected with the third end of the enable control module, and the other end of the capacitor C3 is grounded.
In one embodiment, the control circuit further comprises:
and one end of the resistor R5 is connected with the second end of the enable control module, and the other end of the resistor R5 is grounded.
In one embodiment, the control circuit further comprises:
the first end of the voltage detection module is connected with the output end of the voltage conversion module, and the second end of the voltage detection module is connected with the first end of the switch control module;
the voltage detection module is used for outputting a first signal when the output voltage is not less than a preset voltage; the switch control module is used for judging that the output voltage is detected when the first signal is received.
In one embodiment, the voltage detection module comprises a resistor R6, a resistor R7 and a comparator U8;
the common terminal of the resistor R6 and the VCC terminal of the comparator U8 is the first terminal of the voltage detection module, and the common terminal of the comparator U8
Figure BDA0002786755720000041
The common end of the end and the resistor R7 is a second end of the voltage detection module;
the other end of the resistor R6 and the comparator U8
Figure BDA0002786755720000042
The end is connected, and the GND end of the comparator U8 and the other end of the resistor R7 are both grounded.
In one embodiment, the voltage detection module further comprises a capacitor C4 and a capacitor C5 which are connected in parallel, one end of the capacitor C4 and one end of the capacitor C5 are connected with the VCC end of the comparator U8, and the other end of the capacitor C4 and the other end of the capacitor C5 are grounded.
A DC-DC power supply comprises a voltage conversion module, wherein the input end of the voltage conversion module is the input end of the DC-DC power supply, the output end of the voltage conversion module is the output end of the DC-DC power supply, and the DC-DC power supply further comprises any one of the control circuits.
An electronic device, characterized in that the electronic device comprises the above DC-DC power supply.
When the input voltage of the voltage conversion module at the input end is not less than the first threshold voltage, the enabling control module outputs a first enabling signal to the enabling end of the voltage conversion module so as to control the voltage conversion module to convert the input voltage into the output voltage, the switch control module starts to work after detecting the output voltage, and outputs a first switch signal to the enabling control module when the input voltage is not less than the second threshold voltage, and outputs a second switch signal to the enabling control module when the input voltage is less than the second threshold voltage; the enabling control module outputs a first enabling signal when receiving the first switching signal, outputs a second enabling signal to an enabling end of the voltage conversion module when receiving the second switching signal, and controls the voltage conversion module to stop working, wherein the difference value between the first threshold voltage and the second threshold voltage is not less than the difference value between the input voltage and the output voltage of the output end of the direct-current power supply. Through the interaction of the enabling control module and the switch control module, the working voltage of the voltage conversion module in the DC-DC power supply for converting the input voltage into the output voltage is greater than the voltage for stopping working, and the difference between the working voltage and the output voltage is not less than the difference between the input voltage and the output voltage of the output end of the DC power supply, so that the problem that the output voltage is fluctuated and the load circuit is influenced because the DC-DC power supply is repeatedly started and shut off in the process that the load circuit stops working is solved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a block diagram of a control circuit for a DC-DC power supply in one embodiment;
fig. 2 is a schematic circuit configuration diagram of a control circuit of the DC-DC power supply in the first embodiment;
FIG. 3 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the second embodiment;
FIG. 4 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the third embodiment;
FIG. 5 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the fourth embodiment;
fig. 6 is a schematic circuit configuration diagram of a control circuit of the DC-DC power supply in the fifth embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. The first resistance and the second resistance are both resistances, but they are not the same resistance.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, as used in this specification, the term "and/or" includes any and all combinations of the associated listed items.
When the input voltage Vin of the DC-DC power supply input end is not less than the lower limit working voltage of the DC-DC power supply, a certain line loss voltage exists between the DC-DC power supply input end and the DC power supply output end in the working process of the load circuit, and the line loss voltage is larger when the load power is larger. When the input voltage Vin of the input end of the DC-DC power supply is smaller than the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is turned off, the load circuit stops working, the line loss voltage disappears instantly, the input voltage Vin rebounds to be equal to the output voltage Vcc at the moment, when the input voltage Vin rebounds to the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is restarted, the line loss voltage appears, the input voltage Vin is lower than the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is turned off, after the power supply is turned off, the input voltage Vin rebounds, and when the input voltage Vin rebounds to the lower limit working voltage of the DC-DC power supply, the DC-DC power supply is restarted.
In view of the above, the present application provides a control circuit for a DC-DC power supply.
Referring to fig. 1, a block diagram of a control circuit of a DC-DC power supply in an embodiment is shown.
As shown in fig. 1, in one embodiment, a control circuit of a DC-DC power supply is provided, and is connected to a voltage conversion module 10 in the DC-DC power supply, wherein an input terminal of the voltage conversion module 10 is connected to an output terminal of a direct current power supply, and the control circuit includes: enable control module 20 and switch control module 30.
A first terminal of the enable control module 20 is connected to the input terminal of the voltage conversion module 10, a second terminal of the enable control module 20 is connected to the enable terminal of the voltage conversion module 10, and the enable control module 20 is configured to output a first enable signal when an input voltage at the input terminal of the voltage conversion module 10 is not less than a first threshold voltage VT1, where the first enable signal is used to control the voltage conversion module 10 to convert the input voltage into an output voltage.
The first terminal of the switch control module 30 is connected to the output terminal of the voltage conversion module 10, the second terminal of the switch control module 30 is connected to the third terminal of the enable control module 20, and the switch control module 30 is configured to start working after detecting the output voltage, and output a first switch signal when the input voltage is not less than a second threshold voltage VT2, and output a second switch signal when the input voltage is less than a second threshold voltage VT 2;
the enable control module 20 is further configured to output a first enable signal when receiving the first switch signal, and output a second enable signal when receiving the second switch signal, where the second enable signal is used to control the voltage conversion module to stop working; the first threshold voltage VT1 is greater than the second threshold voltage VT2, and the difference between the first threshold voltage VT1 and the second threshold voltage VT2 is not less than the difference between the input voltage and the output voltage of the output terminal of the DC power supply.
In one embodiment, the first threshold voltage VT1 is 7V and the second threshold voltage VT2 is 4V. In practice, the first threshold voltage VT1 and the second threshold voltage VT2 may be adjusted by the switch control module 20 and the enable control module 30.
In this embodiment, when the input voltage Vin at the input end of the voltage conversion module 10 is not less than the first threshold voltage VT1, that is, the input voltage Vin provided by the output voltage VCC at the output end of the dc power supply to the input end of the voltage conversion module 10 is not less than the first threshold voltage VT1, the enable control module 20 outputs a first enable signal to the enable end of the voltage conversion module 10, and the voltage conversion module 10 converts the input voltage Vin into the output voltage Vout to supply power to the load after receiving the first enable signal, where the effective enable voltage VEN0 corresponds to the minimum operating voltage of the voltage conversion module 10, and the first enable signal indicates that the enable voltage VEN output by the enable control module 20 to the enable end of the voltage conversion module 10 is not less than the effective enable voltage VEN 0.
The switch control module 30 starts to operate when detecting the output voltage Vout, and during operation, if the input voltage Vin is greater than or equal to the second threshold voltage VT2, outputs a first switch signal to the enable control module 20; if the input voltage Vin is less than a second threshold voltage VT2, a second switching signal is output to the enable control module 20, wherein the second threshold voltage VT2 is a preset turn-off voltage of the power conversion module 10. When receiving the first switching signal or the input voltage Vin is greater than or equal to the first threshold voltage VT1, the enable control module 20 outputs the first enable signal to the enable terminal of the voltage conversion module 10, and when receiving the second switching signal, the enable control module 20 outputs the second enable signal to the enable terminal of the voltage conversion module 10, thereby controlling the voltage conversion module 10 to stop operating, i.e., stopping providing the output voltage Vout to the load.
In one embodiment, after the switching control module 30 starts operating, when the input voltage Vin is less than the second threshold voltage VT2, the second switching signal is output to the enable control module 20, and the operation is stopped until the output voltage Vout is detected.
In one embodiment, the enable control module 20 outputs the first enable signal with a different value when receiving the first switching signal and the input voltage Vin is greater than or equal to the first threshold voltage VT 1.
Fig. 2 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the first embodiment.
As shown in fig. 2, in one embodiment, the switch control module 30 includes a resistor R1 and a switch Q1;
one end of the resistor R1 is a first end of the switch control module 30, and the input end of the switch Q1 is a second end of the switch control module 30;
the other end of the resistor R1 is connected with the control end of the switch tube Q1, and the output end of the switch tube Q1 is grounded. By turning on and off the switching tube Q1, the switching control module 30 outputs the first switching signal and the second switching signal to the third terminal of the enable control module, respectively.
In one embodiment, the switching transistor Q1 comprises an NPN transistor. The base of the NPN type triode is the control end of the switching tube Q1, the collector of the NPN type triode is the input end of the switching tube Q1, and the emitter of the NPN type triode is the output end of the switching tube Q1.
In one embodiment, the switching tube Q1 comprises an NMOS tube. The grid electrode of the NMOS tube is the control end of the switch tube Q1, the drain electrode of the NMOS tube is the input end of the switch tube Q1, and the source electrode of the NMOS tube is the output end of the switch tube Q1.
As shown in fig. 2, in one embodiment, the switch control module 30 further includes a capacitor C1, one end of the capacitor C1 is connected to the control end of the switching tube Q1, and the other end of the capacitor C1 is grounded. The filtering effect of the capacitor C1 can reduce the overshoot when the enable voltage VEN falls.
Fig. 3 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the second embodiment.
As shown in FIG. 3, in one embodiment, the enable control module 20 includes: the resistor R2, the resistor R3, the resistor R4 and the switch tube Q2;
a common terminal of the resistor R2 and the resistor R3 is a first terminal of the enable control module 20, a common terminal of the resistor R3 and the resistor R4 is a second terminal of the enable control module 20, and a control terminal of the switch tube Q2 is a third terminal of the enable control module 20;
the other end of the resistor R2 output by the enable control module 20 is connected to the control end of the switch tube Q2, the other end of the resistor R4 is connected to the input end of the switch tube Q2, and the output end of the switch tube Q2 is grounded.
By turning on and off the switch Q2, the enable control module 20 adjusts the magnitude of the enable voltage VEN output to the enable terminal of the voltage conversion module 10, so as to achieve the purpose of adjusting the enable signal. When the switching tube Q2 is turned off, the enable voltage VEN is equal to the input voltage Vin, when the switching tube Q2 is turned on, the enable voltage VEN is equal to the voltage across the resistor R4, and when VEN is equal to VEN0, the voltage conversion module 10 receives the first enable signal, and converts the input voltage Vin into the output voltage Vout to supply power to the load. In practical applications, the first threshold voltage VT1 and the second threshold voltage VT2 may be adjusted by resistances of the resistor R2, the resistor R3, and the resistor R4.
In one embodiment, the switching transistor Q2 comprises an NPN transistor. The base of the NPN type triode is the control end of the switching tube Q2, the collector of the NPN type triode is the input end of the switching tube Q2, and the emitter of the NPN type triode is the output end of the switching tube Q2.
In one embodiment, the switching tube Q2 comprises an NMOS tube. The grid electrode of the NMOS tube is the control end of the switch tube Q2, the drain electrode of the NMOS tube is the input end of the switch tube Q2, and the source electrode of the NMOS tube is the output end of the switch tube Q2.
Fig. 4 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the third embodiment.
As shown in fig. 4, in one embodiment, the control circuit further includes:
a capacitor C2, one end of the capacitor C2 is connected to the first end of the enable control module, and the other end of the capacitor C2 is connected to the second end of the enable control module. The filtering effect of the capacitor C2 can reduce the overshoot when the enable voltage VEN falls.
As shown in fig. 4, in one embodiment, the control circuit further includes:
and one end of the capacitor C3 is connected with the third end of the enable control module, and the other end of the capacitor C3 is grounded. The filtering effect of the capacitor C3 can reduce the overshoot when the enable voltage VEN falls.
As shown in fig. 4, in one embodiment, the control circuit further includes:
and one end of the resistor R5 is connected with the second end of the enable control module, and the other end of the resistor R5 is grounded.
When the switching tube Q2 is turned off, the resistor R3 and the resistor R5 are connected in series and then form a loop with the input voltage Vin, the enable voltage VEN is equal to the divided voltage at the two ends of the resistor R4, when the switching tube Q2 is turned on, the resistor R4 and the resistor R5 are connected in parallel and then connected in series with the resistor R3, the enable voltage VEN is equal to the divided voltage at the two ends of the parallel resistors R4 and R5, and when VEN is equal to VEN0, the voltage conversion module 10 receives a first enable signal and converts the input voltage Vin into the output voltage Vout to supply power to the load. Through the resistor R5, the magnitude of the enable voltage VEN output by the enable control module 20 to the enable terminal of the voltage conversion module 10 can be adjusted, so as to adjust the input voltage Vin corresponding to the enable signal and the first threshold voltage VT 1. In practical applications, the first threshold voltage VT1 and the second threshold voltage VT2 are adjusted by the resistance of the resistor R5.
Fig. 5 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the fourth embodiment.
As shown in fig. 5, in one embodiment, the control circuit further includes:
a voltage detection module 40, wherein a first end of the voltage detection module 40 is connected with the output end of the voltage conversion module 10, and a second end of the voltage detection module 40 is connected with a first end of the switch control module 30;
the voltage detection module 40 is configured to output a first signal when the output voltage Vout is not less than the preset voltage VT 3; the switch control module 30 is configured to determine that the output voltage Vout is detected when receiving the first signal.
The preset output voltage VT3 is smaller than the threshold voltage of the voltage conversion module 10, and when the output voltage Vout is smaller than the preset output voltage VT3, the output voltage Vout is determined to be a ripple voltage, and the voltage conversion module 10 performs voltage conversion on the input voltage Vin to obtain a voltage. When the output voltage Vout is greater than or equal to the preset output voltage VT3, it is determined that the output voltage Vout is a voltage obtained by the voltage conversion module 10 performing voltage conversion on the input voltage Vin. The voltage detection module 40 can eliminate the influence of voltage fluctuation at the output end of the voltage conversion module 10 on the switch control module 30, and avoid the repeated start and stop of the DC-DC power supply in the process of stopping the work of the load circuit.
Fig. 6 is a schematic diagram of a circuit configuration of a control circuit of the DC-DC power supply in the fifth embodiment.
As shown in FIG. 6, in one embodiment, the voltage detection module 40 includes a resistor R6, a resistor R7, and a comparator U8;
the common terminal of the resistor R6 and the VCC terminal of the comparator U8 is the first terminal of the voltage detection module 40, and the common terminal of the comparator U8
Figure BDA0002786755720000121
The common end of the end and the resistor R7 is a second end of the voltage detection module 40;
the other end of the resistor R6 and the comparator U8
Figure BDA0002786755720000122
The end is connected, and the GND end of the comparator U8 and the other end of the resistor R7 are both grounded.
As shown in fig. 6, in one embodiment, the voltage detection module 40 further includes a capacitor C4 and a capacitor C5 connected in parallel, one end of the capacitor C4 and one end of the capacitor C5 are connected to the VCC terminal of the comparator U8, and the other end of the capacitor C4 and the other end of the capacitor C5 are grounded. The influence of the fluctuation of the output voltage of the DC-DC power supply (i.e. the output voltage of the voltage conversion module 10) on the comparator can be reduced by the filtering action of the capacitor C4 and the capacitor C5.
The DC-DC power supply provided by the above embodiments is further described below with reference to the working principle:
as shown in fig. 4, assuming that the resistor R1-R2-10K Ω, the resistor R3-60K Ω, the resistor R4-R5-20K Ω, and the VEN 0-1V, the voltage conversion module is operated to convert the input voltage into an output voltage of 3.3V, assuming that the input voltage Vin is linearly increased from 0V to 10V and then linearly decreased to 0V. Firstly, when Vin starts to rise from 0V to 1.7V, the switching tubes Q1 and Q2 are turned off (Vgs of the MOS tube increases with the increase of Vin, but does not reach the voltage for turning on the MOS in the early stage), so the enabling voltage VEN is approximately equal to the voltage value at two ends of the resistor R5 after Vin is divided by the resistor R3 and the resistor R5, that is, VEN is approximately equal to Vin/4< VEN 0.
Secondly, when Vin rises to about 1.7V, the switching tube Q2 is completely opened, the VEN has a small descending jump, one end of the resistor R4 and the resistor R5 are connected with GND after being connected in parallel, the other end of the resistor R3 is connected with the resistor R3 in series, the enabling voltage VEN is approximately equal to a voltage value obtained by dividing the Vin through the resistors R4 and R5 which are connected in parallel, namely VEN is approximately equal to Vin/7< VEN 0.
And when Vin rises to 7V, at this time, Vin/7 is VEN0, and the input voltage of the DC-DC power reaches the threshold value of the DC-DC power on. The DC-DC power supply works normally, and Vout is changed from 0V to 3.3V at the moment. The switch tube Q1 is turned on, the grid of the switch tube Q2 is pulled low, so the switch tube Q2 is turned off, the voltage value of the VEN jumps to be the voltage value at two ends of the resistor R5 after Vin is divided by the R3 and the R5, namely VEN is approximately equal to Vin/4; vin is 7V, which is the turn-on voltage of the voltage conversion module 10, i.e. the minimum operating voltage at which the voltage conversion module 10 is turned on.
And fourthly, when the power supply of the direct current power supply is turned off and Vin begins to drop, because the VEN is approximately equal to Vin/4 at the moment, when the VEN drops to 1V, Vin is approximately equal to 4V, namely the Vin needs to drop to 4V, the DC-DC power supply is turned off, the switch tube Q1 is turned off at the moment, the grid electrode of the switch tube Q2 is pulled to Vin, the switch tube Q2 is turned on, the value of Vin is changed into a voltage value obtained by dividing the Vin through the resistors R4 and R5 which are connected in parallel, namely the Vin is approximately equal to Vin/7, and the voltage of the VEN drops and jumps.
At the last stage, in the process that the Vin voltage drops to approach 0V, the gate voltage of the switching tube Q2 drops along with Vin, when the gate voltage is lower than the turn-on voltage of the switching tube Q2, the switching tube Q2 is turned off, and at this time, the voltage of the VEN is approximately equal to the voltage value of Vin at the two ends of the resistor R5 after the Vin is divided by the resistor R3 and the resistor R5, namely, the VEN is approximately equal to Vin/4, and the voltage of the VEN rises and jumps.
The minimum working voltage, namely, the opening voltage of the voltage conversion module 10 is adjusted to the first threshold voltage VT1 through the enabling control module 20 and the switch control module 30, and the stop working voltage, namely, the closing voltage is adjusted to the second threshold voltage VT2, so that a hysteresis protection interval (VT1-VT2) is formed, the influence of voltage rebound caused by line loss voltage when the load disappears is shielded, the stability of the circuit is ensured, and the possible circuit damage caused by repeated short-time switching is avoided.
In one embodiment, a DC-DC power supply is provided, which includes a voltage conversion module, an input terminal of which is an input terminal of the DC-DC power supply, and an output terminal of which is an output terminal of the DC-DC power supply, and the DC-DC power supply further includes the control circuit described in any one of the above items.
In one embodiment, an electronic device is provided that includes the above DC-DC power supply.
When the input voltage of the voltage conversion module at the input end is not less than the first threshold voltage, the enabling control module outputs a first enabling signal to the enabling end of the voltage conversion module so as to control the voltage conversion module to convert the input voltage into the output voltage, the switch control module starts to work after detecting the output voltage, and outputs a first switch signal to the enabling control module when the input voltage is not less than the second threshold voltage, and outputs a second switch signal to the enabling control module when the input voltage is less than the second threshold voltage; the enabling control module outputs a first enabling signal when receiving the first switching signal, outputs a second enabling signal to an enabling end of the voltage conversion module when receiving the second switching signal, and controls the voltage conversion module to stop working, wherein the difference value between the first threshold voltage and the second threshold voltage is not less than the difference value between the input voltage and the output voltage of the output end of the direct-current power supply. Through the interaction of the enabling control module and the switch control module, the working voltage of the voltage conversion module in the DC-DC power supply for converting the input voltage into the output voltage is greater than the voltage for stopping working, and the difference between the working voltage and the output voltage is not less than the difference between the input voltage and the output voltage of the output end of the DC power supply, so that the problem that the output voltage is fluctuated and the load circuit is influenced because the DC-DC power supply is repeatedly started and shut off in the process that the load circuit stops working is solved.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A control circuit for a DC-DC power supply, the control circuit being connected to a voltage conversion module in the DC-DC power supply, an input terminal of the voltage conversion module being connected to an output terminal of a DC power supply, the control circuit comprising:
the first end of the enabling control module is connected with the input end of the voltage conversion module, the second end of the enabling control module is connected with the enabling end of the voltage conversion module, and the enabling control module is used for outputting a first enabling signal when the input voltage at the input end of the voltage conversion module is not less than a first threshold voltage, and the first enabling signal is used for controlling the voltage conversion module to convert the input voltage into the output voltage;
the first end of the switch control module is connected with the output end of the voltage conversion module, the second end of the switch control module is connected with the third end of the enable control module, the switch control module is used for starting to work after the output voltage is detected, outputting a first switch signal when the input voltage is not less than a second threshold voltage, and outputting a second switch signal when the input voltage is less than the second threshold voltage;
the enabling control module is further used for outputting a first enabling signal when receiving a first switching signal, and outputting a second enabling signal when receiving a second switching signal, wherein the second enabling signal is used for controlling the voltage conversion module to stop working; the first threshold voltage is greater than a second threshold voltage, and a difference between the first threshold voltage and the second threshold voltage is not less than a difference between the input voltage and an output voltage of an output end of the direct-current power supply.
2. The control circuit of claim 1, the switch control module comprising a resistor R1 and a switching tube Q1;
one end of the resistor R1 is a first end of the switch control module, and the input end of the switch tube Q1 is a second end of the switch control module;
the other end of the resistor R1 is connected with the control end of the switch tube Q1, and the output end of the switch tube Q1 is grounded.
3. The control circuit of claim 2, wherein the switch control module further comprises a capacitor C1, one end of the capacitor C1 is connected to the control end of the switching tube Q1, and the other end of the capacitor C1 is grounded;
the switching tube Q1 includes an NPN transistor and an NMOS tube.
4. The control circuit of claim 1, wherein the enable control module comprises: the resistor R2, the resistor R3, the resistor R4 and the switch tube Q2;
a common terminal of the resistor R2 and the resistor R3 is a first terminal of the enable control module, a common terminal of the resistor R3 and the resistor R4 is a second terminal of the enable control module, and a control terminal of the switch tube Q2 is a third terminal of the enable control module;
the other end of the resistor R2 is connected with the control end of the switch tube Q2, the other end of the resistor R4 is connected with the input end of the switch tube Q2, and the output end of the switch tube Q2 is grounded.
5. The control circuit of claims 1-4, further comprising:
a capacitor C2, one end of the capacitor C2 is connected to the first end of the enable control module, and the other end of the capacitor C2 is connected to the second end of the enable control module;
a capacitor C3, wherein one end of the capacitor C3 is connected with the third end of the enable control module, and the other end of the capacitor C3 is grounded;
and one end of the resistor R5 is connected with the second end of the enable control module, and the other end of the resistor R5 is grounded.
6. The control circuit of claim 1, further comprising:
the first end of the voltage detection module is connected with the output end of the voltage conversion module, and the second end of the voltage detection module is connected with the first end of the switch control module;
the voltage detection module is used for outputting a first signal when the output voltage is not less than a preset voltage; the switch control module is used for judging that the output voltage is detected when the first signal is received.
7. The control circuit of claim 6, wherein the voltage detection module comprises a resistor R6, a resistor R7, and a comparator U8;
the common terminal of the resistor R6 and the VCC terminal of the comparator U8 is the first terminal of the voltage detection module, and the common terminal of the comparator U8
Figure FDA0002786755710000031
The common end of the end and the resistor R7 is a second end of the voltage detection module;
the other end of the resistor R6 and the comparator U8
Figure FDA0002786755710000032
The end is connected, and the GND end of the comparator U8 and the other end of the resistor R7 are both grounded.
8. The control circuit of claim 7, wherein the voltage detection module further comprises a capacitor C4 and a capacitor C5 connected in parallel, one end of the capacitor C4 and one end of the capacitor C5 are connected to the VCC end of the comparator U8, and the other end of the capacitor C4 and the other end of the capacitor C5 are connected to ground.
9. A DC-DC power supply comprising a voltage conversion module, an input of which is an input of the DC-DC power supply, and an output of which is an output of the DC-DC power supply, characterized in that the DC-DC power supply further comprises a control circuit according to any one of claims 1 to 8.
10. An electronic device, characterized in that the electronic device comprises the DC-DC power supply of claim 9.
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CN117595626B (en) * 2023-11-28 2024-05-31 北京伽略电子股份有限公司 Multi-output enabling circuit

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