CN119070617A - A switching power supply with power supply interference resistance - Google Patents
A switching power supply with power supply interference resistance Download PDFInfo
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- CN119070617A CN119070617A CN202411574247.4A CN202411574247A CN119070617A CN 119070617 A CN119070617 A CN 119070617A CN 202411574247 A CN202411574247 A CN 202411574247A CN 119070617 A CN119070617 A CN 119070617A
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- tube
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- 238000002955 isolation Methods 0.000 claims abstract description 18
- 239000003990 capacitor Substances 0.000 claims description 18
- 238000010586 diagram Methods 0.000 description 6
- 238000001514 detection method Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000004088 simulation Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/325—Means for protecting converters other than automatic disconnection with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
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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
- H02M3/158—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 including plural semiconductor devices as final control devices for a single load
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The switching power supply comprises a power management chip, a first resistor and a second resistor which are connected in series between an output voltage end and the ground, wherein a common end of the first resistor and the second resistor is connected with an emitter of a triode, a base electrode of the triode is connected with an input voltage end of the switching power supply, a collector electrode of the triode is connected with a third resistor, a collector electrode of the triode is connected with a grid electrode of a switching tube, a source electrode and a drain electrode of the switching tube are respectively connected with the input voltage end of the power management chip and the emitter of the triode, and the switching power supply further comprises an isolation diode, wherein an anode of the isolation diode is connected with the input voltage end of the switching power supply, and a cathode of the isolation diode is connected with the input power end of the power management chip. The anti-power-interference switching power supply can avoid the chip closing caused by the short fluctuation of the input voltage, reduce the fluctuation of the output voltage and effectively improve the influence of a low-quality power supply on the output voltage.
Description
Technical Field
The invention belongs to the technical field of switching power supplies, and particularly relates to a switching power supply resistant to power supply interference.
Background
The switching power supply is a switching power supply device which outputs direct current voltages with different levels through switching conversion of a power tube, and the power management chip detects input voltage and output voltage and controls the switching state of the power tube to output stable direct current voltage.
Taking a BOOST type direct current controller as an example, as shown in fig. 1, for a power management chip U1 with an external power tube, the BOOST type direct current controller generally comprises an input voltage pin VCC, a feedback voltage pin FB and a switching tube pin SW, and in the circuit shown in fig. 1, a typical BOOST structure is formed by an inductor L, a freewheeling diode D1, a power tube M1 and the power management chip U1, and the duty ratio of a square wave signal output on the pin of the power tube M1 is adjusted by detecting the input voltage and the feedback voltage, so that the output voltage is adjusted to gradually reach a stable output voltage in a dynamic adjustment process.
Most power management chips have an under-voltage protection function, when the input voltage is reduced to a certain degree, the chips are turned off, so that the chips cannot work normally or damage caused by long-term large duty ratio operation of the power tube is avoided, but under the condition that the input voltage is unstable, the under-voltage protection function easily causes frequent switching of the power management chips when the input voltage has ripples, and the repeated fluctuation of the output voltage is caused to influence the normal work of the load.
Disclosure of Invention
Aiming at the defects in the prior art, the invention discloses a switching power supply resistant to power supply interference.
The invention relates to a power supply interference-resistant switching power supply, which comprises a power supply management chip, a first resistor and a second resistor, wherein the first resistor and the second resistor are connected in series between an output voltage end and the ground, a common end of the first resistor and the second resistor is connected with an emitting electrode of a triode, a base electrode of the triode is connected with an input voltage end of the switching power supply, a collector electrode of the triode is connected with a third resistor, the collector electrode of the triode is connected with a grid electrode of a switching tube, and a source electrode and a drain electrode of the switching tube are respectively connected with the input voltage end of the power supply management chip and the emitting electrode of the triode;
The switching power supply further comprises an isolation diode, wherein the positive electrode of the isolation diode is connected with the input voltage end of the switching power supply, and the negative electrode of the isolation diode is connected with the input power end of the power supply management chip.
Preferably, the resistance of the third resistor R3 is more than 10 times that of the second resistor.
Preferably, the circuit further comprises an operational amplifier connected between the triode and the switching tube, wherein the output end and the inverting input end of the operational amplifier are connected with the drain electrode of the switching tube, the non-inverting input end is connected with the emitting electrode of the triode, and the operational amplifier is powered by the voltage of the voltage division voltage end.
Preferably, a second capacitor is connected between the output end of the operational amplifier and the ground.
Preferably, the power amplifier further comprises an overvoltage protection module, the overvoltage protection module comprises a protection tube, a source electrode and a drain electrode of the protection tube are respectively connected with an enabling end and a voltage dividing end of the operational amplifier, a grid electrode of the protection tube is connected with a grid electrode of the power tube, and a third capacitor and a fourth resistor are further connected in parallel between the source electrode of the protection tube and the ground.
Preferably, the circuit further comprises a pull-down tube, wherein the source electrode and the drain electrode of the pull-down tube are respectively connected with the ground and the second resistor, the second feedback resistor is composed of a first feedback voltage divider resistor and a second feedback voltage divider resistor, and the common end of the two feedback voltage divider resistors is connected with the control end of the pull-down tube.
Preferably, the switching circuit further comprises a rectifying diode, wherein the anode and the cathode of the rectifying diode are respectively connected with the drain electrode of the switching tube and the cathode of the isolating diode.
The anti-power-interference switching power supply can avoid under-voltage shutdown of a power management chip caused by transient fluctuation of input voltage, reduce fluctuation of output voltage, and effectively improve the influence of a low-quality power supply on the output voltage.
Drawings
FIG. 1 is a schematic diagram of a switching power supply according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of another embodiment of the switching power supply of the present invention;
FIG. 3 is a schematic diagram of an embodiment of the overvoltage protection module according to the present invention;
FIG. 4 is a schematic diagram of another embodiment of the switching power supply according to the present invention for voltage bootstrap using an existing switching tube;
FIG. 5 is a schematic diagram of a simulation curve of a switching power supply according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a simulation curve of another embodiment of the switching power supply according to the present invention;
The reference numerals in the figure are U1-power management chip, L-inductance, D1-freewheeling diode, D2-isolation diode, D3-rectifying diode, M1-power tube, M2-triode, M3-switching tube, M4-protection tube, M5-pull-down tube, RFB 1-first feedback resistor, RFB 2-second feedback resistor, RFB 21-first feedback voltage divider resistor, RFB 22-second feedback voltage divider resistor, INV-inverter, OR-OR gate, R1-first resistor, R2-second resistor, R3-third resistor, RL-load resistor, VIN-input voltage terminal, VOUT-output voltage terminal, VC-divided voltage terminal, VS-feedback voltage divider resistor common terminal, VCC-input voltage pin, FB-feedback voltage pin, SW-switching tube pin, SW 1-square wave signal, C1-first capacitor, C2-second capacitor, C3-third capacitor, G-power tube grid, operational amplifier, and amplifier enable amplifier.
Detailed Description
For a more intuitive and clear description of the technical solution of the present invention, the following detailed description will be given with reference to specific embodiments and example drawings.
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely explained below in connection with the detailed description of the present invention and the corresponding drawings, and it is obvious that the described embodiments are only some, but not all, embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, the anti-power-interference switching power supply of the present invention includes a power management chip U1, and further includes a first resistor and a second resistor connected in series between an output voltage terminal VOUT and ground, where a common terminal of the first resistor and the second resistor is connected to an emitter of a triode, a base electrode of the triode is connected to an input voltage terminal VIN of the switching power supply, a collector electrode of the triode is connected to a third resistor R3 between the collector electrode and ground, and a collector electrode of the triode is connected to a gate electrode of the switching tube M3, and source electrodes and drain electrodes of the switching tube are respectively connected to an input voltage terminal of the power management chip U1 and an emitter of the triode.
The switching power supply further comprises an isolation diode D2, wherein the positive electrode of the isolation diode is connected with the input voltage end VIN of the switching power supply, and the negative electrode of the isolation diode is connected with the input power end of the power supply management chip U1. Wherein the input voltage terminal VIN is also connected to the input voltage terminal of the switching power supply topology, for example, for the BOOST structure of fig. 1, VIN is also connected to the inductor L in the BOOST structure.
The power management chip U1, the inductor L, the freewheeling diode D1 and the power tube M1 form a BOOST topology structure together, and a load resistor RL and a first capacitor C1 are further connected between the output voltage end VOUT and the ground to serve as a voltage stabilizing capacitor.
In the prior art, the voltage on the feedback voltage pin FB is generally 1.22V of a bandgap reference voltage, the switching power supply generally sets the output voltage through the proportion of the first feedback resistor RFB1 and the second feedback resistor RFB2, and after the feedback resistor is set, the output voltage at the output voltage end is set to be a constant value.
In the invention, a resistor string is added, and the voltage of an output voltage end is set to be in a proportion of a first resistor and a second resistor, so that when the output voltage is stable, the voltage division voltage obtained at the common end of the two resistors is higher than a set input voltage undervoltage threshold value, and the difference value is the starting voltage VBE of the triode.
For example, the input voltage undervoltage threshold of the power management chip U1 is 2.7V, the output voltage is 12V, the triode starting voltage vbe=0.3v, the first resistor r1=900K and the second resistor r2=300K are set, and the voltage division voltage end VC obtained at the common end after the output voltage is divided by the first resistor and the second resistor is 3V. When the input voltage of the input voltage end VIN of the switching power supply is lower than 2.7V, the triode M2 is conducted, the collector voltage of the triode is increased, the switching tube M3 is conducted, the power management chip U1 is changed to be powered by the voltage division voltage end VC, the voltage division voltage is 3V and is higher than the set input voltage undervoltage threshold value of 2.7V, at the moment, the power management chip U1 judges that undervoltage is avoided, the chip continues to normally work, meanwhile, due to the unidirectional conduction effect of the isolation diode D2, the voltage of the input power supply end is isolated by the isolation diode D2 and is not powered again, the voltage is switched to be powered by the voltage division voltage end VC, under the condition that the capacitance of the output end is large and the load is not heavy, the electric energy stored by the output voltage end is continuously powered by the condition that the fluctuation of the input power supply voltage is lower than the input voltage undervoltage threshold value in a short period, the triode is turned off, after the input voltage is recovered to be normal, the third resistor R3 pulls down the grid voltage of the switching tube M3, the switching tube M3 is turned off, the function of the third resistor is that the switching tube grid voltage is pulled down when the triode is turned off, the third resistor R3 can take the maximum value, the value R3 can be set to be larger than the theoretical value, the value of the third resistor R2 can be ignored in the range of the amplitude of the average value is equal to be equal to or equal to the value of 100.
By arranging the triode as a detection device, the detection and reaction speed is high, as long as the voltage difference between the voltage of the base electrode and the voltage of the emitter electrode is detected to be smaller than the starting voltage, the triode is quickly started and the switching tube is opened, the boosting topological structure is immediately switched to be powered by the VC voltage of the voltage division voltage terminal, the response speed is high, and the power management chip U1 can be prevented from judging that the undervoltage is found and then the chip is closed. The ratio of the first resistor to the second resistor can be used to make the voltage at the switching position higher than the input voltage undervoltage threshold, for example, the first resistor r1=900K and the second resistor r2=320K are set, so that when the input voltage is reduced to 2.85V, the switching is powered by the divided voltage VC, and at this time, the situation that the input voltage continues to drop until reaching the input voltage undervoltage threshold and the chip is turned off can be avoided.
Meanwhile, as the difference value between the divided voltage VC and the undervoltage threshold is set to be the starting voltage VBE of the triode, when the VBE is lower, the power supply state after switching is not changed greatly, the duty ratio is not changed drastically, and the output voltage is not obviously fluctuated by selecting a transistor device with low starting voltage.
The lower limit value of the working voltage of the power management chip is generally higher than the set input voltage undervoltage threshold by 0.2-0.5V, for example, when the input voltage undervoltage threshold is 2.7V, the lower limit of the corresponding normal voltage working range is generally about 3V, and the difference value is set to be a triode starting voltage VBE, so that the chip can work in the normal working voltage range.
In the starting stage, the voltage of the output voltage end VOUT is lower, after voltage division, the voltage is generally lower than the input voltage plus VBE, at the moment, the triode is not started to ensure that the starting and electrifying are normal, when the voltage of the output voltage end is abnormally increased to the voltage of the voltage division voltage end VC higher than the power supply voltage due to the short circuit of the load resistor RL or other conditions, the triode is started at the moment, the switching power supply can normally work, an actual circuit is not externally supplied after the triode is started, the output voltage is inevitably reduced after a certain time, the voltage division voltage VC is lower than the power supply voltage, and the triode is turned off again.
In the specific embodiment shown in fig. 1, the triode M2 is a PNP tube, the power tube M1 and the switching tube M3 are NMOS devices, and a person skilled in the art can replace the PNP tube and the PMOS device as required, and the same control manner can be realized by simply changing the connection relationship according to the control principle described in the present invention. A simulation curve for the circuit of the embodiment shown in fig. 1 is shown in fig. 5, where the voltage at the output voltage terminal VOUT hardly fluctuates when the VIN-input voltage terminal VIN voltage has ripple.
A further embodiment of the invention is shown in fig. 2, which differs from the embodiment shown in fig. 1 in that it further comprises an operational amplifier AMP connected between the transistor and the switching tube, the output terminal and the inverting input terminal of the operational amplifier being connected to the drain of the switching tube, the non-inverting input terminal being connected to the emitter of the transistor, the operational amplifier being supplied with the voltage at the divided voltage terminal VC and being connectable to a second capacitor C2 between the output terminal of the operational amplifier and ground.
The negative feedback connection of the operational amplifier AMP enables the voltage of the output end of the operational amplifier to be equal to the divided voltage VC, when the triode is started and the switching tube is opened, the operational amplifier supplies power for the switching power supply topology and the power management chip U1 through the electric energy stored in the second capacitor C2 in advance, the direct power supply of the divided voltage VC can be effectively avoided to pull down the voltage of the output voltage end VOUT, and the electric charge is stored in the second capacitor C2 in advance, so that the switching response time is not influenced after the operational amplifier is increased, and only the triode and the switching tube are still required to be started. Because the second capacitor C2 is adopted for short-term power supply, the first resistor and the second resistor can adopt resistors with larger resistance values, and the static power consumption of the output voltage terminal is reduced.
In the embodiment shown in fig. 1, when the voltage at the input voltage terminal is recovered or suddenly increased due to the ripple, the switching tube M3 is turned on at this time, the voltage at the input voltage terminal directly affects the output voltage terminal, and the operational amplifier in fig. 2 is configured to isolate the effect of the voltage at the input voltage terminal on the output voltage terminal.
In the actual use process, the output voltage is abnormally increased due to load short circuit or other reasons, under the condition that the voltage of the output voltage end is abnormally increased and continuously, the voltage of the divided voltage end VC is abnormally increased and higher than the input voltage which is not under voltage, at the moment, even if the input voltage end is not under voltage, the triode is still possibly conducted, in order to avoid that the switching tube is still continuously conducted at the position of the higher divided voltage end VC to supply power under the condition that the output voltage has reached the overvoltage state, in a preferred embodiment, the enabling control end of the operational amplifier is also connected with an overvoltage protection module, as shown in fig. 3, the overvoltage protection module comprises a protection tube M4, the source electrode and the drain electrode of the protection tube M4 are respectively connected with an enabling end EN of the operational amplifier and a divided voltage end VC, the grid electrode of the protection tube is connected with a grid electrode G of the power tube, and a third capacitor C3 and a fourth resistor R4 are also connected between the source electrode and the ground of the protection tube M4 in parallel.
Under the normal working state, the power tube grid G is a continuous square wave signal, a larger fourth resistor is arranged, so that the charge quantity of the third capacitor C3 in each high level period is larger than the charge quantity discharged through the fourth resistor R4 in the low level period, after a plurality of periods, the voltage on the third capacitor C3 is larger than the logic high level, the operational amplifier can work normally, and as long as the square wave signal exists, the third capacitor C3 is continuously charged and can maintain the high level.
Under the overvoltage condition, the power management chip detects the overvoltage through detecting the output voltage and turns off the power tube M1, the grid electrode G of the power tube is continuously low level, the grid electrode of the protection tube M4 is continuously low, the protection tube M4 is turned off, the electric quantity on the third capacitor C3 is continuously discharged through the fourth resistor R4 until the electric quantity is reduced to the logic low level, at the moment, the enable end EN of the operational amplifier is low level, the operational amplifier is enabled to not work and output the low level, and the switching tube M3 is turned off.
Through above-mentioned overvoltage protection module, need not direct detection overvoltage condition, utilize the overvoltage protection detection function of chip self to close the switching tube to can maintain the normal opening of switching tube under non-overvoltage condition, circuit structure is simple.
As shown in fig. 6, a functional simulation curve of the overvoltage protection module is given, when external excitation is applied to the output voltage terminal VOUT to make the voltage rapidly rise beyond the overvoltage point 15V set inside the power management chip, at this time, the square wave output by the power transistor gate G becomes a continuous low level, after the power of the operational amplifier enable terminal EN is turned off, the operational amplifier does not work any more, and the output voltage AMP-OUT of the operational amplifier drops to zero.
In the embodiment shown in fig. 3, the protection tube M4 is an NMOS device, and a person skilled in the art may replace the protection tube M4 with a PMOS device according to needs, and the same control manner may be implemented by simply changing the connection relationship according to the control principle described in the present invention.
As shown in fig. 4, a further preferred embodiment of the present invention is provided, in which the existing switching tube is utilized for voltage bootstrap, and the voltage bootstrap includes a pull-down tube M5 having a source and a drain respectively connected to ground and a second resistor, where the second feedback resistor is composed of a first feedback voltage divider resistor RFB21 and a second feedback voltage divider resistor RFB22, and a common terminal VS of the two feedback voltage divider resistors is connected to a control terminal of the pull-down tube.
The specific circuit shown in fig. 4 is based on the existing device, and the output voltage of the switching power supply can be bootstrapped by adding only one pull-down tube M5, when the initial voltage is low, the voltage obtained by dividing the feedback voltage by the feedback resistors is low, when the output voltage reaches the rated value, the feedback voltage obtained by dividing the voltage is usually the bandgap reference voltage of 1.22, the starting period is far lower than 1.22V, and after the feedback voltage is divided again by the first feedback voltage divider resistor RFB21 and the second feedback voltage divider resistor RFB22, the voltage is necessarily lower than the feedback voltage, and by adjusting the resistance values of the first feedback voltage divider resistor RFB21 and the second feedback voltage divider resistor RFB22, for example, when the feedback voltage is 1.22V, the common output voltage of the two feedback voltage divider resistors is 1V, and when the terminal voltage is lower than the logic high level in the starting period, the pull-down tube M5 is closed, the circuit formed by the first resistor and the second resistor is broken, and the voltage of the voltage dividing voltage branch VC is equal to the voltage of the output voltage terminal VOUT.
When the voltage of the output voltage end VOUT is extremely low, the triode is not conducted, the output voltage end VOUT is raised to be larger than the voltage of the input voltage end VIN, after the triode is started to be VBE, the triode is conducted, the collector voltage is raised after the triode is conducted, the switching tube M3 is started, and the voltage of the voltage division voltage end VC, namely the voltage of the output voltage end VOUT, is directly bootstrapped, so that the voltage boosting speed of a starting stage is accelerated.
When the output voltage rises to enable the voltage of the VS end to be higher than the logic high level and is generally about 0.6-1V, the output voltage still possibly does not reach the rated value, but the distance between the output voltage and the rated value is not large, a pull-down tube M5 is started, a branch consisting of a first resistor and a second resistor is conducted, the voltage of a voltage division voltage end VC is reduced to the voltage after voltage division, the emitter voltage of a triode is lower than the base voltage, the triode is closed, the grid voltage of a switching tube is pulled down to zero by a third resistor, the switching tube is closed, and power supply by the voltage on an input voltage end VIN is changed again.
By the bootstrap circuit, the bootstrap of the voltage of the output voltage end can be utilized, the low-voltage starting speed is rapidly improved in the starting stage, the starting time is shortened, and particularly in an application environment that the load is not connected in the starting stage and the voltage of the output voltage end needs to be rapidly increased and has no consumption.
If the subsequent input voltage terminal VIN is under-voltage, the operation state in the embodiment shown in fig. 1 is restored, and for the embodiment shown in fig. 4, the power supply voltage of the power management chip preferably adopts the input voltage at the input voltage terminal VIN, and when the bootstrap voltage is low or the process withstand voltage selected by the power management chip itself is high, the voltage transmitted to the voltage division voltage terminal VC of the drain electrode of the switching tube M3 may also be selected to supply power.
If the voltage of the common end VS of the feedback voltage dividing sub-resistor drops again to close the pull-down tube M5 due to the fact that the voltage of the common end VS of the feedback voltage dividing sub-resistor drops rapidly due to external reasons such as sudden short circuit of a load, the voltage of the voltage dividing voltage end VC is equal to that of the output voltage end VOUT, the power management chip U1 is bootstrapped by the output voltage end VOUT, the switching speed and the switching voltage of the switching tube are actually increased, the voltage recovery of the output voltage end VOUT is facilitated, if the duty ratio reaches the upper limit and still cannot reach the rated value of the output voltage, the overcurrent protection or overtemperature protection function inside the power management chip is triggered at the moment, the power management chip is closed, and damage caused by load short circuit is avoided.
In the specific embodiment shown in fig. 4, only by adding a pull-down tube based on the existing structure of the invention, when the output voltage is lower in the starting stage, the output voltage which is raised to be higher than the input voltage but still lower is taken as the power supply of the power management chip to realize the output voltage bootstrap, so that the starting speed is accelerated, the bootstrap is ended when the rated value of the output voltage is not reached, the high voltage of the output voltage is avoided being applied to the power management chip, in the specific embodiment shown in fig. 4, a rectifying diode D3 can be added between the cathode of an isolation diode D2 and the drain electrode of the switching tube, the anode and the cathode of the rectifying diode D3 are respectively connected with the drain electrode of the switching tube and the cathode of the isolation diode D2, the voltage of the input voltage end is prevented from directly flowing into the output end when the output voltage is extremely low, and an operational amplifier AMP can be added as shown in fig. 2, and the input voltage is prevented from directly flowing into the output end when the output voltage is extremely low.
The foregoing description of the preferred embodiments of the present invention is not obvious contradiction or on the premise of a certain preferred embodiment, but all the preferred embodiments can be used in any overlapped combination, and the embodiments and specific parameters in the embodiments are only for clearly describing the invention verification process of the inventor and are not intended to limit the scope of the invention, and the scope of the invention is still subject to the claims, and all equivalent structural changes made by applying the specification and the content of the drawings of the present invention are included in the scope of the invention.
Claims (7)
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| CN202411574247.4A CN119070617B (en) | 2024-11-06 | 2024-11-06 | Anti-power-interference switching power supply |
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| CN202411574247.4A CN119070617B (en) | 2024-11-06 | 2024-11-06 | Anti-power-interference switching power supply |
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| CN119070617A true CN119070617A (en) | 2024-12-03 |
| CN119070617B CN119070617B (en) | 2025-03-14 |
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| CN119070617B (en) | 2025-03-14 |
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