CN212085808U - Linear voltage-stabilized power supply output short-circuit protection circuit - Google Patents
Linear voltage-stabilized power supply output short-circuit protection circuit Download PDFInfo
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- CN212085808U CN212085808U CN202020698185.9U CN202020698185U CN212085808U CN 212085808 U CN212085808 U CN 212085808U CN 202020698185 U CN202020698185 U CN 202020698185U CN 212085808 U CN212085808 U CN 212085808U
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Abstract
The utility model discloses a linear voltage-stabilized power supply output short-circuit protection circuit in the field of voltage-stabilized power supply short-circuit protection, which comprises a voltage comparator, a reference circuit and an isolation diode, wherein the output end of the voltage comparator is connected with a power supply through a pull-up resistor, and is simultaneously connected with the cathode of the isolation diode, and the anode of the isolation diode is connected to the output control end of the voltage-stabilized power supply; the inverting input end of the voltage comparator is connected with the reference voltage provided by the reference circuit, and the non-inverting input end of the voltage comparator is connected with the output voltage of the stabilized voltage supply through the input resistor. The utility model adopts the voltage sampling mode, tracks the abnormal change of the output voltage by directly sampling the output voltage, and has the advantages of simple circuit and quick response time; when the output of the voltage-stabilized power supply is short-circuited, the short-circuit protection circuit can immediately turn off the output control of the voltage-stabilized power supply, so that the turn-off protection is realized, and the safety and the reliability of the circuit are improved.
Description
Technical Field
The utility model relates to a constant voltage power supply short-circuit protection field specifically is a linear constant voltage power supply output short-circuit protection circuit.
Background
The linear voltage-stabilized power supply has the advantages of small output ripple voltage and the like, and is widely applied to power supply of large-scale or ultra-large-scale integrated circuits such as CPUs, DSPs, FPGAs and the like as a tertiary power supply so as to improve the quality of a power supply and avoid faults such as error codes, missing codes, messy codes and the like caused by large ripple voltage of the power supply. When the linear voltage-stabilized power supply is used, the short-circuit phenomenon cannot be avoided due to load abnormity, and in order to enable the linear voltage-stabilized power supply to have higher reliability and safety, an output short-circuit protection circuit is very necessary.
The design idea of the output short-circuit protection circuit generally includes two kinds: one is a current sampling type short-circuit protection circuit, and the other is a voltage sampling type short-circuit protection circuit. A current sampling type short-circuit protection circuit adopts a small-resistance (generally m omega level) resistor to directly or indirectly sample output current, sets output threshold current, and starts working when the output current is larger than the threshold current. The current sampling type short-circuit protection circuit is an overcurrent protection mode, when the protection circuit is started, the output is turned off, the output current is rapidly reduced, and when the output current is smaller than the output threshold current, the protection circuit stops protection work. Therefore, the current sampling type short-circuit protection circuit is usually a kind of hiccup type protection, and the power consumed by the sampling resistor is large.
The voltage sampling type short-circuit protection circuit is used for directly or indirectly sampling output voltage, when the output short-circuit occurs, the voltage of a sampling point becomes very low, even 0V, and at the moment, the short-circuit protection circuit starts to work and turns off the working state of the circuit. When the circuit is in an off state, the output voltage is 0V, and the sampling value of the short-circuit protection circuit to the output voltage is also 0V. Therefore, the voltage sampling type short-circuit protection circuit is 'off' type protection, and under the protection state, the power consumption of the circuit is very small, and the circuit is safer and more reliable. When the output end is short-circuited and withdrawn, the short-circuit protection circuit stops the protection work, and the circuit immediately restores to the normal working state.
At present, the applicant provides a linear stabilized power supply output short-circuit protection circuit aiming at the problems that the design of the short-circuit protection circuit of the stabilized power supply is complicated, the power loss of the current sampling type hiccup type protection circuit is large, the voltage sampling type short-circuit protection circuit is difficult to restart, and the time from voltage sampling to the interruption of the output of the stabilized power supply is long.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a linear constant voltage power supply output short-circuit protection circuit to solve the problem that proposes among the above-mentioned background art.
In order to achieve the above object, the utility model provides a following technical scheme:
the output end of the voltage comparator is connected with a power supply through a pull-up resistor and is also connected with the cathode of an isolation diode, and the anode of the isolation diode is connected to the output control end of the stabilized voltage power supply; the inverting input end of the voltage comparator is connected with the reference voltage provided by the reference circuit, and the non-inverting input end of the voltage comparator is connected with the output voltage of the stabilized voltage supply through the input resistor.
As an improvement of the present invention, in order to provide a suitable reference voltage for the voltage comparator, the reference circuit includes at least two voltage dividing resistors and a reference voltage led out from the regulated power supply, one end of each voltage dividing resistor is connected to the reference voltage after being connected in series, and the other end of each voltage dividing resistor is grounded; and the output end of the divider resistor is connected with the inverting input end of the voltage comparator.
As the utility model discloses an improvement scheme, in order to slow down reference voltage's establishment, at least one divider resistance's both ends are parallelly connected to have the start-up to restrain electric capacity.
As the utility model discloses an improvement scheme, in order to prevent that short-circuit protection circuit influences the normal work of constant voltage power supply, the voltage comparator is OC door output comparator.
Has the advantages that: the utility model adopts the voltage sampling mode, tracks the abnormal change of the output voltage by directly sampling the output voltage, and has the advantages of simple circuit and quick response time; when the output of the voltage-stabilized power supply is short-circuited, the short-circuit protection circuit can immediately turn off the output control of the voltage-stabilized power supply, so that the turn-off protection is realized, and the safety and the reliability of the circuit are improved.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention;
in the figure: 1-a regulated power supply circuit; 2-short-circuit protection circuit.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
In embodiment 1, referring to fig. 1, the regulated power supply circuit includes an output transistor V1, a voltage reference source N12, and an error amplifier N11, wherein the output transistor V1 is an NMOS transistor, and a D terminal of the output transistor V1 is connected to an input voltage Vin and an S terminal is an output terminal to output a control voltage Vout. The voltage-stabilized power supply circuit comprises sampling resistors R12 and R13, wherein one end of the sampling resistor R12 is connected with the S pole of the output adjusting tube V1 after being connected with the R13 in series, the other end of the sampling resistor R12 is grounded, the sampling resistor R is mainly used for dividing and sampling the output voltage Vout, and the sampling value is input to the inverting input end of the error amplifier N11.
A reference end of the voltage reference source N12 outputs a reference voltage Vref1, and the reference voltage Vref1 is input to a non-inverting input end of the error amplifier N11; the output end of the error amplifier N11 is connected to the G pole of the output adjusting tube V1 through a current limiting resistor R11. The sampling resistors R12 and R13, the error amplifier N11 and the voltage reference source N12 form a sampling feedback network, and the output adjusting tube V1 is regulated or controlled in a closed loop mode. The current limiting resistor R11 is used for reducing the dynamic gain of the loop when the stabilized voltage supply circuit 1 works normally, thereby reducing the output ripple voltage; when the output of the linear voltage-stabilized power supply 1 is short-circuited, the error amplifier N11 outputs a high level, the voltage comparator N2 outputs a low level, and at the moment, the R11 plays a role in limiting the output current of the error amplifier N11 and ensuring the working safety of the error amplifier N11.
When the output voltage Vout is increased by some factor, the sampled value of the output voltage is increased and is greater than the reference voltage Vref1, at this time, the output voltage Vo of the error amplifier N11 is decreased, the input control voltage VGS (V1) of the output adjusting tube V1 is decreased, and the bias voltage VDS (V1) is increased, so that the output voltage Vout is decreased, that is, Vout ═ → Vo (N11) ↓ → VGS (V1) ↓ → VDS (V1) → Vout ↓, and the output voltage Vout tends to be stable. When the output voltage Vout is lowered by some factor, the sampled value of the output voltage Vout is lowered, and when the output voltage Vout is smaller than the reference voltage Vref1, the output voltage Vo of the error amplifier N11 is increased, the input control voltage VGS (V1) of the output adjustment transistor V1 is increased, and the bias voltage VDS (V1) is decreased, so that the output voltage Vout is raised, that is, Vout ↓ (N11) → VGS (V1) → VDS (V1) ↓ → Vout ×, and the output voltage Vout tends to be stable. The stabilization of the output voltage is realized by a closed-loop feedback system.
The embodiment provides a linear voltage-stabilized power supply output short-circuit protection circuit, which comprises a voltage comparator N2, a reference circuit and an isolation diode V21, wherein the output end of the voltage comparator N2 is connected with a power supply Vin through a pull-up resistor R24, and is also connected with the cathode of the isolation diode V21, and the anode of the isolation diode V21 is connected with the output control end of the voltage-stabilized power supply, namely the G pole of an output adjusting tube V1 is connected; the inverting input end of the voltage comparator is connected with a reference voltage Vref2 provided by a reference circuit, and the non-inverting input end of the voltage comparator is connected with the output voltage Vout of the regulated power supply through an input resistor R21.
The implementation principle of the embodiment is that the short-circuit protection circuit 2 directly collects the output voltage Vout, the output voltage Vout is connected to the non-inverting input end of the voltage comparator N2 through the input resistor R21, the reference voltage Vref1 is divided into the reference voltage Vref2 through the voltage dividing resistor and is input to the inverting input end of the voltage comparator N2, the output end of the voltage comparator N2 is connected to the G pole of the output adjusting tube V1 of the voltage stabilizing power supply circuit 1 through the isolating diode V21, and timely control over the output adjusting tube V1 during output short circuit is achieved.
When the output of the linear stabilized voltage power supply 1 is normal, the voltage of the non-inverting input terminal of the voltage comparator N2 is higher than that of the inverting input terminal, and a high level (namely, a voltage value VIN) is output, and because the isolation diode V21 is cut off and is not conducted, the high level output by the voltage comparator N2 does not act on the output adjusting tube V1 of the stabilized voltage power supply circuit 1; when the voltage of the inverting input end of the voltage comparator N2 is higher than that of the non-inverting input end when the voltage stabilized power supply circuit 1 outputs short circuit, the voltage comparator N2 outputs low level (the voltage value is about 0V), the isolation diode V21 is conducted, the voltage G of the output adjusting tube V1 of the voltage stabilized power supply circuit 1 is pulled to be about 0.7V, VGS of the output adjusting tube V1 is about 0.7V at the moment, the VGS is lower than the threshold voltage, the output adjusting tube V1 is immediately cut off, and the voltage stabilized power supply circuit 1 is in an off state, so that the function of 'off protection' when the output short circuit occurs is realized.
The reference circuit comprises at least two voltage-dividing resistors and reference voltage led out from a stabilized voltage supply, the number of the voltage-dividing resistors is two in the embodiment, the two voltage-dividing resistors are respectively R23 and R24, after the voltage-dividing resistors R23 and R24 are connected in series, one end of the voltage-dividing resistor is connected to the reference voltage Vref1, and the other end of the voltage-dividing resistor is grounded; the output end of the divider resistor is connected with the inverting input end of the voltage comparator N2, namely, the reference voltage Vref2 is output to the voltage comparator N2. When the voltage dividing resistors are two, two ends of one voltage dividing resistor are connected in parallel with a start-up suppression capacitor, so that the establishment of the reference voltage Vref2 at the inverting input end of the voltage comparator N2 is slowed down when the circuit is powered on, the voltage comparator N2 is ensured to output high level when the circuit is powered on, and the normal start and the establishment of the working state of the voltage-stabilized power supply circuit 1 are not influenced.
In this embodiment, the voltage comparator is an OC gate output comparator, so that the voltage value when the voltage comparator N2 outputs a high level is the supply voltage value Vin, and it is ensured that the isolation diode V21 is always in a reverse bias state when the regulated power supply circuit 1 works normally, thereby preventing the short-circuit protection circuit 2 from affecting the normal work of the regulated power supply circuit 1.
The utility model adopts the voltage sampling mode, tracks the abnormal change of the output voltage by directly sampling the output voltage, and has the advantages of simple circuit and quick response time; when the output of the voltage-stabilized power supply is short-circuited, the short-circuit protection circuit can immediately turn off the output control of the voltage-stabilized power supply, so that the turn-off protection is realized, and the safety and the reliability of the circuit are improved.
Although the present description is described in terms of embodiments, not every embodiment includes only a single embodiment, and such description is for clarity only, and those skilled in the art should be able to integrate the description as a whole, and the embodiments can be appropriately combined to form other embodiments as will be understood by those skilled in the art.
In the description of the present invention, it is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, 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 process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Therefore, the above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application; all changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
Claims (4)
1. The output short-circuit protection circuit of the linear stabilized voltage supply comprises a voltage comparator, a reference circuit and an isolation diode, and is characterized in that the output end of the voltage comparator is connected with a power supply through a pull-up resistor and is also connected with the cathode of the isolation diode, and the anode of the isolation diode is connected with the output control end of the stabilized voltage supply; the inverting input end of the voltage comparator is connected with the reference voltage provided by the reference circuit, and the non-inverting input end of the voltage comparator is connected with the output voltage of the stabilized voltage supply through the input resistor.
2. The output short-circuit protection circuit of a linear stabilized voltage power supply according to claim 1, characterized in that the reference circuit comprises at least two voltage-dividing resistors and a reference voltage led out from the stabilized voltage power supply, wherein one end of the voltage-dividing resistors is connected to the reference voltage after being connected in series, and the other end of the voltage-dividing resistors is grounded; and the output end of the divider resistor is connected with the inverting input end of the voltage comparator.
3. The output short-circuit protection circuit of a linear voltage-stabilized power supply according to claim 2, wherein a start-up suppression capacitor is connected in parallel to two ends of at least one voltage-dividing resistor.
4. The output short-circuit protection circuit of a linear voltage-stabilized power supply according to claim 1 or 3, wherein the voltage comparator is an OC gate output comparator.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020698185.9U CN212085808U (en) | 2020-04-29 | 2020-04-29 | Linear voltage-stabilized power supply output short-circuit protection circuit |
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| CN202020698185.9U CN212085808U (en) | 2020-04-29 | 2020-04-29 | Linear voltage-stabilized power supply output short-circuit protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115189569A (en) * | 2022-07-23 | 2022-10-14 | 广州精信仪表电器有限公司 | External supply sensor power supply circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115189569A (en) * | 2022-07-23 | 2022-10-14 | 广州精信仪表电器有限公司 | External supply sensor power supply circuit |
| CN115189569B (en) * | 2022-07-23 | 2024-01-30 | 广州精信仪表电器有限公司 | External supply sensor power supply circuit |
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