CN220754335U - Overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment - Google Patents
Overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment Download PDFInfo
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- CN220754335U CN220754335U CN202322481257.0U CN202322481257U CN220754335U CN 220754335 U CN220754335 U CN 220754335U CN 202322481257 U CN202322481257 U CN 202322481257U CN 220754335 U CN220754335 U CN 220754335U
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Abstract
The overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is arranged in the POE power supply or power receiving circuit and comprises a MOS tube control circuit and a MOS tube of the POE, and a self-recovery fuse, a thermistor and a load are connected in series between a D pin of the MOS tube and positive power supply output to form the protection circuit. According to the technical scheme, the technical problem that the response speed of the self-recovery fuse is too slow to play a role in protection in the prior art is solved, and the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is simple and practical in circuit structure, low in cost, high in reliability and high in applicability.
Description
Technical Field
The utility model relates to the field of protection circuits, in particular to an overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment.
Background
The POE power supply and receiving technology utilizes the existing network architecture, does not change the original network, and can realize one device by only replacing one network device capable of supplying power and replacing one network device capable of receiving power, and supplies power to the other device through the network. POE power supply equipment is divided into standard POE power supply equipment and nonstandard POE power supply equipment.
Standard POE power supply equipment: is a power supply device that meets the ieee802.3af and ieee802.3at standards. Before power is supplied to the power receiving equipment, whether the power receiving equipment meets the handshake condition of a protocol or not is detected, and the power supply is started to the power receiving equipment when the handshake condition is met; after power-on, the protection circuit for various working conditions also needs to be designed by equipment manufacturers according to the actual conditions; however, the MOS tube is not protected at the moment of power-on, and if the current is too large or the load is short-circuited at the moment, the MOS tube can be burnt out no matter the power supply equipment or the power receiving equipment. Aiming at the situation, the utility model has good protection effect.
Nonstandard POE power supply equipment: the power supply device directly supplies power to the power receiving device through the network cable, and if the power supply or the power receiving device has overlarge current or is in short circuit, the MOS tube and even the power supply device or the power receiving device are burnt. Aiming at the situation, the utility model has good protection effect.
POE power receiving equipment is divided into standard POE power receiving equipment and nonstandard POE power receiving equipment.
The standard POE powered device is a powered device that meets the ieee802.3af and ieee802.3at standards, and when connected to the standard POE powered device, the standard POE powered device sends a protocol handshake query signal to the powered device of the standard POE, and if the handshake condition is met, the POE powered device supplies power to the standard POE powered device. If the powered device is a nonstandard POE powered device, the powered device cannot supply power after being connected with a standard POE power supply device.
In the existing POE power supply system, the situation that nonstandard POE and standard POE are mixed simultaneously occurs, so that once overcurrent or short circuit occurs at the moment of power supply, MOS (metal oxide semiconductor) tubes in a power supply or power receiving loop can be burnt. Aiming at the situation, the utility model has good protection effect.
All the above conditions require over-current and short-circuit protection.
In the prior art, a self-recovery fuse is connected in series in a POE power supply loop, and the circuit can play a role in protecting the overcurrent of the circuit, but can not play a role in protecting the instant short circuit of the circuit. Illustrating: for example, the normal current of the circuit is 1A, the continuous conduction current of the MOS tube is 2A, the MOS tube can work for a long time, 5A can last for 60 seconds, the maximum impact current is 10A, the maximum impact current can last for 1 second, the fuse is self-recovered, the normal current 1A, the 2A current is protected after 10 seconds, the short-circuit protection is delayed for 5 seconds, and the maximum current is 15A when the circuit is short-circuited; if the power-on instant short circuit occurs, the mos tube is burnt out in less than 1 second, and the self-recovery fuse acts after 5 seconds; if the current of the circuit is 2A of overload, the MOS tube can work for a long time and cannot burn out, and the fuse is automatically restored to be protected after 10 seconds.
The existing protection circuit of MOS using self-recovery fuse has protection effect on the over-current of the circuit, but when the circuit suddenly short-circuits and the current instantaneously exceeds the bearing capacity of the MOS tube, the response speed of the self-recovery fuse is too slow to play a role in protection.
Disclosure of Invention
The utility model aims to solve the technical problems of the existing structure and provides an overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment.
In order to solve the technical problems, the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is adopted and is arranged in the POE power supply or power receiving circuit, and the POE power supply or power receiving circuit comprises a MOS tube control circuit of POE, a MOS tube, a load and a self-recovery fuse, wherein the self-recovery fuse, a thermistor and the load are connected in series between a D pin of the MOS tube and the output of a positive power supply to form the protection circuit.
Preferably, N protection circuits are arranged between the D pin of the MOS tube and the positive power supply output, the N protection circuits are mutually connected in parallel, and each protection circuit is connected with a self-recovery fuse, a thermistor and a load in series.
Preferably, the thermistor and the load are connected in series to form a circuit a, and after being connected in parallel, the circuit a is connected in series with a self-recovery fuse to form a circuit b, wherein the circuit b is a protection circuit between a D pin of the MOS tube and the positive power supply output.
Preferably, the circuit b is I-bar, the I-bar circuits b are mutually connected in parallel to form a protection circuit between the D pin of the MOS tube and the positive power supply output.
Preferably, the number of the loads is J, and the J loads are connected in parallel and then connected in series with the self-recovery fuse and the thermistor to form a protection circuit between the D pin of the MOS tube and the positive power supply output.
The beneficial effects of the utility model are as follows: the utility model relates to a circuit for protecting overcurrent and short circuit of a poe power supply and receiving circuit by using an MOS tube as a switch and connecting a self-recovery fuse and a thermistor in series in the circuit. Based on a basic circuit formed by connecting a self-recovery fuse and a thermistor in series, the self-recovery fuse, the thermistor and a load are connected in series in any order; the self-recovery fuse comprises a plurality of loads, wherein each load is connected with 1 thermistor in series and then connected with 1 self-recovery fuse in series; the self-recovery fuse comprises a plurality of loads, wherein each load is connected with 1 thermistor in series and then connected with 1 public self-recovery fuse in parallel; the protection circuit is formed by grouping a plurality of loads, wherein each load is connected with a common self-recovery fuse in series with the respective load group after being connected with 1 thermistor in series; the protection circuit is composed of 1 thermistor in series and 1 self-recovery fuse in series. Through the technical scheme, the power supply circuit without the MOS tube as a switch has the same protection function on overcurrent and short circuit of the circuit; and because of the existence of the thermistor, the short-circuit current is greatly reduced, and the impact on a power supply circuit is also greatly reduced.
Drawings
Fig. 1 is a circuit diagram of a POE power supply or power receiving circuit, with MOS transistors directly connected to a load without protection;
FIG. 2 is a prior art circuit diagram;
FIG. 3 is a circuit diagram of example 1;
FIG. 4 is a circuit diagram of example 2;
FIG. 5 is a circuit diagram of example 5;
FIG. 6 is a circuit diagram of embodiment 4;
fig. 7 is a circuit diagram of example 5.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the utility model; all other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
Term interpretation:
POE: power Over Ethernet, for supplying power through a network cable.
POE power supply equipment: a device for providing electrical energy to other network devices via a network cable; for short PSE.
POE powered device: the equipment receives power supply through a network cable; abbreviated as PD.
POE power supply circuit: and a circuit for controlling power supply output is arranged inside the POE power supply equipment.
POE power receiving circuit: and a circuit for controlling power supply input inside the POE power receiving equipment.
An overcurrent protection circuit: when the self or load current of the equipment is too large and exceeds a limited value, the circuit starts a protection function to avoid burning the equipment.
Short-circuit protection circuit: when the equipment or the load is short-circuited, the circuit starts the protection function, so that the equipment is prevented from being burnt.
MOS tube: usually, a semiconductor field effect transistor is called an MOS transistor, and plays a role of a switch in a POE circuit.
Self-restoring fuses: is a semiconductor material with 1 positive temperature coefficient, and has larger and larger resistance with the rise of temperature, and finally has the breaking effect; the advantages are low temperature, low resistance, and low response speed.
Negative temperature coefficient thermistor: a semiconductor component with resistance value is called as a negative temperature coefficient thermistor as the temperature increases and the resistance value becomes smaller.
Load: in the power supply loop, electric energy is consumed for realizing the part of the required functions.
PD versus load distinction: the PD is also a load, in particular a load of a poe power sourcing equipment PSE.
As shown in fig. 1, the POE power supply or power receiving circuit, the MOS transistor is directly connected to the load without protection. The protection circuit of the prior art is shown in fig. 2, in which a self-recovery fuse is connected in series in a POE power supply loop. But the response speed of the self-recovery fuse is too slow for the circuit to suddenly short, and the protection effect is not achieved.
Example 1:
as shown in fig. 3, the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is arranged in the POE power supply or power receiving circuit, and a self-recovery fuse 4, a thermistor 3 and a load 2 are connected in series on a protection circuit comprising a POE MOS tube control circuit, a MOS tube 1, a D pin of the MOS tube 1 and a positive power supply output. In specific use, the sequential positions of the self-restoring fuse 4, the thermistor 3 and the load 2 are changeable, so long as the self-restoring fuse 4, the thermistor 3 and the load 2 are in a series relationship.
When the self-recovery fuse is specifically used, the normal current of the circuit is 1A, the continuous conduction current of the MOS tube 1 is 2A, the MOS tube can work for a long time, 5A can last for 60 seconds, the maximum impact current is 10A, the maximum impact current can last for 1 second, the normal current of the self-recovery fuse 4 is 1A, the 2A current is protected after 10 seconds, the short-circuit protection is delayed for 5 seconds, and the nominal 10 omega of the thermistor 3 is under the normal temperature of 25 ℃.
The positive and negative power inputs are supplied with 1 forward supply voltage, typically between 36V-55V, and no more than 57V at maximum.
And controlling the MOS tube 1 to be conducted, if the load 2 is short-circuited at the moment, the voltage is fully added to the self-recovery fuse 4 and the thermistor 3, at the moment, the resistance value on the thermistor 3 is 10Ω, the resistance of the self-recovery fuse 4 is very small 1 Ω, the current is equal to 55V/1Ω=5A, the MOS tube 1 cannot be burnt out immediately, the thermistor 3 and the self-recovery fuse 4 can generate heat along with the continuous flow of the current, and the resistance of the self-recovery fuse 4 can be increased along with the increase of the temperature due to the positive temperature coefficient, the larger the resistance is, the faster the temperature rise is, and the faster the resistance can be increased. The thermistor 3 has a negative temperature coefficient, so that the temperature is reduced with the increase of the temperature, the resistance is smaller with the increase of the temperature, the temperature rise is slower, and the resistance reducing speed is slower. So the total resistance will increase over time and the total current will decrease until the resistance of the self-healing fuse 4 is sufficiently high and the current in the supply loop approaches 0 and the protection is completed.
Because the protection circuit is connected with the self-recovery fuse and the thermistor in series, the maximum current at the moment of short circuit is 5A, the maximum duration of the MOS tube 1 under 5A is 60 seconds, the self-recovery fuse 4 is protected after 10 seconds under the current exceeding 2A, the MOS tube 1 is intact at the moment, and the description of the 1 complete protection process is completed. Although the self-recovery fuse and the thermistor are different with different voltages between the positive power supply input and the negative power supply input or different parameters of the MOS tube 1, the protection principle and effect are not affected.
Example 2:
as shown in fig. 4, the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is provided in a POE power supply or power receiving circuit, and includes a MOS transistor control circuit and a MOS transistor 1 of POE. N protection circuits are arranged between the D pin of the MOS tube 1 and the positive power supply output, the N protection circuits are mutually connected in parallel, and each protection circuit is connected with a self-recovery fuse 4, a thermistor 3 and a load 2 in series. The number of N is determined according to the actual situation. Therefore, in the switching loop of the MOS tube 1, a plurality of loads 2 are arranged, each load 2 is respectively connected in series with the self-recovery fuse 4 and the thermistor 3, any load 2 is in overcurrent or short circuit, and the protection effect is achieved, and the overcurrent of other loads is not influenced.
Example 3:
as shown in fig. 5, the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is provided in a POE power supply or power receiving circuit, and includes a MOS transistor control circuit and a MOS transistor 1 of POE. The thermistor 3 and the load 2 are connected in series to form a circuit a, M circuits a are connected in parallel and then connected in series with a self-recovery fuse 4 to form a circuit b, and the circuit b is a protection circuit between the D pin of the MOS tube 1 and the positive power supply output. The number of M is determined according to the actual situation. The plurality of loads 2, each of which is connected in series with a thermistor 3 and then connected in series with a self-recovery fuse 4, is very suitable for the case that the whole circuit is protected as long as one load is short-circuited, compared with the embodiment 2.
Example 4:
as shown in fig. 6, the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is provided in a POE power supply or power receiving circuit, and includes a MOS transistor control circuit and a MOS transistor 1 of POE. The thermistor 3 and the load 2 are connected in series to form a circuit a, M circuits a are connected in parallel and then connected in series with a self-recovery fuse 4 to form a circuit b, the circuit b is I, the I circuits b are connected in parallel, and a protection circuit between the D pin of the MOS tube 1 and the positive power supply output is formed. The number of M and the number of I are determined as the case may be. In the figure, M is 2, i is 2, after 4 loads 2 are connected in series with a thermistor 3, the thermistor 3 is divided into 2 groups, and each group shares 1 self-recovery fuse 4, and the design has the advantages that the circuit cost of the embodiment 3 is slightly high, but 1 group is short-circuited, and the other 1 group can work, so that the flexibility is higher.
Example 5:
as shown in fig. 7, the overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment is provided in a POE power supply or power receiving circuit, and includes a MOS transistor control circuit and a MOS transistor 1 of POE. The number of the loads 2 is J, and the J loads 2 are connected in parallel and then connected with the self-recovery fuse 4 and the thermistor 3 in series to form a protection circuit between the D pin of the MOS tube 1 and the positive power supply output. Embodiment 5 is the lowest cost protection scheme in all embodiments, any 1 load 2 in the loop is shorted, and the other loads are protected and not powered.
In addition, the utility model has protection effect on the overcurrent and short circuit of the power supply circuit without the MOS tube as a switch; and because of the existence of the thermistor, the short-circuit current is greatly reduced, and the impact on a power supply circuit is also greatly reduced.
Claims (5)
- Overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment sets up in POE power supply or power receiving circuit, including MOS pipe control circuit, MOS pipe (1), load (2) and the self-recovery fuse (4) of POE, its characterized in that: a self-recovery fuse (4), a thermistor (3) and a load (2) are connected in series between a D pin of the MOS tube (1) and the positive power supply output to form a protection circuit.
- 2. The over-current and short-circuit protection circuit of POE power sourcing and sourcing equipment of claim 1, wherein: n protection circuits are arranged between the D pin of the MOS tube (1) and the positive power supply output, the N protection circuits are mutually connected in parallel, and each protection circuit is connected with a self-recovery fuse (4), a thermistor (3) and a load (2) in series.
- 3. The over-current and short-circuit protection circuit of POE power sourcing and sourcing equipment of claim 1, wherein: the thermistor (3) and the load (2) are connected in series to form a circuit a, M circuits a are connected in parallel and then connected with a self-recovery fuse (4) in series to form a circuit b, and the circuit b is a protection circuit between the D pin of the MOS tube (1) and the positive power supply output.
- 4. The over-current and short-circuit protection circuit for POE power sourcing and sourcing equipment of claim 3, wherein: the circuit b is I, the I circuits b are mutually connected in parallel to form a protection circuit between the D pin of the MOS tube (1) and the positive power supply output.
- 5. The over-current and short-circuit protection circuit of POE power sourcing and sourcing equipment of claim 1, wherein: the number of the loads (2) is J, and the J loads (2) are connected in parallel and then connected with the self-recovery fuse (4) and the thermistor (3) in series to form a protection circuit between the D pin of the MOS tube (1) and the positive power supply output.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322481257.0U CN220754335U (en) | 2023-09-13 | 2023-09-13 | Overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322481257.0U CN220754335U (en) | 2023-09-13 | 2023-09-13 | Overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment |
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| Publication Number | Publication Date |
|---|---|
| CN220754335U true CN220754335U (en) | 2024-04-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322481257.0U Active CN220754335U (en) | 2023-09-13 | 2023-09-13 | Overcurrent and short-circuit protection circuit of POE power supply and power receiving equipment |
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| CN (1) | CN220754335U (en) |
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- 2023-09-13 CN CN202322481257.0U patent/CN220754335U/en active Active
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