CN103050932A - Electronic switch circuit for power over Ethernet - Google Patents

Electronic switch circuit for power over Ethernet Download PDF

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Publication number
CN103050932A
CN103050932A CN2012105301542A CN201210530154A CN103050932A CN 103050932 A CN103050932 A CN 103050932A CN 2012105301542 A CN2012105301542 A CN 2012105301542A CN 201210530154 A CN201210530154 A CN 201210530154A CN 103050932 A CN103050932 A CN 103050932A
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CN
China
Prior art keywords
output
electronic switch
comparator
switching circuit
circuit
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Pending
Application number
CN2012105301542A
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Chinese (zh)
Inventor
阮世良
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Shenzhen Gospell Electric Technology Co Ltd
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Shenzhen Gospell Electric Technology Co Ltd
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Priority to CN2012105301542A priority Critical patent/CN103050932A/en
Publication of CN103050932A publication Critical patent/CN103050932A/en
Pending legal-status Critical Current

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Abstract

The invention discloses an electronic switch circuit for power over Ethernet. The electronic switch circuit comprises positive/negative input ends, positive/negative output ends, an output current sampling circuit, a control module and an electronic switch, wherein the electronic switch is connected between an input end and an output end of the electronic switch circuit in series; the electronic switch is turned on/off under the control of the control module according to an output current sampling value provided by the output current sampling circuit, and the electronic switch is turned off under the control of the control module to carry out current overload protection when output current is overloaded; and after the electronic switch is turned off, the output load condition is detected by the control module to restart the circuit. The electronic switch circuit disclosed by the invention has the advantages that overcurrent output control can be realized through the adoption of the electronic switch in the control of output, and output work is restarted under the condition that the output load returns to a normal value; and overload protection and short-circuit protection can be realized, and the requirement of application under loaded, power-on and other various conditions can be met.

Description

A kind of electronic switching circuit for Power over Ethernet
[technical field]
The present invention relates to the Power over Ethernet technology, relate in particular to a kind of electronic switching circuit for Power over Ethernet.
[background technology]
Power over Ethernet technology (POE) is in wireless coverage, security protection, application etc. occasion is more and more extensive, be the various application of standard, the IEEE802.3 standard code two kinds of standard application, wherein the long-term power of af standard code is 13w, the long-term power of at standard code is 25w, in the application of satisfying this standard, need adopt PSE(power source equipment at feeder ear) equipment powers, need adopt PD(power device at receiving end) be subjected to electric control, by standard code a series of power detection and Power Limitation related protocol and application.The application of satisfying this standard agreement can realize safe application.
Because the POE cost of standard agreement is very high, and in some practical applications, wish to use the power requirement that is above standard, in some low-end applications, have various nonstandard application demands to exist, a large amount of POE products that do not meet standard-required that use of these occasions.In these off-gauge application, the product of existing market is only supplied with power supply network interface output (most of employing 4,5 just, 7,8 negative powering modes), the recoverable fuse of perhaps only in the loop, connecting, each port does not have current limliting, can't realize the accurate power restriction of port, there is very large potential safety hazard in these nonstandard application; The operate time that can recover to insure is very long, and fault freedom is poor.
[summary of the invention]
The technical problem to be solved in the present invention provides a kind of nonstandard application that is suitable for, and automatically opens defencive function, can prevent potential safety hazard, the electronic switching circuit that is used for Power over Ethernet that fault freedom is good.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is, a kind of electronic switching circuit for Power over Ethernet, comprise positive-negative input end, positive-negative output end, output current sample circuit, control module and electronic switch, electronic switch are serially connected between the input and output of electronic switching circuit; The output current sampled value that control module provides according to the output current sample circuit is controlled the break-make of electronic switch, and when the output current excess load, the control electronic switch turn-offs, and carries out overcurrent protection; Electronic switch closes has no progeny, and control module detects the output loading situation, carries out circuit and restarts.
Above-described electronic switching circuit for Power over Ethernet; comprise output voltage sampling circuit; described control module is single-chip microcomputer; the output voltage sampled value that control module provides according to output voltage sampling circuit is controlled the break-make of electronic switch; when the output voltage excess load; the control electronic switch turn-offs, and carries out the voltage overload protection.
Above-described electronic switching circuit for Power over Ethernet; the output voltage sampled value that the output current sampled value that control module provides according to the output current sample circuit and output voltage sampling circuit provide; determine whether excess load of power output; when the power output excess load; the control electronic switch turn-offs, and carries out the power overload protection.
Above-described electronic switching circuit for Power over Ethernet, electronic switch close has no progeny, and control module control electronic switch is restarted, and single-chip microcomputer sends pwm waveform, and the control electronic switch is in the PWM operating state, and output voltage is lower than input voltage.
Above-described electronic switching circuit for Power over Ethernet is being restarted the stage, and control module is normal, overload or short circuit according to current sampling data and voltage sample value decision circuitry operating state, when load is normal, and the electronic switch conducting; When load short circuits or overload, electronic switch is by the work of PWM control current limliting.
Above-described electronic switching circuit for Power over Ethernet, described electronic switch is metal-oxide-semiconductor, described current sampling circuit comprises current sampling resistor, the negative input of the first termination electronic switching circuit of current sampling resistor, the source electrode of the second termination metal-oxide-semiconductor of current sampling resistor, the drain electrode of metal-oxide-semiconductor connects the cathode output end of electronic switching circuit; The grid of metal-oxide-semiconductor connects the control signal output of control module, the current sampling signal input of the second termination control module of current sampling resistor.
Above-described electronic switching circuit for Power over Ethernet, described control module comprises the first comparator and the second comparator, the second end of the anti-phase input termination current sampling resistor of the first comparator, the in-phase input end of the first comparator connects the first reference voltage; The in-phase input end of output termination second comparator of the first comparator, anti-phase input termination second reference voltage of the second comparator; The grid of the output termination metal-oxide-semiconductor of the second comparator.
Above-described electronic switching circuit for Power over Ethernet comprises the first resistance, the second resistance, the 3rd resistance and the first diode, a chip termination working power of the first resistance, the output of another termination the first comparator; The output of the first comparator connects the in-phase input end of the second comparator by the second resistance; The negative electrode of the first diode connects the output of the first comparator, and anode connects the in-phase input end of the second comparator; The in-phase input end of one termination, second comparator of the 3rd resistance, the output of another termination the second comparator.
Above-described electronic switching circuit for Power over Ethernet comprises the first electric capacity, the in-phase input end of a termination second comparator of the first electric capacity, other end ground connection.
Above-described electronic switching circuit for Power over Ethernet comprises input filter capacitor, output filter capacitor, filter inductance and the second diode; The drain electrode of metal-oxide-semiconductor connects the cathode output end of electronic switching circuit by filter inductance, and the anode of the second diode connects the drain electrode of metal-oxide-semiconductor, and negative electrode connects the cathode output end of electronic switching circuit; Output filter capacitor is connected between the positive and negative electrode output of electronic switching circuit; Input filter capacitor is connected between the positive and negative electrode input of electronic switching circuit.
The electronic switching circuit that the present invention is used for Power over Ethernet adopts electronic switch that output is controlled, and when output current surpasses the limit value of setting, automatically opens defencive function, cuts off output, realizes can preventing the generation of security incident to the circuit power restriction.Control module detects the output loading situation after turn-offing output, carries out circuit and restarts, and fault freedom is better.The present invention enough realizes overload protection and short-circuit protection, satisfies the application of being with under the various conditions such as carrying start.
[description of drawings]
The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.
Fig. 1 is the schematic diagram that the present invention is used for the electronic switching circuit embodiment 1 of Power over Ethernet.
Fig. 2 is the schematic diagram that the present invention is used for the electronic switching circuit embodiment 2 of Power over Ethernet.
[embodiment]
The embodiment 1 that is used for the electronic switching circuit of Power over Ethernet in the present invention shown in Figure 1, the electronic switching circuit that is used for Power over Ethernet, comprise positive-negative input end, positive-negative output end, output current sample circuit, output voltage sampling circuit, single-chip microcomputer (MCU), metal-oxide-semiconductor Q1, input filter capacitor C2, output filter capacitor C1, filter inductance T1 and diode D1.
The drain electrode of metal-oxide-semiconductor Q1 connects the cathode output end of electronic switching circuit by filter inductance T1, and the anode of diode D1 connects the drain electrode of metal-oxide-semiconductor Q1, and negative electrode connects the cathode output end of electronic switching circuit.Output filter capacitor C1 is connected between the positive and negative electrode output of electronic switching circuit.Input filter capacitor C2 is connected between the positive and negative electrode input of electronic switching circuit.
Current sampling circuit comprises current sampling resistor R1, the negative input of the first termination electronic switching circuit of current sampling resistor R1, the source electrode of the second termination metal-oxide-semiconductor Q1.The grid of metal-oxide-semiconductor Q1 meets the control signal output Drive of single-chip microcomputer (MCU), the current sampling signal input Is of the second termination single-chip microcomputer (MCU) of current sampling resistor R1.
The first voltage sampling signal input Vin of the cathode output end of voltage sampling circuit connecting electronic switching circuit and single-chip microcomputer (MCU), the second voltage sampled signal input Vs of the cathode output end of connecting electronic switching circuit and single-chip microcomputer (MCU).
The positive and negative electrode input of electronic switching circuit
The break-make of the output current sampled value control metal-oxide-semiconductor Q1 that single-chip microcomputer (MCU) provides according to the output current sample circuit, when the output current excess load of electronic switching circuit, control metal-oxide-semiconductor Q1 turn-offs, and carries out overcurrent protection.
The output voltage sampled value that single-chip microcomputer (MCU) provides according to output voltage sampling circuit is controlled the break-make of metal-oxide-semiconductor Q1, and when electronic switching circuit output voltage excess load, control metal-oxide-semiconductor Q1 turn-offs, and carries out the voltage overload protection.
The output voltage sampled value that the output current sampled value that single-chip microcomputer (MCU) provides according to the output current sample circuit and output voltage sampling circuit provide is carried out computing; determine whether excess load of electronic switching circuit power output; when the power output excess load; control metal-oxide-semiconductor Q1 turn-offs, and carries out the power overload protection.
Metal-oxide-semiconductor Q1 closes and has no progeny, and single-chip microcomputer (MCU) control metal-oxide-semiconductor Q1 is restarted.At this moment, single-chip microcomputer sends pwm waveform, and control metal-oxide-semiconductor Q1 works under the PWM state, because duty ratio is less than 1, this moment, the output voltage of electronic switching circuit was lower than input voltage.
Restarting the stage, single-chip microcomputer (MCU) is normal, overload or short circuit according to current sampling data and voltage sample value decision circuitry operating state, when load is normal, and metal-oxide-semiconductor Q1 conducting.During load short circuits, metal-oxide-semiconductor Q1 turn-offs.During overload, metal-oxide-semiconductor Q1 carries out current limliting work according to the PWM control of single-chip microcomputer (MCU) to electronic switching circuit.
Single-chip microcomputer carries out output voltage sampling and metal-oxide-semiconductor current sample.The basic principle of control is as follows:
When the long-term conducting of metal-oxide-semiconductor, the metal-oxide-semiconductor electric current is output current, but when electric current during greater than set point, single-chip microcomputer turn-offs metal-oxide-semiconductor Q1, and then single-chip microcomputer sends the PWM waveform, and Q1 is restarted control to metal-oxide-semiconductor, detects simultaneously output voltage and metal-oxide-semiconductor electric current.According to the detection of output current and voltage, can realize that output loading is normal, overload, the judgement of the various states such as short circuit; by the judgement of these states, metal-oxide-semiconductor Q1 is carried out conducting, turn-off the various controls such as PWM; thereby realize output, protection, the various operating states such as current limliting.Adopt the method for software, can carry out various intelligent decision and control, thereby realize output overloading, the protection of short circuit and restarting.
Under restarting mode; electronic switch circuit for working is in being equivalent to a Buck circuit working state; output voltage is lower than input voltage; this moment detected electrons switching current or output current; and output voltage, judge the state of output loading, judging that output loading is normal; overload, the various states such as short circuit also carry out correspondingly restarting or protecting action.
This electronic switching circuit has three kinds of operating states:
A. electronic switch pass-through state: the complete conducting of electronic switch, input voltage is directly exported.
B. electronic switch off state: electronic switch turn-offs fully, and output is turn-offed, and this is a kind of guard mode.
C. electronic switch PWM operating state: this moment, electronic switch was operated in the Buck circuit state, output voltage is lower than input voltage, according to testing result, can be to output voltage, output currents etc. carry out corresponding judgement, determine whether output loading is normal, overload, perhaps short circuit etc., and carry out the conversion of various operating states.
During real work, normal operation is in A condition, and Protection is at the B state, restarts or is operated in the C state during judgement of output loading, by the conversion between these states, realizes the Current limited Control to output loading.
Employing is with upper type, can carry out Current limited Control behind the output overloading, also can realize output short circuit protection, and perhaps long-term work under the output short-circuit state can not damage, the reliable use in convenient actual the use.
The present invention be used for Power over Ethernet electronic switching circuit embodiment 2 as shown in Figure 2.The main circuit of embodiment 2 is identical with the main circuit of embodiment 1, but control circuit is realized that by discrete component control circuit comprises the first comparator U3-C and the second comparator U3-D.
The second end of the anti-phase input termination current sampling resistor R2 of the first comparator U3-C, the in-phase input end of the first comparator U3-C meets the first reference voltage ISET.The output of the first comparator U3-C connects the in-phase input end of the second comparator U3-D, anti-phase input termination the second reference voltage V REF of the second comparator U3-D by resistance R 37.The grid of the output termination metal-oxide-semiconductor Q2 of the second comparator U3-D.
One chip termination working power VDD of resistance R 36, the output of another termination the first comparator U3-C.The negative electrode of diode D7 connects the output of the first comparator U3-C, and anode connects the in-phase input end of the second comparator U3-D.The in-phase input end of one termination, the second comparator U3-D of resistance R 23, the output of another termination the second comparator U3-D.The in-phase input end of one termination, the second comparator U3-D of capacitor C 6, other end ground connection.
The input voltage that detects inverting input as the first comparator U3-C is during less than given voltage ISET, and the first comparator U3-C exports high level, and the second comparator U3-D also exports high level, the complete conducting of metal-oxide-semiconductor Q2; The input voltage that detects inverting input as the first comparator U3-C is during greater than given voltage ISET, the first comparator U3-C output low level causes the action as the second comparator U3-D simultaneously, is output as low level, the grid voltage of metal-oxide-semiconductor Q2 is low, and metal-oxide-semiconductor Q2 is turn-offed; Metal-oxide-semiconductor Q2 closes and to have no progeny, and the first comparator U3-C output transfers high level to, and therefore the second comparator U3-D is turn-offing metal-oxide-semiconductor Q2 after set time, and it becomes the output high level automatically, makes metal-oxide-semiconductor Q2 conducting.Because the output of the end of electronic switching circuit has the effect of inductance L, the electric current of detection can not suddenly change, if load is less, output current can not meet or exceed the current value I set of setting, and metal-oxide-semiconductor Q2 is with long-term conducting; If load goes beyond the scope or output short-circuit, will cause metal-oxide-semiconductor Q2 again to turn-off, operating state in this case is the fixedly PWM operating state of turn-off time, output voltage will descend, thus output current has obtained restriction.Adopt this principle, can realize the current limliting of power output and the machine that automatically opens after the protection, and can realize conditional power stage in the situation of output short-circuit.

Claims (10)

1. electronic switching circuit that is used for Power over Ethernet, comprise positive-negative input end and positive-negative output end, it is characterized in that, comprise the output current sample circuit, control module and electronic switch, electronic switch are serially connected between the input and output of electronic switching circuit; The output current sampled value that control module provides according to the output current sample circuit is controlled the break-make of electronic switch, and when the output current excess load, the control electronic switch turn-offs, and carries out overcurrent protection; Electronic switch closes has no progeny, and control module detects the output loading situation, carries out circuit and restarts.
2. the electronic switching circuit for Power over Ethernet according to claim 1; it is characterized in that; comprise output voltage sampling circuit; described control module is single-chip microcomputer; the output voltage sampled value that control module provides according to output voltage sampling circuit is controlled the break-make of electronic switch; when the output voltage excess load, the control electronic switch turn-offs, and carries out the voltage overload protection.
3. the electronic switching circuit for Power over Ethernet according to claim 2; it is characterized in that; the output voltage sampled value that the output current sampled value that control module provides according to the output current sample circuit and output voltage sampling circuit provide; determine whether excess load of power output; when the power output excess load; the control electronic switch turn-offs, and carries out the power overload protection.
4. the electronic switching circuit for Power over Ethernet according to claim 2 is characterized in that, electronic switch closes has no progeny, control module control electronic switch is restarted, single-chip microcomputer sends pwm waveform, and the control electronic switch is in the PWM operating state, and output voltage is lower than input voltage.
5. the electronic switching circuit for Power over Ethernet according to claim 4, it is characterized in that, restarting the stage that control module is normal, overload or short circuit according to current sampling data and voltage sample value decision circuitry operating state, when load is normal, the electronic switch conducting; When load short circuits or overload, electronic switch is by the work of PWM control current limliting.
6. the electronic switching circuit for Power over Ethernet according to claim 1, it is characterized in that, described electronic switch is metal-oxide-semiconductor, described current sampling circuit comprises current sampling resistor, the negative input of the first termination electronic switching circuit of current sampling resistor, the source electrode of the second termination metal-oxide-semiconductor of current sampling resistor, the drain electrode of metal-oxide-semiconductor connects the cathode output end of electronic switching circuit; The grid of metal-oxide-semiconductor connects the control signal output of control module, the current sampling signal input of the second termination control module of current sampling resistor.
7. the electronic switching circuit for Power over Ethernet according to claim 6, it is characterized in that, described control module comprises the first comparator and the second comparator, the second end of the anti-phase input termination current sampling resistor of the first comparator, the in-phase input end of the first comparator connects the first reference voltage; The in-phase input end of output termination second comparator of the first comparator, anti-phase input termination second reference voltage of the second comparator; The grid of the output termination metal-oxide-semiconductor of the second comparator.
8. the electronic switching circuit for Power over Ethernet according to claim 7, it is characterized in that, comprise the first resistance, the second resistance, the 3rd resistance and the first diode, a chip termination working power of the first resistance, the output of another termination the first comparator; The output of the first comparator connects the in-phase input end of the second comparator by the second resistance; The negative electrode of the first diode connects the output of the first comparator, and anode connects the in-phase input end of the second comparator; The in-phase input end of one termination, second comparator of the 3rd resistance, the output of another termination the second comparator.
9. the electronic switching circuit for Power over Ethernet according to claim 7 is characterized in that, comprises the first electric capacity, the in-phase input end of a termination second comparator of the first electric capacity, other end ground connection.
10. the electronic switching circuit for Power over Ethernet according to claim 6 is characterized in that, comprises input filter capacitor, output filter capacitor, filter inductance and the second diode; The drain electrode of metal-oxide-semiconductor connects the cathode output end of electronic switching circuit by filter inductance, and the anode of the second diode connects the drain electrode of metal-oxide-semiconductor, and negative electrode connects the cathode output end of electronic switching circuit; Output filter capacitor is connected between the positive and negative electrode output of electronic switching circuit; Input filter capacitor is connected between the positive and negative electrode input of electronic switching circuit.
CN2012105301542A 2012-12-11 2012-12-11 Electronic switch circuit for power over Ethernet Pending CN103050932A (en)

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Cited By (7)

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CN104656486A (en) * 2013-11-18 2015-05-27 鸿富锦精密工业(深圳)有限公司 Energy-saving voltage detection circuit
CN104701808A (en) * 2013-12-04 2015-06-10 联想(北京)有限公司 Power protection chip
CN105471591A (en) * 2015-12-30 2016-04-06 浙江光大通信设备有限公司 POE power supply system and power supply method
CN109450653A (en) * 2018-11-30 2019-03-08 锐捷网络股份有限公司 A kind of Power over Ethernet guard method and device
CN109683550A (en) * 2018-12-21 2019-04-26 济南浪潮高新科技投资发展有限公司 A kind of power on/off system and method
CN110308391A (en) * 2019-06-07 2019-10-08 横店集团英洛华电气有限公司 A kind of low cost current of electric Acquisition Circuit and its acquisition method
CN111812377A (en) * 2019-04-10 2020-10-23 杭州海康威视数字技术股份有限公司 Network power supply detection device

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CN101447729A (en) * 2008-12-24 2009-06-03 北京新雷能有限责任公司 Drive circuit of MOSFET of P ditch in BUCK regulator
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US20080062586A1 (en) * 2006-09-05 2008-03-13 Silicon Laboratories, Inc. Integrated circuit including a switching regulator design for power over Ethernet devices
US20100066169A1 (en) * 2008-09-15 2010-03-18 Silicon Laboratories Inc. Circuit device including multiple parameterized power regulators
CN101447729A (en) * 2008-12-24 2009-06-03 北京新雷能有限责任公司 Drive circuit of MOSFET of P ditch in BUCK regulator
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104656486A (en) * 2013-11-18 2015-05-27 鸿富锦精密工业(深圳)有限公司 Energy-saving voltage detection circuit
CN104701808A (en) * 2013-12-04 2015-06-10 联想(北京)有限公司 Power protection chip
CN104701808B (en) * 2013-12-04 2018-01-23 联想(北京)有限公司 A kind of power protection chip
CN105471591A (en) * 2015-12-30 2016-04-06 浙江光大通信设备有限公司 POE power supply system and power supply method
CN105471591B (en) * 2015-12-30 2018-08-21 浙江光大通信设备有限公司 POE power supply systems and method of supplying power to
CN109450653A (en) * 2018-11-30 2019-03-08 锐捷网络股份有限公司 A kind of Power over Ethernet guard method and device
CN109683550A (en) * 2018-12-21 2019-04-26 济南浪潮高新科技投资发展有限公司 A kind of power on/off system and method
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CN111812377A (en) * 2019-04-10 2020-10-23 杭州海康威视数字技术股份有限公司 Network power supply detection device
CN110308391A (en) * 2019-06-07 2019-10-08 横店集团英洛华电气有限公司 A kind of low cost current of electric Acquisition Circuit and its acquisition method

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Application publication date: 20130417