PD power supply circuit

Abstract

The utility model relates to the technical field of PD power supply, in particular to a PD power supply circuit, which comprises an input rectifier module, a PD detection and identification module, a PD grading module, a power supply module and a selection module, an external power supply input is input into the PD detection and identification module after passing through the input rectifier module, the PD detection and identification module is used for judging whether a load is standard PD equipment or not, and the PD grading module is used for grading the PD equipment. The input end of the selection module is connected with the output end of the input rectification module, when the load is judged to be standard PD equipment, the selection module enables the PD classification module to classify the PD equipment according to the voltage value of the output rectification module, and the power supply module supplies power to the load according to the classification result of the PD classification module. The PD power supply circuit provided by the utility model has the advantages of simple circuit principle, no need of using a PD chip, low cost and short production period.

Description

Technical Field

[0001] The utility model relates to the technical field of PD power supply, in particular to a PD power supply circuit. Background Art

[0002] With the development of network technology and the Internet of Things, switches with Power over Ethernet (PoE) function are becoming more and more popular in the market. PoE technology can transmit power and data signals on standard Ethernet cables without the need for additional power cables, greatly simplifying the deployment and maintenance of network equipment. Among them, the Power Delivery (PD) standard is an important part of PoE technology, which can provide higher power transmission capabilities to meet the energy needs of modern network equipment.

[0003] Most of the PD power supply solutions commonly used in the market are based on PD chips from companies such as Texas Instruments (TI) and MPS. While these solutions implement PD power supply, they also bring the following problems:

[0004] Cost issue: The price of PD chips is relatively high, which increases the overall cost of the switch;

[0005] Supply chain issues: The long delivery cycle of PD chips extends the production cycle of switches, affecting market response speed and customer experience. Summary of the invention

[0006] The utility model provides a PD power supply circuit for the problems of the prior art, which has a simple circuit principle, does not need to use a PD chip, has low cost and short production cycle.

[0007] In order to solve the above technical problems, the utility model adopts the following technical solutions: a PD power supply circuit, including an input rectifier module, a PD detection and identification module, a PD grading module, a power supply module and a selection module. The external power supply input passes through the input rectifier module and then inputs the PD detection and identification module. The PD detection and identification module is used to determine whether the load is a standard PD device. The input end of the selection module is connected to the output end of the input rectifier module. When the load is judged to be a standard PD device, the selection module enables the PD grading module to grade the PD device according to the voltage value of the output rectifier module, and the power supply module supplies power to the load according to the classification result of the PD grading module.

[0008] Preferably, the selection module includes a diode D2, a diode D3, a resistor R10, a resistor R11, a resistor R12 and a switch unit, the cathode of the diode D2 and the cathode of the diode D3 are both connected to the output end of the input rectifier module, the anode of the diode D2 is grounded through the resistor R10, one end of the resistor R11 is connected to the anode of the diode D2, the other end of the resistor R11 is connected to the control end of the switch unit, the anode of the diode D3 is grounded through the resistor R12, and the switch end of the switch unit is connected to the control end of the PD grading module.

[0009] Preferably, the switching unit includes a switch tube Q1 and a switch tube Q2, the control end of the switch tube Q1 is connected to the other end of the resistor R11, one switch end of the switch tube Q1 is connected to the anode of the diode D3 through the control end of the switch tube Q2, the other switch end of the switch tube Q1 is grounded, one switch end of the switch tube Q2 is connected to the control end of the PD grading module, and the other switch end of the switch tube Q2 is grounded.

[0010] Preferably, the PD grading module includes a three-terminal regulator U1 and multiple grading resistors, the multiple grading resistors have different resistance values, and the multiple grading resistors are arranged in parallel. The control end of the three-terminal regulator U1 is connected to the selection module through one end of the grading resistor, the voltage input end of the three-terminal regulator U1 is connected to the output end of the input rectifier module, and the output end of the three-terminal regulator U1 is connected to the other end of the grading resistor.

[0011] Preferably, the power supply module includes a diode D4, a diode D7, a switch tube Q3, a resistor R8 and a resistor R13, the diode D4 is connected to the output end of the input rectifier module, the anode of the diode D4 is connected to the control end of the switch tube Q3 through the resistor R8, the cathode of the diode D7 is connected to the control end of the switch tube Q3, the anode of the diode D7 is grounded, the resistor R13 is connected in parallel with the diode D7, and the switch end of the switch tube Q3 is grounded.

[0012] Preferably, the PD detection and identification module includes a diode D5, a resistor R3 and a capacitor C1, the cathode of the diode D5 is connected to the output end of the input rectifier module, the anode of the diode D5 is grounded, and the resistor R3 and the capacitor C1 are connected in parallel with the diode D3.

[0013] Beneficial effects of the utility model:

[0014] 1. No need to use PD chip, the cost is lower than the PD chip design solution, which greatly reduces the design cost of the machine;

[0015] 2. Short design and production cycle. Discrete components have a shorter delivery time than PD chips, which will greatly reduce the production cycle of PoE switches with PD function.

[0016] 3. Faults are easy to eliminate and maintenance costs are low, making quality more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a circuit schematic diagram of the utility model.

[0018] exist Figure 1 Reference numerals in the drawings include:

[0019] 1-input rectifier module, 2-PD detection and identification module, 3-PD classification module, 4-power supply module, 5-selection module. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the implementation modes are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0021] This embodiment provides a PD power supply circuit, such as Figure 1 , including an input rectifier module 1, a PD detection and identification module 2, a PD grading module 3, a power supply module 4 and a selection module 5. The external power input passes through the input rectifier module 1 and then inputs the PD detection and identification module 2. The PD detection and identification module 2 is used to determine whether the load is a standard PD device. The input end of the selection module 5 is connected to the output end of the input rectifier module 1. When the load is determined to be a standard PD device, the selection module 5 enables the PD grading module 3 to grade the PD device according to the voltage value of the output rectifier module, and the power supply module 4 supplies power to the load according to the classification result of the PD grading module 3.

[0022] Specifically, when the present embodiment is working, for the input rectifier module 1, the PSE voltage (detection voltage / power supply voltage) must be rectified by the rectifier bridge stack after being input from the RJ45, because there are two modes of power supply in the PoE protocol, A mode (12+, 36-) / B mode (45+, 78-). After the rectifier circuit is provided, whether it is A mode or B mode, the positive and negative poles of the PoE voltage can be unified after rectification by the input rectifier module 1;

[0023] After being rectified by the input rectifier module 1, it will pass through a PD detection and identification module 2. The detection voltage will then pass through the PA detection and identification module to determine whether the PD is a standard PD device. If so, PD classification will begin;

[0024] After determining that the PD is a standard PD device, the PSE detection voltage will increase (10V to 20V), and classification will begin at this time, so that the PD device has a fixed PD level. Class 0 to Class 4 are distinguished by different resistors (different currents pass through). Through the feedback current, the PSE will identify the PD level and try to start power supply;

[0025] After the classification is completed, the PSE starts to increase the voltage to about 50V-57V. At this time, the voltage above 50V will pass through the power supply module 4, so that according to the PD classification result, the PSE end starts to supply power to the PD normally.

[0026] Among them, the principle of this embodiment is as follows Figure 1 As shown, the input rectifier module 1 includes two rectifier bridges D1 and D6. The principle of rectification is the existing technology and is not described here. Then it passes through the PD detection and identification module 2, which includes a diode D5, a resistor R3 and a capacitor C1. After PD identification, PD classification is performed. The PD classification module 3 includes a three-terminal regulator U1 and multiple classification resistors. The multiple classification resistors include R1, R2, R4, R5, and R7. According to the classification result, the power supply module 4 supplies the corresponding current and voltage. The power supply module 4 includes a diode D4, a diode D7, a switch tube Q3, resistor R8 and resistor R13; this embodiment further provides a selection module 5 for making the PD classification module 3 or the power supply module 4 work, the selection module 5 includes a diode D2, a diode D3, a resistor R10, a resistor R11, a resistor R12 and a switch unit, the switch unit includes a switch tube Q1 and a switch tube Q2, wherein the diode D2, the diode D3, the diode D4, the diode D5 and the diode D7 are all voltage regulator tubes, the switch tube Q1 and the switch tube Q2 are both MOS tubes, the switch tube Q3 is a triode, and the specific connection method is as follows Figure 1 shown.

[0027] The specific working principle of this embodiment is:

[0028] 1. When the PSE power supply starts to supply power to the PD device through RJ45, the detection voltage (about 10V) at the PSE end first passes through the rectifier bridge stacks D1 and D6 to unify the positive and negative poles of the PoE voltage (compatible with 12 / 36 power supply and 45 / 78 power supply at the PSE end);

[0029] 2. When the detection voltage (about 10V) passes through the rectifier bridge stack D1 and D6, and then passes through the resistor R3, which is the detection resistor of the standard PD (24.9K, characteristic value), after passing through the resistor R3, the PSE power supply end determines that the PD device is a standard PD device, and then starts the classification operation;

[0030] 3. When the PSE power supply determines that the PD device is a standard PD device, the detection voltage of about 10V at this time rises to about 20V (PD classification voltage), and will pass through diode D2 (20V voltage regulator), but will not break down D2, because the voltage after voltage division is only 10V, which cannot break down the 20V voltage regulator, and then pass through diode D3, which is a 9.1V voltage regulator. Resistors R8 and R12 are parallel voltage division protection resistors, so diode D3 is broken down to reach the gate of switch tube Q2 and the emitter of switch tube Q1. Because no current flows through the base of switch tube Q1, switch tube Q1 is not conducting at this time. Switch tube Q2 has a driving voltage at the gate, and switch tube Q2 is turned on to ground. The three-terminal regulator U1 connected in parallel with it starts to work. By changing the resistance value of the resistor (R1, R2, R4, R5, R7, one of the five resistors) on the feedback path of U1 to change the current in the loop path, the purpose of classification is achieved, as follows:

[0031] Class 0, 510R, 2.5mA

[0032] Class 1, 120R, 10mA

[0033] Class 2, 68R, 18mA

[0034] Class 3, 43R, 29mA

[0035] Class 4, 31R, 40mA;

[0036] 4. After the classification process is completed, the PSE power supply end starts to try to output the PoE standard voltage of 50V to 57V. When the PoE voltage passes through the 20V diode D2, the resistors R10 and R11 are parallel voltage-dividing protection resistors. At this time, the diode D2 is broken down, turning on the switch tube Q1, and the gate of the switch tube Q2 is also short-circuited to the ground. The switch tube Q2 is turned off, and the three-terminal regulator U1 no longer works. At this time, the PoE standard voltage passes through the diode D4 (30V voltage regulator tube) and breaks down the diode D4. Through the series connection of the resistor R6 and the diode D7, a 12V stable voltage is applied to the switch tube Q3, turning on the switch tube Q3. At this time, the negative pole is fully turned on, and PoE starts to supply power normally.

[0037] Therefore, the circuit principle of this embodiment is simple, and there is no need to use a PD chip. Discrete components are used to build the power-on detection and classification process of the standard PD (IEE802.3af / IEEE802.3at protocol). The cost is lower than the PD chip design solution, which greatly reduces the design cost of the machine; and the design and production cycle is short, and the delivery time of discrete components is shorter than that of PD chips, which will greatly shorten the production cycle of POE switches with PD function; further, the circuit principle design is simple and reliable, faults are easy to eliminate, maintenance costs are low, and reliability and practicality are higher.

[0038] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Although the utility model is disclosed as a preferred embodiment as above, it is not used to limit the utility model. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content disclosed above without departing from the scope of the technical solution of the utility model. However, any simple modification, equivalent change and modification made to the above embodiments according to the technology of the utility model, which does not depart from the content of the technical solution of the utility model, belongs to the scope of the technical solution of the utility model.

Claims

1. A PD power supply circuit, characterized in that: It includes an input rectifier module, a PD detection and identification module, a PD grading module, a power supply module and a selection module. The external power supply input passes through the input rectifier module and then inputs the PD detection and identification module. The PD detection and identification module is used to determine whether the load is a standard PD device. The input end of the selection module is connected to the output end of the input rectifier module. When the load is determined to be a standard PD device, the selection module enables the PD grading module to grade the PD device according to the voltage value of the output rectifier module, and the power supply module supplies power to the load according to the classification result of the PD grading module.

2. A PD power supply circuit according to claim 1, characterized in that: The selection module includes a diode D2, a diode D3, a resistor R10, a resistor R11, a resistor R12 and a switch unit. The cathode of the diode D2 and the cathode of the diode D3 are both connected to the output end of the input rectifier module, the anode of the diode D2 is grounded through the resistor R10, one end of the resistor R11 is connected to the anode of the diode D2, the other end of the resistor R11 is connected to the control end of the switch unit, the anode of the diode D3 is grounded through the resistor R12, and the switch end of the switch unit is connected to the control end of the PD grading module.

3. A PD power supply circuit according to claim 2, characterized in that: The switch unit includes a switch tube Q1 and a switch tube Q2. The control end of the switch tube Q1 is connected to the other end of the resistor R11. One switch end of the switch tube Q1 is connected to the anode of the diode D3 through the control end of the switch tube Q2. The other switch end of the switch tube Q1 is grounded. One switch end of the switch tube Q2 is connected to the control end of the PD grading module. The other switch end of the switch tube Q2 is grounded.

4. The PD power supply circuit according to claim 1, characterized in that: The PD grading module includes a three-terminal regulator U1 and multiple grading resistors. The resistance values ​​of the multiple grading resistors are different. The multiple grading resistors are arranged in parallel. The control end of the three-terminal regulator U1 is connected to the selection module through one end of the grading resistor, the voltage input end of the three-terminal regulator U1 is connected to the output end of the input rectifier module, and the output end of the three-terminal regulator U1 is connected to the other end of the grading resistor.

5. The PD power supply circuit according to claim 2, characterized in that: The power supply module includes a diode D4, a diode D7, a switch tube Q3, a resistor R8 and a resistor R13. The diode D4 is connected to the output end of the input rectifier module, the anode of the diode D4 is connected to the control end of the switch tube Q3 through the resistor R8, the cathode of the diode D7 is connected to the control end of the switch tube Q3, the anode of the diode D7 is grounded, the resistor R13 is connected in parallel with the diode D7, and the switch end of the switch tube Q3 is grounded.

6. A PD power supply circuit according to claim 2, characterized in that: The PD detection and identification module includes a diode D5, a resistor R3 and a capacitor C1. The cathode of the diode D5 is connected to the output end of the input rectifier module, the anode of the diode D5 is grounded, and the resistor R3 and the capacitor C1 are connected in parallel with the diode D3.

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