Planar transformer assembly and power adapter

Abstract

This disclosure provides a planar transformer assembly and a power supply. The planar transformer assembly includes a first printed circuit board. The first printed circuit board includes a magnetic core, a first primary printed circuit board winding, a first secondary printed circuit board winding, and a second secondary printed circuit board winding. The magnetic core passes through the first printed circuit board. The magnetic core includes a first cover plate, a second cover plate, and a first magnetic post. The first magnetic post is connected to the first cover plate. The first magnetic post is spaced from the second cover plate by a first air gap. The first primary printed circuit board winding winds a first portion of the first magnetic post. The first secondary printed circuit board winding and the second secondary printed circuit board winding winds wind a second portion of the first magnetic post. The second portion is located below the first portion. The second portion is a single portion of the first magnetic post.

Description

[Technical Field]

[0001] This invention relates to planar transformer assemblies and power supplies, and more particularly to planar transformers for planar transformer assemblies and power supplies. [Previous Technology]

[0002] With technological advancements and the rapid development of portable electronic products, the performance of switching converters in various applications is receiving increasing attention. In recent years, due to significant progress in power electronics technology and the development of nanotechnology, electronic devices are increasingly trending towards designs that are thin, light, energy-efficient, and cost-effective. Therefore, the design of their internal power converters also needs to move towards thinner, lighter, lower-power, more energy-efficient, and lower-manufacturing-cost designs. Most electrical appliances typically require a power supply to convert the input power (battery or AC mains) into a specific rated output power. With technological advancements, it has become common practice for power supplies to operate more efficiently and have higher conversion efficiencies. [Summary of the Invention]

[0003] This invention provides a planar transformer assembly. The planar transformer assembly includes a first printed circuit board. The first printed circuit board includes a magnetic core, a first primary printed circuit board winding, a first secondary printed circuit board winding, and a second secondary printed circuit board winding. The magnetic core passes through the first printed circuit board. The magnetic core includes a first cover plate, a second cover plate, and a first magnetic post. The second cover plate is opposite to the first cover plate. The first magnetic post connects to the first cover plate and extends from the first cover plate to the second cover plate. The first magnetic post is separated from the second cover plate by a first air gap. The first primary printed circuit board winding winds around a first portion of the first magnetic post. The first secondary printed circuit board winding and the second secondary printed circuit board winding winds around a second portion of the first magnetic post. The second portion of the first magnetic post is below the first portion of the first magnetic post. The second portion is a single portion of the first magnetic post.

[0004] This embodiment of the invention provides a power supply. The power supply includes a main printed circuit board and an auxiliary printed circuit board. The main printed circuit board has a pair of primary metal-oxide-semiconductor field-effect transistor switches and a high-potential input port for conducting modulated high-potential current. The auxiliary printed circuit board is mounted on the main printed circuit board. The auxiliary printed circuit board includes a primary-side circuit and a center-tapped secondary-side circuit. The primary-side circuit includes a plurality of primary printed circuit board windings connected in series. The primary-side circuit is configured to conduct modulated high-potential current. The center-tapped secondary-side circuit includes a top secondary printed circuit board winding circuit and a bottom secondary printed circuit board winding circuit. The top and bottom secondary printed circuit board winding circuits are stacked below the primary-side circuit.

Implementation Method

[0006] The present disclosure is described more fully below with reference to the accompanying drawings of embodiments of the present invention. However, the present disclosure may be implemented in various different ways and should not be limited to the embodiments described herein. The thickness of layers and regions in the drawings may be enlarged for clarity, and the same or similar reference numerals in the drawings denote the same or similar elements.

[0007] Figure 1 is a top view of a planar transformer assembly 500 according to some embodiments of the present disclosure. Figure 2 is a block diagram of the planar transformer assembly 500 according to some embodiments of the present disclosure in Figure 1. Figure 3 is an equivalent circuit diagram of the power adapter 400 (e.g., an inductor-inductor-capacitor resonant converter) of the planar transformer assembly 500 according to some embodiments of the present disclosure in Figures 1 and 2. In some embodiments, the planar transformer assembly 500 includes a power adapter (e.g., an AC-DC power adapter) 400 manufactured using a planar transformer 200 and a multi-layer printed circuit board (PCB) process. For example, the primary PCB winding and secondary PCB winding of the planar transformer 200 of the planar transformer assembly 500 are formed by conductive layers and vias in the printed circuit board. In addition, the primary printed circuit board winding and the secondary printed circuit board winding of the planar transformer 200 are separated from each other through the core substrate of the printed circuit board or the dielectric layer of the layered structure (formed of polypropylene (PP) or prepreg).

[0008] As shown in Figure 1, the planar transformer assembly 500 includes a main printed circuit board (PCB) 100 and an auxiliary printed circuit board (PCB) 300 mounted on the main PCB 100.

[0009] As shown in Figures 2 and 3, the power supply 400 of the planar transformer assembly 500 includes a primary-side signal generating circuit 150, a planar transformer 200 (including planar transformers 200A and 200B shown in Figures 4A and 4B), and a secondary-side rectifying circuit 350. The power supply 400 can receive AC power from a high-potential (high-voltage) input port Vin. The high-potential input port Vin is configured to conduct modulated high-potential current. Additionally, the power supply 400 can be configured to provide a converted DC voltage to the output port Vout.

[0010] As shown in Figures 1 to 3, the main printed circuit board 100 may include a high-potential input port Vin and a primary-side signal generation circuit 150. The primary-side signal generation circuit 150 configured on the main printed circuit board 100 includes a pair of primary metal-oxide-semiconductor field-effect transistor switches PMS1 and PMS2, an inductor Lr (also called a resonant inductor Lr), a capacitor Cr (also called a resonant capacitor Cr), and a high-potential input port Vin.

[0011] In some embodiments, the above-described metal-oxide-semiconductor field-effect transistor switches PMS1 and PMS2 are implemented using half-bridge topologies. Furthermore, the series-connected metal-oxide-semiconductor field-effect transistor switches PMS1 and PMS2 are configured to generate a switching signal from a high-potential input port Vin.

[0012] As shown in Figures 1 to 3, the auxiliary printed circuit board 300 includes a pair of inductors L m1, L m2 (also known as magnetizing inductors L m1, L m2), a planar transformer 200, a secondary rectifier circuit 350, and an output port V out.

[0013] The capacitor Cr and inductor Lr on the main printed circuit board 100 and a pair of inductors Lm1 and Lm2 on the auxiliary printed circuit board 300 are connected in series. The aforementioned pair of inductors Lm1 and Lm2 and capacitor Cr are connected to (coupled to) the connection point 102 of the aforementioned pair of primary metal-oxide-semiconductor field-effect transistor switches PMS1 and PMS2 and the ground terminal GND to form an inductor-inductor-capacitor (LLC) structure 600 (e.g., an inductor-inductor-capacitor resonant tank). The inductor-inductor-capacitor structure 600 is configured to provide a modulated high-potential current to the high-potential input port Vin (the inductor-inductor-capacitor structure 600 is configured to output a resonant sinusoidal current, which is scaled and rectified by the planar transformer 200 and the secondary-side rectifier 350).

[0014] The planar transformer 200, configured on the auxiliary printed circuit board 300, includes a primary side circuit (PSC) and a center-tapped secondary side circuit (CSC) isolated from each other. The planar transformer 200 is configured to step down the voltage from the primary side circuit (PSC) to the center-tapped secondary side circuit (CSC). The primary side circuit (PSC) includes primary PCB windings (P1 and P2) connected in series. The aforementioned inductors (Lm1 and Lm2) are connected in parallel with the first and second terminals of the primary side circuit (PSC) of the planar transformer 200. The inductor (Lr), the second terminal of the primary side circuit (PSC), and the capacitor (Cr) are connected in series. The first terminal of the primary side circuit (PSC) is connected to the connection point 102 of the aforementioned primary metal-oxide-semiconductor (MOSFET) field-effect transistor (MOSFET) switches (PMS1 and PMS2) through the capacitor (Cr). In addition, the second terminal of the primary side circuit (PSC) is connected to the ground terminal (GND) of the aforementioned MOSFET switches (PMS1 and PMS2) through the inductor (Lr). The primary side circuit PSC is configured to conduct modulated high-potential current from the primary side signal generation circuit 150.

[0015] The center tap secondary side circuit CSC includes the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB. The top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB are connected in parallel.

[0016] The top secondary PCB winding circuit ST includes a secondary PCB winding ST1 and a secondary PCB winding ST2 connected in series. Furthermore, the secondary PCB winding ST1 and the secondary PCB winding ST2 are wound in opposite directions to have opposite voltage potential directions. For example, one of the secondary PCB windings ST1 and ST2 is wound clockwise, while the other is wound counterclockwise. As shown in Figure 3, the secondary PCB winding ST1 has opposing ends T1 and T2. The secondary PCB winding ST2 has opposing ends T2 and T3. In some embodiments, the secondary PCB windings ST1 and ST2 share a common end T2, which provides an output (output terminal) to the output port Vout. In other words, the end T2 of the secondary PCB winding ST1 is connected to the end T2 of the secondary PCB winding ST2. Therefore, the top secondary printed circuit board winding circuit ST formed by the secondary printed circuit board windings ST1 and ST2 is also called the center-tapped secondary circuit ST.

[0017] Similarly, the bottom secondary printed circuit board winding circuit SB includes secondary printed circuit board windings SB1 and SB2 connected in series. Furthermore, secondary printed circuit board windings SB1 and SB2 are wound in opposite directions to have opposite voltage potential directions. For example, one of secondary printed circuit board windings SB1 and SB2 is wound clockwise, while the other is wound counterclockwise. As shown in Figure 3, secondary printed circuit board winding SB1 has opposing ends T4 and T5. Secondary printed circuit board winding SB2 has opposing ends T5 and T6. In some embodiments, secondary printed circuit board windings SB1 and SB2 have a common end T5, which is provided as an output (output terminal) to the output port Vout. That is, end T5 of secondary printed circuit board winding SB1 is connected to end T5 of secondary printed circuit board winding SB2. Therefore, the bottom secondary printed circuit board winding circuit SB formed by secondary printed circuit board windings SB1 and SB2 is also called a center-tapped secondary circuit SB.

[0018] The planar transformer 200 disposed on the auxiliary printed circuit board 300 further includes a shielding layer GL sandwiched between the center-tapped secondary side circuit CSC (including the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB) and the primary side circuit PSC (including the primary printed circuit board windings P1 and P2). In some embodiments, the shielding layer GL is connected to the ground terminal GND to suppress common mode noise induced on the center-tapped secondary side circuit CSC.

[0019] The secondary-side rectifier circuit 350 configured on the auxiliary printed circuit board 300 includes at least two pairs of secondary metal-oxide-semiconductor (MOSFET) field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 and a capacitor Co (also referred to as the output capacitor Co). The two pairs of MOSFET switches SMS1, SMS2, SMS3, and SMS4 are electrically connected to the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB. More specifically, the pairs of MOSFET switches SMS1 and SMS2 are electrically connected to the secondary printed circuit board windings ST1 and ST2 of the top secondary printed circuit board winding circuit ST. The pairs of MOSFET switches SMS3 and SMS4 are electrically connected to the secondary printed circuit board windings SB1 and SB2 of the bottom secondary printed circuit board winding circuit SB. The output of the center tap secondary circuit CSC is rectified by the two pairs of secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 and filtered by the capacitor Co to generate a DC voltage to the output port Vout.

[0020] In some embodiments, the power supply 400 of the planar transformer assembly 500 further includes analog integrated circuits (ICs) 160 and 360. Analog IC 160 is connected (coupled) to the primary-side signal generation circuit 150. Additionally, analog IC 360 is connected (coupled) to the secondary-side rectifier circuit 350. Analog ICs 160 and 360 are configured to control the inductor-inductor-capacitor structure 600 of the primary-side signal generation circuit 150 and the secondary-side rectifier circuit 350.

[0021] Figure 4A is a side view of a planar transformer 200A formed in an attached printed circuit board 300 of a planar transformer assembly 500 according to some embodiments of the present disclosure, as shown in Figures 1 to 3. Figure 4B is a top view of each printed circuit board layer of the planar transformer 200A in Figure 4A. To illustrate the configuration of the primary winding, secondary winding, and shielding layer of the planar transformer 200A, the core substrate or dielectric layer of the attached printed circuit board 300 is not shown in Figures 4A and 4B. Furthermore, Figure 4B shows the magnetic core 210 of the planar transformer 200A.

[0022] As shown in Figure 4A, the planar transformer 200A of the planar transformer assembly 500 includes a magnetic core 210, primary printed circuit board windings P1, P2, secondary printed circuit board windings ST1, ST2, SB1, SB2 and a shielding layer GL.

[0023] The magnetic core 210 may be formed as an opening (not shown) through the attached printed circuit board 300, and the aforementioned opening of the attached printed circuit board 300 is formed through the attached printed circuit board 300. Additionally, the magnetic core 210 may be provided with a primary side circuit PSC (including primary printed circuit board windings P1, P2) and a center-tap secondary side circuit CSC (including secondary printed circuit board windings ST1, ST2, SB1, SB2) formed on the attached printed circuit board 300. In some embodiments, the magnetic core 210 includes cover plates 210B and 210T, side cores 210S, and magnetic posts 210P1 and 210P2. Cover plate 210T is opposite to cover plate 210B. Side core 210S is disposed between cover plates 210B and 210T to fix cover plates 210B and 210T. Magnetic post 210P1 is disposed on cover plate 210B. Additionally, the magnetic post 210P1 extends from the first cover plate 210B to the second cover plate 210T along direction 10 (i.e., the extension direction 10 of the magnetic post 210P1). The magnetic post 210P2 is disposed on the cover plate 210B and located next to the magnetic post 210P1. Furthermore, the magnetic post 210P2 extends from the first cover plate 210B to the second cover plate 210T along the extension direction 10 (direction 10).

[0024] As shown in Figure 4A, the magnetic post 210P1 has opposing ends E1 and E2. The magnetic post 210P2 has opposing ends E3 and E4. Ends E1 of magnetic post 210P1 and E3 of magnetic post 210P2 are connected to the cover plate 210B. In some embodiments, the first magnetic post 210P1 and the second magnetic post 210P2 have a height DP (i.e., the distance between opposing ends E1 and E2 of magnetic post 210P1 or the distance between opposing ends E3 and E4 of magnetic post 210P2), which is less than the first distance D1 between the first cover plate 210B and the second cover plate 210T in direction 10. Therefore, end E2 of magnetic post 210P1 is close to cover plate 210T and separated from cover plate 210T through air gap AG1. End E4 of magnetic post 210P2 is close to cover plate 210T and separated from cover plate 210T through air gap AG2.

[0025] Magnetic post 210P1 has a portion A1 and a portion A2 adjacent to portion A1 in direction 10. Portion A1 is closer to end E2 and air gap AG1 than portion A2. Furthermore, portion A2 is closer to end E1 than portion A1. Additionally, magnetic post 210P2 has a portion A3 and a portion A4 adjacent to portion A3 in direction 10. Portion A4 is closer to end E4 and air gap AG2 than portion A3. Furthermore, portion A4 is closer to end E3 than portion A3.

[0026] In some embodiments, an auxiliary printed circuit board 300 including primary and secondary windings is located near the first cover plate 210B and away from air gaps AG1 and AG2. As shown in Figures 3 and 4A, the primary printed circuit board winding P1 of the primary side circuit PSC and the secondary printed circuit board windings ST1 and ST2 of the top secondary printed circuit board winding circuit ST of the center tap secondary side circuit CSC surround the magnetic post 210P1. More specifically, the primary printed circuit board winding P1 is wound on a portion A1 of the magnetic post 210P1. The secondary printed circuit board windings ST1 and ST2 are wound on a portion A2, and the portion A2 is below the portion A1. In some embodiments, the secondary printed circuit board windings ST1 and ST2 are wound on the portion A2 of the magnetic post 210P1 in opposite directions. For example, one of the secondary printed circuit board windings ST1 and ST2 is wound clockwise, while the other of the secondary printed circuit board windings ST1 and ST2 is wound counterclockwise. Additionally, the secondary printed circuit board windings ST1 and ST2 are located away from the air gap AG1. In other words, the primary printed circuit board winding P1 of the primary side circuit PSC is closer to the air gap AG1 than the secondary printed circuit board windings ST1 and ST2 of the top secondary printed circuit board winding circuit ST of the center-tapped secondary side circuit CSC. In some embodiments, portion A2 is a single portion of the magnetic post 210P1.

[0027] Similarly, as shown in Figures 3 and 4A, the primary printed circuit board winding P2 of the primary side circuit PSC and the secondary printed circuit board windings SB1 and SB2 of the bottom secondary printed circuit board winding circuit SB of the center tap secondary side circuit CSC surround the magnetic post 210P2. More specifically, the first primary printed circuit board winding P2 is wound on a portion A3 of the magnetic post 210P2. The secondary printed circuit board windings SB1 and SB2 are wound on a portion A4, and the portion A4 is below the portion A3. In some embodiments, the secondary printed circuit board windings SB1 and SB2 are wound on the portion A4 of the magnetic post 210P1 in opposite directions. For example, one of the secondary printed circuit board windings SB1 and SB2 is wound clockwise, while the other of the secondary printed circuit board windings SB1 and SB2 is wound counterclockwise. In addition, the secondary printed circuit board windings SB1 and SB2 are located away from the air gap AG2. In other words, the primary printed circuit board winding P2 of the primary side circuit PSC is closer to the air gap AG2 than the secondary printed circuit board windings SB1 and SB2 of the bottom secondary printed circuit board winding circuit SB of the center tap secondary side circuit CSC. In some embodiments, portion A4 is a single portion of the magnetic post 210P2.

[0028] As shown in Figure 4A, the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB are both stacked along direction 10 below the primary printed circuit board windings P1 and P2. In other words, the primary printed circuit board winding P1 of the primary side circuit PSC is stacked along the extension direction 10 (direction 10) of the magnetic post 210P1 on the secondary printed circuit board windings ST1 and ST2 of the top secondary printed circuit board winding circuit ST of the center tap secondary side circuit CSC. Therefore, the primary printed circuit board winding P1 can generate an excitation current flowing through the secondary printed circuit board windings ST1 and ST2.

[0029] Similarly, the primary printed circuit board winding P2 of the primary side circuit PSC is stacked along the extension direction 10 (direction 10) of the magnetic post 210P2 on the secondary printed circuit board windings SB1 and SB2 of the bottom secondary printed circuit board winding circuit SB of the center tap secondary side circuit CSC. Therefore, the primary printed circuit board winding P2 can generate an excitation current flowing through the secondary printed circuit board windings SB1 and SB2.

[0030] As shown in Figures 3 and 4A, the shielding layer GL of the planar transformer 200A is a single shielding layer located below the primary printed circuit board windings P1 and P2 and above the secondary printed circuit board windings ST1, ST2, SB1, and SB2. In other words, the shielding layer GL is disposed on one side of each primary printed circuit board winding P1 and P2 away from the air gaps AG1 and AG2. It should be noted that there is no shielding layer GL between the air gap AG1 and the primary printed circuit board winding P1, or between the air gap AG2 and the primary printed circuit board winding P2. In addition, the single shielding layer GL has a top surface GL-T and a bottom surface GL-B. The top surface GL-T is close to the air gaps AG1 and AG2. The bottom surface GL-B is away from the air gaps AG1 and AG2. The primary printed circuit board windings P1 and P2 are disposed above the top surface GL-T of the single shielding layer GL. The secondary printed circuit board windings ST1, ST2, SB1, and SB2 are disposed below the bottom surface GL-B of the single shielding layer GL.

[0031] As shown in Figure 4B, the auxiliary printed circuit board 300 including the planar transformer 200A is an 8-layer printed circuit board. The 8-layer auxiliary printed circuit board 300 includes a first conductive layer L1, a second conductive layer L2, a third conductive layer L3, a fourth conductive layer L4, a fifth conductive layer L5, a sixth conductive layer L6, a seventh conductive layer L7, and an eighth conductive layer L8 arranged sequentially. In addition, the first conductive layer L1 is closer to the air gaps AG1 and AG2 than the second conductive layers L2 to the eighth conductive layers L8.

[0032] In the planar transformer 200A, primary printed circuit board windings P1 and P2 are formed by a first conductive layer L1, a second conductive layer L2, a third conductive layer L3, a fourth conductive layer L4, and a fifth conductive layer L5 of an eight-layer auxiliary printed circuit board 300. Each of the primary printed circuit board windings P1 and P2 has one turn of wire CT1 in each of the first conductive layer L1 to the fifth conductive layer L5. In other words, each of the first conductive layer L1 to the fifth conductive layer L5 includes two one-turn wires CT1 arranged side by side. One is used for the primary printed circuit board winding P1, and the other is used for the primary printed circuit board winding P2. In each of the primary printed circuit board windings P1 and P2, the one-turn wires CT1 in the first conductive layer L1 to the fifth conductive layer L5 are connected in series via a via (not shown). In addition, the primary printed circuit board windings P1 and P2 are connected in series via a via (not shown) to form a 10-turn primary printed circuit board winding. In other words, the total number of turns (wires) of the first and second primary printed circuit board windings is 10 turns.

[0033] In some embodiments, a single shielding layer GL is formed by a sixth conductive layer L6 of an 8-layer attached printed circuit board 300.

[0034] The secondary printed circuit board windings ST1 and SB1 are formed by the seventh conductive layer L7 of the 8-layer subsidiary printed circuit board 300. Furthermore, the secondary printed circuit board windings ST2 and SB2 are formed by the eighth conductive layer L8 of the 8-layer subsidiary printed circuit board 300. In some embodiments, each secondary printed circuit board winding ST1 and SB1 has one turn of wire CT2 on the seventh conductive layer L7. Each of the secondary printed circuit board windings ST2 and SB2 has one turn of wire CT2 on the eighth conductive layer L8. In other words, each of the seventh conductive layer L7 and the eighth conductive layer L8 includes two one-turn wires CT2 arranged side-by-side. One is for the secondary printed circuit board winding ST1 (or secondary printed circuit board winding ST2), and the other is for the secondary printed circuit board winding SB1 (or secondary printed circuit board winding SB2). Each of the secondary printed circuit board windings ST1, SB1, ST2, and SB2 forms one turn of secondary printed circuit board winding. In other words, each of the secondary printed circuit board windings ST1, SB1, ST2, and SB2 has one turn (wire).

[0035] In the planar transformer 200A, in each of the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB, the turns ratio of the primary printed circuit board windings P1 and P2 to any one of the secondary printed circuit board windings ST1, SB1, ST2, and SB2 is 10:1. In other words, in each of the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB of the planar transformer 200A, the turns ratio of the primary printed circuit board windings P1 and P2 to the clockwise or counterclockwise wound secondary printed circuit board windings ST1, SB1, ST2, and SB2 is 10:1.

[0036] Figure 5A is a side view of a planar transformer 200B formed in an attached printed circuit board 300 of a planar transformer assembly 500 according to some embodiments of the present disclosure, as shown in Figures 1 to 3. Figure 5B is a top view of each printed circuit board layer of the planar transformer 200B in Figure 5A. The components of the following embodiments are the same as or similar to those previously described with reference to Figures 4A and 4B, and will not be repeated for the sake of brevity. To illustrate the configuration of the primary and secondary windings and the shielding layer of the planar transformer 200B, the core substrate or dielectric layer of the attached printed circuit board 300 is not shown in Figures 5A and 5B. Please refer to both Figures 5A and 5B, where Figure 5B shows the magnetic core 210 of the planar transformer 200B.

[0037] The planar transformer 200A shown in Figures 4A and 4B differs from the planar transformer 200B shown in Figures 5A and 5B in that the auxiliary printed circuit board 300 including the planar transformer 200B is a 6-layer printed circuit board. The 6-layer auxiliary printed circuit board 300 includes a first conductive layer L1, a second conductive layer L2, a third conductive layer L3, a fourth conductive layer L4, a fifth conductive layer L5, and a sixth conductive layer L6 arranged sequentially. In addition, the first conductive layer L1 is closer to the air gaps AG1 and AG2 than the second conductive layers L2 to the sixth conductive layers L6.

[0038] In the planar transformer 200B, primary printed circuit board windings P1 and P2 are formed by a first conductive layer L1, a second conductive layer L2, and a third conductive layer L3 of a six-layer auxiliary printed circuit board 300. Each of the primary printed circuit board windings P1 and P2 has one turn of wire CT1 in one of the first conductive layers L1 to the third conductive layer L3. Furthermore, each of the other two primary printed circuit board windings P1 and P2 has two two-turn wires CT3 in the other two of the first conductive layers L1 to the third conductive layer L3. For example, each of the primary printed circuit board windings P1 and P2 has one one-turn wire CT1 in the first conductive layer L1 and two two-turn wires CT2 in both the second conductive layer L2 and the third conductive layer L3. In other words, the first conductive layer L1 includes two one-turn wires CT1 arranged side-by-side. One is for the primary printed circuit board winding P1, and the other is for the primary printed circuit board winding P2. Each of the second conductive layer L2 and the third conductive layer L3 contains two two-turn wires CT3 arranged side-by-side. One is used for primary printed circuit board winding P1, and the other is used for primary printed circuit board winding P2.

[0039] In each of the primary printed circuit board windings P1 and P2, one turn of wire CT1 in the first conductive layer L1 is connected in series with two two-turn wires CT3 in the second conductive layer L2 and the third conductive layer L3 through a via (not shown). Furthermore, the primary printed circuit board windings P1 and P2 are connected in series through vias (not shown) to form a 10-turn primary printed circuit board winding. In other words, the total number of turns (wires) in the first and second primary printed circuit board windings is 10 turns.

[0040] In some embodiments, a single shielding layer GL is formed from a fourth conductive layer L4 of a six-layer attached printed circuit board 300.

[0041] The secondary printed circuit board windings ST1 and SB1 are formed by the fifth conductive layer L5 of the 6-layer auxiliary printed circuit board 300. The secondary printed circuit board windings ST2 and SB2 are formed by the sixth conductive layer L6 of the 6-layer auxiliary printed circuit board 300. Furthermore, each of the secondary printed circuit board windings ST2 and SB2 has one turn of wire CT2 in the sixth conductive layer L6. In other words, each of the fifth conductive layer L5 and the sixth conductive layer L6 contains two parallel one-turn wires CT2. One is used for the secondary printed circuit board winding ST1 (or ST2), and the other is used for the secondary printed circuit board winding SB1 (or SB2). Each of the secondary printed circuit board windings ST1, SB1, ST2, and SB2 forms one turn of secondary printed circuit board winding. In other words, each of the secondary printed circuit board windings ST1, SB1, ST2, and SB2 has one turn (wire).

[0042] In the planar transformer 200B, in each of the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB, the turns ratio of the primary printed circuit board windings P1 and P2 to any one of the secondary printed circuit board windings ST1, SB1, ST2, and SB2 is 10:1. In other words, in each of the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB of the planar transformer 200B, the turns ratio of the primary printed circuit board windings P1 and P2 to the clockwise or counterclockwise wound secondary printed circuit board windings ST1, SB1, ST2, and SB2 is 10:1.

[0043] The planar transformer 200 has the following advantages. In some embodiments, the planar transformer 200 uses a single shielding layer GL, which is configured on one side of the primary side circuit PSC away from the air gaps AG1 and AG2. Therefore, the primary side circuit PSC (including the primary printed circuit board windings P1, P2) and the entire center-tapped secondary side circuit CSC (including the secondary printed circuit board windings ST1, ST2, SB1, SB2) are configured to be close to the opposite surfaces (top surface GL-T and bottom surface GL-B) of the same shielding layer GL. The arrangement order of the primary printed circuit board windings P1, P2, the single shielding layer GL, and the secondary printed circuit board windings ST1, ST2, SB1, SB2 of the planar transformer 200 can be referred to as a PSS (primary winding-secondary winding-secondary winding) structure. Where S represents the secondary winding and P represents the primary winding. Compared to conventional planar transformers that use two shielding layers to isolate the primary and secondary windings (having an SPS (secondary winding-primary winding-secondary winding) structure), the planar transformer 200 of the planar transformer assembly 500 can release at least one printed circuit board conductive layer. This released conductive layer can be used for the primary printed circuit board winding. Therefore, the resistance of the primary winding (e.g., DC resistance, Rdc) can be reduced.

[0044] In some embodiments, the magnetic core 210 of the planar transformer 200 may include air gaps AG1 and AG2 to provide the desired inductance for energy storage in the planar transformer 200. Furthermore, the secondary printed circuit board windings ST1, ST2, SB1, and SB2 are configured to be located away from the air gaps AG1 and AG2. Compared to conventional planar transformers with an SPS structure, the induced current in the secondary printed circuit board windings ST1, ST2, SB1, and SB2 of the planar transformer 200 of the planar transformer assembly 500 is more uniform.

[0045] In some embodiments, the primary and secondary printed circuit board windings of the planar transformer 200 are formed on a double-sided printed circuit board (PCB). Considering the trade-offs between impedance, leakage inductance, power losses (e.g., DC resistance losses in the primary and secondary windings, and eddy current and hysteresis losses in the core), and manufacturing costs, the planar transformer assembly 500 may use 6-layer or 8-layer printed circuit boards to form the primary and secondary printed circuit board windings of the planar transformer 200. For example, the primary printed circuit board windings P1, P2 and the secondary printed circuit board windings ST1, ST2, SB1, SB2 of the planar transformer 200A are formed on an 8-layer subsidiary printed circuit board 300. The primary printed circuit board windings P1, P2 and the secondary printed circuit board windings ST1, ST2, SB1, SB2 of the planar transformer 200B are formed on a 6-layer subsidiary printed circuit board 300. However, the planar transformer 200 may also be applied to other printed circuit boards with different numbers of conductive layers.

[0046] Figure 6 is a partial bottom view of the attached printed circuit board 300 of the planar transformer assembly 500 according to some embodiments of the present disclosure, showing the secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 of the planar transformer assembly 500 according to some embodiments of the present disclosure in Figure 1. Figure 7 is a cross-sectional view of part 270 of Figure 5A, showing the electrical connection between the secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 of the planar transformer assembly 500 according to some embodiments of the present disclosure and the top secondary printed circuit board winding circuit ST and the bottom secondary printed circuit board winding circuit SB.

[0047] As shown in Figures 5A and 6, the 6-layer auxiliary printed circuit board 300 also includes two pairs of secondary metal-oxide-semiconductor (MOSFET) field-effect transistor (FET) switches SMS1, SMS2, SMS3, and SMS4, which are mounted on the back surface 300B of the auxiliary printed circuit board 300 and close to the planar transformer 200B, providing the advantage of heat dissipation. Furthermore, the back surface 300B of the auxiliary printed circuit board 300 is a flat surface to facilitate the mounting of the aforementioned two pairs of MOSFET switches SMS1, SMS2, SMS3, and SMS4. For example, the aforementioned pairs of MOSFET switches SMS1 and SMS2 are mounted on the back surface 300B of the auxiliary printed circuit board 300 and close to the top secondary printed circuit board winding circuit ST of the center-tap secondary side circuit CSC. Additionally, the aforementioned pairs of MOSFET switches SMS3 and SMS4 are mounted on the back surface 300B of the auxiliary printed circuit board 300 and close to the bottom secondary printed circuit board winding circuit SB of the center-tap secondary side circuit CSC. Furthermore, the two pairs of secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 are located away from the primary printed circuit board windings P1 and P2 and the air gaps AG1 and AG2. In some embodiments, the two pairs of secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 of the 8-layer auxiliary printed circuit board 300 have a similar configuration to the planar transformer 200A as shown in Figure 4A. Compared with conventional planar transformers (with SPS structure) that mount the secondary metal-oxide-semiconductor field-effect transistor switches on opposite sides of the auxiliary printed circuit board, the positions of the two pairs of secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 (all mounted on the back side 300B of the auxiliary printed circuit board 300) can have the advantage of low resistive loss.

[0048] As shown in Figure 7, in the aforementioned secondary metal-oxide-semiconductor field-effect transistor switches SMS1 and SMS2, one of the secondary metal-oxide-semiconductor field-effect transistor switches SMS1 and SMS2 (e.g., secondary metal-oxide-semiconductor field-effect transistor switch SMS2) is electrically connected to the secondary printed circuit board winding ST1 of the top secondary printed circuit board winding circuit ST through one or more vias (output vias) V1, and is not connected to the bottom secondary printed circuit board winding circuit SB. The one or more vias V1 can conduct from the first protrusion of the conductor of the fifth conductive layer L5 to the input port of the secondary metal-oxide-semiconductor field-effect transistor switch SMS2, and the first protrusion is formed in direction 10 through the core substrate / dielectric layer 302 between the fifth conductive layer L5 and the sixth conductive layer L6 of the auxiliary printed circuit board 300. Additionally, one of the secondary metal-oxide-semiconductor (MOSFET) switches SMS1 and SMS2 (e.g., MOSFET switch SMS1) is electrically connected to the secondary printed circuit board winding ST2 of the top secondary printed circuit board winding circuit ST via a port near the bottom surface of the attached printed circuit board 300. The conductors of the sixth conductive layer L6 have a second protrusion below the first protrusion of the conductors of the fifth conductive layer L5. The length of the first protrusion is greater than the length of the second protrusion, allowing one or more vias to be disposed on the first protrusion without directly connecting the vias to the conductors of the sixth conductive layer L6.

[0049] Similarly, in the above-described secondary metal-oxide-semiconductor field-effect transistor switches SMS3 and SMS4, one of the secondary metal-oxide-semiconductor field-effect transistor switches SMS3 and SMS4 (e.g., secondary metal-oxide-semiconductor field-effect transistor switch SMS4) is electrically connected to the secondary printed circuit board winding SB1 of the bottom secondary printed circuit board winding circuit SB through the through-hole V1, and is not connected to the top secondary printed circuit board winding circuit ST. Additionally, the other of the secondary metal-oxide-semiconductor field-effect transistor switches SMS3 and SMS4 (e.g., secondary metal-oxide-semiconductor field-effect transistor switch SMS3) can be electrically connected to the secondary printed circuit board winding SB2 of the bottom secondary printed circuit board winding circuit SB without the through-hole V1.

[0050] According to the PCB clearance rule, in the planar transformer assembly 500, the distance between the primary metal-oxide-semiconductor field-effect transistor switches PMS1 and PMS2 and the high-potential input port Vin is greater than the distance between the secondary metal-oxide-semiconductor field-effect transistor switches SMS1, SMS2, SMS3, and SMS4 and the through hole V1.

[0051] This disclosure provides a planar transformer assembly, such as a power supply. The planar transformer assembly includes a first printed circuit board. The first printed circuit board includes a magnetic core, a first primary printed circuit board winding, a first secondary printed circuit board winding, and a second secondary printed circuit board winding. The magnetic core passes through the first printed circuit board. The magnetic core includes a first cover plate, a second cover plate, and a first magnetic post. The first magnetic post is connected to and extends from the first cover plate to the second cover plate. The first magnetic post is spaced apart from the second cover plate through a first air gap.

[0052] The planar transformer assembly also includes a planar transformer comprising a magnetic core, a first primary printed circuit board winding, a first secondary printed circuit board winding, a second secondary printed circuit board winding, and a single shielding layer. The first primary printed circuit board winding winds around a first portion of a first magnetic post. The first and second secondary printed circuit board windings wind around a second portion of the first magnetic post, the second portion of the first magnetic post being below the first portion of the first magnetic post. The second portion is a single portion of the first magnetic post. The single shielding layer is located below the first primary printed circuit board winding and above the first and second secondary printed circuit board windings. The shielding layer is connected to a ground terminal.

[0053] In some embodiments, the first portion of the magnetic post is closer to the first air gap than the second portion of the first magnetic post. In some embodiments, each of the first secondary printed circuit board winding and the second secondary printed circuit board winding has a first end and a second end, and the second end of the first secondary printed circuit board winding is connected to the first end of the second secondary printed circuit board winding.

[0054] In some embodiments, the magnetic core further includes a second magnetic post located next to the first magnetic post. The second magnetic post is connected to the first cover plate and extends from the first cover plate to the second cover plate. The second magnetic post is spaced apart from the second cover plate through a second air gap. In some embodiments, the first printed circuit board further includes a second primary printed circuit board winding, a third secondary printed circuit board winding, and a fourth secondary printed circuit board winding. The second primary printed circuit board winding is wound around a third portion of the second magnetic post. The first primary printed circuit board winding and the second primary printed circuit board winding are connected in series. The third secondary printed circuit board winding and the fourth secondary printed circuit board winding are wound around a fourth portion of the second magnetic post, the fourth portion of the second magnetic post being below the third portion of the second magnetic post. The fourth portion is a single portion of the second magnetic post.

[0055] The third portion of the second magnetic post is closer to the second air gap than the fourth portion of the second magnetic post. In some embodiments, each of the third and fourth secondary printed circuit board windings has a third end and a fourth end. The fourth end of the third secondary printed circuit board winding is connected to the third end of the fourth secondary printed circuit board winding. In some embodiments, the first secondary printed circuit board winding forms a first center-tapped secondary circuit. In some embodiments, the total number of turns (wires) of the first and second primary printed circuit board windings is 10 turns, and each of the first, second, third, and fourth secondary printed circuit board windings has 1 turn (wire).

[0056] In some embodiments, the first printed circuit board is an 8-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, a sixth conductive layer, a seventh conductive layer, and an eighth conductive layer arranged sequentially. A first primary printed circuit board winding and a second primary printed circuit board winding are formed by the first conductive layer, the second conductive layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer of the first printed circuit board. A single shielding layer is formed by the sixth conductive layer of the first printed circuit board. A first secondary printed circuit board winding and a third secondary printed circuit board winding are formed by the seventh conductive layer of the first printed circuit board. A second secondary printed circuit board winding and a fourth secondary printed circuit board winding are formed by the eighth conductive layer of the first printed circuit board.

[0057] In some embodiments, the first printed circuit board is a six-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, and a sixth conductive layer arranged sequentially. A first primary printed circuit board winding and a second primary printed circuit board winding are formed by the first conductive layer, the second conductive layer, and the third conductive layer of the first printed circuit board. A single shielding layer is formed by the fourth conductive layer of the first printed circuit board. A first secondary printed circuit board winding and a third secondary printed circuit board winding are formed by the fifth conductive layer of the first printed circuit board. A second secondary printed circuit board winding and a fourth secondary printed circuit board winding are formed by the sixth conductive layer of the first printed circuit board.

[0058] In some embodiments, the planar transformer assembly further includes a second printed circuit board for providing a first printed circuit board mounted thereon. The second printed circuit board includes a pair of primary metal-oxide-semiconductor (MOSFET) field-effect transistor (FET) switches. The first printed circuit board also includes a pair of inductors, a capacitor, and at least two pairs of secondary MOSFET switches. The inductor and capacitor are connected to the primary MOSFET switches to form an inductor-inductor-capacitor structure. The two pairs of secondary MOSFET switches are mounted on the back side of the first printed circuit board. Some of the secondary MOSFET switches are electrically connected through vias to a first center-tapped secondary circuit and a second center-tapped secondary circuit.

[0059] Additionally, this disclosure embodiment provides a power supply. The power supply includes a main printed circuit board and an auxiliary printed circuit board. The main printed circuit board has a pair of primary metal-oxide-semiconductor field-effect transistor switches and a high-potential input port for conducting modulated high-potential current. The auxiliary printed circuit board is mounted on the main printed circuit board. The auxiliary printed circuit board includes a primary-side circuit and a center-tapped secondary-side circuit. The primary-side circuit includes a plurality of primary printed circuit board windings connected in series. The primary-side circuit is configured to conduct modulated high-potential current. The center-tapped secondary-side circuit includes a top secondary printed circuit board winding circuit and a bottom secondary printed circuit board winding circuit. The top and bottom secondary printed circuit board winding circuits are stacked below the primary printed circuit board winding circuits.

[0060] The power supply also includes a planar transformer consisting of a primary side circuit, a center-tapped secondary side circuit, and a single shielding layer. The single shielding layer is sandwiched between the top secondary printed circuit board winding circuit and the primary printed circuit board winding. The shielding layer is connected to ground to suppress common-mode noise induced on the center-tapped secondary side circuit.

[0061] In some embodiments, the auxiliary printed circuit board further includes a magnetic core passing through the auxiliary printed circuit board. The magnetic core includes a first cover plate, a second cover plate, a side core, and a magnetic post. The side core secures the first cover plate and the second cover plate. The magnetic post extends from the first cover plate to the second cover plate. The magnetic post has a first end and a second end. The first end is connected to the first cover plate. The second end is adjacent to the second cover plate and spaced apart from the second cover plate through an air gap.

[0062] In some embodiments, the primary side circuit and the center-tapped secondary side circuit are wound around the magnetic column. In some embodiments, the primary side circuit is closer to the air gap than the center-tapped secondary side circuit. In some embodiments, the primary side circuit is stacked on top of the center-tapped secondary side circuit in the extension direction of the magnetic column to generate an excitation current flowing through the center-tapped secondary side circuit.

[0063] In some embodiments, the auxiliary printed circuit board further includes a pair of magnetizing inductors, a capacitor, a resonant inductor, and at least two pairs of secondary metal-oxide-semiconductor (MOSFET) field-effect transistor (FET) switches. The aforementioned pair of magnetizing inductors, capacitors, and resonant inductors are connected to the aforementioned pair of primary MOSFET switches to form an inductor-inductor-capacitor structure. The inductor-inductor-capacitor structure is configured to provide a modulated high-potential current to a high-potential input port. The aforementioned two pairs of secondary MOSFET switches are mounted on the back side of the auxiliary printed circuit board. One of the secondary MOSFET switches is electrically connected to the top secondary printed circuit board winding circuit through a plurality of vias, but not to the bottom secondary printed circuit board winding circuit.

[0064] In some embodiments, the top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit are connected in parallel. In some embodiments, the first distance between the primary metal-oxide-semiconductor field-effect transistor switch and the high-potential input port is greater than the second distance between the secondary metal-oxide-semiconductor field-effect transistor switch and the via. In some embodiments, in each of the top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit, the turns ratio of the plurality of primary printed circuit board windings of the primary side circuit to the clockwise or counterclockwise wound secondary printed circuit board windings is 10:1.

[0065] In some embodiments, the auxiliary printed circuit board is an 8-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, a sixth conductive layer, a seventh conductive layer, and an eighth conductive layer arranged sequentially. The primary-side circuit is formed by the first, second, third, fourth, and fifth conductive layers of the auxiliary printed circuit board. A single shielding layer is formed by the sixth conductive layer of the auxiliary printed circuit board. The top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit are formed by the seventh and eighth conductive layers of the auxiliary printed circuit board. Each of the primary-side circuit primary printed circuit board windings has one turn of wire in each of the first, second, third, fourth, and fifth conductive layers.

[0066] In some embodiments, the auxiliary printed circuit board is a six-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, and a sixth conductive layer arranged sequentially. The primary-side circuit is formed by the first, second, and third conductive layers of the auxiliary printed circuit board. A single shielding layer is formed by the fourth conductive layer of the auxiliary printed circuit board. The top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit are formed by the fifth and sixth conductive layers of the auxiliary printed circuit board. Each of the primary printed circuit board windings of the primary-side circuit has two 2-turn conductors in two of the first, second, and third conductive layers.

[0067] In some embodiments, the planar transformer assembly (e.g., a power supply) comprises a multilayer printed circuit board to increase the configuration area of ​​the primary-side signal generation circuit, the planar transformer, and the secondary-side rectifier circuit. In some embodiments, the planar transformer uses a single shielding layer disposed on one side of the primary-side circuit (including the primary printed circuit board winding) to isolate the primary-side circuit and the center-tapped secondary-side circuit (including the secondary printed circuit board windings of the top and bottom secondary printed circuit board winding circuits). In some embodiments, in each of the top and bottom secondary printed circuit board winding circuits, the turns ratio of the primary printed circuit board winding to the clockwise or counterclockwise wound secondary printed circuit board winding is approximately 10:1. Compared to conventional planar transformers that use two shielding layers to isolate the primary and secondary windings, the planar transformer of the planar transformer assembly can provide at least one additional printed circuit board conductive layer for the primary printed circuit board winding. Therefore, the resistance of the primary winding (e.g., DC resistance Rdc) can be reduced. Additionally, the secondary printed circuit board winding is configured away from the air gap of the magnetic core. Compared to conventional planar transformers, the induced current in the secondary printed circuit board winding of the planar transformer assembly is more uniform. Furthermore, considering the trade-offs between impedance, leakage inductance, power loss, and manufacturing cost, the planar transformer assembly can utilize 6-layer or 8-layer printed circuit boards with double-sided printed circuit board processes to form both the primary and secondary printed circuit board windings.

[0068] Although the present invention has been disclosed above with reference to the foregoing embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0005] To make the features and advantages of the present invention more apparent and understandable, different embodiments are described below in detail with reference to the accompanying drawings: Figure 1 is a top view of a planar transformer assembly according to some embodiments of the present disclosure. Figure 2 is a block diagram of the planar transformer assembly according to some embodiments of the present disclosure in Figure 1. Figure 3 is an equivalent circuit diagram of the power supply of the planar transformer assembly according to some embodiments of the present disclosure in Figure 2. Figure 4A is a side view of the planar transformer formed in the printed circuit board of the planar transformer assembly according to some embodiments of the present disclosure in Figures 1 to 3. Figure 4B is a top view of each printed circuit board layer of the planar transformer in Figure 4A. Figure 5A is a side view of the planar transformer formed in the printed circuit board of the planar transformer assembly according to some embodiments of the present disclosure in Figures 1 to 3. Figure 5B is a top view of each printed circuit board layer of the planar transformer in Figure 5A. Figure 6 is a partial bottom view of the planar transformer assembly according to some embodiments of the present disclosure, showing the secondary metal-oxide-semiconductor field-effect transistor switch of the planar transformer assembly according to some embodiments of the present disclosure in Figure 1. Figure 7 is a partial cross-sectional view of Figure 5A, showing the electrical connection between the secondary metal-oxide-semiconductor field-effect transistor switch and the secondary printed circuit board winding circuit of a planar transformer according to some embodiments of the present disclosure.

Claims

1. A planar transformer assembly, comprising: A first printed circuit board includes: a magnetic core passing through the first printed circuit board, wherein the magnetic core includes: a first cover plate; a second cover plate opposite to the first cover plate; and a first magnetic post connected to the first cover plate and extending from the first cover plate to the second cover plate, wherein the first magnetic post is separated from the second cover plate by a first air gap; a first primary printed circuit board winding wound around a first portion of the first magnetic post; and a first secondary printed circuit board winding and a second secondary printed circuit board winding wound around a second portion of the first magnetic post, wherein the second portion of the first magnetic post is below the first portion of the first magnetic post, wherein the second portion is a single portion of the first magnetic post.

2. The planar transformer assembly as claimed in claim 1, wherein the first printed circuit board further comprises: A single shielding layer is located below the first primary printed circuit board winding and above the first secondary printed circuit board winding and the second secondary printed circuit board winding, wherein the single shielding layer is connected to a ground terminal.

3. The planar transformer assembly as claimed in claim 2, wherein the first portion of the first magnetic post is closer to the first air gap than the second portion of the first magnetic post.

4. The planar transformer assembly as claimed in claim 2, wherein each of the first secondary printed circuit board winding and the second secondary printed circuit board winding has a first end and a second end, and the second end of the first secondary printed circuit board winding is connected to the first end of the second secondary printed circuit board winding.

5. The planar transformer assembly as described in claim 3, wherein the magnetic core further comprises: A second magnetic post is disposed next to the first magnetic post, wherein the second magnetic post is connected to the first cover plate and extends from the first cover plate to the second cover plate, and wherein the second magnetic post is separated from the second cover plate by a second air gap.

6. The planar transformer assembly as claimed in claim 5, wherein the first printed circuit board further comprises: A second primary printed circuit board winding is wound around a third portion of the second magnetic post, wherein the first primary printed circuit board winding is connected in series with the second primary printed circuit board winding; and a third secondary printed circuit board winding and a fourth secondary printed circuit board winding are wound around a fourth portion of the second magnetic post, wherein the fourth portion of the second magnetic post is below the third portion of the second magnetic post, wherein the fourth portion is a single portion of the second magnetic post.

7. The planar transformer assembly as claimed in claim 6, wherein the third portion of the second magnetic post is closer to the second air gap than the fourth portion of the second magnetic post.

8. The planar transformer assembly as claimed in claim 6, wherein each of the third secondary printed circuit board winding and the fourth secondary printed circuit board winding has a third end and a fourth end, and the fourth end of the third secondary printed circuit board winding is connected to the third end of the fourth secondary printed circuit board winding.

9. The planar transformer assembly as claimed in claim 8, wherein the first secondary printed circuit board winding and the second secondary printed circuit board winding form a first center-tapped secondary circuit, the third secondary printed circuit board winding and the fourth secondary printed circuit board winding form a second center-tapped secondary circuit, and the first center-tapped secondary circuit and the second center-tapped secondary circuit are connected in parallel.

10. The planar transformer assembly as claimed in claim 9, wherein the total number of turns of the first primary printed circuit board winding and the second primary printed circuit board winding is 10 turns, and the number of turns of each of the first secondary printed circuit board winding, the second secondary printed circuit board winding, the third secondary printed circuit board winding and the fourth secondary printed circuit board winding is 1 turn.

11. The planar transformer assembly as described in claim 10, wherein: The first printed circuit board is an 8-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, a sixth conductive layer, a seventh conductive layer, and an eighth conductive layer arranged sequentially. The first primary printed circuit board winding and the second primary printed circuit board winding are formed by the first conductive layer, the second conductive layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer of the first printed circuit board. The single shielding layer is formed by the sixth conductive layer of the first printed circuit board. The first secondary printed circuit board winding and the third secondary printed circuit board winding are formed by the seventh conductive layer of the first printed circuit board, and the second secondary printed circuit board winding and the fourth secondary printed circuit board winding are formed by the eighth conductive layer of the first printed circuit board.

12. The planar transformer assembly as described in claim 10, wherein: A first printed circuit board is a 6-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, and a sixth conductive layer arranged sequentially. The first primary printed circuit board winding and the second primary printed circuit board winding are formed by the first conductive layer, the second conductive layer, and the third conductive layer of the first printed circuit board. The single shielding layer is formed by the fourth conductive layer of the first printed circuit board. The first secondary printed circuit board winding and the third secondary printed circuit board winding are formed by the fifth conductive layer of the first printed circuit board, and the second secondary printed circuit board winding and the fourth secondary printed circuit board winding are formed by the sixth conductive layer of the first printed circuit board.

13. The planar transformer assembly as described in claim 10, further comprising: A second printed circuit board is provided for mounting the first printed circuit board thereon, wherein the second printed circuit board includes: a pair of primary metal-oxide-semiconductor (MOSFET) field-effect transistor (FET) switches, wherein the first printed circuit board further includes: a pair of inductors and a capacitor connected to the pair of primary MOSFET switches to form an inductor-inductor-capacitor structure; and at least two pairs of secondary MOSFET switches mounted on a back side of the first printed circuit board, wherein a portion of the secondary MOSFET switches is electrically connected to the first center-tap secondary circuit and the second center-tap secondary circuit through a plurality of vias.

14. A power supply, comprising: A main printed circuit board having a pair of primary metal-oxide-semiconductor field-effect transistor switches and a high-potential input port for conducting a modulated high-potential current. And an auxiliary printed circuit board mounted on the main printed circuit board, wherein the auxiliary printed circuit board includes: a primary side circuit including a plurality of primary printed circuit board windings connected in series, wherein the primary side circuit is configured to conduct the modulated high-potential current; and a center-tapped secondary side circuit including a top secondary printed circuit board winding circuit and a bottom secondary printed circuit board winding circuit, wherein the top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit are stacked below the primary side circuit.

15. The power supply as claimed in claim 14, wherein the associated printed circuit board further comprises: A single shielding layer is sandwiched between the winding circuit of the top secondary printed circuit board and the primary side circuit, wherein the single shielding layer is connected to a ground terminal to suppress common-mode noise induced on the center tap secondary side circuit.

16. The power supply as claimed in claim 14, wherein the auxiliary printed circuit board further includes a magnetic core passing through the auxiliary printed circuit board, wherein the magnetic core includes: First cover plate; A second cover plate; One side core, fixing the first cover plate and the second cover plate; And a magnetic column extending from the first cover plate to the second cover plate, wherein the magnetic column has a first end and a second end, the first end being connected to the first cover plate, and the second end being adjacent to the second cover plate and separated from the second cover plate by an air gap.

17. The power supply as claimed in claim 16, wherein the primary side circuit and the center tap secondary side circuit are wound around the magnetic post.

18. The power supply as claimed in claim 16, wherein the primary side circuit is closer to the air gap than the center tap secondary side circuit.

19. The power supply as claimed in claim 16, wherein the primary side circuit is stacked on the center tap secondary side circuit in one extension direction of the magnetic post to generate an excitation current flowing through the center tap secondary side circuit.

20. The power supply as claimed in claim 14, wherein the associated printed circuit board further comprises: A pair of magnetized inductors and a capacitor are connected to the pair of primary metal-oxide-semiconductor field-effect transistor switches via a resonant inductor to form an inductor-inductor-capacitor structure, wherein the inductor-inductor-capacitor structure is configured to provide the modulated high-potential current to the high-potential input port; and at least two pairs of secondary metal-oxide-semiconductor field-effect transistor switches are mounted on a back side of the associated printed circuit board, wherein one of the secondary metal-oxide-semiconductor field-effect transistor switches is electrically connected to the winding circuit of the top secondary printed circuit board through a plurality of vias, and is not connected to the winding circuit of the bottom secondary printed circuit board through the vias.

21. The power supply as claimed in claim 14, wherein the top secondary printed circuit board winding circuit is connected in parallel with the bottom secondary printed circuit board winding circuit.

22. The power supply as claimed in claim 20, wherein a first distance between the pair of primary metal-oxide-semiconductor field-effect transistor switches and the high-potential input port is greater than a second distance between the secondary metal-oxide-semiconductor field-effect transistor switches and the vias.

23. The power supply as claimed in claim 14, wherein in each of the top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit, the turns ratio of the primary printed circuit board winding circuit of the primary side circuit to the clockwise or counterclockwise wound primary and secondary printed circuit board windings is 10:

1.

24. The power supply as described in claim 15, wherein: The auxiliary printed circuit board is an 8-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, a sixth conductive layer, a seventh conductive layer, and an eighth conductive layer arranged in sequence. The primary side circuit is formed by the first conductive layer, the second conductive layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer of the auxiliary printed circuit board. The single shielding layer is formed by the sixth conductive layer of the auxiliary printed circuit board. The top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit are formed by the seventh conductive layer and the eighth conductive layer of the auxiliary printed circuit board. Each primary printed circuit board winding of the primary side circuit has one turn of wire in each of the first conductive layer, the second conductive layer, the third conductive layer, the fourth conductive layer, and the fifth conductive layer.

25. The power supply as described in claim 15, wherein: The auxiliary printed circuit board is a 6-layer printed circuit board, including a first conductive layer, a second conductive layer, a third conductive layer, a fourth conductive layer, a fifth conductive layer, and a sixth conductive layer arranged in sequence. The primary side circuit is formed by the first conductive layer, the second conductive layer, and the third conductive layer of the auxiliary printed circuit board. The single shielding layer is formed by the fourth conductive layer of the auxiliary printed circuit board. The top secondary printed circuit board winding circuit and the bottom secondary printed circuit board winding circuit are formed by the fifth conductive layer and the sixth conductive layer of the auxiliary printed circuit board. Each primary printed circuit board winding of the primary side circuit has two 2-turn wires in two of the first, second, and third conductive layers.

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