Switching power supply

Abstract

The utility model provides a switching power supply, a power switch module comprises an enhancement mode switch and a depletion mode switch unit, a source electrode of the enhancement mode switch is connected with a low potential end, the depletion mode switch unit is connected with a drain electrode and a high potential end of the enhancement mode switch, the depletion mode switch unit comprises at least one serially connected depletion mode switch, and the depletion mode switch unit is connected with the drain electrode of the enhancement mode switch. And the grid electrode of each depletion type switch is connected with a corresponding bias voltage. The enhancement type switch and the depletion type switch which are connected in series are used for replacing an existing power switch, and the voltage withstanding requirement of each switch is greatly reduced; meanwhile, due to the fact that an accumulation layer channel exists when the depletion type switch is turned on, compared with a power switch adopting a DMOS device, the on resistance can be greatly reduced, and therefore the on resistance and the parasitic capacitance can be greatly reduced while the total withstand voltage of the power switch module is not reduced, and the conversion efficiency of the switching power supply is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a switching power supply. Background Art

[0002] A switching power supply is a power supply that uses modern power electronics technology to maintain a stable output voltage by controlling the on-time ratio of the power switch. At present, switching power supplies are widely used in almost all electronic devices due to their small size, light weight and high efficiency. They are an indispensable power supply for the rapid development of today's electronic information industry.

[0003] The performance of the power switch in the switching power supply has a great impact on the conversion efficiency. Due to the influence of parasitic parameters in the circuit (especially parasitic inductance), the power switch will generate a high voltage overshoot between its drain and source during the switching process. In order to avoid device damage, the power switch must have sufficient withstand voltage, so the power switch often uses DMOS (Double-diffused Metal Oxide Semiconductor MOSFET) devices. DMOS devices have a long and lightly doped drift region to achieve sufficient withstand voltage, but at the same time, the lightly doped drift region will cause the device to have a higher on-resistance when it is turned on, resulting in higher power consumption on the power switch when the circuit is working, which in turn leads to low conversion efficiency of the switching power supply. Summary of the invention

[0004] The object of the present invention is to provide a switching power supply to solve the problem of low conversion efficiency of the existing switching power supply.

[0005] In order to achieve the above object, the present invention provides a switching power supply, including a power switch module, wherein the power switch module includes:

[0006] an enhanced switch, wherein a source of the enhanced switch is connected to the low potential terminal; and

[0007] The depletion switch unit has two ends connected to the drain and the high potential end of the enhancement switch respectively, and includes at least one depletion switch connected in series, and the gate of each depletion switch is connected to a corresponding bias voltage.

[0008] Optionally, the enhancement-mode switch and each of the depletion-mode switches are independent switch devices.

[0009] Optionally, the enhancement mode switch and all the depletion mode switches are formed on the same substrate and are the same switch device.

[0010] Optionally, the switch device includes:

[0011] substrate;

[0012] a drift region extending from a surface of the substrate into the substrate;

[0013] a body region extending from a surface of the drift region into the drift region;

[0014] a source region extending from a surface of the body region into the body region;

[0015] a drain region extending from a surface of the drift region into the drift region and laterally spaced apart from the body region;

[0016] an insulating layer extending from the surface of the drift region into the drift region and located between the body region and the drain region;

[0017] a first gate structure, located on the substrate and spanning the body region and the insulating layer, for forming a gate of the enhancement mode switch; and

[0018] At least one second gate structure is located on the insulating layer and is spaced apart from each other in the lateral direction, and is used to form a gate of the corresponding depletion-type switch.

[0019] Optionally, the source region and the body region are connected to the low potential end, and the drain region is connected to the high potential end.

[0020] Optionally, when the enhancement-mode switch is turned on, the depletion-mode switches are all turned on; and / or, when the enhancement-mode switch is turned off, the depletion-mode switches are all turned on or all turned off.

[0021] Optionally, the bias voltage connected to the gate of each depletion-mode switch is equal; or, the bias voltage connected to the gate of each depletion-mode switch gradually increases from the low potential end to the high potential end.

[0022] Optionally, the switching power supply further includes:

[0023] At least one bias power supply, the input end of the bias power supply is connected to the source of the enhancement mode switch, the output end of the bias power supply is connected to the gate of the corresponding depletion mode switch, and is used to provide the bias voltage to the corresponding depletion mode switch.

[0024] Optionally, the switching power supply further includes:

[0025] A switch driving unit, wherein the power supply end of the switch driving unit is connected to the power supply voltage, the output end of the switch driving unit is connected to the gate of the enhanced switch, and is used to provide a driving signal to the enhanced switch, and the gate of each depletion switch is connected to the power supply end of the switch driving unit.

[0026] Optionally, the switching power supply includes two power switch modules, a diode and a capacitor, the two power switch modules respectively serve as high-side and low-side power switches of the switching power supply, and are connected in series between a power supply terminal and a ground terminal, and the depletion-type switch unit of each power switch module includes two depletion-type switches, namely a first depletion-type switch and a second depletion-type switch, and the first depletion-type switch is closer to the corresponding enhancement-type switch than the second depletion-type switch;

[0027] The switching power supply further comprises two switch driving units, wherein the power supply end of the switch driving unit is connected to the power supply voltage, and the output end of the switch driving unit is connected to the gate of the corresponding enhanced switch, and is used to provide a driving signal to the corresponding enhanced switch according to the received control signal;

[0028] The anode of the diode is connected to the power supply terminal, the cathode of the diode is connected to the first end of the capacitor, and the second end of the capacitor is connected to the source of the enhanced switch of the power switch module of the high side; and

[0029] The gates of the first depletion-type switches of the two power switch modules are connected to the power supply end of the corresponding switch driving unit, the gate of the second depletion-type switch of the power switch module on the low side is connected to the power supply end, and the gate of the second depletion-type switch of the power switch module on the high side is connected to the cathode of the diode and the first end of the capacitor.

[0030] In the switching power supply provided by the present invention, the power switch module includes an enhancement switch and a depletion switch unit, wherein the source of the enhancement switch is connected to the low potential end, the depletion switch unit is connected to the drain and the high potential end of the enhancement switch, and the depletion switch unit includes at least one depletion switch connected in series, and the gate of each depletion switch is connected to a corresponding bias voltage. The present invention replaces the existing power switch with an enhancement switch and a depletion switch connected in series, and the withstand voltage requirement of each switch will be greatly reduced; at the same time, since the depletion switch has an accumulation layer channel when it is turned on, the on-resistance will be greatly reduced compared to the power switch using a DMOS device. Therefore, the present invention can greatly reduce the on-resistance and parasitic capacitance without reducing the total withstand voltage of the power switch module, thereby improving the conversion efficiency of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A partial circuit diagram of a switching power supply provided in Embodiment 1 of the present invention;

[0032] Figure 2 A schematic diagram of the structure of an enhanced switch provided in Embodiment 1 of the present invention;

[0033] Figure 3A schematic diagram of the structure of a depletion-type switch provided in Embodiment 1 of the present invention;

[0034] Figure 4 A schematic diagram of the structure of a switch device provided in Embodiment 2 of the present invention;

[0035] Figure 5 A circuit diagram of a switching power supply provided in Embodiment 3 of the present invention;

[0036] Figure 6 A circuit diagram of a switching power supply provided in Embodiment 4 of the present invention;

[0037] Figure 7 A circuit diagram of a switching power supply provided in Embodiment 5 of the present invention;

[0038] Wherein, the accompanying drawings are marked as follows:

[0039] Mb, Mb1, Mb2-enhancement switch; Ma, Ma1, Ma2-depletion switch unit; Ma1...Man, Ma11, Ma21-depletion switch; Ma12, Ma22-first depletion switch; Ma13, Ma23-second depletion switch; VL-low potential end; VH-high potential end; BPSa1...BPSan-bias power supply; driver-switch driver unit; HS driver-high-side switch driver unit; LS driver-low-side switch driver unit; VDR-power supply voltage; VIN-power supply end; PGND-ground end; D1, Db-diode; L-inductor; C, Cb-capacitor; R-load; SW-node;

[0040] 101, 102, 103-substrate; 201, 202, 203-drift region; 301, 302-body region; 401, 402, 403-source region; 501, 502, 503-drain region; 601, 602-heavily doped region; 701, 702-gate structure; 703-first gate structure; 704-second gate structure; 801, 802-insulating layer. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer based on the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0042] Embodiment 1

[0043] Figure 1 This is a partial circuit diagram of the switching power supply provided in this embodiment. Figure 1As shown, the switching power supply includes a power switch module, which includes an enhanced switch Mb and a depletion switch unit Ma. The source of the enhanced switch Mb is connected to the low potential terminal VL, and the depletion switch unit Ma is connected to the drain of the enhanced switch Mb and the high potential terminal VH. That is to say, the enhanced switch Mb and the depletion switch unit Ma are connected in series and connected in sequence between the low potential terminal VL and the high potential terminal VH. The depletion switch unit Ma includes at least one depletion switch connected in series, Figure 1 It is shown that the depletion switch unit Ma includes n (n is greater than 1) depletion switches connected in series, namely, depletion switches Ma1 ... Man. Specifically, the source of the depletion switch Ma1 is connected to the drain of the enhancement switch Mb, the drain of the depletion switch Ma1 is connected to the source of the next depletion switch, ... the drain of the depletion switch Man is connected to the high potential terminal VH.

[0044] Furthermore, the switching power supply further includes at least one bias power supply, and the bias power supplies correspond to the depletion-type switches one by one, and each bias power supply is used to input a corresponding bias voltage to the gate of the corresponding depletion-type switch. In this embodiment, there are n bias power supplies, namely bias power supplies BPSa1...BPSan, and the bias power supply BPSa1 is used to input a bias voltage to the gate of the depletion-type switch Ma1, ... and the bias power supply BPSan is used to input a bias voltage to the gate of the depletion-type switch Man.

[0045] In this embodiment, the bias voltage connected to the gate of each depletion-type switch gradually increases from the low potential end VL to the high potential end VH, that is, from the depletion-type switch Ma1 to the depletion-type switch Man, the bias voltage connected to the gate gradually increases, thereby improving the voltage resistance performance of the power switch module.

[0046] Of course, in some embodiments, the bias voltage connected to the gate of each depletion-mode switch may also be equal, that is, the bias voltage connected to the gate of the depletion-mode switches Ma1...Man are all equal. In this case, in order to simplify the circuit structure, the switching power supply may only be provided with one bias power supply, and this bias power supply may output n identical bias voltages.

[0047] In this embodiment, the input end of the bias power supply is connected to the source of the enhancement switch Mb, and the output end of the bias power supply is connected to the gate of the corresponding depletion switch. Figure 1 It can also be seen that the input ends of the bias power supplies BPSa1…BPSan are all connected to the source of the enhancement switch Mb, and the output ends of the bias power supplies BPSa1…BPSan are correspondingly connected to the gates of the depletion switches Ma1…Man, thereby inputting bias voltages to the gates of the corresponding depletion switches Ma1…Man. At this time, the output ends of the bias power supplies BPSa1…BPSan can maintain a stable potential relative to the source of the enhancement switch Mb.

[0048] Of course, the switching power supply also includes a switch driving unit driver. The power supply end of the switch driving unit driver is used to access the power supply voltage VDR, and the power supply voltage VDR can supply power to the switch driving unit driver; the output end of the switch driving unit driver is connected to the gate of the enhanced switch Mb, so as to input a driving signal to the gate of the enhanced switch Mb, thereby driving the enhanced switch Mb.

[0049] Please continue reading Figure 1 In this embodiment, when the enhancement switch Mb is turned on, the voltage of its drain will be close to the voltage of its source. At the same time, the bias voltage output by the bias power supply BPSa1...BPSan is higher than the voltage of the source of the corresponding depletion switch Ma1...Man. The depletion switch Ma1...Man is turned on and an accumulation layer channel is formed. Compared with the power switch using DMOS devices, the on-resistance will be greatly reduced.

[0050] Furthermore, when the enhancement switch Mb is turned off, its drain will first withstand the withstand voltage. At the same time, if the bias voltage output by the bias power supply BPSa1…BPSan is lower than the voltage of the source of the corresponding depletion switch Ma1…Man to a certain value (corresponding threshold voltage), the depletion switch Ma1…Man will be turned off and withstand a certain withstand voltage. At this time, the withstand voltage between the high potential end VH and the low potential end VL is determined by the sum of the withstand voltages of the devices connected in series therebetween (that is, the sum of the withstand voltages of the enhancement switch Mb and the depletion switch Ma1…Man), so the effect of withstanding high voltage can be achieved, reducing the withstand voltage requirements for the enhancement switch Mb and each depletion switch.

[0051] Of course, when the enhancement switch Mb is turned off, the depletion switches Ma1 ... Man do not necessarily have to be turned off. In the case where the voltage resistance of the enhancement switch Mb is sufficient, when the enhancement switch Mb is turned off, the depletion switches Ma1 ... Man may also be turned on.

[0052] Furthermore, in this embodiment, the enhancement-mode switch Mb and the depletion-mode switches Ma1 . . . Man are all independent switch devices, that is, the enhancement-mode switch Mb and each depletion-mode switch are independent devices.

[0053] Figure 2 FIG. 1 is a schematic diagram of the structure of the enhanced switch Mb provided in this embodiment. Figure 2 As shown, the enhancement switch Mb includes a substrate 101 which may be formed of single crystal silicon or other semiconductor materials, and the substrate 101 preferably changes the conductivity (e.g., N-type or P-type) of the substrate material by adding impurities or dopants (e.g., boron, phosphorus, arsenic, etc.). In this embodiment, the enhancement switch Mb is an N-type transistor, so the substrate 101 has a P-type conductivity type, and thus can be referred to as a p-substrate (P-SUB).

[0054] The substrate 101 has a lightly doped drift region 201 extending from the surface of the substrate 101 into the substrate 101. The drift region 201 has a conductivity type opposite to that of the substrate 101, namely, N-type conductivity type, and is therefore also referred to as an N-type drift region (NDD).

[0055] The drift region 201 has a body region 301, which extends from the surface of the drift region 201 to the inside of the drift region 201. The body region 301 has a conductivity type opposite to that of the drift region 201, that is, a P-type conductivity type, and is therefore also referred to as a P-type body region (p-body).

[0056] The body region 301 includes a source region 401 and a heavily doped region 601, which extend from the surface of the body region 301 to the inside of the body region 301, and are arranged adjacent to each other in the lateral direction. The heavily doped region 601 has the same conductivity type as the body region 301, i.e., the P-type conductivity type, and the source region 401 has the opposite conductivity type to the body region 301, i.e., the N-type conductivity type. The source region 401 and the heavily doped region 601 will eventually form the source of the enhancement switch Mb.

[0057] The drift region 201 also has a drain region 501, which extends from the surface of the drift region 201 into the drift region 201, and the drain region 501 is spaced apart from the body region 301 in the lateral direction, so that the drain region 501 is also spaced apart from the source region 401 and the heavily doped region 601 in the lateral direction. The drain region 501 has an opposite conductivity type to the body region 301, that is, an N-type conductivity type. The drain region 501 will eventually form the drain of the enhancement switch Mb.

[0058] A gate structure 701 is disposed on the substrate 101. The gate structure 701 is located between the source region 401 and the drain region 501 and covers a portion of the body region 301 and a portion of the drift region 201. The gate structure 701 will eventually form a gate of the enhancement mode switch Mb.

[0059] Figure 3 This is a schematic diagram of the structure of the depletion type switch provided in this embodiment. Figure 3 As shown, the depletion switch includes a substrate 102 which may be formed of single crystal silicon or other semiconductor materials, and the substrate 102 is preferably modified by adding impurities or dopants (e.g., boron, phosphorus, arsenic, etc.) to change the conductivity (e.g., N-type or P-type) of the substrate material. In this embodiment, the enhancement switch Mb is an N-type transistor, so the substrate 102 has a P-type conductivity type, and thus may be referred to as a p-substrate (P-SUB).

[0060] The substrate 102 has a lightly doped drift region 202 extending from the surface of the substrate 102 into the substrate 102. The drift region 202 has a conductivity type opposite to that of the substrate 102, namely, N-type conductivity type, and is therefore also referred to as an N-type drift region (NDD).

[0061] The drift region 202 includes a source region 402 and a drain region 502, both of which extend from the surface of the drift region 202 into the drift region 202, and the source region 402 and the drain region 502 are spaced apart in the lateral direction. The source region 402 and the drain region 502 have a conductivity type opposite to that of the substrate 102, that is, an N-type conductivity type. The source region 402 and the drain region 502 will eventually form the source and drain of the depletion-type switch.

[0062] An insulating layer 801 is formed on the substrate 102 . The insulating layer 801 extends from the surface of the drift region 202 to the inside of the drift region 202 and is located between the source region 402 and the drain region 502 , thereby isolating the source region 402 from the drain region 502 .

[0063] The substrate 102 also has a gate structure 702, which is located on the insulating layer 801. The gate structure 701 will eventually form a gate of a depletion-mode switch.

[0064] Embodiment 2

[0065] The difference from the first embodiment is that in this embodiment, the enhancement switch Mb and the depletion switches Ma1…Man are formed on the same substrate and are the same switch device. In this way, the enhancement switch Mb and all the depletion switches can be prepared synchronously, simplifying the preparation process, reducing the size of the device, and improving the consistency of the device.

[0066] Figure 4 Schematic diagram of the structure of the switch device provided in this embodiment. Figure 4 As shown, the switch device includes a substrate 103 which may be formed of single crystal silicon or other semiconductor materials, and the substrate 103 is preferably modified by adding impurities or dopants (e.g., boron, phosphorus, arsenic, etc.) to change the conductivity (e.g., N-type or P-type) of the substrate material. In this embodiment, the enhancement switch Mb is an N-type transistor, so the substrate 103 has a P-type conductivity type, and thus may be referred to as a p-substrate (P-SUB).

[0067] The substrate 103 has a lightly doped drift region 203 extending from the surface of the substrate 103 to the inside of the substrate 103. The drift region 203 has a conductivity type opposite to that of the substrate 103, that is, an N-type conductivity type, and is therefore also referred to as an N-type drift region (NDD).

[0068] The drift region 203 has a body region 302, which extends from the surface of the drift region 203 to the inside of the drift region 203. The body region 302 has a conductivity type opposite to that of the drift region 203, that is, a P-type conductivity type, and is therefore also referred to as a P-type body region (p-body).

[0069] The body region 302 includes a source region 403 and a heavily doped region 602, which extend from the surface of the body region 302 to the inside of the body region 302, and are arranged adjacent to each other in the lateral direction. The heavily doped region 602 has the same conductivity type as the body region 302, i.e., a P-type conductivity type, and the source region 403 has an opposite conductivity type to the body region 302, i.e., an N-type conductivity type.

[0070] The drift region 203 also has a drain region 503, which extends from the surface of the drift region 203 to the inside of the drift region 203, and the drain region 503 is spaced apart from the body region 302 in the lateral direction, so that the drain region 503 is also spaced apart from the source region 403 and the heavily doped region 602 in the lateral direction. The drain region 503 has an opposite conductivity type to the body region 302, that is, an N-type conductivity type.

[0071] An insulating layer 802 is formed on the substrate 102 . The insulating layer 802 extends from the surface of the drift region 203 to the inside of the drift region 203 and is located between the body region 302 and the drain region 503 , thereby isolating the source region 403 from the drain region 503 .

[0072] A first gate structure 703 is disposed on the substrate 103. The first gate structure 703 is located between the source region 403 and the drain region 503 and covers a portion of the body region 302 and a portion of the insulating layer 802. The first gate structure 703 will eventually form a gate of the enhancement mode switch Mb.

[0073] The substrate 103 also has at least one second gate structure 704, which is located on the insulating layer 802 and is spaced apart from each other in the lateral direction. The second gate structure 704 is also spaced apart from the first gate structure 703 in the lateral direction. The second gate structures 704 correspond to the depletion switches one by one, and each second gate structure 704 will eventually form the gate of the corresponding depletion switch.

[0074] In this way, the switch device is equivalent to a series structure of an enhancement switch Mb and at least one depletion switch. When in use, the source region 503 and the body region 302 are connected to the low potential terminal VL, and the drain region 503 is connected to the high potential terminal VH.

[0075] Embodiment 3

[0076] The difference from the first embodiment is that in this embodiment, there is no bias power supply in the switching power supply, which simplifies the structure of the switching power supply.

[0077] Specifically, Figure 5 The circuit diagram of the switching power supply provided in this embodiment. Figure 5 As shown, in this embodiment, the gates of the depletion switches Ma1 ... Man are all connected to the power supply end of the switch driving unit driver, and at this time, the power supply voltage VDR serves as the bias voltage of the depletion switches Ma1 ... Man. Further, the input end of the switch driving unit driver is connected to the source of the enhancement switch Mb, so the power supply end of the switch driving unit driver can maintain a stable potential relative to the source of the enhancement switch Mb, thereby replacing the bias power supply solution.

[0078] Embodiment 4

[0079] The difference from the first embodiment is that in this embodiment, the switching power supply is a Buck-Boost structure.

[0080] Specifically, Figure 6 The circuit diagram of the switching power supply provided in this embodiment. Figure 6 As shown, the switching power supply includes two power switch modules, which are connected in series between the power supply terminal VIN and the ground terminal PGND. Among the two power switch modules, the power switch module close to the power supply terminal VIN is a high-side power switch module, which serves as the high-side power switch of the switching power supply; the power switch module close to the ground terminal PGND is a low-side power switch module, which serves as the low-side power switch of the switching power supply.

[0081] Further, the high-side power switch module includes an enhanced switch Mb1 and a depletion switch unit Ma1, and the depletion switch unit Ma1 includes a depletion switch Ma11; the low-side power switch module includes an enhanced switch Mb2 and a depletion switch unit Ma2, and the depletion switch unit Ma2 includes a depletion switch Ma21. The source of the enhanced switch Mb2 is connected to the ground terminal PGND, the drain of the enhanced switch Mb2 is connected to the source of the depletion switch Ma21, the drain of the depletion switch Ma21 is connected to the source of the enhanced switch Mb1, the drain of the enhanced switch Mb1 is connected to the source of the depletion switch Ma11, and the drain of the depletion switch Ma11 is connected to the power supply terminal VIN. In this way, the enhancement switch Mb2, the depletion switch Ma21, the enhancement switch Mb1 and the depletion switch Ma11 are sequentially connected in series between the ground terminal PGND and the power supply terminal VIN, and the power supply terminal VIN serves as the high potential end of the high-side power switch module, the node SW between the source of the enhancement switch Mb1 and the drain of the depletion switch Ma21 serves as the low potential end of the high-side power switch module and the high potential end of the low-side power switch module, and the ground terminal PGND serves as the low potential end of the low-side power switch module.

[0082] The switching power supply also includes two switch driving units, namely, a high-side switch driving unit HS driver and a low-side switch driving unit LS driver. The power supply end of the high-side switch driving unit HS driver is connected to the power supply voltage VDR through a reverse-connected diode D1, and the power supply voltage VDR can supply power to the high-side switch driving unit HS driver; the output end of the high-side switch driving unit HS driver is connected to the gate of the enhanced switch Mb1, so that a driving signal is input to the gate of the enhanced switch Mb1 according to the received control signal, thereby driving the enhanced switch Mb1. Similarly, the power supply end of the low-side switch driving unit LS driver is connected to the power supply voltage VDR, and the power supply voltage VDR can also supply power to the low-side switch driving unit LS driver; the output end of the low-side switch driving unit LS driver is connected to the gate of the enhanced switch Mb2, so that a driving signal is input to the gate of the enhanced switch Mb2 according to the received control signal, thereby driving the enhanced switch Mb2.

[0083] Please continue reading Figure 6 , the gate of the depletion switch Ma11 is connected to the power supply end of the high-side switch driving unit HS driver, at which time, the power supply voltage VDR is used as the bias voltage of the depletion switch Ma11 after passing through the diode D1; the gate of the depletion switch Ma21 is connected to the power supply end of the low-side switch driving unit LS driver, at which time, the power supply voltage VDR is used as the bias voltage of the depletion switch Ma21. Further, the input end of the high-side switch driving unit HS driver is connected to the source of the enhanced switch Mb1, so the power supply end of the high-side switch driving unit HS driver can maintain a stable potential relative to the source of the enhanced switch Mb1, thereby replacing the bias power supply solution; the input end of the low-side switch driving unit LS driver is connected to the source of the enhanced switch Mb2, so the power supply end of the low-side switch driving unit LS driver can maintain a stable potential relative to the source of the enhanced switch Mb2, thereby replacing the bias power supply solution.

[0084] The switching power supply further includes an inductor L, a capacitor C and a load R. The inductor L and the capacitor C are connected in series and connected between the node SW and the ground terminal PGND in sequence. The load R is connected in parallel to the capacitor C. Of course, the switching power supply may also have other components, which will not be described one by one here.

[0085] Please continue reading Figure 6In this embodiment, when the enhancement switch Mb1 and the enhancement switch Mb2 are turned on, the voltage of their drains will be close to the voltage of their sources. At the same time, the supply voltage VDR is higher than the voltage of the source of the depletion switch Ma21 and the voltage of the source of the depletion switch Ma11. The depletion switch Ma21 and the depletion switch Ma11 are both turned on and form an accumulation layer channel, thereby reducing the on-resistance.

[0086] Furthermore, when the enhanced switch Mb1 and the enhanced switch Mb2 are turned off, their drains will first withstand the withstand voltage. At the same time, the power supply voltage VDR is lower than the voltage of the source of the depletion switch Ma21 to a certain value (the threshold voltage of the depletion switch Ma21), and the power supply voltage VDR is lower than the voltage of the source of the depletion switch Ma11 to a certain value (the threshold voltage of the depletion switch Ma11). The depletion switch Ma21 and the depletion switch Ma11 will be turned off and withstand a certain withstand voltage. At this time, the withstand voltage between the ground terminal PGND and the power supply terminal VIN is determined by the sum of the withstand voltages of the devices connected in series therebetween (that is, the sum of the withstand voltages of the enhanced switch Mb, the enhanced switch Mb2, the depletion switch Ma11, and the depletion switch Ma21). Therefore, the effect of withstanding high voltage can be achieved, and the withstand voltage requirements for the enhanced switch Mb1, the enhanced switch Mb2, and each depletion switch are reduced.

[0087] When the switching power supply is working, the high-side power switch module and the low-side power switch module may be turned on alternately. At this time, the off power switch module will withstand the withstand voltage. The withstand voltage between the ground terminal PGND and the power supply terminal VIN is generally determined by the sum of the withstand voltages of each series device in the off state. Since each power switch module can use a depletion switch to withstand the withstand voltage in addition to the enhanced switch, the withstand voltage effect can also be achieved on the basis of reducing the withstand voltage requirements of the enhanced switch.

[0088] Of course, when the enhancement switch Mb1 and the enhancement switch Mb2 are turned off, the depletion switch Ma11 and the depletion switch Ma21 do not necessarily have to be turned off. When the voltage resistance of the enhancement switch Mb1 and the enhancement switch Mb2 is sufficient, the depletion switch Ma11 and the depletion switch Ma21 can also be turned on when the enhancement switch Mb1 and the enhancement switch Mb2 are turned off.

[0089] It should be understood that the switching power supply is not limited to the Buck-Boost structure, and other topological structures may also be used, such as Buck structure, Boost structure, Flyback structure, etc., which will not be illustrated one by one here. As long as the switching power supply has a power switch solution, the solution of the present invention can be applied.

[0090] Embodiment 5

[0091] Figure 7The circuit diagram of the switching power supply provided in this embodiment. Figure 7 As shown, the difference from the fourth embodiment is that in this embodiment, the depletion type switch unit Ma1 and the depletion type switch unit Ma2 each include two depletion type switches.

[0092] Specifically, the depletion switch unit Ma1 includes a first depletion switch Ma12 and a second depletion switch Ma13 connected in series, and the depletion switch unit Ma2 includes a first depletion switch Ma22 and a second depletion switch Ma23 connected in series. The source of the enhancement switch Mb2 is connected to the ground terminal PGND, the drain of the enhancement switch Mb2 is connected to the source of the first depletion switch Ma22, the drain of the first depletion switch Ma22 is connected to the source of the second depletion switch Ma23, the drain of the second depletion switch Ma23 is connected to the source of the enhancement switch Mb1, the drain of the enhancement switch Mb1 is connected to the source of the first depletion switch Ma12, the drain of the first depletion switch Ma12 is connected to the source of the second depletion switch Ma13, and the drain of the second depletion switch Ma13 is connected to the power supply terminal VIN. In this way, the enhanced switch Mb2, the first depletion switch Ma22, the second depletion switch Ma23, the enhanced switch Mb1, the first depletion switch Ma12 and the second depletion switch Ma13 are sequentially connected in series between the ground terminal PGND and the power supply terminal VIN; and the power supply terminal VIN serves as the high potential end of the high-side power switch module, the node SW between the source of the enhanced switch Mb1 and the drain of the second depletion switch Ma23 serves as the low potential end of the high-side power switch module and the high potential end of the low-side power switch module, and the ground terminal PGND serves as the low potential end of the low-side power switch module.

[0093] Further, the gate of the first depletion-mode switch Ma12 is connected to the power supply end of the high-side switch driving unit HS driver, and at this time, the power supply voltage VDR is used as the bias voltage of the depletion-mode switch Ma11 after passing through the diode D1. The switching power supply also includes a bias power supply composed of a diode Db and a capacitor Cb, the anode of the diode Db is connected to the power supply end VIN, the cathode of the diode Db is connected to the first end of the capacitor Cb, the second end of the capacitor Cb is connected to the source of the enhancement switch Mb1, and the gate of the second depletion-mode switch Ma13 is connected to the cathode of the diode Db and the first end of the capacitor Cb. The gate of the first depletion-mode switch Ma22 is connected to the power supply end of the low-side switch driving unit LS driver, and at this time, the power supply voltage VDR is used as the bias voltage of the first depletion-mode switch Ma22; the gate of the second depletion-mode switch Ma23 is connected to the power supply end VIN, and the voltage of the power supply end VIN is used as the voltage of the second depletion-mode switch Ma23.

[0094] In this way, the bias voltage connected to the gate of the second depletion-mode switch Ma13 can be greater than the bias voltage connected to the gate of the first depletion-mode switch Ma12, and the bias voltage connected to the gate of the second depletion-mode switch Ma23 can also be greater than the bias voltage connected to the gate of the first depletion-mode switch Ma22, thereby improving the voltage resistance performance of the two power switch modules when in the off state and the conduction performance when in the on state.

[0095] In summary, in the switching power supply provided by the embodiment of the present invention, the power switch module includes an enhancement switch and a depletion switch unit, wherein the source of the enhancement switch is connected to the low potential end, the depletion switch unit is connected to the drain and the high potential end of the enhancement switch, and the depletion switch unit includes at least one depletion switch connected in series, and the gate of each depletion switch is connected to a corresponding bias voltage. The present invention replaces the existing power switch with an enhancement switch and a depletion switch connected in series, and the withstand voltage requirement of each switch will be greatly reduced; at the same time, since the depletion switch has an accumulation layer channel when it is turned on, the on-resistance will be greatly reduced compared to the power switch using a DMOS device. Therefore, the present invention can greatly reduce the on-resistance and parasitic capacitance without reducing the total withstand voltage of the power switch module, thereby improving the conversion efficiency of the switching power supply.

[0096] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0097] It should also be noted that, although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

[0098] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are merely used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0099] It should also be recognized that the terms described herein are only used to describe specific embodiments and are not intended to limit the scope of the invention. It should be noted that the singular forms "a" and "an" used herein and in the appended claims include plural references unless the context clearly indicates otherwise. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or", rather than a logical "exclusive or", unless the context clearly indicates otherwise. In addition, the implementation of the method and / or device in the embodiments of the present invention may include performing the selected task manually, automatically, or in combination.

Claims

1. A switching power supply, characterized in that: A power switch module is included, wherein the power switch module includes: an enhanced switch, wherein a source of the enhanced switch is connected to the low potential terminal; and The depletion switch unit has two ends connected to the drain and the high potential end of the enhancement switch respectively, and includes at least one depletion switch connected in series, and the gate of each depletion switch is connected to a corresponding bias voltage.

2. The switching power supply according to claim 1, characterized in that: The enhancement-mode switch and each of the depletion-mode switches are independent switch devices.

3. The switching power supply according to claim 1, characterized in that: The enhancement mode switch and all the depletion mode switches are formed on the same substrate and are the same switch device.

4. The switching power supply according to claim 3, characterized in that: The switch device comprises: substrate; a drift region extending from a surface of the substrate into the substrate; a body region extending from a surface of the drift region into the drift region; a source region extending from a surface of the body region into the body region; a drain region extending from a surface of the drift region into the drift region and laterally spaced apart from the body region; an insulating layer extending from the surface of the drift region into the drift region and located between the body region and the drain region; a first gate structure, located on the substrate and spanning the body region and the insulating layer, for forming a gate of the enhancement mode switch; and At least one second gate structure is located on the insulating layer and is spaced apart from each other in the lateral direction, and is used to form a gate of the corresponding depletion-type switch.

5. The switching power supply according to claim 4, characterized in that: The source region and the body region are connected to the low potential end, and the drain region is connected to the high potential end.

6. The switching power supply according to claims 1 to 5, characterized in that: When the enhancement-mode switch is turned on, the depletion-mode switches are all turned on; and / or, when the enhancement-mode switch is turned off, the depletion-mode switches are all turned on or all turned off.

7. The switching power supply according to any one of claims 1 to 5, characterized in that: The bias voltage connected to the gate of each depletion-mode switch is equal; or, the bias voltage connected to the gate of each depletion-mode switch gradually increases from the low potential end to the high potential end.

8. The switching power supply according to claim 7, characterized in that: The switching power supply further comprises: At least one bias power supply, the input end of the bias power supply is connected to the source of the enhancement mode switch, and the output end of the bias power supply is connected to the gate of the corresponding depletion mode switch, for providing the bias voltage to the corresponding depletion mode switch.

9. The switching power supply according to claim 7, characterized in that: The switching power supply further comprises: A switch driving unit, wherein the power supply end of the switch driving unit is connected to the power supply voltage, the output end of the switch driving unit is connected to the gate of the enhanced switch, and is used to provide a driving signal to the enhanced switch, and the gate of each depletion switch is connected to the power supply end of the switch driving unit.

10. The switching power supply according to claim 7, characterized in that: The switching power supply comprises two power switch modules, a diode and a capacitor, the two power switch modules respectively serve as high-side and low-side power switches of the switching power supply, and are connected in series between a power supply terminal and a ground terminal, the depletion-type switch unit of each power switch module comprises two depletion-type switches, namely a first depletion-type switch and a second depletion-type switch, wherein the first depletion-type switch is closer to the corresponding enhancement-type switch than the second depletion-type switch; The switching power supply further comprises two switch driving units, wherein the power supply end of the switch driving unit is connected to the power supply voltage, and the output end of the switch driving unit is connected to the gate of the corresponding enhanced switch, and is used to provide a driving signal to the corresponding enhanced switch according to the received control signal; The anode of the diode is connected to the power supply terminal, the cathode of the diode is connected to the first end of the capacitor, and the second end of the capacitor is connected to the source of the enhanced switch of the power switch module of the high side; and The gates of the first depletion-type switches of the two power switch modules are connected to the power supply end of the corresponding switch driving unit, the gate of the second depletion-type switch of the power switch module on the low side is connected to the power supply end, and the gate of the second depletion-type switch of the power switch module on the high side is connected to the cathode of the diode and the first end of the capacitor.

Images