CN209982063U

CN209982063U - Power supply switching circuit and electronic equipment

Info

Publication number: CN209982063U
Application number: CN201921310813.5U
Authority: CN
Inventors: 姜东帅
Original assignee: Beijing Baiyou Technology Co Ltd
Current assignee: Beijing Baiyou Technology Co Ltd
Priority date: 2019-08-13
Filing date: 2019-08-13
Publication date: 2020-01-21
Anticipated expiration: 2029-08-13

Abstract

The utility model provides a power supply switching circuit and electronic equipment, this power supply switching circuit includes: the low dropout linear regulator comprises a DC-DC conversion circuit, an electronic switching circuit and a low dropout linear regulator; the input end of the DC-DC conversion circuit is connected with the input end of the low-dropout linear regulator, and the input end of the DC-DC conversion circuit is used for connecting a direct-current power supply; the output end of the DC-DC conversion circuit is connected with the input end of the electronic switch circuit; the output end of the electronic switching circuit is connected with the output end of the low dropout linear regulator, the output end of the electronic switching circuit is used for being connected with a load, and the output voltage of the DC-DC conversion circuit is greater than the maximum output voltage of the low dropout linear regulator. The utility model discloses utilize low dropout linear voltage regulator and DC-DC converting circuit's parallel structure and according to the seamless switching low dropout linear voltage regulator of different states of load and DC-DC converting circuit for the load power supply, improved the overall efficiency of system's power etc..

Description

Power supply switching circuit and electronic equipment

Technical Field

The utility model relates to a power technical field especially relates to a power supply switching circuit and electronic equipment.

Background

Basically, all electronic products require power supply, and the power supply is an essential component of the electronic products. The power supply of the control panel of each electronic circuit is basically direct current power supply, such as 12V/24V direct current power supply output by rectifying an alternating current power supply, or a battery power supply mode. At present, a DC input power of an electronic board card on the market generally employs a DC-DC conversion circuit or a low dropout regulator (LDO) to implement voltage reduction or voltage boosting of the DC input power, as shown in fig. 1A and 1B, respectively, and then supplies power to each chip and module on a load control board.

For electronic products, the power efficiency parameter of the control board is an important index for evaluating the comprehensive performance of the power supply, and particularly for products with higher requirements on standby power consumption and energy efficiency level, low-power-consumption products powered by batteries are more important. However, for the power supply topologies shown in fig. 1A and fig. 1B, the overall efficiency of the system power supply is not high due to different losses of different voltage conversion circuits under different load conditions.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention provides a power switching circuit and an electronic device, which can improve the overall efficiency of a system power supply by connecting a low dropout regulator and a DC-DC conversion circuit in parallel and realizing seamless switching according to different states of a load.

An embodiment of the utility model provides a power supply switching circuit, include: the input end of the DC-DC conversion circuit is connected with the input end of the low dropout linear regulator, and the input end of the DC-DC conversion circuit is used for connecting a direct current power supply;

the output end of the DC-DC conversion circuit is connected with the input end of the electronic switch circuit, and the enable end of the DC-DC conversion circuit and the enable end of the electronic switch circuit are both used for connecting a control end;

the output end of the electronic switching circuit is connected with the output end of the low dropout linear regulator, and the output end of the electronic switching circuit is used for connecting a load, wherein the output voltage of the DC-DC conversion circuit is greater than the maximum output voltage of the low dropout linear regulator;

the control end is used for starting the DC-DC conversion circuit and switching on the electronic switch circuit when the load is in a non-light load state so as to enable the DC-DC conversion circuit to supply power to the load;

and the control end is also used for enabling the DC-DC conversion circuit not to be started and the electronic switch circuit to be switched off when the load is in a light load state, so that the low dropout linear regulator supplies power to the load.

Further, the power supply switching circuit described above further includes: and the enabling end of the DC-DC conversion circuit and the enabling end of the electronic switch circuit are both connected with the power management chip as the control end.

Further, in the above power switching circuit, the control terminal is a main control chip of the load, and both the enable terminal of the DC-DC conversion circuit and the enable terminal of the electronic switch circuit are used for connecting the main control chip.

Further, in the above power switching circuit, the electronic switch circuit includes an electronic switch, and the electronic switch is a transistor, a MOS transistor, or a relay.

Further, in the above power switching circuit, when the electronic switch is an MOS transistor, a gate of the MOS transistor is used for connecting the control terminal, a source of the MOS transistor is connected to the output terminal of the DC-DC conversion circuit, and a drain of the MOS transistor is used for connecting the load.

Further, the power supply switching circuit described above further includes: the input end of the AC-DC adapter is used for connecting an alternating current power supply, and the output end of the AC-DC adapter is connected with the input end of the DC-DC conversion circuit;

the AC-DC adapter is used for converting the alternating current power supply into a direct current power supply and then inputting the direct current power supply into the DC-DC conversion circuit and the low dropout linear regulator.

Further, the power supply switching circuit described above further includes: and the battery terminal is used for connecting a battery and is connected with the input end of the DC-DC conversion circuit.

Further, the power supply switching circuit described above further includes: and the battery is connected with the battery terminal and is a dry battery or a storage battery.

Another embodiment of the present invention further provides an electronic device, including the above power switching circuit.

Further, in the above electronic device, the electronic device is an intelligent door lock or an intelligent doorbell.

The utility model discloses technical scheme is through with DC-DC converting circuit and the linear stabiliser parallel connection of low dropout in load end to carry out seamless switching according to the different states of load, can improve the overall efficiency of system's power etc.. The isolation between the DC-DC conversion circuit and the low dropout linear regulator can be effectively realized by adding an electronic switch circuit, and the mutual influence of the DC-DC conversion circuit and the low dropout linear regulator in the switching process is avoided, so that the reliability of the power supply switching circuit is ensured, and the like.

In order to make the aforementioned and other objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1A and 1B respectively show a schematic structure diagram of a conventional power supply circuit;

fig. 2 shows a first schematic structure diagram of a power switching circuit according to an embodiment of the present invention;

fig. 3 shows a second schematic diagram of the power switching circuit according to the embodiment of the present invention;

fig. 4 shows a third structural schematic diagram of the power switching circuit according to the embodiment of the present invention.

Description of the main element symbols:

100-power switching circuit; a 10-DC-DC conversion circuit; 20-an electronic switching circuit; 30-low dropout linear regulator; 40-a power management chip; 50-AC-DC adapter.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the templates herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in fig. 1A, in this scheme, the DC input power is supplied to the load through the output of the DC-DC conversion circuit, and normally, the enable terminal EN1 of the DC-DC conversion circuit is substantially high, i.e., connected to the DC input terminal, so that the DC-DC conversion circuit can enter an operating state as soon as power is supplied. Of course, the enable terminal EN1 may be controlled separately. With this scheme, when the load is in a light load state, the conversion efficiency of the DC-DC conversion circuit is low, and generally, the power conversion efficiency thereof is 20% or less at an output current of 10 uA. In fact, for some low power consumption device products, such as the intelligent hardware product of the internet of things, the main control IC is in a sleep state most of the time, and only when the main control IC is awakened, the main control IC enters a normal power supply mode, and the current consumed in standby at this time can reach a microampere level. It can be seen that the conversion efficiency of the DC-DC conversion circuit in the standby state is very low, which will greatly reduce the overall efficiency of the system power supply.

As shown in fig. 1B, in this scheme, a dc input power is output to a load through a low dropout linear regulator (i.e., LDO) to supply power, and the LDO generally has no enable terminal, so that when the power supply meets the requirement of normal start of the LDO, the LDO can normally operate to output a target voltage. The LDO output has small self-loss under the condition that the load is idle or is switched off. However, when the LDO is in a normal operation mode, such as an output current of more than 10mA, the loss of the LDO is large, and the power conversion efficiency is greatly reduced compared to the DC-DC conversion circuit. After the device is converted into the normal operating mode, the load current is much higher than the standby state, even more than 1000 times, so the power efficiency in the normal operating mode is also not negligible.

Based on this, the utility model provides a power supply switching circuit to realize optimizing system power architecture and remove the overall efficiency that improves the system power. It should be understood that, in the present invention, the standby state, the sleep state, and the off state of the device are all collectively referred to as the light load state. It will be appreciated that in the light load state, the power of the power supply required by the load is small or zero, and the device is in a low power consumption state. Conversely, the non-light load state may include a normal working state of the load, a heavy load state, and the like. For example, if the device is awakened by an external event and then changes from the sleep state to the normal operating state, the device master will operate at full frequency. Taking the door lock device as an example, if a door opening instruction is received, the door lock master control will drive the motor to work, and at this time, the transient load current will be very large, which can be regarded as the above-mentioned heavy load state.

Example 1

Referring to fig. 2, the present embodiment provides a power switching circuit 100, which can be applied to various electronic devices including power devices, such as an intelligent door lock, an intelligent doorbell, and the like. The overall efficiency of the entire electronic device, etc., can be improved by the power switching circuit 100. The power switching circuit 100 will be described in detail below.

As shown in fig. 2, the power switching circuit 100 includes a DC-DC conversion circuit 10, an electronic switching circuit 20, and a low dropout linear regulator 30. Exemplarily, an input terminal of the DC-DC conversion circuit 10 is connected to an input terminal of the low dropout regulator 30, and an input terminal of the DC-DC conversion circuit 10 is used for connecting a direct current power supply, that is, the DC-DC conversion circuit 10 and the low dropout regulator 30 are connected in parallel to the same direct current power supply. The output end of the DC-DC conversion circuit 10 is connected to the input end of the electronic switching circuit 20, the output end of the electronic switching circuit 20 is connected to the output end of the low dropout regulator 30, and the output end of the electronic switching circuit 20 is used for connecting to a load, that is, the DC-DC conversion circuit 10 is connected in parallel to the same load with the low dropout regulator 30 after passing through the electronic switching circuit.

In this embodiment, the output voltage of the DC-DC conversion circuit 10 is set to be greater than the maximum output voltage of the low dropout regulator 30. Exemplarily, as shown in fig. 2, the output voltage Vout1 of the DC-DC conversion circuit 10 may be set to be slightly larger than the maximum output voltage Vout2 of the low dropout linear regulator 30, for example, may be set to be larger than about 0.1V. Since the load power supply usually has a certain voltage range, it is only necessary to ensure that both Vout1 and Vout2 are within the voltage range.

In this embodiment, the enable terminal of the DC-DC conversion circuit 10 and the enable terminal of the electronic switch circuit 20 are both used to connect to a control terminal. The control terminal may be a power management chip dedicated to power management, wherein the power management chip can be used to monitor the operating state of a connected load. Of course, the control terminal may also be a main control chip of a connected load, and the like.

Specifically, the control terminal is configured to enable the DC-DC conversion circuit 10 and the electronic switch circuit 20 when the connected load is in a non-light load state, even if the DC-DC conversion circuit 10 is started and the electronic switch circuit 20 is turned on, so that the DC-DC conversion circuit 10 can perform voltage conversion on the accessed direct current power supply to supply power to the load.

The control terminal is further configured to disable the DC-DC conversion circuit 10 and disconnect the electronic switch circuit 20 when the connected load is in a light load state, so that the low dropout linear regulator 30 performs voltage conversion on the accessed DC power supply to supply power to the load.

In this embodiment, the electronic switching circuit 20 is mainly used to implement isolation between the DC-DC conversion circuit 10 and the low dropout regulator 30. The electronic switching circuit 20 illustratively includes an electronic switch, which may be, for example, a transistor, a MOS transistor, a relay, or the like. The triode comprises an NPN tube and a PNP tube, and the MOS tube comprises a P-channel MOS tube, an N-channel MOS tube and the like.

For example, if the electronic switch is a P-channel MOS transistor, as shown in fig. 3, the gate of the P-channel MOS transistor is connected to the power management chip as the control terminal, the source is connected to the output terminal of the DC-DC conversion circuit 10, and the drain is connected to the load. Of course, a corresponding current-limiting resistor can be further arranged between the gate of the P-channel MOS transistor and the power management chip, and the current-limiting resistor can be specifically arranged according to actual requirements.

Generally, in the DC-DC conversion circuit 10, such as a Boost circuit, a BUCK circuit, or a Boost-BUCK Boost circuit, a relatively large energy storage capacitor is included, and the energy storage capacitor is discharged when the DC-DC conversion circuit 10 is turned off. Some DC-DC conversion circuits 10 have fast discharge circuits therein, that is, the energy storage capacitor is discharged quickly when turned off. If the DC-DC conversion circuit 10 and the LDO are directly connected in parallel, that is, there is no isolation through the electronic switch circuit 20, at this time, after the LDO is powered, most of the output voltage of the LDO will be absorbed by the discharge circuit, thereby increasing the power consumption of the system, and thus the purpose of light load and high efficiency cannot be achieved. Therefore, the electronic switch circuit 20 can effectively isolate the mutual influence of the LDO and the DC-DC conversion circuit 10 in the switching process, thereby not only ensuring the reliability of the circuit, but also being beneficial to the high-efficiency realization in the light load state, and further improving the overall efficiency of the system power supply.

Optionally, as shown in fig. 4, the power switching circuit 100 further includes a power management chip 40, where the power management chip 40 is used as the control terminal for controlling the enabling terminals of the DC-DC conversion circuit 10 and the electronic switch circuit 20 accordingly. Exemplarily, the enable terminal of the DC-DC conversion circuit 10 and the enable terminal of the electronic switch circuit 20 are both connected to the power management chip 40.

Since the enable terminal of the DC-DC conversion circuit 10 and the enable terminal of the electronic switch circuit 20 have the same control logic, preferably, the enable terminal of the DC-DC conversion circuit 10 is connected to the power management chip 40 in parallel with the enable terminal of the electronic switch circuit 20, that is, two enable terminals share one control pin of the power management chip 40, so as to reduce occupation of chip pins and the like.

As another alternative, the control terminal is a main control chip of the load, that is, the main control chip is used to control the enabling terminals of the DC-DC conversion circuit 10 and the electronic switch circuit 20. Exemplarily, the enable terminal of the DC-DC conversion circuit 10 and the enable terminal of the electronic switch circuit 20 are both used for connecting a main control chip of a load. Or the enable ends of the two are connected in parallel to the same control pin of the main control chip.

Optionally, the power switching circuit 100 further includes an AC-DC adapter 50, wherein an input end of the AC-DC adapter 50 is used for connecting an alternating current power source, and an output end of the AC-DC adapter 50 is connected to an input end of the DC-DC conversion circuit 10. The AC-DC adapter 50 is used to convert the connected AC power into DC power, and then input the DC power into the DC-DC conversion circuit 10 and the low dropout regulator 30, respectively. It can be understood that the AC-DC adapter 50 is mainly used for voltage drop, rectification, filtering and other processing of the connected AC power, such as AC 110V-220V.

As another alternative, the power switching circuit 100 further includes a battery terminal for connecting a battery, and the battery terminal is connected to the input terminal of the DC-DC conversion circuit 10 and the input terminal of the low dropout linear regulator 30. Optionally, the power switching circuit 100 further includes a battery connected to the above-mentioned battery terminal, and the battery is to be input as a direct-current power to the DC-DC conversion circuit 10 and the low dropout regulator 30. The battery may be a dry cell battery, a secondary battery, or the like, such as a lithium battery, an AA/AAA battery, or the like.

The operation of the power switching circuit 100 will be described with reference to fig. 2.

(1) When the load is in a light load state, such as a standby state, a sleep state, etc., the control terminal will make the DC-DC conversion circuit 10 not activated, i.e., not operated, and make the electronic switch circuit 20 in an off state, for example, it can specifically set the enable terminals EN1 and EN2 to be at a low level, and at this time, the LDO output voltage supplies power to the load.

It can be understood that when the load is in a light load state, the current required by the load is 0 or very small current, such as a nanoamp level or a milliamp level, and the LDO consumes its own static current, which is very low and therefore has very small loss, thereby ensuring high efficiency of the system power supply.

(2) When the load is converted into a non-light load state, such as a normal operating state, the control terminal enables the DC-DC conversion circuit 10 and the electronic switch circuit 20, that is, the DC-DC conversion circuit 10 is started and the electronic switch circuit 20 is turned on, and if the enable terminals EN1 and EN2 are set to be at a high level, the output voltage Vout1 of the DC-DC conversion circuit 10 supplies power to the load after passing through the electronic switch circuit 20.

As shown in fig. 2, neglecting the conduction loss of the electronic switch in the electronic switch circuit 20, the output voltage Vout1 of the DC-DC converter circuit 10 is nearly equal to the output voltage Vout1_1 of the electronic switch circuit 20, i.e., Vout1 ≈ Vout1_1> the maximum output voltage Vout2 of LDO. Since the output voltage Vout1 of the DC-DC converter circuit 10 is smaller than the DC power voltage applied to the input terminal thereof, the LDO does not have a current backward flow phenomenon, and the output voltage thereof is regulated depending on the load current. If the output voltage of the LDO is pulled up to the maximum output voltage Vout2 by the connected load, since Vout1> Vout2 is set, the LDO will not enter the operating state. It will be appreciated that only the DC-DC converter circuit 10 is supplying the load with high efficiency at this time.

(3) When the load is turned into a light load state again, the control end sets the enable ends EN1 and EN2 to be low level again, and the system is turned into LDO output again.

Therefore, the seamless switching between the DC-DC conversion circuit 10 and the LDO power supply is realized according to the repeated state change of the load, and the overall efficiency of the system power supply is improved compared with the two existing power supply schemes.

Compared with the prior art scheme as shown in fig. 1A, the power switching circuit 100 of the present embodiment can also effectively prevent the electromagnetic interference problem of the DC-DC conversion circuit 10. This is because, for the solution shown in fig. 1A, the DC-DC converter circuit 10 usually reduces the operating frequency of the internal switch in the light load state for the purpose of achieving light load efficiency. Since the transition of the load from the light load state to the non-light load state or from the non-light load state to the light load state causes a change in the operating frequency, in addition, the DC-DC converter circuit 10 mutually changes between the Current Continuous Mode (CCM) and the discontinuous mode (DCM), both of which are extremely liable to cause the problem of electromagnetic interference. The power switching circuit 100 of the embodiment controls the LDO and the DC-DC conversion circuit 10 to seamlessly switch between the light load state and the non-load state, and the noise of the LDO in the light load mode is very low, so that the problem of electromagnetic interference is avoided to a great extent.

The power supply switching circuit of the embodiment can improve the overall efficiency of the system power supply by connecting the DC-DC conversion circuit and the low dropout linear regulator in parallel at the load end and carrying out seamless switching according to different states of the load. In addition, the arrangement of the electronic switching circuit can effectively realize the isolation of the DC-DC conversion circuit and the low dropout linear regulator, and avoid the mutual influence of the DC-DC conversion circuit and the low dropout linear regulator in the switching process, thereby ensuring the reliability of the power switching circuit and the like.

Referring to fig. 2, another embodiment of the present invention provides an electronic device, which can use the power switching circuit 100 of embodiment 1 as a power architecture. It is to be understood that the alternatives described in embodiment 1 above are also applicable to the electronic device of this embodiment, and therefore will not be described in detail here.

The electronic device may be powered by an AC power source, and the power switching circuit 100 should include the AC-DC adapter 50, but of course, the electronic device of this embodiment may also be a device powered by a DC power source such as a battery, and a device having a higher requirement on the overall efficiency of the power source. Exemplarily, the electronic device may include, but is not limited to, a smart door lock, a smart doorbell, a digital clock, a notebook computer, and the like. The overall efficiency of the electronic equipment system power supply is improved through the power supply switching circuit.

In all examples shown and described herein, any particular value should be construed as merely exemplary, and not as a limitation, and thus other examples of example embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

The above-described embodiments are merely illustrative of several embodiments of the present invention, which are described in detail and specific, but not intended to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention.

Claims

1. A power switching circuit, comprising: the input end of the DC-DC conversion circuit is connected with the input end of the low dropout linear regulator, and the input end of the DC-DC conversion circuit is used for connecting a direct current power supply;

2. The power switching circuit of claim 1, further comprising: and the enabling end of the DC-DC conversion circuit and the enabling end of the electronic switch circuit are both connected with the power management chip as the control end.

3. The power switching circuit according to claim 1, wherein the control terminal is a main control chip of the load, and both the enable terminal of the DC-DC conversion circuit and the enable terminal of the electronic switch circuit are used for connecting the main control chip.

4. The power switching circuit of claim 1, wherein the electronic switching circuit comprises an electronic switch that is a transistor, a MOS transistor, or a relay.

5. The power switching circuit of claim 4, wherein when the electronic switch is a MOS transistor, the gate of the MOS transistor is connected to the control terminal, the source of the MOS transistor is connected to the output terminal of the DC-DC converting circuit, and the drain of the MOS transistor is connected to the load.

6. The power switching circuit of claim 1, further comprising: the input end of the AC-DC adapter is used for connecting an alternating current power supply, and the output end of the AC-DC adapter is connected with the input end of the DC-DC conversion circuit;

7. The power switching circuit of claim 1, further comprising: and the battery terminal is used for connecting a battery and is connected with the input end of the DC-DC conversion circuit.

8. The power switching circuit of claim 7, further comprising: a battery as the DC power source, the battery being connected to the battery terminal; the battery is a dry battery or a storage battery.

9. An electronic device characterized by comprising the power switching circuit according to any one of claims 1 to 8.

10. The electronic device of claim 9, wherein the electronic device is an intelligent door lock or an intelligent doorbell.