Low-noise power path management charging circuit and electric equipment power supply system

Abstract

The utility model discloses a low-noise power supply path management charging circuit and an electric equipment power supply system, which are used for switching on and off a lithium battery and electric equipment according to a charging power supply, and comprise a power supply access detection unit and a path switching-off unit, the power supply access detection unit is electrically connected with the path turn-off unit; the lithium battery is electrically connected with electric equipment through the path turn-off unit; and the power supply access detection unit is electrically connected with the charging power supply. The beneficial effects are that high-frequency noise output by the power supply is substantially reduced, it is ensured that electric equipment obtains a purer and more stable power supply, and the power supply is especially suitable for precision electronic equipment with high requirements for power supply quality. The design is helpful for reducing the influence of power supply noise on sensitive instruments or equipment and improving the working precision of the equipment.

Description

Technical Field

[0001] This utility model relates to the field of equipment power supply, and in particular to a low-noise power path management charging circuit and a power supply system for electrical equipment. Background Technology

[0002] When designing devices, built-in batteries are typically incorporated for portability or offline use. Lithium-ion batteries are usually the preferred choice due to considerations of capacity, size, and availability. Existing lithium-ion batteries are charged using compatible chargers, with charging and discharging usually occurring through the same interface. Chargers generally employ a switching power supply topology design, primarily consisting of integrated control chips, high-frequency transformers, and power switching transistors.

[0003] The charging process of a lithium battery includes four stages: trickle charging (also known as pre-charging), constant current charging, constant voltage charging, and charging termination. The constant current charging stage uses the highest current. In the constant voltage charging stage, the current gradually decreases from its maximum value as the charging process continues, depending on the cell's saturation level. Charging is considered terminated when the current decreases to one percent of the constant current charging current. Trickle charging is used to pre-charge (recovery charging) fully discharged battery cells; the trickle charging current is typically one-tenth of the constant current charging current.

[0004] However, when using devices with lithium batteries while charging, the significant power noise from the charger often affects the background noise of the device, thus impacting its accuracy.

[0005] When a lithium battery is over-discharged, directly connecting it to a charger can often cause devices with high starting current requirements to fail to power on.

[0006] Lithium batteries have issued warnings about the use of batteries while charging. Although charging while using batteries is safe in most cases, there is still a very small probability that it may cause problems such as bulging, leakage, or even spontaneous combustion of the lithium battery, and the consequences of these situations are mostly unacceptable. Utility Model Content

[0007] Purpose of the utility model: The purpose of this utility model is to solve the problems in the prior art and provide a low-noise power path management charging circuit and power supply system for electrical equipment.

[0008] Technical solution: A low-noise power path management charging circuit is proposed to control the switching of the lithium battery and the electrical device based on the charging power supply, including:

[0009] Power access detection unit and path shutdown unit;

[0010] The power access detection unit and the path shutdown unit are electrically connected;

[0011] The lithium battery is electrically connected to the electrical equipment through a path shutdown unit;

[0012] The power supply detection unit is electrically connected to the charging power supply.

[0013] Preferably, the path shutdown unit includes a first PMOS transistor and a second PMOS transistor;

[0014] The drain of the first PMOS transistor is electrically connected to the output terminal of the lithium battery, the source of the first PMOS transistor is electrically connected to the source of the second PMOS transistor, and the drain of the second PMOS transistor is electrically connected to the electrical device.

[0015] The source of the first PMOS transistor is electrically connected to the power supply detection unit;

[0016] The gates of the first PMOS transistor and the second PMOS transistor are electrically connected and then electrically connected to the power supply detection unit.

[0017] Preferably, the power supply detection unit includes a PNP transistor, an NPN transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor;

[0018] The charging power supply is grounded in sequence through the third resistor and the fifth resistor. One end of the third resistor and the fourth resistor is electrically connected to the base of the NPN transistor. The emitter of the NPN transistor is grounded. The emitter of the NPN transistor is electrically connected to the gate of the first PMOS transistor through the fourth resistor.

[0019] The collector of the NPN transistor is electrically connected to one end of the first resistor and the second resistor, respectively. The other end of the first resistor is electrically connected to the source of the first PMOS transistor and the emitter of the PNP transistor, respectively. The other end of the second resistor is electrically connected to the base of the PNP transistor. The collector of the PNP transistor is electrically connected to the gate of the first PMOS transistor.

[0020] Preferably, the charging power supply includes an AC transformer connected to a 220V mains power supply, a full-bridge rectifier and filter circuit, and a linear regulated power supply;

[0021] The AC transformer is electrically connected to a linear regulated power supply through a full-bridge rectifier and filter circuit. The linear regulated power supply is electrically connected to the electrical equipment so as to directly supply power to the electrical equipment.

[0022] The full-bridge rectifier and filter circuit is electrically connected to the lithium battery through the lithium battery charging management circuit, and the full-bridge rectifier and filter circuit is electrically connected to the power supply access detection unit.

[0023] Preferably, the AC transformer is a 220V AC mains power to 12V AC transformer;

[0024] The full-bridge rectifier and filter circuit is a rectifier circuit that converts 12V AC to 17V DC.

[0025] The linear regulated power supply is a 17V DC to 12.6V DC transformer;

[0026] The lithium battery outputs 12.6V.

[0027] Preferably, a power supply system for electrical equipment is also proposed, including a charging power supply, a lithium battery, and the electrical equipment;

[0028] The charging power supply is electrically connected to the electrical equipment.

[0029] The lithium battery is electrically connected to the power-consuming device through a low-noise power path management charging circuit as described in the above embodiments;

[0030] The charging power supply is also electrically connected to the low-noise power path management charging circuit as described in the above embodiments.

[0031] Preferably, a power supply system for electrical equipment includes an AC transformer connected to a 220V mains power supply, a full-bridge rectifier and filter circuit, and a linear regulated power supply.

[0032] The AC transformer is electrically connected to a linear regulated power supply through a full-bridge rectifier and filter circuit. The linear regulated power supply is electrically connected to the electrical equipment so as to directly supply power to the electrical equipment.

[0033] The full-bridge rectifier and filter circuit is electrically connected to the lithium battery through the lithium battery charging management circuit, and the full-bridge rectifier and filter circuit is electrically connected to the power supply access detection unit. Beneficial effects

[0034] When the electrical equipment is being charged, this invention uses a high-power linear regulated power supply to power the equipment and disconnects the lithium battery charging management circuit from the equipment. The lithium battery charging management circuit is essentially a switching power supply. In this application, the lithium battery is disconnected from the equipment during charging, thus avoiding the noise impact of the switching power supply on the equipment and achieving the goal of reducing power supply noise during charging.

[0035] The power path management circuit can automatically cut off the discharge path of the lithium battery when the 220V mains power is connected, preventing excessive switching when the lithium battery is charging and discharging at the same time, avoiding the risk of lithium crystal precipitation inside the lithium battery, thereby reducing the safety hazards of lithium battery bulging, leakage or even spontaneous combustion, and improving the safety of battery use.

[0036] This invention designs a power supply path for electrical devices when the lithium battery is in trickle charging mode. Even when the lithium battery is over-discharged, a high-power linear regulated power supply can still provide sufficient voltage to the device, ensuring that the device is not affected by insufficient lithium battery power when it is turned on. This design avoids the problem of the device failing to start due to over-discharge of the lithium battery, improving the convenience of device use.

[0037] Through the power path management circuit, the power supply path of lithium battery charging and electrical equipment is reasonably isolated, avoiding the lithium battery from working in a charging and discharging mode, ensuring high efficiency and safety during the lithium battery charging process, reducing the heat and instability that may be generated during charging, and extending the battery's lifespan.

[0038] When the mains power is connected, the power path management circuit of the present invention can switch to a high-power linear regulated power supply to power the device, thereby providing a more stable power output and avoiding the impact of mains power fluctuations on the operation of the device. At the same time, when the mains power is disconnected, the lithium battery can still provide a stable power supply to the device, ensuring the continuous operation of the device. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0040] Figure 2 This is a circuit diagram of this utility model. Detailed Implementation

[0041] To make the technical solution of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example

[0042] To make the technical solution of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but does not exclude other elements or objects.

[0044] In response to the problems existing in the current technology, combined with Figure 1-2 A low-noise power path management charging circuit 5, used to switch the lithium battery 7 and the electrical device 4 on and off according to the charging power supply, includes:

[0045] Power access detection unit 9 and path shutdown unit;

[0046] The power access detection unit 9 and the path shutdown unit are electrically connected;

[0047] The lithium battery 7 is electrically connected to the electrical equipment 4 through a path shutdown unit;

[0048] The power access detection unit 9 is electrically connected to the charging power supply.

[0049] In some specific embodiments, the path shutdown unit includes a first PMOS transistor Q1 and a second PMOS transistor Q2;

[0050] The drain D of the first PMOS transistor Q1 is electrically connected to the output terminal of the lithium battery 7, the source S of the first PMOS transistor Q1 is electrically connected to the source S of the second PMOS transistor Q2, and the drain D of the second PMOS transistor Q2 is electrically connected to the electrical device 4.

[0051] The source S of the first PMOS transistor Q1 is electrically connected to the power supply detection unit 9;

[0052] After the gate G of the first PMOS transistor Q1 and the gate G of the second PMOS transistor Q2 are electrically connected, they are electrically connected to the power supply detection unit 9.

[0053] In some specific embodiments, the power access detection unit 9 includes a PNP transistor Q3, an NPN transistor Q4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.

[0054] The charging power supply is grounded in sequence through the third resistor R3 and the fifth resistor R5. One end of the third resistor R3 and the fourth resistor R4 is connected to the base of the NPN transistor Q4. The emitter of the NPN transistor Q4 is grounded. The emitter of the NPN transistor Q4 is connected to the gate G of the first PMOS transistor Q1 through the fourth resistor R4.

[0055] The collector of the NPN transistor Q4 is electrically connected to one end of the first resistor R1 and the second resistor R2, respectively. The other end of the first resistor R1 is electrically connected to the source S of the first PMOS transistor Q1 and the emitter of the PNP transistor Q3, respectively. The other end of the second resistor R2 is electrically connected to the base of the PNP transistor Q3. The collector of the PNP transistor Q3 is electrically connected to the gate G of the first PMOS transistor Q1.

[0056] In some specific embodiments, the charging power supply includes an AC transformer 1 connected to a 220V AC mains power supply 8, a full-bridge rectifier and filter circuit 2, and a linear regulated power supply 3;

[0057] The AC transformer 1 is electrically connected to the linear regulated power supply 3 through the full-bridge rectifier and filter circuit 2. The linear regulated power supply 3 is electrically connected to the electrical equipment 4 so as to directly supply power to the electrical equipment 4.

[0058] The full-bridge rectifier filter circuit 2 is electrically connected to the lithium battery 7 through the lithium battery 7 charging management circuit, and the full-bridge rectifier filter circuit 2 is electrically connected to the power supply detection unit 9.

[0059] In some specific embodiments, the AC transformer 1 is a 220V AC mains power 8 converted to a 12V AC transformer 1;

[0060] The full-bridge rectifier filter circuit 2 is a rectifier circuit that converts 12V AC to 17V DC.

[0061] The linear regulated power supply 3 is a transformer that converts 17V DC to 12.6V DC;

[0062] The lithium battery 7 has an output power of 12.6V.

[0063] In some specific embodiments, a power supply system for an electrical device 4 includes a charging power supply, a lithium battery 7, and the electrical device 4.

[0064] The charging power supply is electrically connected to the electrical device 4;

[0065] The lithium battery 7 is electrically connected to the electrical device 4 through the low-noise power path management charging circuit as described in the above embodiment;

[0066] The charging power supply is also electrically connected to the low-noise power path management charging circuit as described in the above embodiments.

[0067] In some specific embodiments, the charging power supply includes an AC transformer 1 connected to a 220V AC mains power supply 8, a full-bridge rectifier and filter circuit 2, and a linear regulated power supply 3;

[0068] The AC transformer 1 is electrically connected to the linear regulated power supply 3 through the full-bridge rectifier and filter circuit 2. The linear regulated power supply 3 is electrically connected to the electrical equipment 4 so as to directly supply power to the electrical equipment 4.

[0069] The full-bridge rectifier filter circuit 2 is electrically connected to the lithium battery 7 through the lithium battery 7 charging management circuit, and the full-bridge rectifier filter circuit 2 is electrically connected to the power supply access detection unit 9.

[0070] The specific process is as follows:

[0071] Operating status when 220V AC mains power is not connected

[0072] Working principle of power path management circuit:

[0073] The state of NPN transistor Q4:

[0074] When the 220V mains power is not connected, there is no voltage input between the third resistor R3 and the output terminal of the full-bridge rectifier filter circuit 2. Therefore, the base of the NPN transistor Q4 is pulled down to ground by the fifth resistor R5, resulting in a base voltage of 0V for the NPN transistor Q4. Under these circumstances, the NPN transistor Q4 enters the cutoff state and cannot be turned on.

[0075] Operating status of PNP transistor Q3:

[0076] The emitter of PNP transistor Q3 is connected to the source of the first PMOS transistor Q1 and the second PMOS transistor Q2. The voltage VG at this connection point is the battery voltage VBAT minus the body diode voltage of the first PMOS transistor Q1, which is approximately VBAT-0.6V.

[0077] Since NPN transistor Q4 is in the off state, the base voltage of PNP transistor Q3 is approximately equal to VG voltage. That is, the base voltage and emitter voltage of PNP transistor Q3 are equal, so PNP transistor Q3 is also in the off state.

[0078] The states of PMOS transistors Q1 and Q2:

[0079] When PNP transistor Q3 is in the off state, the gate levels of the first PMOS transistor Q1 and the second PMOS transistor Q2 are pulled down to about 0V through the fourth resistor R4. This makes the source levels of the first PMOS transistor Q1 and the second PMOS transistor Q2 about VBAT-0.6V, that is, the gate voltage of the PMOS transistor is lower than the source voltage, so the two PMOS transistors are in the on state.

[0080] In this state, the battery voltage VBAT supplies power to the electrical equipment through PMOS transistors Q1 and Q2.

[0081] Operating status when connected to 220V AC mains power

[0082] The NPN transistor Q4 is turned on:

[0083] When 220V AC mains power is connected, the full-bridge rectifier and filter circuit outputs a voltage of approximately 17V. Through the voltage division effect of the third resistor R3 and the fifth resistor R5, the base voltage of the NPN transistor Q4 is pulled up, causing the NPN transistor Q4 to enter the conduction state.

[0084] The PNP transistor Q3 is turned on:

[0085] The emitter of PNP transistor Q3 is connected to the source of the first PMOS transistor Q1 and the second PMOS transistor Q2. The voltage VG at the connection point is 12.6V - 0.6V (the output voltage of the high-power linear power supply minus the body diode voltage of the second PMOS transistor Q2).

[0086] The base voltage of PNP transistor Q3 is 0V, so PNP transistor Q3 is turned on. The voltage difference between its emitter and base causes PNP transistor Q3 to turn on and pulls the gate voltage of PMOS transistors Q1 and Q2 up to close to VG voltage.

[0087] PMOS transistors Q1 and Q2 are off:

[0088] When PNP transistor Q3 is turned on, the gate voltages of the first PMOS transistor Q1 and the second PMOS transistor Q2 are pulled high, and the source level is 12.6V-0.6V. At this time, the gate voltages of PMOS transistors Q1 and Q2 are higher than their source voltages, causing both PMOS transistors to be in the off state.

[0089] Therefore, the connection between the lithium battery and the electrical equipment is cut off. The electrical equipment is powered by a high-power linear regulated power supply, and the lithium battery is only used for charging and no longer supplies power to the electrical equipment.

[0090] When the 220V AC mains power 8 is connected, the power path management circuit 5 effectively isolates the lithium battery charging circuit and the electrical equipment 4, avoiding the impact of high-frequency power noise on the electrical equipment during charging. The electrical equipment is powered by a high-power linear regulated power supply, ensuring the purity of the power supply and avoiding noise interference.

[0091] Since the lithium battery and the electrical device 4 are completely disconnected when the mains power is connected, the lithium battery 7 is prevented from entering the working mode of charging and using at the same time, which greatly improves the safety of the system. This design effectively prevents lithium branch crystal precipitation when the lithium battery 7 is charging and discharging at the same time, thereby preventing battery damage or safety hazards.

[0092] Even when the lithium battery is over-discharged, when the charger enters trickle charging mode, the device 4 is still powered by a high-power linear regulated power supply. The device will not fail to start due to insufficient charging current. Through this design, the charging of the battery and the operation of the device are managed independently, ensuring that the device can start and run stably.

[0093] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A low-noise power path management charging circuit, characterized in that, Used to switch lithium batteries and electrical devices on and off according to the charging power supply, including: Power access detection unit and path shutdown unit; The power access detection unit and the path shutdown unit are electrically connected; The lithium battery is electrically connected to the electrical equipment through a path shutdown unit; The power supply detection unit is electrically connected to the charging power supply; The path shutdown unit includes a first PMOS transistor and a second PMOS transistor; The drain of the first PMOS transistor is electrically connected to the output terminal of the lithium battery, the source of the first PMOS transistor is electrically connected to the source of the second PMOS transistor, and the drain of the second PMOS transistor is electrically connected to the electrical device. The source of the first PMOS transistor is electrically connected to the power supply detection unit; The gates of the first PMOS transistor and the second PMOS transistor are electrically connected and then electrically connected to the power supply detection unit.

2. The low-noise power path management charging circuit according to claim 1, characterized in that, The power access detection unit includes a PNP transistor, an NPN transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; The charging power supply is grounded in sequence through the third resistor and the fifth resistor. One end of the third resistor and the fourth resistor is electrically connected to the base of the NPN transistor. The emitter of the NPN transistor is grounded. The emitter of the NPN transistor is electrically connected to the gate of the first PMOS transistor through the fourth resistor. The collector of the NPN transistor is electrically connected to one end of the first resistor and the second resistor, respectively. The other end of the first resistor is electrically connected to the source of the first PMOS transistor and the emitter of the PNP transistor, respectively. The other end of the second resistor is electrically connected to the base of the PNP transistor. The collector of the PNP transistor is electrically connected to the gate of the first PMOS transistor.

3. The low-noise power path management charging circuit according to claim 1, characterized in that, The charging power supply includes an AC transformer connected to 220V AC mains power, a full-bridge rectifier and filter circuit, and a linear regulated power supply. The AC transformer is electrically connected to a linear regulated power supply through a full-bridge rectifier and filter circuit. The linear regulated power supply is electrically connected to the electrical equipment so as to directly supply power to the electrical equipment. The full-bridge rectifier and filter circuit is electrically connected to the lithium battery through the lithium battery charging management circuit, and the full-bridge rectifier and filter circuit is electrically connected to the power supply access detection unit.

4. The low-noise power path management charging circuit according to claim 3, characterized in that, The AC transformer is a 220V AC power conversion transformer that converts mains power to 12V AC power. The full-bridge rectifier and filter circuit is a rectifier circuit that converts 12V AC to 17V DC. The linear regulated power supply is a 17V DC to 12.6V DC transformer; The lithium battery outputs 12.6V.

5. A power supply system for electrical equipment, characterized in that, This includes charging power supplies, lithium batteries, and electrical equipment; The charging power supply is electrically connected to the electrical equipment. The lithium battery is electrically connected to the power-consuming device through the low-noise power path management charging circuit as described in any one of claims 1-4; The charging power supply is also electrically connected to the low-noise power path management charging circuit as described in any one of claims 1-4.

6. A power supply system for electrical equipment according to claim 5, characterized in that, The charging power supply includes an AC transformer connected to 220V AC mains power, a full-bridge rectifier and filter circuit, and a linear regulated power supply. The AC transformer is electrically connected to a linear regulated power supply through a full-bridge rectifier and filter circuit. The linear regulated power supply is electrically connected to the electrical equipment so as to directly supply power to the electrical equipment. The full-bridge rectifier and filter circuit is electrically connected to the lithium battery through the lithium battery charging management circuit, and the full-bridge rectifier and filter circuit is electrically connected to the power supply access detection unit.

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