Circuit for accelerating discharge of capacitor after shutdown and battery power supply product

Abstract

The utility model relates to the technical field of battery power supply, in particular to a circuit for accelerating capacitor discharge after shutdown and a battery power supply product. The circuit comprises a comparator U2 and an MOS tube Q4, the pin voltage VBAT of a battery input pin of the IC chip and the pin voltage VBATTOSYS of an output pin of the IC chip are connected to the two input ends of the comparator U2 respectively, and the output end of the comparator is connected with the grid electrode of the MOS tube Q4; two pin voltages are respectively connected to one end of the discharge resistor R16, the other end of the discharge resistor R16 is connected with the drain electrode of the MOS tube Q4, the source electrode of the MOS tube Q4 is grounded, and the comparator U2 and the MOS tube Q4 are configured as follows: when the pin voltage VBAT is smaller than the pin voltage VBATTOSYS, the drain electrode and the source electrode of the MOS tube Q4 are connected. According to the invention, rapid discharge of a large capacitor in a battery power supply product is realized, and stable work of a system of the battery power supply product is ensured.

Description

Technical Field

[0001] This application belongs to the technical field of battery power supply, and particularly relates to a circuit for accelerating capacitor discharge after shutdown and a battery-powered product. Background Art

[0002] For battery-powered products, such as cameras, in order to increase the battery life of the product, the system is usually divided into two parts during design. One part is the part that can be powered off, and the other part is the part that always maintains constant power supply. The part that can be powered off is in a sleep state for a long time and is only awakened to work when there is an event. For example, when a pedestrian or vehicle passes by the camera, the camera is enabled to take pictures.

[0003] By the above method, the camera can be enabled to take pictures when it detects that a pedestrian or vehicle passes by. After the pedestrian or vehicle leaves, the system powers off and enters the sleep state to save power and increase the battery life of the product. However, such products usually have large capacitors designed to ensure stable voltage output. Therefore, after power-off, the large capacitors in the camera system may still maintain a certain time. At this time, if a new pedestrian or vehicle passes by and the camera needs to be immediately powered on to take pictures, it may not be able to power on immediately because the electricity stored in the capacitor has not been discharged completely, and the device is not really shut down during this period, resulting in failed photography. The length of this period is jointly determined by the capacitance of the capacitor and the size of the load, and may range from a few seconds to more than ten seconds. Summary of the Utility Model

[0004] In order to solve the above technical problems, this application provides a circuit for accelerating capacitor discharge after shutdown and a battery-powered product to solve the problem of rapid discharge of large capacitors after the electronic product is shut down.

[0005] In the first aspect of this application, a circuit for accelerating capacitor discharge after shutdown is provided, mainly including a comparator U2 and a MOS transistor Q4. Among them, the two input terminals of the comparator U2 are respectively connected to the pin voltage VBAT of the battery input pin of the IC chip and the pin voltage VBAT_TO_SYS of the output pin of the IC chip. The output terminal of the comparator is connected to the gate of the MOS transistor Q4; the pin voltage VBAT and the pin voltage VBAT_TO_SYS are respectively connected to one end of a discharge resistor R16 through a diode. The other end of the discharge resistor R16 is connected to the drain of the MOS transistor Q4, and the source of the MOS transistor Q4 is grounded. The comparator U2 and the MOS transistor Q4 are configured such that when the pin voltage VBAT is less than the pin voltage VBAT_TO_SYS, the drain and source of the MOS transistor Q4 are connected.

[0006] Preferably, a voltage regulating resistor R18 and a voltage regulating resistor R20 are provided between the comparator U2 and the MOS transistor Q4.

[0007] Preferably, the comparator U2 is powered by the pin voltage VBAT_TO_SYS.

[0008] Preferably, the MOS transistor Q4 is an N-channel MOS transistor of model SSC8022GS6, and the comparator U2 is a comparator of model LTC8701.

[0009] Preferably, the discharge resistor R16 is an adjustable resistor.

[0010] In the second aspect of the present application, a battery-powered product is provided, including a battery pack, a power supply control circuit, an IC chip, a powered product, a main controller MCU, and a circuit for accelerating capacitor discharge after shutdown as described above. The IC chip has an input pin and an output pin. The input pin is connected to the battery pack through the power supply control circuit, and the output pin is connected to the powered product. The main controller MCU is configured to send a power-on / off signal to the power supply control circuit.

[0011] Preferably, the battery-powered product includes a camera.

[0012] The present application realizes the rapid discharge of large capacitors in battery-powered products, ensuring the stable operation of the systems of battery-powered products. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the power supply circuit of the battery-powered product of the present application.

[0014] Figure 2 It is a schematic diagram of the circuit structure of a preferred embodiment of the circuit for accelerating capacitor discharge after shutdown of the present application.

[0015] Among them, 1 - battery pack, 2 - power supply control circuit, 3 - IC chip, 4 - charging circuit. Detailed Embodiments

[0016] To make the purpose, technical solutions, and advantages of the implementation of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The described embodiments are some, but not all, of the embodiments of the present application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the drawings.

[0017] The first aspect of the present application provides a circuit for accelerating capacitor discharge after shutdown, as Figure 1 shown, mainly including a comparator U2 and a MOS transistor Q4. Among them, the two input terminals of the comparator U2 are respectively connected to the pin voltage VBAT of the battery input pin of the IC chip and the pin voltage VBAT_TO_SYS of the output pin of the IC chip. The output terminal of the comparator is connected to the gate of the MOS transistor Q4; the pin voltage VBAT and the pin voltage VBAT_TO_SYS are respectively connected to one end of a discharge resistor R16 through a diode. The other end of the discharge resistor R16 is connected to the drain of the MOS transistor Q4, and the source of the MOS transistor Q4 is grounded. The comparator U2 and the MOS transistor Q4 are configured such that when the pin voltage VBAT is less than the pin voltage VBAT_TO_SYS, the drain and source of the MOS transistor Q4 are connected.

[0018] First of all, it should be noted that the battery input pin of the IC chip is connected to the battery, and the pin voltage VBAT is set here. Refer to Figure 2 , the output pin is connected to the load device, and the pin voltage VBAT_TO_SYS is set here. In order to provide a stable voltage for the load device, large capacitors C7 and C8 are set here. When the load device is working normally, since the IC chip consumes a certain voltage, the pin voltage VBAT is usually greater than the pin voltage VBAT_TO_SYS. The pin voltage VBAT_TO_SYS is connected to the positive pole of the comparator U2, and the pin voltage VBAT is connected to the negative pole of the comparator U2. At this time, the comparator outputs a low level, and the MOS transistor Q4 is in the off state. Neither the pin voltage VBAT_TO_SYS nor the pin voltage VBAT will consume power through the discharge resistor R16.

[0019] When the device is turned off, the circuit connecting the battery to the IC chip is disconnected, and the pin voltage VBAT drops rapidly. However, due to the presence of large capacitors C7 and C8, the pin voltage VBAT_TO_SYS drops more slowly. At this time, the pin voltage VBAT will be less than the pin voltage VBAT_TO_SYS, the comparator U2 outputs a high level, the MOS transistor Q4 is turned on, and the pin voltages VBAT_TO_SYS and VBAT can consume power simultaneously through the discharge resistor R16. Eventually, the voltage will be consumed to the minimum voltage of the operating condition of the comparator U2, and this voltage is related to the type of comparator selected. For example, in some alternative embodiments, the MOS transistor Q4 is an N-channel MOS transistor of model SSC8022GS6, and the comparator U2 is a comparator of model LTC8701. The comparator LTC8701 is a low-voltage and low-power comparator with an operating voltage of 1.7V - 5.5V. Accordingly, the pin voltages VBAT and VBAT_TO_SYS can quickly drop to about 1.7V. The pin voltage VBAT_TO_SYS is the voltage for supplying the subsequent load device, and the load device voltage generally enters the true shutdown state at about 3.3V, thus realizing the fast discharge function of the large capacitors C7 and C8.

[0020] In some alternative embodiments, a voltage-regulating resistor R18 and a voltage-regulating resistor R20 are provided between the comparator U2 and the MOS transistor Q4.

[0021] This embodiment is used to adjust the high level output by the comparator U2 to the operating voltage of the MOS transistor Q4, that is, above the threshold voltage or turn-on voltage of the MOS transistor Q4, so as to determine the appropriate conductivity.

[0022] In some alternative embodiments, the comparator U2 is powered by the pin voltage VBAT_TO_SYS.

[0023] In some alternative embodiments, the discharge resistor R16 is an adjustable resistor.

[0024] In this embodiment, the discharge resistor R16 can be set as an adjustable resistor, or discharge resistors R16 with different resistance values and powers can be selected for assembly. Adjusting the discharge resistor R16 actually adjusts the discharge speed of the large capacitors C7 and C8.

[0025] The second aspect of the present application provides a battery-powered product, mainly including a battery pack 1, a power supply control circuit 2, an IC chip 3, a power supply product, a main controller MCU, and a circuit for accelerating capacitor discharge after shutdown as above. The IC chip 3 has an input pin and an output pin. The input pin is connected to the battery pack 1 through the power supply control circuit, and the output pin is connected to the power supply product. The main controller MCU is configured to send a power-on / off signal to the power supply control circuit 2.

[0026] In this embodiment, the battery pack 1, the power supply control circuit 2, the IC chip 3, the power supply product, and the main controller MCU are all finished products. The power supply control circuit 2 is used to connect the battery pack 1 and the IC chip 3, and it is controlled by the main controller MCU or manually. For example, Figure 2 as shown, after the user presses the power on / off button, or after the main controller MCU outputs a power on / off signal, the power supply control circuit 2 is controlled to cut off the power supply to the IC chip 3, so as to realize the function of turning the device on and off. During charging, the VIN pin of the IC chip 3 is connected to the input of the adapter through the charging circuit 4, so as to input the external 5V voltage to the battery pack 1 with the help of the IC chip 3 and the MOS transistors Q1 and Q2 of the power supply control circuit 2. During power supply, the battery pack 1 supplies power to the power supply product through the power supply control circuit 2 and the IC chip 3, and the large capacitors C7 and C8 are used to ensure the stability of the power supply voltage. When the device is turned off, the circuit for accelerating the capacitor discharge after shutdown as described above will quickly participate in the work at this time, releasing the electric energy stored in the large capacitors C7 and C8, so as to realize the quick shutdown of the power supply product.

[0027] In some alternative embodiments, the battery-powered product includes a camera.

[0028] The above is only the specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A circuit for accelerating the discharge of a capacitor after shutdown, characterized in that It includes a comparator U2 and an MOS transistor Q4. Among them, the two input terminals of the comparator U2 are respectively connected to the pin voltage VBAT of the battery input pin of the IC chip and the pin voltage VBAT_TO_SYS of the output pin of the IC chip. The output terminal of the comparator is connected to the gate of the MOS transistor Q4; the pin voltage VBAT and the pin voltage VBAT_TO_SYS are respectively connected to one end of a discharge resistor R16 through a diode. The other end of the discharge resistor R16 is connected to the drain of the MOS transistor Q4, and the source of the MOS transistor Q4 is grounded. The comparator U2 and the MOS transistor Q4 are configured such that when the pin voltage VBAT is less than the pin voltage VBAT_TO_SYS, the drain and source of the MOS transistor Q4 are connected.

2. The circuit for accelerating the discharge of the capacitor after shutdown according to claim 1, wherein A voltage regulating resistor R18 and a voltage regulating resistor R20 are provided between the comparator U2 and the MOS transistor Q4.

3. The circuit for accelerating the discharge of the capacitor after shutdown according to claim 1, characterized in that The comparator U2 is powered by the pin voltage VBAT_TO_SYS.

4. The circuit for accelerating capacitor discharge after shutdown according to claim 1, characterized in that, The MOS transistor Q4 uses an N-channel MOS transistor of model SSC8022GS6, and the comparator U2 uses a comparator of model LTC8701.

5. The circuit for accelerating the discharge of the capacitor after shutdown according to claim 1, wherein, The discharge resistor R16 is a variable resistor.

6. A battery-powered product, characterized in that, It includes a battery pack (1), a power supply control circuit (2), an IC chip (3), a power supply product, a main controller MCU, and a circuit for accelerating capacitor discharge after shutdown as described in claim 1. The IC chip (3) has an input pin and an output pin. The input pin is connected to the battery pack (1) through the power supply control circuit, and the output pin is connected to the power supply product. The main controller MCU is configured to send a power-on / off signal to the power supply control circuit (2).

7. The battery-powered product according to claim 6, wherein, The battery-powered product includes a camera.

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