Start-up circuits, power conversion devices and energy storage devices for power management chips

Abstract

The present application provides a startup circuit, a power conversion device and an energy storage device for a power management chip. In the startup circuit, the first switch circuit is used to connect when a DC input voltage is connected, and output a first output voltage. The second switch circuit is connected to the first switch circuit through a startup resistor, and the second switch circuit is also connected to the power pin of the power management chip. The second switch circuit is used to connect when the first switch circuit outputs the first output voltage and the switching power supply is not working, and output the startup voltage to the power pin to start the power management chip. The control circuit is used to control the second switch circuit to disconnect when the switching power supply is working, so that the startup resistor is disconnected from the power pin. The power supply circuit is used to power the power management chip when the switching power supply is working. The startup circuit of the present application generates less loss, which is conducive to improving the startup efficiency of the power management chip and widening the input voltage range, and is conducive to extending the service life of the battery in the battery application scenario.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a startup circuit, a power conversion device and an energy storage device of a power management chip. Background Art

[0002] As the control chip of the switching power supply, the power management chip plays a vital role. The power pin of the power management chip will be connected to the startup circuit. After the power is connected, the startup circuit can provide the required voltage for the power management chip so that the power management chip can start and work. The traditional startup circuit is composed of a startup resistor. The selection of the startup resistor value and power needs to be determined based on the startup current, DC input voltage, and startup time of the power management chip. If the selected resistance value is large, the voltage charging time will be long. If the resistance value is too large, the startup current may not be reached and the power management chip will not work. Therefore, when the input voltage range is wide, in order to ensure that the power management chip can start normally when the input voltage is low, the startup resistor value is usually selected to be smaller. However, the loss caused by the startup resistor is very large when the high voltage input is applied. If it is not well designed, it is easy to overheat and damage when the high voltage input is applied. Especially in battery applications, the startup circuit is always working and will consume battery power all the time. When the battery is low, the startup circuit will completely discharge the battery, causing battery damage. Utility Model Content

[0003] In view of this, the present application provides a startup circuit, a power conversion device and an energy storage device for a power management chip, which can effectively reduce losses, help improve the startup efficiency of the power management chip and widen the input voltage range, and help extend the battery life in battery application scenarios.

[0004] In a first aspect, the present application provides a startup circuit of a power management chip, wherein a control pin of the power management chip is connected to a switching power supply, and is used to control the switching power supply to work after startup. The startup circuit comprises: a first switching circuit, a startup resistor, a second switching circuit, a control circuit and a power supply circuit, wherein the first switching circuit is used to be connected when a DC input voltage is connected, and output a first output voltage; the second switching circuit is connected to the first switching circuit through a startup resistor, and the second switching circuit is also connected to a power pin of the power management chip; the second switching circuit is used to be connected when the first switching circuit outputs the first output voltage and the switching power supply is not working, and output a startup voltage to the power pin, and the startup voltage is used to start the power management chip; the control circuit connects the switching power supply and the second switching circuit, and the control circuit is used to control the second switching circuit to disconnect when the switching power supply is working, so that the startup resistor is disconnected from the power pin; the power supply circuit is connected to the power pin and the switching power supply, and the power supply circuit is used to output the second output voltage to the power pin when the switching power supply is working, so as to power the power management chip.

[0005] In one embodiment, the second switching circuit includes a depletion-type switching tube, a first anti-reverse diode and a voltage divider circuit, wherein the first connection end of the depletion-type switching tube is connected to the cathode of the first anti-reverse diode, and the anode of the first anti-reverse diode is connected to the first switching circuit through a starting resistor; the second connection end of the depletion-type switching tube is connected to the control circuit through the voltage divider circuit, the control end of the depletion-type switching tube is connected to the voltage divider circuit, and the second connection end of the depletion-type switching tube is also connected to the power pin; the depletion-type switching tube is used to output a first output voltage in the first switching circuit, and is turned on when the switching power supply is not working, and outputs a starting voltage to the power pin; and is used to turn off when the switching power supply is working, and stop outputting the starting voltage.

[0006] In one embodiment, the first switching circuit includes an enhanced switching tube, a first current limiting resistor and a voltage stabilizing circuit, wherein the first connection end of the enhanced switching tube is connected to the first current limiting resistor and the voltage stabilizing circuit, the first current limiting resistor and the voltage stabilizing circuit are used to access a DC input voltage, the second connection end of the enhanced switching tube is connected to a starting resistor, and the control end of the enhanced switching tube is connected to the voltage stabilizing circuit; the enhanced switching tube is used to be turned on when the DC input voltage is connected, and output a first output voltage to the starting resistor.

[0007] In one embodiment, the sum of the withstand voltage value of the depletion-mode switch tube and the withstand voltage value of the enhancement-mode switch tube is not less than the DC input voltage.

[0008] In one embodiment, the depletion-type switch tube is further used to output a constant startup current to a power pin when the first switch circuit outputs a first output voltage and the switch power supply is not working.

[0009] In one embodiment, the control circuit includes a driving switch tube, a second anti-reverse diode and an anti-interference circuit, wherein the first connection end of the driving switch tube is connected to the second switching circuit, the second connection end of the driving switch tube is connected to the second switching circuit and ground, the control end of the driving switch tube is connected to the second connection end of the driving switch tube and the cathode of the second anti-reverse diode through the anti-interference circuit, and the anode of the second anti-reverse diode is connected to the switching power supply; the driving switch tube is used to be turned on when the switching power supply is working, so as to form a loop with the voltage divider circuit, so that the driving voltage generated by the voltage divider circuit is connected between the control end of the depletion-type switch tube and the second connection end of the depletion-type switch tube, and the driving voltage is used to drive the depletion-type switch tube to turn off.

[0010] In one embodiment, the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, one end of the first voltage divider resistor is connected to the second connection end of the depletion type switch tube, the other end of the first voltage divider resistor is connected to the control end of the depletion type switch tube, and is connected to the control circuit through the second voltage divider resistor.

[0011] In one embodiment, the power supply circuit includes a rectifier circuit and a third anti-reverse diode, the rectifier circuit is connected between an anode of the third anti-reverse diode and a switching power supply, and a cathode of the third anti-reverse diode is connected to a power pin.

[0012] The second aspect of the present application provides a power conversion device. The power conversion device includes a switching power supply, a power management chip, and a startup circuit as described in the first aspect or any one of the embodiments of the first aspect, wherein the startup circuit is connected to a power pin of the power management chip, and a control pin of the power management chip is connected to the switching power supply.

[0013] The third aspect of the present application provides an energy storage device. The energy storage device includes a battery pack, a switching power supply, a power management chip, and the startup circuit described in the first aspect or any one of the embodiments of the first aspect, wherein the power pins of the battery pack and the power management chip are respectively connected to the startup circuit, and the control pin of the power management chip is connected to the switching power supply.

[0014] Compared with the prior art, this application has at least the following advantages:

[0015] 1. The startup circuit of the present application can start the power management chip, and after the power management chip is started, the startup circuit can automatically cut off the second switch circuit and the startup resistor, and at the same time can switch to the switching power supply to power the power management chip. In this way, the startup resistor will no longer consume electrical energy after the power management chip is started, so the loss generated by the startup circuit can be reduced.

[0016] 2. In the startup circuit of the present application, the enhanced switch tube in the first switch circuit and the depletion switch tube in the second switch circuit are connected in series. Therefore, the enhanced switch tube and the depletion switch tube can jointly bear the DC input voltage, thereby reducing the voltage borne by the enhanced switch tube and the depletion switch tube, and reducing the risk of overvoltage. In addition, the enhanced switch tube and the depletion switch tube can use semiconductor devices with a smaller withstand voltage value, which can reduce costs and make selection more convenient. Moreover, the withstand voltage value of the enhanced switch tube and the depletion switch tube can also have a larger margin, which is conducive to widening the input voltage range of the startup circuit, realizing wide voltage input and high voltage input, and at high input voltage, the risk of overvoltage of the switch device is low, and the risk of overheating and damage of the startup resistor is low. Therefore, such a circuit design is easy to implement and has a wide range of applications.

[0017] 3. In the starting circuit of the present application, the enhanced switch tube is a normally closed switch, thereby preventing the switch tube in the first switch circuit from being abnormally turned on due to noise interference when the DC input voltage is not connected or the connected voltage does not reach the DC input voltage.

[0018] 4. In the startup circuit of the present application, the depletion-type switch tube is a normally-open switch. Therefore, when the startup circuit is connected to a DC input voltage, the time waiting for the depletion-type switch tube to turn on can be omitted, and power can be supplied to the power pin of the power management chip more quickly, so the startup efficiency can be improved.

[0019] 5. When the startup circuit of the present application is applied to an energy storage device (ie, a battery scenario), before starting the power management chip, the startup circuit will not consume the power of the battery pack because the enhanced switch tube is turned off. In the process of starting the power management chip, the startup circuit can quickly provide a startup voltage and a constant current startup current, so the startup time of the power management chip is short and the efficiency is high. After starting the power management chip, the startup circuit can automatically turn off the depletion-type switch tube, so the startup circuit causes very little power loss in the battery pack, which contributes to the efficiency of the energy storage device. Therefore, when the energy storage device is in long-term standby mode, the energy storage device can be in ultra-low power standby mode. When the battery pack is depleted (ie, insufficient power), the power of the battery pack is not easily exhausted, thus avoiding damage to the battery pack due to empty power. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the circuit diagram of the traditional starting circuit.

[0021] Figure 2 This is a connection diagram of a startup circuit provided in an embodiment of the present application.

[0022] Figure 3 This is a circuit diagram of a startup circuit provided in an embodiment of the present application.

[0023] Figure 4 It is a schematic diagram of a power conversion device provided in an embodiment of the present application.

[0024] Figure 5 It is a schematic diagram of an energy storage device provided in an embodiment of the present application.

[0025] Main component symbols

[0026] Startup circuit 100

[0027] The first switch circuit 11

[0028] Voltage regulator circuit 111

[0029] Overvoltage protection circuit 112

[0030] Start-up resistor 12

[0031] The second switch circuit 13

[0032] Voltage divider circuit 131

[0033] Power supply circuit 14

[0034] Rectification circuit 141

[0035] Control circuit 15

[0036] Anti-interference circuit 151

[0037] Power Management Chip 200

[0038] Switching Power Supply 300

[0039] DC Power Supply 400

[0040] Battery Pack 500

[0041] Power conversion equipment 1000

[0042] Energy Storage Devices 2000 DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only embodiments of a part of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present application. In the absence of conflict, the following different embodiments and features in the embodiments can be combined with each other.

[0044] As the control chip of the switching power supply, the power management chip plays a vital role. Figure 1 , the power pin VCC of the power management chip will be connected to the startup circuit. After power is connected, the startup circuit can provide the required voltage for the power management chip so that the power management chip can start and work. The traditional startup circuit consists of a startup resistor (such as Figure 1 It is composed of resistors R1 and R2 connected in series.

[0045] The selection of the starting resistor value and power needs to be determined based on the starting current, DC input voltage, and starting time of the power management chip. If the selected resistance value is large, the voltage charging time will be long, affecting the efficiency. If the resistance value is too large, the starting current may not be reached and the power management chip will not work. Therefore, when the input voltage range is wide, in order to ensure that the power management chip can start normally when the input voltage is low, the starting resistor value is usually selected to be smaller. However, the loss caused by the starting resistor is very large when the high voltage input is applied, and if it is not designed well, it is easy to overheat and be damaged when the high voltage input is applied. Especially in battery applications, the starting circuit is always working and will always consume battery power. When the battery is low, the starting circuit will completely discharge the battery power, causing battery damage.

[0046] Therefore, the embodiment of the present application proposes a startup circuit of a power management chip, which can effectively reduce losses, help improve the startup efficiency of the power management chip and widen the DC input voltage range, and help extend the service life of the battery in battery application scenarios.

[0047] Specifically, see Figure 2 , which is a connection diagram of the starting circuit of an embodiment of the present application.

[0048] like Figure 2 As shown, the startup circuit 100 is connected to the power pin VCC of the power management chip 200 and the DC power supply 400. The startup circuit 100 can access the DC input voltage from the DC power supply 400, and generate the startup voltage required for the power management chip 200 to start the power management chip 200 to the power management chip 200. Understandably, the power pin VCC of the power management chip 200 can be grounded through the energy storage capacitor Cvcc, and the capacitor Cvcc plays a role in voltage stabilization. The control pin OUT of the power management chip 200 is connected to the switching power supply 300. After the power management chip 200 is started, its control pin OUT can output a control signal to the switching power supply 300 to control the switching power supply 300 to work. The power pin VCC of the power management chip 200 is also connected to the switching power supply 300, so the power management chip 200 can also be powered by the working switching power supply 300.

[0049] The DC power supply 400 may be, for example, a battery pack, a rectifier circuit or other equipment / module / circuit / component that can provide DC power. The switching power supply 300 may be configured according to actual needs, for example, it may include an isolated power conversion circuit (including a transformer).

[0050] The power management chip 200 may be, for example, a PWM (Pulse Width Modulation) chip. It should be understood that Figure 2 The pin numbers of the power management chip 200 shown in the figure are only examples and do not constitute a specific limitation on the embodiments of the present application. In practical applications, other pin numbers of the power management chip 200 may also be used to implement Figure 2 The functions of the pins are shown in .

[0051] Please also read Figure 3 The startup circuit 100 of the embodiment of the present application may include a first switch circuit 11, a startup resistor 12, a second switch circuit 13, a control circuit 15 and a power supply circuit 14.

[0052] The first switch circuit 11 is connected to the DC power supply 400, and the first switch circuit 11 is connected to the second switch circuit 13 through the starting resistor 12. When the DC power supply 400 provides the DC input voltage Vin, the first switch circuit 11 is connected and outputs the first output voltage Vo1. At this time, the voltage on the starting resistor 12 is Vo1 (ignoring the line resistance). The second switch circuit 13 is connected to the voltage Vo1 of the starting resistor 12. On the contrary, when the DC power supply 400 does not provide the DC input voltage Vin, the first switch circuit 11 is disconnected and cannot output the first output voltage Vo1, and the second switch circuit 13 is not connected to the first output voltage Vo1.

[0053] The control circuit 15 is connected to the switching power supply 300 and the second switching circuit 13. When the switching power supply 300 is working, the control circuit 15 controls the second switching circuit 13 to be disconnected (the control circuit 15 at this time can be powered by the switching power supply 300). On the contrary, when the switching power supply 300 is not working, the control circuit 15 cannot control the second switching circuit 13 to be disconnected (the control circuit 15 at this time loses the power supply of the switching power supply 300).

[0054] The second switch circuit 13 is also connected to the power pin VCC of the power management chip 200. When the second switch circuit 13 receives the first output voltage Vo1 (that is, the first switch circuit 11 outputs the first output voltage Vo1) and the switching power supply 300 is not working, the second switch circuit 13 is connected and outputs a startup voltage to the power pin VCC, and the startup voltage is used to start the power management chip 200. On the contrary, when the switching power supply 300 is working, the second switch circuit 13 is disconnected and cannot output the startup voltage. At this time, the startup resistor 12 is disconnected (that is, the startup resistor 12 is disconnected from the second switch circuit 13 and the power pin VCC).

[0055] The power pin VCC of the power management chip 200 is also connected to the switching power supply 300 through the power supply circuit 14. When the switching power supply 300 is working, the power supply circuit 14 can output the second output voltage Vo2 to the power pin VCC to supply power to the power management chip 200.

[0056] It should be understood that the embodiments of the present application do not limit the specific structures of the first switch circuit 11, the start-up resistor 12, the second switch circuit 13, the control circuit 15 and the power supply circuit 14, as long as the first switch circuit 11, the start-up resistor 12, the second switch circuit 13, the control circuit 15 and the power supply circuit 14 can achieve the corresponding functions. Figure 3 The specific circuit example shown is used to describe the startup circuit 100 in detail.

[0057] Specifically, Figure 3As shown, the first switch circuit 11 may include an enhanced switch tube Q1, a first current limiting resistor and a voltage stabilizing circuit 111. The enhanced switch tube Q1 may be an enhanced MOS tube. Figure 3 The enhanced switch tube Q1 is an enhanced NMOS tube as an example for demonstration. The control terminal of the enhanced MOS tube is the gate, the first connection terminal of the enhanced MOS tube is the drain, and the second connection terminal of the enhanced MOS tube is the source. It can be understood that the enhanced NMOS tube is a normally closed switch. The first current limiting resistor may include a resistor element, or multiple resistor elements connected in series, in parallel, or in series and parallel. Figure 3 The first current limiting resistor is resistor R3 as an example. The voltage stabilizing circuit 111 can be any circuit that can achieve a voltage stabilizing function. Figure 3 The voltage stabilizing circuit 111 shown in the example includes a second current limiting resistor R2 and a first voltage stabilizing diode ZD1. The structure and resistance value of the starting resistor 12R4 can be set accordingly according to actual needs and are not specifically limited here. Figure 3 In the figure, the starting resistor 12 is taken as the resistor R4 as an example.

[0058] The first connection end of the enhanced switch tube Q1 is connected to the positive electrode (DC+) of the DC power supply 400 through the first current limiting resistor R3, and the negative electrode (DC-) of the DC power supply 400 is grounded. One end of the second current limiting resistor R2 is connected to the positive electrode of the DC power supply 400, and the other end of the second current limiting resistor R2 is connected to the cathode of the first voltage zener diode ZD1 and the control end of the enhanced switch tube Q1, and the anode of the first voltage zener diode ZD1 is grounded. The second connection end of the enhanced switch tube Q1 is connected to the starting resistor R4.

[0059] Among them, the first current limiting resistor R3 can limit the current on the first connection end of the enhanced switch tube Q1 to prevent the enhanced switch tube Q1 from being damaged by overcurrent. The first voltage-limiting diode ZD1 can stabilize the voltage and current on the control end of the enhanced switch tube Q1 to prevent the enhanced switch tube Q1 from being damaged by overstress. The second current limiting resistor R2 can limit the current of the first anti-reverse diode ZD1 to prevent the first anti-reverse diode ZD1 from being damaged by overcurrent. It can be understood that the resistance value of the second current limiting resistor R2 can be very large, but too large a resistance value will cause the voltage-stabilizing value of the voltage-stabilizing tube to be too small, and a small voltage-stabilizing value will cause the voltage at both ends of the enhanced switch tube Q1 to be too high, so it is necessary to select a suitable resistance value in combination with the characteristics of the first voltage-stabilizing diode ZD1 and the withstand voltage value of the enhanced switch tube Q1. When the DC input voltage Vin is higher than the voltage-stabilizing value V1 of the first voltage-stabilizing diode ZD1, the second current limiting resistor R2 will generate power consumption P=(Vin-V1)*(Vin-V1) / R2.

[0060] In one embodiment, an overvoltage protection circuit 112 may be connected between the control terminal and the second connection terminal of the enhanced switch tube Q1. Figure 3As shown, the overvoltage protection circuit 112 may include, for example, a first filter capacitor C1 and a second zener diode ZD2 connected in parallel. The first filter capacitor C1 may smooth the voltage between the control end and the second connection end of the enhanced switch tube Q1. The second zener diode ZD2 may stabilize the voltage between the control end and the second connection end of the enhanced switch tube Q1, thereby preventing the enhanced switch tube Q1 from being damaged by overvoltage.

[0061] Please continue reading Figure 3 The second switch circuit 13 may include a depletion switch tube Q2, a first anti-reverse diode D2 and a voltage divider circuit 131. The depletion switch tube Q2 may be a depletion MOS tube. Figure 3 In the example, the depletion-type switch tube Q2 is a depletion-type NMOS tube. The control end of the depletion-type MOS tube is the gate, the first connection end of the depletion-type MOS tube is the drain, and the second connection end of the depletion-type MOS tube is the source. It can be understood that the depletion-type switch tube Q2 itself forms a communication, so it is a normally open switch. The voltage divider circuit 131 can be any circuit that can realize the voltage divider function. Figure 3 The illustrated voltage dividing circuit 131 includes a first voltage dividing resistor R5 and a second voltage dividing resistor R6.

[0062] The first connection end of the depletion-type switch tube Q2 is connected to the cathode of the first anti-reverse diode D2, and the anode of the first anti-reverse diode D2 is connected to the second connection end of the enhanced switch tube Q1 through the start-up resistor R4. Therefore, the depletion-type switch tube Q2 and the enhanced switch tube Q1 are equivalent to a series connection relationship. The second connection end of the depletion-type switch tube Q2 is connected to one end of the first voltage-dividing resistor R5, and the other end of the first voltage-dividing resistor R5 is connected to the control end of the depletion-type switch tube Q2, and is connected to the control circuit 15 through the second voltage-dividing resistor R6. The second connection end of the depletion-type switch tube Q2 is also connected to the power pin VCC of the power management chip 200.

[0063] The first anti-reverse diode D2 can use its unidirectional conductivity to achieve an anti-reverse function to protect the enhanced switch tube Q1 and the depletion switch tube Q2. In addition, a third current limiting resistor R7 can be provided between the second connection end of the depletion switch tube Q2 and the power pin VCC. The third current limiting resistor R7 can limit the current on the second connection end of the depletion switch tube Q2 and the power pin VCC to prevent the depletion switch tube Q2 and the power pin VCC from being damaged by overcurrent.

[0064] Please refer again Figure 3 The power supply circuit 14 may include a rectifier circuit 141 and a third anti-reverse diode D5. The rectifier circuit 141 may be any circuit that can achieve a rectifier function. For ease of understanding, Figure 3In the figure, the rectifier circuit 141 includes a rectifier diode D4 and a fifth filter capacitor C5 as an example for demonstration. The anode of the rectifier diode D4 is connected to the switching power supply 300, and the cathode of the rectifier diode D4 is grounded through the fifth filter capacitor C5. The cathode of the rectifier diode D4 is connected to the anode of the third anti-reverse diode D5 and the control circuit 15. The cathode of the third anti-reverse diode D5 is connected to the power pin VCC of the power management chip 200. Therefore, the voltage output by the switching power supply 300 can be transmitted to the control circuit 15 after rectification by the rectifier circuit 141, and then transmitted to the power pin VCC through the third anti-reverse diode D5. The voltage received by the power pin VCC is equal to the voltage output by the switching power supply 300 minus the conduction voltage drop of the rectifier diode D4 and the conduction voltage drop of the third anti-reverse diode D5. Here, the rectifier circuit 141 can convert the voltage of the switching power supply 300 into a DC voltage. The third anti-reverse diode D5 can not only transmit voltage, but also play an anti-reverse role.

[0065] As mentioned above, the switching power supply 300 may include an isolated power conversion circuit, and the isolated power conversion circuit includes a transformer. Figure 3 As shown, the anode of the rectifier diode D4 can be connected to the output end of the auxiliary winding of the transformer in the switching power supply 300, and connected to the voltage Vaux output by the auxiliary winding. Of course, in other embodiments, the anode of the rectifier diode D4 can also be connected to other components, modules or circuits in the switching power supply 300, as long as the switching power supply 300 can output a suitable voltage to the power supply circuit 14 after startup. In one embodiment, the rectifier circuit 141 can also be integrated into the switching power supply 300, so the rectifier circuit 141 can also be omitted in the power supply circuit 14.

[0066] like Figure 3 As shown, the control circuit 15 includes a driving switch tube Q3, a second anti-reverse diode D3 and an anti-interference circuit 151. For the convenience of description, Figure 3 In the example, the driving switch tube Q3 is a low-voltage triode. The control end of the triode is the base, the first connection end of the triode is the collector, and the second connection end of the triode is the emitter. It can be understood that the driving switch tube Q3 is a normally closed switch. The anti-interference circuit 151 can be any circuit that can realize the anti-interference function. Figure 3 The illustrated anti-interference circuit 151 includes a first filter resistor R8, a second filter resistor R9 and a second filter capacitor C3.

[0067] The first connection end of the driving switch tube Q3 is connected to the second voltage-dividing resistor R6, so as to form a connection with the control end of the depletion-type switch tube Q2 through the second voltage-dividing resistor R6. The second connection end of the driving switch tube Q3 is connected to the second connection end of the depletion-type switch tube Q2 and ground. The control end of the driving switch tube Q3 is connected to the second connection end and ground of the driving switch tube Q3 through the second filter resistor R9, and is connected to the cathode of the second anti-reverse diode D3 through the first filter resistor R8. The second filter capacitor C3 is connected in parallel with the second filter resistor R9, that is, the second filter capacitor C3 is connected between the control end of the driving switch tube Q3 and the ground. The anode of the second anti-reverse diode D3 is connected to the cathode of the rectifier diode D4 in the power supply circuit 14.

[0068] Among them, the first filter resistor R8, the second filter resistor R9 and the second filter capacitor C3 constitute an RC low-pass filter circuit, which can be used to filter out the high-frequency interference caused by the switching power supply 300, so as to prevent the high-frequency interference from affecting the normal on-off of the driving switch tube Q3. In one embodiment, the anode of the second anti-reverse diode D3 can also be connected to the third filter capacitor C4, and the cathode of the second anti-reverse diode D3 can also be connected to the fourth filter capacitor C2. The third filter capacitor C4 and the fourth filter capacitor C2 can further enhance the filtering effect. In addition, a third voltage stabilizing diode ZD3 can be connected between the second connection end of the driving switch tube Q3 and the second connection end of the depletion-type switch tube Q2. The third voltage stabilizing diode ZD3 can stabilize the voltage on the power pin VCC to prevent the power management chip 200 from being damaged by overvoltage.

[0069] based on Figure 3 The circuit design shown in the figure, the working process of the startup circuit 100 is as follows:

[0070] When the switching power supply 300 and the power management chip 200 are not started, there is no voltage input to the power supply circuit 14 and the control circuit 15, and the driving switch tube Q3, the second anti-reverse diode D3 in the control circuit 15 and the third anti-reverse diode D5 in the power supply circuit 14 cannot be turned on. Therefore, the control circuit 15 and the power supply circuit 14 are not working, or in other words, the control circuit 15 and the power supply circuit 14 are disconnected.

[0071] When the first switch circuit 11 is connected to the DC power supply 400, and the DC power supply 400 provides a DC input voltage Vin, the control terminal and the first connection terminal of the enhanced switch tube Q1 in the first switch circuit 11 both have voltage inputs, so the enhanced switch tube Q1 can be switched from the off state to the on state, and its second connection terminal can output the first output voltage Vo1 to the start-up resistor R4. The voltage of the start-up resistor R4 is the first output voltage Vo1. The first output voltage Vo1 is equal to the difference between the DC input voltage Vin and the on-threshold voltage of the enhanced switch tube Q1.

[0072] Furthermore, the first connection end of the depletion-type switch tube Q2 in the second switch circuit 13 can be connected to the first output voltage Vo1 of the start-up resistor R4 through the first anti-reverse diode D2, and there is no voltage at the control end and the second connection end of the depletion-type switch tube Q2. Therefore, when the first switch circuit 11 outputs the first output voltage Vo1 and the switching power supply 300 is not working, the depletion-type switch tube Q2 is in a naturally conducting state, and its second connection end can output the start-up voltage and start-up current to the power pin VCC, so that the capacitor Cvcc on the power pin VCC can be charged and stored. In addition, the start-up voltage can also be transmitted to the first connection end of the drive switch tube Q3 in the control circuit 15 through the first voltage-dividing resistor R5 and the second voltage-dividing resistor R6.

[0073] It should be understood that at this time, the control end and the second connection end of the depletion-type switch tube Q2 are not connected to the voltage, that is, Vgs = 0V. Therefore, the depletion-type switch tube Q2 can be equivalent to a constant current source, which can output a constant starting current to the power pin VCC to charge the capacitor Cvcc with a constant current, so as to avoid the problem of current spikes. Moreover, no matter whether the DC input voltage Vin is high or low, the charging time of the capacitor Cvcc can be basically the same. Among them, the constant starting current is Vo1 / R4, and its current size can be adjusted by selecting corresponding device parameters according to actual needs.

[0074] It is understandable that if the DC power supply 400 does not provide the DC input voltage Vin, the enhancement-mode switch tube Q1 remains in the off state, and thus, the depletion-mode switch tube Q2 will be unable to output voltage and current.

[0075] When the voltage of the capacitor Cvcc is charged to the startup voltage required by the power management chip 200, the power management chip 200 can be started. After startup, a working current flows through the power pin VCC of the power management chip 200, and the power management chip 200 generates a control signal and outputs the control signal to the switching power supply 300 through the control pin OUT. The switching power supply 300 starts and starts working under the control of the control signal, so the voltage Vaux output by the switching power supply 300 rises and stabilizes at a certain voltage value.

[0076] The voltage Vaux output by the switching power supply 300 can be rectified by the rectifier circuit 141. Since the rectified voltage is greater than the conduction voltage drop of the second anti-reverse diode D3 in the control circuit 15, the rectified voltage can be transmitted to the control end of the driving switch tube Q3 through the second anti-reverse diode D3 and the first filter resistor R8 of the anti-interference circuit 151, so that the driving switch tube Q3 can be switched from the off state to the on state. Therefore, the driving switch tube Q3 can be connected to the voltage divider circuit 131 (i.e., the first voltage divider resistor R5 and the second voltage divider resistor R6) to form a loop. Therefore, the working current of the power management chip 200 can flow from the power pin VCC to the third current limiting resistor R7, and after passing through the third current limiting resistor R7, the first voltage divider resistor R5 and the second voltage divider resistor R6, through the turned-on driving switch tube Q3 to the ground GND, so that the voltage VGS between the control end and the second connection end of the depletion type switch tube Q2 is equal to the voltage across the first voltage divider resistor R5, that is, VGS=-VCC / (R5+R6)*R5.

[0077] When the absolute value of VGS of the depletion-type switch tube Q2 is greater than the turn-off threshold voltage of the depletion-type switch tube Q2, the communication of the depletion-type switch tube Q2 will be gradually depleted, so the depletion-type switch tube Q2 will switch from the on state to the off state, and stop outputting voltage and current to the power pin VCC. Therefore, the second switch circuit 13 stops supplying power to the power management chip 200. At this time, the startup resistor 12 is disconnected from the second switch circuit 13 and the power pin VCC. It can be seen that the voltage VGS is used to drive the depletion-type switch tube Q2 to turn off, so the voltage VGS can be called a driving voltage.

[0078] At the same time, the voltage Vaux output by the switching power supply 300 is transmitted to the third anti-reverse diode D5 after rectification, and the third anti-reverse diode D5 transmits the second output voltage Vo2 to the power pin VCC, so that the switching power supply 300 can supply power to the power management chip 200 through the power supply circuit 14. The second output voltage Vo2 is equal to the rectified voltage of the switching power supply 300 minus the conduction voltage drop of the third anti-reverse diode D5.

[0079] It can be seen that the startup circuit 100 can be used to start the power management chip 200, and after the power management chip 200 is started, the startup circuit 100 can automatically cut off the second switch circuit 13 and the startup resistor 12, and at the same time can switch to the switching power supply 300 to power the power management chip 200.

[0080] It can be understood that when the depletion-type switch tube Q2 is turned off, the startup resistor 12 is disconnected from the second switch circuit 13 and the power pin VCC, and no current flows through the startup resistor 12, so no electric energy is consumed. Therefore, the loss generated by the startup circuit 100 can be reduced. Moreover, at this time, the startup circuit 100 still has the second current limiting resistor R2 and the first voltage zener diode ZD1 in the first switch circuit 11, the first voltage divider resistor R5 and the second voltage divider resistor R6 in the second switch circuit 13, and the first filter resistor R8 and the second filter resistor R9 in the control circuit 15, which will generate losses. Since the resistance value of the second current limiting resistor R2 can be very large, the loss of R2 is very small. If the DC input voltage Vin is lower than the voltage stabilization value of the first voltage zener diode ZD1, then the first switch circuit 11 can basically generate no loss. The resistance values ​​of the first voltage-dividing resistor R5, the second voltage-dividing resistor R6, the first filter resistor R8, and the second filter resistor R9 can also be very large, and at this time, the power is provided by the switching power supply 300. Therefore, the first voltage-dividing resistor R5, the second voltage-dividing resistor R6, the first filter resistor R8, and the second filter resistor R9 do not generate linear losses, but losses converted by the switching power supply 300, which are relatively small. Therefore, when the power management chip 200 and the switching power supply 300 work normally, the losses generated by the startup circuit 100 can be greatly reduced.

[0081] It should be understood that the embodiment of the present application designs the enhanced switch tube Q1 and the depletion switch tube Q2 to be connected in series, so the enhanced switch tube Q1 and the depletion switch tube Q2 can jointly bear the DC input voltage Vin, thereby reducing the voltage borne by the enhanced switch tube Q1 and the depletion switch tube Q2, and reducing the risk of overvoltage. In addition, the enhanced switch tube Q1 and the depletion switch tube Q2 can use semiconductor devices with smaller withstand voltage values ​​(semiconductor devices with small withstand voltage values ​​are low in price, and have many types and are more common, while high-voltage devices are less common on the market and are much more expensive), without the need to customize high-voltage semiconductor devices, which can reduce costs and make selection more convenient. Moreover, the withstand voltage values ​​of the enhanced switch tube Q1 and the depletion switch tube Q2 can also have a larger margin, which is conducive to widening the input voltage range of the startup circuit 100, realizing wide voltage input and high voltage input, and at high input voltage, the risk of overvoltage of the switch device is low, and the risk of overheating and damage of the startup resistor 12 is low. Therefore, such a circuit design is easy to implement and has a wide range of applications.

[0082] In an embodiment of the present application, the sum of the withstand voltage value of the depletion-type switch tube and the withstand voltage value of the enhancement-type switch tube is not less than the DC input voltage Vin of the DC power supply 400. For example, when the sum of the withstand voltage value of the depletion-type switch tube and the withstand voltage value of the enhancement-type switch tube is equal to Vin, the withstand voltage value of the depletion-type switch tube Q2 is Vo1, and the withstand voltage value of the enhancement-type switch tube Q1 is VIN-Vo1. When the DC input voltage Vin is constant, the higher the withstand voltage value of Q2, the lower the withstand voltage value of Q1. The higher the withstand voltage value of Q1, the lower the withstand voltage value of Q2. When the DC input voltage Vin is high, Q1 and Q2 can select semiconductor devices with lower withstand voltage values ​​and connect them in series to jointly bear higher voltages. When the DC input voltage is very high, Q1 and Q2 can select semiconductor devices with higher withstand voltage values ​​or conventional withstand voltage values ​​and connect them in series to jointly bear higher voltages.

[0083] As a further example, in the energy storage device 2000, a 1500V battery pack is used as the DC power source 400. Then, the enhanced switch tube Q1 can select a semiconductor device with a withstand voltage of 1200V, the depletion switch tube Q2 can select a semiconductor device with a withstand voltage of 600V, and the voltage stabilization value of the first voltage stabilizing diode ZD1 can be about 450V. Obviously, the withstand voltage values ​​of Q1 and Q2 are both conventional withstand voltage values, and the sum of the withstand voltage values ​​of Q1 and Q2, 1800V, has a margin of 300V compared to the battery pack voltage of 1500V, so the overvoltage risk of Q1 and Q2 is relatively small.

[0084] In the embodiment of the present application, since the enhanced switch tube Q1 is a normally closed switch, it can be avoided that the switch tube Q1 in the first switch circuit 11 is abnormally turned on due to noise interference when the DC input voltage Vin is not connected or the connected voltage does not reach the magnitude of the DC input voltage Vin. It can be seen that the startup circuit 100 has a certain anti-interference ability. Since the depletion type switch tube Q2 is a normally open switch, when the startup circuit 100 is connected to the DC input voltage Vin, there is no need to wait for the depletion type switch tube Q2 to be turned on, that is, power can be quickly supplied to the power pin VCC of the power management chip 200, so the startup efficiency can be improved.

[0085] In particular, in the battery scenario, the battery pack serves as a DC power supply 400. When the device (such as an energy storage device) where the battery pack, the switching power supply 300 and the power management chip 200 are located is not started, the startup circuit 100 will not consume the power of the battery pack because the enhanced switch tube Q1 is turned off. In the process of starting the power management chip 200, the startup circuit 100 can quickly provide a startup voltage and a constant current startup current, so the startup time of the power management chip 200 is short and the startup efficiency is high. After starting the power management chip 200, the startup circuit 100 can automatically turn off the depletion switch tube Q2, so the startup circuit 100 causes very little power loss in the battery pack, which helps the efficiency of the device. Therefore, when the device is in long-term standby mode, the device can be in ultra-low power standby mode. In the case of a battery pack loss (i.e., insufficient power), the power of the battery pack is not easily exhausted, which can avoid damage to the battery pack due to empty power.

[0086] Understandably, Figure 3 The control circuit 15 shown uses a triode as the driving switch tube Q3, and the second switch circuit 13 uses a depletion-type MOS tube as the depletion-type switch tube Q2, and the first connection end of the driving switch tube Q3 is connected to the second connection end of the depletion-type switch tube Q2 through a voltage divider, and the second connection end of the driving switch tube Q3 is also connected to the second connection end of the depletion-type switch tube Q2, and the control end of the depletion-type switch tube Q2 is connected to the voltage divider, so that the control voltage output by the driving switch tube Q3 can realize the depletion-type switch tube Q2 to be turned off. Moreover, since the triode has a voltage amplification function, the control voltage output by the triode can reach the turn-off threshold voltage of the MOS tube, and the triode can provide a higher control current. Therefore, based on such a circuit design, the depletion-type switch tube Q2 can be turned off quickly, the turn-off loss of the depletion-type switch tube Q2 can be reduced, and the loss generated by the start-up resistor 12 can be reduced.

[0087] Of course, in other embodiments, the enhanced switch tube Q1 may also adopt an enhanced PMOS tube or other normally closed semiconductor switches, and realize the function of the first switch circuit 11 together with the first current limiting resistor and the voltage stabilizing circuit 111 matched therewith. The depletion switch tube Q2 may also adopt a depletion PMOS tube or other normally open semiconductor switches, and realize the function of the second switch circuit 13 together with the first anti-reverse diode D2 and the voltage divider circuit 131 matched therewith. The driving switch tube Q3 may also adopt other semiconductor switches (such as enhanced MOS tubes, IGBT tubes, etc.) according to actual conditions, and realize the function of the control circuit 15 together with the anti-interference circuit 151 matched therewith. No more examples are given here.

[0088] In addition, in order to protect the DC power supply 400 and the start-up circuit 100, a protection circuit may be provided between the DC power supply 400 and the first switch circuit 11. For example, Figure 3 As shown, the protection circuit includes a fuse FUSE, an input filter capacitor Cin and a fourth anti-reverse diode D1. The fuse FUSE is connected in series with the positive electrode of the DC power supply 400 to provide overcurrent protection. The input filter capacitor Cin is connected between the positive and negative electrodes of the DC power supply 400 to filter out interference and reduce fluctuations in the DC input voltage Vin. The fourth anti-reverse diode D1 is connected in series between the fuse FUSE and the filter capacitor Cin, and the fourth anti-reverse diode D1 can provide voltage anti-reverse function.

[0089] Please also read Figure 4 , an embodiment of the present application also provides a power conversion device 1000.

[0090] like Figure 4 As shown, the power conversion device 1000 includes a startup circuit 100, a power management chip 200 and a switching power supply 300. The startup circuit 100 is connected to the power pin VCC of the power management chip 200, and the control pin OUT of the power management chip 200 is connected to the switching power supply 300. Specifically, the startup circuit 100 can provide a startup voltage and a startup current to the power management chip 200 when a DC input voltage is connected, so that the power management chip 200 is powered on and started. After the power management chip 200 is started, the operation of the switching power supply 300 can be controlled so that the switching power supply 300 generates a voltage. When the voltage generated by the switching power supply 300 reaches the voltage required for the power management chip 200 to work, the startup circuit 100 automatically disconnects from the power pin VCC, and the startup circuit 100 stops supplying power. At this time, the switching power supply 300 continues to supply power to the power management chip 200.

[0091] The power management chip 200, the switching power supply 300 and the startup circuit 100 can be referred to in the aforementioned Figures 2 to 3 The relevant description in the illustrated embodiment will not be repeated here.

[0092] Please also read Figure 5 , an embodiment of the present application also provides an energy storage device 2000.

[0093] like Figure 5 As shown, the energy storage device 2000 includes a battery pack 500, a startup circuit 100, a switching power supply 300 and a power management chip 200. The battery pack 500 is used as a DC power supply. The power pins of the battery pack 500 and the power management chip 200 are respectively connected to the startup circuit 100, and the control pin of the power management chip 200 is connected to the switching power supply 300. Among them, the battery pack 500, the power management chip 200, the switching power supply 300 and the startup circuit 100 can be seen in Figures 2 to 4 The relevant description in the illustrated embodiment will not be repeated here.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A startup circuit of a power management chip, wherein a control pin of the power management chip is connected to a switching power supply, and is used to control the switching power supply to work after startup, characterized in that: The startup circuit includes: a first switch circuit, a startup resistor, a second switch circuit, a control circuit and a power supply circuit, wherein: The first switch circuit is used to be connected when a DC input voltage is connected, and output a first output voltage; The second switch circuit is connected to the first switch circuit through the startup resistor, and the second switch circuit is also connected to the power pin of the power management chip; the second switch circuit is used to be connected when the first switch circuit outputs the first output voltage and the switching power supply is not working, and output a startup voltage to the power pin, and the startup voltage is used to start the power management chip; The control circuit is connected to the switching power supply and the second switching circuit, and the control circuit is used to control the second switching circuit to be disconnected when the switching power supply is working, so that the startup resistor is disconnected from the power supply pin; The power supply circuit is connected to the power pin and the switching power supply, and is used for outputting a second output voltage to the power pin when the switching power supply is working, so as to supply power to the power management chip.

2. The starting circuit according to claim 1, characterized in that: The second switch circuit includes a depletion-type switch tube, a first anti-reverse diode and a voltage divider circuit, wherein: The first connection end of the depletion-type switch tube is connected to the cathode of the first anti-reverse diode, and the anode of the first anti-reverse diode is connected to the first switch circuit through the start-up resistor; The second connection end of the depletion-type switch tube is connected to the control circuit through the voltage divider circuit, the control end of the depletion-type switch tube is connected to the voltage divider circuit, and the second connection end of the depletion-type switch tube is also connected to the power pin; The depletion-type switch tube is used to be turned on when the first switch circuit outputs the first output voltage and the switch power supply is not working, and output the start-up voltage to the power pin; and to be turned off when the switch power supply is working, and stop outputting the start-up voltage.

3. The starting circuit according to claim 2, characterized in that: The first switch circuit includes an enhanced switch tube, a first current limiting resistor and a voltage stabilizing circuit, wherein: The first connection end of the enhanced switch tube is connected to the first current limiting resistor and the voltage stabilizing circuit, the first current limiting resistor and the voltage stabilizing circuit are used to access the DC input voltage, the second connection end of the enhanced switch tube is connected to the starting resistor, and the control end of the enhanced switch tube is connected to the voltage stabilizing circuit; The enhanced switch tube is used to be turned on when connected to the DC input voltage, and output the first output voltage to the starting resistor.

4. The starting circuit according to claim 3, characterized in that: The sum of the withstand voltage value of the depletion-mode switch tube and the withstand voltage value of the enhancement-mode switch tube is not less than the DC input voltage.

5. The starting circuit according to claim 2, characterized in that: The depletion-type switch tube is also used to output a constant starting current to the power pin when the first switch circuit outputs the first output voltage and the switch power supply is not working.

6. The starting circuit according to claim 2, characterized in that: The control circuit includes a driving switch tube, a second anti-reverse diode and an anti-interference circuit, wherein: The first connection end of the driving switch tube is connected to the second switch circuit, the second connection end of the driving switch tube is connected to the second switch circuit and ground, the control end of the driving switch tube is connected to the second connection end of the driving switch tube and the cathode of the second anti-reverse diode through the anti-interference circuit, and the anode of the second anti-reverse diode is connected to the switching power supply; The driving switch tube is used to be turned on when the switching power supply is working, so as to form a loop with the voltage divider circuit, so that the driving voltage generated by the voltage divider circuit is connected between the control end of the depletion-type switch tube and the second connection end of the depletion-type switch tube, and the driving voltage is used to drive the depletion-type switch tube to turn off.

7. The starting circuit according to claim 2, characterized in that: The voltage-dividing circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to the second connection end of the depletion-type switching tube, the other end of the first voltage-dividing resistor is connected to the control end of the depletion-type switching tube, and is connected to the control circuit through the second voltage-dividing resistor.

8. The starting circuit according to claim 1, characterized in that: The power supply circuit includes a rectifier circuit and a third anti-reverse diode, the rectifier circuit is connected between an anode of the third anti-reverse diode and the switching power supply, and a cathode of the third anti-reverse diode is connected to the power supply pin.

9. A power conversion device, characterized in that: The power conversion device includes a switching power supply, a power management chip and a startup circuit as described in any one of claims 1 to 8, wherein the startup circuit is connected to a power pin of the power management chip, and a control pin of the power management chip is connected to the switching power supply.

10. An energy storage device, characterized in that: The energy storage device includes a battery pack, a switching power supply, a power management chip and a starting circuit as described in any one of claims 1 to 8, the power pins of the battery pack and the power management chip are respectively connected to the starting circuit, and the control pin of the power management chip is connected to the switching power supply.

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