Multi-string farad capacitor current-limiting charging circuit

Abstract

The utility model discloses a multi-string farad capacitor current-limiting charging circuit, a collector electrode of an NPN triode is electrically connected to an enabling pin of a control chip, a collector electrode of a PNP triode is electrically connected to an output pin of the control chip, and a current-limiting protection resistor is connected between a base electrode of the NPN triode and the collector electrode of the PNP triode; the PNP triode is also electrically connected to the positive electrode of a diode through a voltage division protection resistor. The diode and a multi-string farad capacitor circuit are connected to a VFC circuit. According to the current-limiting charging circuit, an engineer can conveniently adjust and design the circuit according to the characteristics and string number of the farad capacitor; the device has an element protection function which is not provided by the traditional current-limiting current, and the applied elements are simple; an EN signal of a pre-stage power supply circuit is turned off, electric energy is saved after the farad capacitor is fully charged, and automatic recharging can be performed when the voltage of the farad capacitor is low; the circuit can be directly used through production verification, and the project development process is accelerated.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of charging circuit, concretely relates to a multi string farad capacitor current -limiting charging circuit. BACKGROUND

[0002] Farad capacitor (super capacitor) as a kind of energy storage device with high capacity, fast charge-discharge characteristics and long cycle life, has important application value in wireless communication, intelligent instrument, automotive electronics and backup power supply and other fields.The existing technology is mostly to realize charging control using simple current-limiting resistor or constant current chip.Resistor current-limiting scheme is low in cost, but there is significant energy loss, and high-power resistor needs to be used in large current scene, leading to high PCB area occupation, which is difficult to meet the miniaturization demand.Constant current chip scheme can accurately control current, but high-power charging needs to be matched with high-specification chip and peripheral devices, significantly increasing system cost and complexity.

[0003] For multi string farad capacitor current-limiting charging circuit, farad capacitor has the advantages of fast charging speed (charging is completed in tens of seconds), environmental protection (no pollution) and long service life (charge-discharge times reach hundreds of thousands), but its single rated voltage is usually low (such as 2.7V), which needs to be improved by multi string method.However, when multi string is used, the inconsistency of capacity and internal resistance of farad capacitor caused by manufacturing difference is prominent;The capacitor with smaller capacity will be charged first, and if the charging continues, it will cause overcharge or even breakdown failure.The traditional triode current-limiting circuit is not suitable for direct application in farad capacitor, because the initial voltage of farad capacitor is 0V, if the number of capacitor strings is large, the supply voltage is too high or transient overshoot, which may damage the triode. UTILITY MODEL CONTENTS

[0004] In view of the above problems, the utility model aims at providing a multi string farad capacitor current-limiting charging circuit.

[0005] To achieve the technical purpose, the utility model provides a multi string farad capacitor current-limiting charging circuit, which comprises a control chip with LDO, a multi string farad capacitor circuit and a diode, wherein the collector electrode of NPN triode is electrically connected to the enable pin of control chip, the collector electrode of PNP triode is electrically connected to the output pin of control chip, and the base electrode of NPN triode and the collector electrode of PNP triode are connected to current-limiting protection resistor;The PNP triode is also connected to the anode of diode through voltage division protection resistor, and the diode and multi string farad capacitor circuit are connected to VFC circuit.

[0006] As preferred, the multi-string Faraday capacitor circuit is composed of a first Faraday capacitor, a first equalization resistor, a second Faraday capacitor, a second equalization resistor, and a third Faraday capacitor, and the first equalization resistor, the second equalization resistor, and the third equalization resistor are connected in series and grounded, the first Faraday capacitor is connected in parallel to the first equalization resistor, the second Faraday capacitor is connected in parallel to the second equalization resistor, and the third Faraday capacitor is connected in parallel to the third equalization resistor.

[0007] As preferred, the voltage dividing protection resistor comprises a voltage dividing resistor R1, a voltage dividing resistor R2, and a current limiting protection resistor R4, the emitter of the PNP triode is connected with the voltage dividing resistor R1 and the voltage dividing resistor R2 in sequence, the base of the PNP triode is connected with the current limiting protection resistor R4, the current limiting protection resistor R4 is connected to a first connection point between the voltage dividing resistor R1 and the voltage dividing resistor R2, and the other end of the voltage dividing protection resistor R2 is connected with the anode of the diode.

[0008] As preferred, the input pin VIN of the control chip is further connected with a capacitor C1 and grounded, and the resistor R3 is connected in parallel to the enable pin EN and the input pin VIN of the control chip.

[0009] As preferred, the emitter of the NPN triode is grounded, and the collector of the PNP triode is grounded through the resistor R6.

[0010] As preferred, the diode is a Schottky diode capable of preventing reverse discharge.

[0011] As preferred, the output voltage of the output pin VOUT of the control chip is 9V, and the output pin VOUT is further connected with a capacitor C2 and grounded.

[0012] The current limiting charging circuit of the application can be conveniently adjusted and designed by engineers according to the characteristics and string number of the Faraday capacitor, has the element protection function that the traditional current limiting current does not have, and has simple applied elements; has the EN signal for shutting down the previous stage power supply circuit, saves electric energy after the Faraday capacitor is fully charged, and can be automatically recharged when the Faraday capacitor voltage is low; the circuit is directly used after production verification, and the project development process is accelerated. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The circuit diagram of the application. DETAILED DESCRIPTION

[0014] The application will be further described in detail below in combination with the drawings and specific embodiments. In order to clearly and completely describe the technical solutions, the following embodiments are selected for description; based on the content described in the application, other embodiments obtained without creative labor are also within the protection scope of the application.

[0015] In the following embodiments, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", "top / bottom" and the like orientation or positional relationships are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of clearly describing the embodiments, and do not indicate or imply that the devices or elements referred to must have a particular orientation, so it cannot be understood as a limitation on the present application.

[0016] As Figure 1The utility model discloses a kind of multi-string farad capacitance current-limiting charging circuits, the input pin VIN of control chip is also connected with capacitor C1 (capacitance 10uF) and ground, the enable pin EN and input pin VIN of the control chip (LDO with shut-off function) have resistance R3 (resistance 10KΩ) in parallel.The collector of NPN triode is electrically connected to the enable pin EN of control chip, the collector of PNP triode is electrically connected to the output pin VOUT of control chip, the base of the NPN triode and the collector of PNP triode are connected with current-limiting protection resistance R5 (resistance 1KΩ);The PNP triode is also connected to the positive electrode electric connection of diode through voltage division protection resistance, and the diode is connected to VFC circuit with multi-string farad capacitor circuit;Multi-string farad capacitor circuit is composed of first farad capacitor FC1 (3.3F / 3V), first equalizing resistance R7 (resistance 10KΩ), second farad capacitor FC2 (3.3F / 3V), second equalizing resistance R8 (resistance 10KΩ), third farad capacitor FC3 (3.3F / 3V), third equalizing resistance R9 (resistance 10KΩ), and the first equalizing resistance, second equalizing resistance, third equalizing resistance are connected in series and grounded, the first equalizing resistance is connected with the first farad capacitor in parallel, the second equalizing resistance is connected with the second farad capacitor in parallel, and the third equalizing resistance is connected with the third farad capacitor in parallel.The voltage division protection resistance includes voltage division resistance R1 (resistance 22 ohm), voltage division resistance R2 (resistance 22 ohm), current-limiting protection resistance R4 (resistance 1KΩ), and the emitter of the PNP triode is sequentially electrically connected with voltage division resistance R1 (resistance 22 ohm) and voltage division resistance R2 (resistance 22 ohm);The base of the PNP triode is electrically connected with current-limiting protection resistance R4 (resistance 1KΩ), and the current-limiting protection resistance R4 (resistance 1KΩ) is electrically connected to the first connecting point between voltage division resistance R1 (resistance 22 ohm) and voltage division resistance R2 (resistance 22 ohm), and the other end of voltage division protection resistance R2 (resistance 22 ohm) is electrically connected to the positive electrode of diode.The emitter of the NPN triode is grounded, and the C pole of the PNP triode is grounded by resistance R6 (resistance 10KΩ).The diode is a Schottky diode for preventing reverse discharge.The output voltage of the output pin VOUT of the control chip is 9V, and the output pin VOUT is also connected with capacitor C2 (capacitance 10uF) and ground.

[0017] Combining the attached Figure 1 Take 3-string farad capacitor as an example, main components: control chip U1 is LDO with shut-off function, FC1, FC2, FC3 are farad capacitors, R7, R8, R9 are equalizing resistors; Q1 is PNP triode, Q2 is NPN triode; Schottky diode D1 is used to prevent reverse discharge.

[0018] Brief introduction of working principle: the resistance R6 provides the initial pull-down level of the base of the NPN transistor Q2, turns off the NPN transistor Q2, so that the LDO of the control chip U1 is enabled when the EN pin is pulled up by the resistance R3, and the control chip U1 outputs a voltage of 9V at the VOUT. The voltage dividing resistance R1 provides the base bias voltage of the PNP transistor Q1, and the voltage dividing resistance R1 also realizes the current limiting function, and the current limiting current is about: 0.6V / R1. The voltage dividing resistance R2 is an additional current limiting protection resistance when the transistor fails. Note that the power consumption of the voltage dividing resistance R1 and the voltage dividing resistance R2 should not exceed the allowed dissipation power. The PNP transistor Q1 and the NPN transistor Q2 realize the logic control of the EN pin of the LDO of the control chip U1, and the current limiting protection resistance R4 and the current limiting protection resistance R5 are used for protecting the PNP transistor Q1 and the NPN transistor Q2 respectively. The protection principle of the current limiting protection resistance R4 and the current limiting protection resistance R5 is as follows: at the initial power-on, since the voltage of the farad capacitor is 0V, the conduction voltage drop of the emitter e and the base b pins of the PNP transistor Q1 has not been formed, the base of the PNP transistor Q1 will get 1 / 2 VOUT voltage, about 4.5V, through the voltage dividing function of R1 and R2. At this time, if there is no R4 resistance, the emitter e and the base b pins of the PNP transistor Q1 will bear an excessive voltage, which may damage the PNP transistor Q1. At the same time, when the PNP transistor Q1 is momentarily turned on, a large voltage is applied to the base b and the emitter e of the NPN transistor Q2, which is about equal to VOUT 9V. If there is no current limiting of the R5 resistance, the NPN transistor Q2 will be damaged before the PNP transistor Q1, and the specific failure phenomenon may be that the base b and the emitter e of the NPN transistor Q2 are short-circuited, thereby dragging and damaging the PNP transistor Q1.

[0019] The current limiting charging circuit of the application can enable engineers to conveniently adjust the design circuit according to the characteristics of the farad capacitor and the number of strings; has the element protection function that the traditional current limiting current does not have, and the applied elements are simple; has the EN signal of turning off the previous stage power supply circuit, saves the electric energy after the farad capacitor is fully charged, and can automatically recharge when the voltage of the farad capacitor is low; the circuit is verified by production, can be directly used, and accelerates the project development process.

[0020] The above is only a preferred embodiment of the application, and is not used to limit the application, and any slight modification, equivalent replacement and improvement made according to the technical essence of the application to the above embodiment shall be included in the protection scope of the technical scheme of the application.

Claims

1. A multi-string Faraday capacitor current limiting charging circuit, characterized by, The application relates to a control chip with an LDO, a multi-string farad capacitor circuit and a diode, wherein the collector of an NPN triode is electrically connected to an enable pin of the control chip, the collector of a PNP triode is electrically connected to an output pin of the control chip, and a current-limiting protection resistor is connected between the base of the NPN triode and the collector of the PNP triode; the PNP triode is further connected to the anode of the diode through a voltage division protection resistor, and the diode and the multi-string farad capacitor circuit are connected to a VFC circuit.

2. The multi-string Faraday capacitance current limiting charging circuit according to claim 1, characterized in that: The multi-string farad capacitor circuit is composed of a first farad capacitor, a first equalization resistor, a second farad capacitor, a second equalization resistor and a third farad capacitor, wherein the first equalization resistor, the second equalization resistor and the third equalization resistor are connected in series and grounded, the first farad capacitor is connected in parallel to the first equalization resistor, the second farad capacitor is connected in parallel to the second equalization resistor, and the third farad capacitor is connected in parallel to the third equalization resistor.

3. The multi-string Faraday capacitance current limiting charging circuit according to claim 1, wherein: The voltage division protection resistor comprises a voltage division resistor R1, a voltage division resistor R2 and a current-limiting protection resistor R4, the emitter of the PNP triode is electrically connected to the voltage division resistor R1 and the voltage division resistor R2 in sequence, the base of the PNP triode is electrically connected to the current-limiting protection resistor R4, the current-limiting protection resistor R4 is electrically connected to a first connecting point between the voltage division resistor R1 and the voltage division resistor R2, and the other end of the voltage division protection resistor R2 is electrically connected to the anode of the diode.

4. The multi-string Faraday capacitance current limiting charging circuit of claim 1, wherein: The input pin VIN of the control chip is further connected to a capacitor C1 and grounded, and the enable pin EN and the input pin VIN of the control chip are connected in parallel to a resistor R3.

5. The multi-string Faraday capacitance current limiting charging circuit of claim 1, wherein: The emitter of the NPN triode is grounded, and the collector of the PNP triode is grounded through a resistor R6.

6. The multi-string Faraday capacitance current limiting charging circuit of claim 1, wherein: The diode is a Schottky diode capable of preventing reverse discharge.

7. The multi-string Faraday capacitance current limiting charging circuit of claim 1, wherein: The output voltage of the output pin VOUT of the control chip is 9V, and the output pin VOUT is further connected to a capacitor C2 and grounded.

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