TWS charging bin simple discrete component low-current charging practical circuit

Abstract

The utility model discloses a TWS charging bin simple discrete component low-current charging practical circuit, which adopts a battery anti-reverse-connection circuit, a discrete component low-current charging circuit and a battery protection circuit, and the battery anti-reverse-connection circuit is used for battery anti-reverse-connection protection; the discrete component low-current charging circuit is used for completing low-current charging of the TWS charging bin; and the battery protection circuit is used for activating the battery protection circuit when the voltage of the battery cell is lower than a set voltage threshold value, so that the battery enters a normal charging state. According to the utility model, the production cost is reduced, and the problems of unstable IC price and goods source and cost pressure caused by an MCU development scheme are effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of charging, and in particular discloses a practical circuit for low-current charging using simple discrete components in a TWS charging bin. Background Art

[0002] With the development of wireless audio devices, TWS (True Wireless Stereo) headphones are becoming more and more popular among consumers. TWS headphones usually need to be charged through a charging bin. The charging bin is the storage box and charger for the TWS Bluetooth headset. The charging bin and the TWS Bluetooth headset can communicate with each other, and can realize functions such as opening the cover to turn on the headset, opening the cover to reconnect, and displaying the power level. However, the traditional TWS charging bin charging circuit design is relatively complex, using a large number of integrated circuits and external components, which not only increases the production cost, but also reduces the reliability of the product. Utility Model Content

[0003] The utility model provides a practical circuit for low-current charging of a TWS charging bin using simple discrete components, aiming to solve the technical problem that the traditional TWS charging bin charging circuit design is relatively complex and costly.

[0004] The utility model relates to a TWS charging compartment simple discrete component small current charging practical circuit, including a battery reverse connection protection circuit, a discrete component small current charging circuit and a battery protection circuit, wherein:

[0005] Battery reverse connection protection circuit, used for battery reverse connection protection;

[0006] The discrete component low-current charging circuit is connected to the battery reverse connection protection circuit to complete the low-current charging of the TWS charging bin;

[0007] The battery protection circuit is connected to the battery reverse connection protection circuit and is used to activate the battery protection circuit when the battery cell voltage is lower than the set voltage threshold, so that the battery enters a normal charging state.

[0008] Furthermore, the battery reverse connection protection circuit includes a PMOS transistor, a first resistor and a second resistor, the drain of the PMOS transistor is connected to the positive terminal of the battery, the gate of the PMOS transistor is connected to the negative terminal of the battery through the first resistor, and the two ends of the second resistor are respectively connected to the gate and source of the PMOS transistor.

[0009] Furthermore, the model of the PMOS transistor is AO3401.

[0010] Furthermore, the discrete component low-current charging circuit includes a USB-typec interface, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a diode, a first capacitor, a PNP transistor and an indicator light. The first pin of the USB-typec interface is grounded, the second pin of the USB-typec interface is connected to the power supply end, the third pin of the USB-typec interface is grounded through the third resistor, the fourth pin of the USB-typec interface is grounded through the fourth resistor, and the fifth pin of the USB-typec interface is divided into three paths. The first path is connected to the positive terminal of the battery through a diode and a fifth resistor in series, the second path is grounded through a first capacitor, and the third path is connected to the emitter of the PNP transistor. The base of the PNP transistor is connected to the positive terminal of the battery through the sixth resistor, and the collector of the PNP transistor is grounded after being connected in series with the seventh resistor and the indicator light.

[0011] Furthermore, the indicator light is a red indicator light.

[0012] Furthermore, the model of the PNP transistor is 8550.

[0013] Furthermore, the diode is a Schottky diode, model SS14.

[0014] Furthermore, the battery protection circuit includes a MOS chip and a protection control chip connected to the MOS chip.

[0015] Furthermore, the model of the MOS chip is 8205S.

[0016] Furthermore, the model of the protection control chip is DW01.

[0017] The beneficial effects achieved by the utility model are:

[0018] The utility model provides a TWS charging bin simple discrete component small current charging practical circuit, which adopts a battery anti-reverse connection circuit, a discrete component small current charging circuit and a battery protection circuit. The battery anti-reverse connection circuit is used for battery anti-reverse connection protection; the discrete component small current charging circuit is used to complete the TWS charging bin small current charging; the battery protection circuit is used to activate the battery protection circuit when the battery cell voltage is lower than the set voltage threshold, so that the battery enters a normal charging state. The TWS charging bin simple discrete component small current charging practical circuit provided by the utility model reduces production costs and effectively solves problems such as IC prices, unstable supply and cost pressure caused by MCU development solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a functional block diagram of a practical circuit for low-current charging using simple discrete components in a TWS charging bin of the utility model;

[0020] Figure 2 This is the circuit diagram of a practical circuit for low-current charging using simple discrete components in a TWS charging bin of the utility model.

[0021] Description of Figure Numbers:

[0022] 10. Battery reverse connection protection circuit; 20. Discrete component low current charging circuit; 30. Battery protection circuit. DETAILED DESCRIPTION

[0023] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0024] like Figure 1 and Figure 2 As shown, the first embodiment of the utility model proposes a practical circuit for charging a TWS charging bin with simple discrete components and small current, including a battery anti-reverse connection circuit 10, a discrete component small current charging circuit 20 and a battery protection circuit 30, wherein the battery anti-reverse connection circuit 10 is used for battery anti-reverse connection protection; the discrete component small current charging circuit 20 is connected to the battery anti-reverse connection circuit 10 to complete the TWS charging bin small current charging; the battery protection circuit 30 is connected to the battery anti-reverse connection circuit 10, and is used to activate the battery protection circuit 30 when the battery cell voltage is lower than the set voltage threshold, so that the battery enters a normal charging state. In this embodiment, the battery anti-reverse connection circuit 10, the discrete component small current charging circuit 20 and the battery protection circuit 30 can all adopt functional modules or circuits.

[0025] Further, see Figure 1 and Figure 2 The embodiment provides a simple discrete component low-current charging practical circuit for TWS charging bin. The battery reverse connection protection circuit 10 includes a PMOS transistor Q2, a first resistor R8, and a second resistor R9. The drain of the PMOS transistor Q2 is connected to the positive terminal B+ of the battery, and the gate of the PMOS transistor Q2 is connected to the negative terminal B- of the battery through the first resistor R8. The two ends of the second resistor R9 are respectively connected to the gate and source of the PMOS transistor Q2. In this embodiment, the model of the PMOS transistor is AO3401.

[0026] Preferably, see Figure 1 and Figure 2The present embodiment provides a simple discrete component low-current charging practical circuit for TWS charging bin, the discrete component low-current charging circuit 20 includes a USB-typec interface USB1TypeC, a third resistor R1, a fourth resistor R2, a fifth resistor R3, a sixth resistor R4, a seventh resistor R5, a diode D1, a first capacitor C1, a PNP transistor Q1 and an indicator LED1, the first pin of the USB-typec interface is grounded, the second pin of the USB-typec interface is connected to the power supply terminal CC2, and the third pin of the USB-typec interface is connected to the power supply terminal CC2. The pin is grounded through the third resistor R1, the fourth pin of the USB-typec interface is grounded through the fourth resistor R2, and the fifth pin of the USB-typec interface is divided into three paths. The first path is connected to the positive terminal B+ of the battery through the series-connected diode D1 and the fifth resistor R5, the second path is grounded through the first capacitor C1, and the third path is connected to the emitter of the PNP transistor Q1. The base of the PNP transistor Q1 is connected to the positive terminal of the battery through the sixth resistor R4, and the collector of the PNP transistor is grounded after passing through the series-connected seventh resistor R5 and the indicator LED1. The indicator LED1 is a red indicator. The model used by the PNP transistor is 8550. The diode D1 is a Schottky diode, and the model used is SS14.

[0027] Further, see Figure 1 and Figure 2 The embodiment provides a simple discrete component low current charging practical circuit for TWS charging bin, the battery protection circuit 30 includes a MOS chip U1 and a protection control chip U2 connected to the MOS chip U1. In the embodiment, the model of the MOS chip U1 is 8205S. The model of the protection control chip U2 is DW01.

[0028] like Figure 1 and Figure 2 As shown, the TWS charging bin simple discrete components low current charging practical circuit provided in this embodiment has the following working principle:

[0029] 1. Battery positive and negative pole anti-reverse connection circuit 10: It is composed of voltage-type crystal PMOS transistor; Q2 = AO3401; resistor R8 = 10K; and pull-up resistor R9 = 100K. When the positive and negative poles of the battery are not reversed, the full battery voltage +4.2V reaches the source (S pole) through the body diode of the PMOS tube (DS is not yet turned on), and the S pole voltage is +4.2V. At this time, Ugs = -4.2V, and R8 = 10K is connected in series through the gate (G pole) of the PMOS transistor to prevent the PMOS tube from breaking down. At the VG potential point, a negative voltage will be generated, which will turn on the PMOS tube (DS is turned on), the body diode will be shorted, and the current will flow from DS. After the PMOS tube is turned on, the internal resistance between DS is very small, and the voltage drop generated can be ignored, so the full battery voltage 4.2V is basically equal to 4.2V, and then connected to the battery protection circuit. Another situation: when the positive and negative poles of the battery are reversed, when +4.2V is reversed, the G pole is high level, Ugs>0, and the PMOS tube will not be turned on, thus protecting the subsequent circuit. This is beneficial to production line production and plays a fool-proof role.

[0030] When using a voltage-type crystal PMOS transistor in a battery positive and negative pole anti-reverse connection circuit, the following points should be noted:

[0031] ① Do not use polarity filtering circuits at the input end of the PMOS tube.

[0032] ② Connect a resistor R8 in series to the control G pole to ground to prevent the PMOS tube from breaking down.

[0033] ③ Choose the appropriate turn-on voltage Ugs(th) when selecting the PMOS tube.

[0034] ④ Pay attention to the direction of the body diode of the PMOS tube, that is, the direction of current. If the S pole input and D pole output are used, it cannot prevent reverse connection.

[0035] ⑤This circuit is generally suitable for low-voltage occasions. For 24V, a diode can be used to prevent reverse connection. The 0.7V voltage drop of the squid diode is relatively small compared to 24V.

[0036] 2. Discrete components low current charging circuit: USB-type c; charging identification resistor, R1=R2=5.1K, filter capacitor C1=10UF, Schottky diode D1=SS14, current limiting resistor (1206) R3=2.2R; current type PNP transistor Q1=8550, and corresponding base bias resistor R4=4.7K, red light indicator LED1; red light current limiting resistor R5=330Ω. The Schottky diode D1 is connected in series with the current limiting resistor R3, and the circuit can be normally conducted. In the DC circuit, the positive electrode of the power supply flows in the direction of the positive electrode of the Schottky diode D1, and the current can be conducted. At the same time, the resistors in the circuit are connected in series to divide the voltage and limit the current, thereby protecting the Schottky diode D1 and preventing the Schottky diode D1 from being broken down (or burned out due to large current). Using the unidirectional conductivity of the Schottky diode D1, the metal plate close to the PN junction will form a capacitor, and the two plates of the PN junction of the Schottky diode D1 will also form a junction capacitor, forming an RC loop with the current limiting resistor R3. The typeC charging terminal has a 5V output:

[0037] Function 1: Provide emitter bias voltage to PNP transistor 8550;

[0038] Function 2: Through Schottky diode D1=SS14; 5V-0.7V=4.3V voltage, through the current limiting resistor R3 and the Schottky diode D1 junction capacitor to form a charging circuit, added to the positive electrode of the battery, when the battery voltage rises from 3V to 4.2V, when the PNP transistor conduction condition is reached, the battery voltage VB+=Vb=+4.2V, Ve=5V, that is, Vbe=4.2V-5V=-0.7V<0, so the current type PNP transistor Q1 is turned on, VC=VE=5V, through the LED current limiting R5, the red light indicator LED1 to the ground, forming a loop, the red light is on, and when the battery is fully charged, the red light indicator LED1 is always on.

[0039] Note: Use Schottky diode D1 = SS14 and current limiting resistor (1206) R3 = 2.2R to form a charging circuit. Note the following points:

[0040] ①The battery voltage added to both ends of the battery should be controlled at 4.2V and try not to exceed 5V.

[0041] ②Use constant current charging, and try not to charge the battery more than 0.5 times of the battery capacity.

[0042] ③If there is no circuit to control the battery charging, the charging time should not exceed the formula in the following table: the maximum charging time (hours) = (battery capacity MAH / charging current MA) * 1.5.

[0043] 3. Battery protection circuit: It consists of MOS chip U1=8205S, protection control chip U2=DW01, resistors R7=1K, R6=1K.

[0044] illustrate:

[0045] The negative pole of the battery is connected to resistor R6 = 1K to prevent the battery cells with poor performance on the market from failing to activate the protection circuit and enter the charging state when the cell voltage drops to 0V. Through resistor R6 = 1K, the negative pole of the battery is connected to the ground, and the current on resistor R6 is used to activate the MOS chip, U1 = 8205S, thereby turning on the protection chip DW01, thereby entering the normal charging mode.

[0046] The utility model provides a TWS charging bin with simple discrete components and low current charging practical circuit, and the beneficial effects achieved are as follows:

[0047] 1. The positive and negative poles of the battery use MOS tubes to form an anti-reverse connection circuit.

[0048] 2. Completely discrete electronic components can complete low-current charging of the TWS charging case, greatly improving charging efficiency and reducing charging time.

[0049] 3. The circuit is simple, low cost and occupies little space.

[0050] 4. Reduced heat generation, more intelligent, optimized user experience, while ensuring charging safety.

[0051] 5. It has a wide range of applications and can be used in charging cases for various TWS earphones.

[0052] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A practical circuit for low-current charging of simple discrete components in a TWS charging bin, characterized in that: The invention comprises a battery reverse connection prevention circuit (10), a discrete component low current charging circuit (20) and a battery protection circuit (30), wherein: The battery reverse connection protection circuit (10) is used for battery reverse connection protection; The discrete component low-current charging circuit (20) is connected to the battery reverse connection protection circuit (10) and is used to complete the low-current charging of the TWS charging bin; The battery protection circuit (30) is connected to the battery reverse connection protection circuit (10) and is used to activate the battery protection circuit (30) when the battery cell voltage is lower than a set voltage threshold, so that the battery enters a normal charging state.

2. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 1, characterized in that: The battery reverse connection protection circuit (10) comprises a PMOS transistor, a first resistor and a second resistor, the drain of the PMOS transistor being connected to the positive terminal of the battery, the gate of the PMOS transistor being connected to the negative terminal of the battery via the first resistor, and the two ends of the second resistor being respectively connected to the gate and source of the PMOS transistor.

3. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 2, characterized in that: The model of the PMOS transistor is AO3401.

4. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 1, characterized in that: The discrete component low-current charging circuit (20) comprises a USB-typec interface, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a diode, a first capacitor, a PNP transistor and an indicator light, wherein the first pin of the USB-typec interface is grounded, the second pin of the USB-typec interface is connected to the power supply end, the third pin of the USB-typec interface is grounded through the third resistor, the fourth pin of the USB-typec interface is grounded through the fourth resistor, the fifth pin of the USB-typec interface is divided into three paths, the first path is connected to the positive terminal of the battery through a series-connected diode and the fifth resistor, the second path is grounded through the first capacitor, the third path is connected to the emitter of the PNP transistor, the base of the PNP transistor is connected to the positive terminal of the battery through the sixth resistor, and the collector of the PNP transistor is grounded through the series-connected seventh resistor and the indicator light.

5. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 4, characterized in that: The indicator light is a red indicator light.

6. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 4, characterized in that: The model of the PNP transistor is 8550.

7. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 4, characterized in that: The diode is a Schottky diode, model SS14.

8. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 1, characterized in that: The battery protection circuit (30) comprises a MOS chip and a protection control chip connected to the MOS chip.

9. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 8, characterized in that: The model of the MOS chip is 8205S.

10. The TWS charging compartment simple discrete component low current charging practical circuit as claimed in claim 8, characterized in that: The model of the protection control chip is DW01.

Images