WO2022006697A1

WO2022006697A1 - Deep sleep circuit design for tws

Info

Publication number: WO2022006697A1
Application number: PCT/CN2020/100393
Authority: WO
Inventors: Tieyi LIANG; Zhi Chen
Original assignee: Harman International Industries, Incorporated
Priority date: 2020-07-06
Filing date: 2020-07-06
Publication date: 2022-01-13
Also published as: CN115836454A

Abstract

An earbud for TWS headphone with deep sleep mode is provided. The earbud comprises a shipping mode circuit that works to set the earbud into the deep sleep mode at the factory setting. The power consumption set in the factory of the earbuds is reduced, which greatly improves the transportation and storage time.

Description

DEEP SLEEP CIRCUIT DESIGN FOR TWS

TECHNICAL FIELD

The present invention relates generally to TWS headphone technology. More particularly, the present invention relates to TWS earbuds with deep sleep mode and a method for the TWS earbuds entering the deep sleep mode in its factory setting.

BACKGROUND

The latest trend in wireless headphones is True Wireless Stereo (TWS) system, which usually comprises one or two independent earbuds and a charging case for charging the earbuds.

In the current TWS market, now the industrial design of the earbuds is getting smaller and smaller with more and more functions, so the size and capacity of the battery is getting smaller. However, it is difficult to optimize the power-off current of the whole system of the TWS earbuds to be reduced, which means the TWS headphone during its shipping period from factory to sale to users may slowly consume their battery power, and thus the limited capacity of the earbuds battery will issue a risk of short transportation and storage time after delivery.

Therefore, in order to extend the time of TWS transportation and storage time during its shipment, there may be a need to design TWS earbuds with the shipping mode circuit for remain the earbuds into the deep sleep mode under the shipping condition. It is necessary to set the earbuds to deep sleep mode in the factory setting so as to realize the ultra-low power consumption of earbuds under transportation and storage conditions.

SUMMARY OF THE INVENTION

The present invention overcomes some of the drawbacks by providing an earbud with deep sleep mode for TWS headphone, which comprises an earbuds system and a battery protection IC. The earbuds system comprises a Bluetooth earbud system and a battery supplying power thereto. The earbud further comprises a shipping mode circuit which is connected between the earbuds system and the battery protection IC, and the shipping mode circuit is enabled to set the earbud into the deep sleep mode at factory setting.

A method for an earbud of TWS headphone entering in the deep sleep mode is also provided herein. The method comprising the following steps of: connecting the shipping mode circuit between the earbuds system and the battery protection IC in the earbud, and causing the shipping mode circuit work to set the earbud into the deep sleep mode at factory setting.

In the present invention, the battery protection IC is equipped with an input pin VDD which is connected to the battery. The battery protection IC usually works either in an operation mode or in a power-down mode. When the battery protection IC receives the input voltage above a protection voltage on its input pin VDD, it works in the operation mode. In this case, an output pin VM of the battery protection IC is grounded and an output pin EPAD is disconnected, and the battery continuously supplies power to the Bluetooth earbud system.

When the battery protection IC obtains the input voltage on its input pin VDD which is below the protection voltage, the battery protection IC enters the power-down mode. In this case, the battery protection IC disconnects the battery from the Bluetooth IC and other power consumption parts in the Bluetooth earbud system.

In the present invention, the shipping mode circuit comprises a NMOS transistor. The drain of the NMOS transistor is grounded. The drain of the NMOS transistor is connected between the input pin VDD of the battery protection IC and the battery after connecting a partial-voltage resistor in series. According to the principle of the NMOS transistor, it is turned on by obtaining a high voltage value on its gate, which can be given by a control signal when the earbud is powered up at the factory setting in the invention.

After the NMOS transistor is turned on at the factory setting, because the battery voltage is divided by the partial-voltage resistor of the shipping mode circuit, the input voltage obtained by the battery protection IC on its input pin VDD is pulled down below the protection voltage of the battery protection IC, the battery protection IC enters the power-down mode. Then the earbud enters and remains in the deep sleep mode during the whole shipping period, all other power consumption parts are disconnected and the power consumption set in the factory is reduced, which can greatly improve the transportation and storage time.

Once the earbud is put into a charging case for charging the battery, the earbud returns to a normal mode from the deep sleep mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings. In the figures, like reference numeral designates corresponding parts, wherein:

Figure 1 is block diagram illustrating both the power and control signal transmission in the TWS system according to the invention.

Figure 2 is a schematic circuit diagram illustrating the circuit layout in an earbud of the TWS system according to the invention.

Figure 3 is a flowchart illustrating a method for the earbud of TWS system entering the deep sleep mode at factory setting according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description of the embodiments of the present invention is disclosed hereinafter; however, it is understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

Referring to Figure 1, the block diagram illustrating both the power and control signal transmission in the TWS system according to the invention is shown. As to the power signal transmission, it can be seen in Figure 1 that a battery is arranged in each of the earbuds of the TWS headphone system, which can be such as a lithium battery, a compact battery or battery pack. In each earbud, usually the battery is under the protection of the battery protection IC and supplies power to the Bluetooth earbud system to maintain the power consumption of the Bluetooth IC and other power consumption parts in the earbud. That words, after the TWS headphone is delivered out of the factory, the battery in the earbud can continuously supply power to the Bluetooth earbud system under the protection of the battery protection IC.

On the other hand, the battery in the earbud can be charged by attaching the earbud to a charging case. In this case, the charging IC in the charging case receives the charging case power supply voltage of for example 5V, and transfers the power signal to the battery in the earbud through the battery protection IC.

As to the control signal transmission, still referring to Figure 1, there are control signals transmitted between the charging IC and the Bluetooth earbud system in usage.

In an embodiment of the invention, the earbud further comprises a shipping mode setting to set the earbud into the deep sleep mode at the factory setting. the shipping mode setting may receives a specific point_A control signal from the factory settings, and then gives a point_B power signal to the battery protection IC to cause the battery protection IC enter power-down mode. The corresponding operation will be further explained with reference to Figure 2.

Figure 2 shows the schematic circuit diagram illustrating the circuit layout in the earbud of the TWS system according to the invention. As shown in Figure 2, the earbuds system represents the locations of the Bluetooth earbud system and the battery in the circuit. The battery provides a battery voltage and supplies power to the Bluetooth earbud system. Pin 1 of the battery protection chip U1 is an input pin VDD and is connected to the battery through a resistor R12 which may function as a fuse of the battery protection chip U1. When the battery protection chip U1 receives a battery voltage of for example 3.9V (in the factory setting as 70%of the full battery voltage) , it works in an operation mode, where the battery is used to supply power to the Bluetooth earbud system. Pin 4 used as an output pin VM of the battery protection chip U1 is grounded. At this time, the output pin VM of the battery protection chip U1 forms the ground protection of the battery.

As mentioned previously, there is a shipping mode setting added in each earbud in order to reduce the power consumption of the earbud during the transportation and storage after delivery. The shipping mode setting is realized through a shipping mode circuit, which is connected between the earbuds system and the battery protection IC. Referring to Figure 2, the shipping mode circuit includes a NMOS transistor Q2. The source of the transistor Q2 is grounded, the drain of the transistor Q2 is connected in series to a resistor R19 and then connected between the battery and the input VDD port of the battery protection IC at the point labelled as Point_B in Figure 2. According to the working principle of NMOS transistor, Q2 is turned on when its gate is loaded with a positive voltage, which herein can be provided by sending the Point_A control signal with a high voltage value to Point_A, and the prositive voltage reaches the gate of the NMOS transistor Q2 by passing through a resistor R20 as well as a RC filter composed of a resistor R7 and a capacitor C22. As shown in Figure 2, the resistance value of the resistor R20 is 330K Ohm, the resistor R7 is of 1M Ohm, and the capacitance value of the capacitor C22 is 2.2 uF, respectively.

In the factory setting, when the earbud of headset is powered up, the Point_A control signal is sent to give the positive voltage value to Point_A of the shipping mode circuit, the transistor Q2 is turned on, and then the shipping mode circuit works. The battery voltage is divided by the partial-voltage resistors R12 and R19, respectively, and thus the voltage of Point_B is pulled down to below the protection voltage of the battery protection IC U1. In a way of example, the protection voltage of the battery protection IC U1 can be set to 2.8V. The Point_B voltage below 2.8V received at the input pin VDD triggers the battery protection IC U1 to enter the power-down mode. In this power-down mode, the battery protection IC U1 changes its output port from Pin 4 VM to Pin 5 labelled as EPAD, the battery protection IC U1 cuts off the power supply from the battery to the Bluetooth earbud system, and the whole earbuds system is shut down. In Figure 2, there is also a filter capacitor with the capacitance value of 100NF connected across Pin 1 VDD and Pin 5 EPAD in the earbud circuit, and the battery protection IC U1 further comprises Pin 2 labelled as G2 and Pin 3 labelled as G3 that both are not used herein.

As can be seen from Figure 2, the earbud circuit further leads out a charging connector comprising a pair of positive pole B+ and negative pole B-, respectively. When the earbud is put into the charging case, the connector attaches to the charging IC for receiving the output of charging IC from the charging case. In the earbud circuit, the positive pole B+ is connected to the battery after in series connecting with an inductor L7 with inductance of 100MHz for example, and the negative pole B-is connected to the output pin EPAD (Pin 5) of the battery protection IC U1. The pair of positive and negative poles B+ and B-each further connects with grounded static protectors ESD 11 and ESD 12, respectively, and an ESD filtering capacitor C25 with capacitance value of for example 18PF is connected across therebetween.

Once the earbud is attached to the charging case, the output of charging IC is the power supply voltage such as in range of 4.2～4.4V, and thus the voltage on the positive pole B+ of the connector is over the Point_B voltage, i.e., the voltage on the input pin VDD now is above the protection voltage of 2.8V. The battery protection IC U1 returns to the operation mode, and the earbud exits the Deep sleep mode (i.e., the shipping mode) and returns to the normal mode.

Figure 3 shows a flowchart illustrating a method for the earbud of TWS system to enter the deep sleep mode at the factory setting according to the invention. The method starts and performs the following steps. At step 301, in the factory setting, the earbud of TWS headset is powered up. The factory setting gives a high voltage value in a Point_A control signal sending to Point_A of the shipping mode circuit at step 302. The positive high voltage passing through the RC filter composed of R7 and C22 to the NMOS Q2, the NMOS Q2 is turned on, and the shipping mode circuit works at step 303, the battery voltage is divided by partial resistors R12 and R19 of the shipping mode circuit, and thus the voltage obtained on the input pin VDD is pulled down at Point_B below the protection voltage of the battery protection IC. Then at step 304, The battery protection IC from the operation mode enters the power-down mode, and the whole system is shut down during the transportation and storage time after delivery. At last step 305, when attaching the earbud into the charging case, the earbuds exits the deep sleep mode and returns to normal mode.

In an example, the earbud battery capacity at the factory setting is usually set to be at least 70%of the total battery capacity. For example, the shipment capacity of battery pack is about 15.4 mAh if the earbud is arranged with the battery with the full battery capacity of 22 mAh, and the 70%battery voltage in such shipping condition is about 3.9V.

As the battery power is slowly consumed, the battery voltage is reduced. In the traditional earbud without setting the shipping mode circuit, the earbud is in normal mode. During the transportation and storage after the factory delivery with the battery voltage drops from 3.9V to 3.0V, there are three parts of power-consuming components in the earbud system that consume the battery power, including: the Bluetooth earbud system consuming device dark current of about 2.2 uA, the cell self-discharge consuming about 0.86uA (representative value at ambient temperature of 23℃) , and the protection battery IC circuit in operation mode consuming current about 2uA. Thus, in such conditions, the transportation and storage period are about 126.92 days, for example.

When the battery voltage drops to less than a device cut off voltage of about 3.0V, the earbud cannot be turned on and the dark current of the Bluetooth earbud system tends to be zero. The battery capacity is about 0.11 mAh during the battery voltage in range of 3V to 2.8V, the power-consumptions in the earbuds system includes the cell self-discharge consuming about 0.02uA (representative value at ambient temperature of 23℃) and the protection battery circuit of about 2uA. Thus, in such conditions, the transportation and storage period are about 2.27 days, in this example.

In the example, the protection voltage of the battery protection IC is set to 2.8V. Correspondingly, when the battery voltage drops to below 2.8V, the battery protection IC performs the protection function to cut off the battery power supply, the device dark current in the Bluetooth earbud system is 0. During the battery voltage in range of 2.8V to 2V, the battery capacity is about 0.17 mAh, and the power-consumptions in the earbuds system comprise the cell self-discharge consuming current of about 0.03uA (representative value at ambient temperature of 23℃) and the protection battery circuit performing protection consuming current of about 0.10uA. Thus, in such conditions, the transportation and storage period are about 54.71 days, in this example.

Therefore, in the traditional earbuds without setting the shipping mode circuit, the total transportation and storage period after the factory delivery is about 126.92 + 2.27 + 54.71 =183.90 days. It can be seen that the battery voltage drops to 2V and below if the earbuds are not put in usage in about 184 days after out of the factory, and then the earbuds can be neither turned on nor recharged.

In contrast, in a way of example, setting the initial shipment condition to be the same as the previous example, i.e., the shipment capacity of battery pack is about 15.4 mAh of at least 70%of the total battery capacity 22 mAh, and the 70%battery voltage in the shipping condition is about 3.9V. In the earbud after adding the shipping mode circuit, because the shipping mode circuit has been working since the earbuds were delivered out of the factory, the battery protection IC enters the power-down mode and functions the protection of battery, so the current consumption of the battery protection circuit IC is always 0.1 uA, and the earbuds system is shut down without the dark current consumption. Therefore, during the whole valid transportation and storage period with the battery voltage in range of 3.9V to 2V, the device dark current by the Bluetooth earbud system is always 0, and the current consumption of the protection battery IC is about 0.1uA. The cell self discharge of the battery is determined by the natural of the battery itself, so the power consumption situation of this part is always as usual condition without affecting by the reduction of the battery voltage. Thus, in such conditions, the transportation and storage period can be extend to 671.51 days during the battery voltage in range of 3.9V～ 3 V, 39.41 days with the battery voltage of 3V～2.8V, and 54.71 days with the battery voltage of 2.8V～ 2V, respectively, in this example. Therefore, in the earbuds with adding the shipping mode circuit provided by the present invention, the total transportation and storage period after the factory delivery can be extended to about 671.51 + 39.14 + 54.71 = 765.36 days.

Corresponding to the examples raised above, Table 1 below shows the earbuds power consumption status without setting the sleep mode circuit of the invention, and Table 2 below shows the earbuds power consumption status with setting the sleep mode circuit under the same shipment conditions.

Table 1. No shipping mode circuit in earbuds

Table 2. After adding shipping mode circuit in earbuds to deep sleep mode

In summary, at the factory setting, the power consumption differences between the earbuds with the shipping mode circuit and without the shipping mode circuit is in that:

Table 3. differences between earbuds with and without shipping mode circuit

Therefore, after the shipping mode circuit is added, all other unnecessary power consumption parts are disconnected, and the power consumption set in the factory is reduced by at least 4uA, which can greatly improve the transportation and storage time.

As used in this application, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is stated. Furthermore, references to “one embodiment” or “one example” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. The terms “first, ” “second, ” and “third, ” etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.

Claims

A earbud with deep sleep mode for TWS headphone, comprising:

a Bluetooth earbud system;

a battery for providing a battery voltage; and

a battery protection IC;

wherein the earbud further comprises a shipping mode circuit connected between the earbuds system and the battery protection IC, and the shipping mode circuit is enabled to set the earbud into the deep sleep mode at factory setting.
The earbud of claim 1, wherein the shipping mode circuit comprises a NMOS transistor, and the drain of the NMOS transistor is connected between an input pin VDD of the battery protection IC and the battery after connecting a partial-voltage resistor in series.
The earbud of claim 1, wherein the NMOS transistor is on by obtaining a high voltage value on its gate, which is given by a control signal when the earbud is powered up at the factory setting.
The earbud of claim 1, wherein the battery protection IC is either in an operation mode or in a power-down mode.
The earbud of claim 4, wherein the battery supplies power to the Bluetooth earbud system when the battery protection IC is in the operation mode.
The earbud of claim 4, wherein the battery protection IC obtains an input voltage on the input pin VDD, and the battery protection IC enters the power-down mode from the operation mode when the input voltage is below a protection voltage.
The earbud of claim 5, wherein the battery protection IC further comprises an output pin VM and an output pin EPAD, wherein the output pin VM is grounded and the output pin EPAD is disconnected when the battery protection IC is in the operation mode, and wherein the output pin VM is grounded and the output pin EPAD is disconnected when the battery protection IC is in the operation mode.
The earbuds of claim 4, wherein the battery protection IC disconnects the battery from the Bluetooth earbud system and other power consumption parts when the battery protection IC is in the power-down mode.
The earbud of claim 1, wherein the earbud returns to a normal mode from the deep sleep mode once the earbud is put into a charging case for charging the battery.
The earbud of claim 1, wherein the number of the earbud included in the TWS headphone can be one or two.
A method for an earbud of TWS headphone entering in deep sleep mode, comprising:

connecting a shipping mode circuit between an earbuds system and a battery protection IC in the earbud; and

causing the shipping mode circuit work to set the earbud into a deep sleep mode at factory setting.
The method of claim 11, wherein the shipping mode circuit comprises a NMOS transistor, and connecting a shipping mode circuit comprises connecting the drain of the NMOS transistor between an input pin VDD of the battery protection IC and the battery after connecting a partial-voltage resistor in series.
The method of claim 11, wherein causing the shipping mode circuit work comprises obtaining a high voltage value on the gate of the NMOS transistor, which is given by a control signal when the earbud is powered up at the factory setting.
The method of claim 11, wherein the battery protection IC is either in an operation mode or in a power-down mode.
The method of claim 14, wherein the battery supplies power to the Bluetooth earbud system when the battery protection IC is in the operation mode.
The method of claim 14, wherein the battery protection IC obtains an input voltage on the input pin VDD, and the battery protection IC enters the power-down mode from the operation mode when the input voltage is below a protection voltage.
The method of claim 15, wherein the battery protection IC further comprises an output pin VM and an output pin EPAD, wherein the output pin VM is grounded and the output pin EPAD is disconnected when the battery protection IC is in the operation mode, and wherein the output pin VM is grounded and the output pin EPAD is disconnected when the battery protection IC is in the operation mode.
The method of claim 14, wherein the battery protection IC disconnects the battery from the Bluetooth earbud system and other power consumption parts when the battery protection IC is in the power-down mode.
The method of claim 11, wherein the earbud returns to a normal mode from the deep sleep mode once the earbud is put into a charging case for charging the battery.
The method of claim 11, wherein the number of the earbud included in the TWS headphone can be one or two.