TWI676334B - A device and a method of switches for charging and discharging lithium battery - Google Patents

Abstract

The invention provides a lithium battery charge-discharge switch device and a control method thereof. The device has a first end and a second end, and a series connection and a jumper of a charge switch and a discharge switch are connected between the first end and the second end. A current channel switch, the control method, when the lithium battery is overcharged, turning off the charging switch and controlling the current channel switch to pass a discharge current and prohibiting a charging current; and when the lithium battery is overdischarged, closing the discharge switch And control the current channel switch to pass the charging current and prohibit the discharging current.

Description

Lithium battery charge-discharge switch device and control method thereof

The invention relates to a battery protection device and method, in particular to a lithium battery charge-discharge switch device and a control method thereof having a low internal resistance effect in a charge-discharge path or a small area effect in integrated circuitization.

Electronic products are trending towards lighter weight, smaller size, and long-term use. Rechargeable batteries (secondary batteries) are widely used in electronic products. Among them, lithium batteries with high energy density and many times of charge and discharge are the most common. However, in order to meet the safety of charging and discharging lithium batteries with high energy density, lithium batteries must still be equipped with lithium battery protection devices to ensure that the charging and discharging process is safe.

For the safety of charge and discharge, please refer to the first figure, which shows the voltage change of the conventional lithium battery during the charge and discharge process. The lithium battery protection device includes at least three states to support a normal charge-discharge state 2, an over-charge protection state 1, and an over-discharge protection state 3. When the lithium battery protection device is operated in the normal charge and discharge state 2, the lithium battery can freely receive external power to charge or discharge external loads. If the lithium battery protection device detects that the battery voltage is higher than the set 4.3V, the lithium battery protection device performs the overcharge protection state 1 and cuts off the charging path or cuts off the charging current but retains the discharging path. The battery voltage can be reduced to the normal charging and discharging state 2; if the lithium battery protection device detects that the battery voltage has fallen below the set 2.5V, the lithium battery protection device performs the over-discharge protection state 3 and cuts off the discharge path or cuts the discharge Current but keeps the charging path, the battery is charged to make The battery voltage can rise back to the normal charging and discharging state2.

Please refer to the second figure for the circuit principle of the lithium battery protection device 100, which is a circuit diagram showing a conventional lithium battery protection device 100. The traditional lithium battery protection device 100 includes a lithium battery 13, a protection circuit 10, and a battery charge-discharge switching device composed of two MOSFETs 11, 12 connected in series. The protection circuit 10 is used to detect the battery voltage and output control signals OC and OD control. Battery charge / discharge switching devices MOSFETs 11, 12 are turned on or off, especially when MOSFETs 11, 12 are turned off, there are equivalent diodes 11a, 12a in different directions, so when one of the MOSFETs 11 or 12 is turned off , The equivalent diode 11a or 12a restricts the current to flow only in one direction, and achieves the protection function of overcharge protection state 1 or overdischarge protection state 3.

That is, when the lithium battery protection device 100 is in the normal charge and discharge state 2, when the battery charge and discharge switch devices MOSFETs 11 and 12 are on, the current can flow in both directions to ensure the charge and discharge of the lithium battery in the normal state; however, when When the protection circuit 10 detects that the battery voltage charge is higher than the set 4.3V and enters the overcharge state 1, the control signal OC is changed from a high potential to a low potential to turn off the MOSFET 12 to ensure the current of the lithium battery protection device 100 Only discharge from the positive terminal VBAT + of the lithium battery protection device 100 and cannot be charged; while the protection circuit 10 detects that the battery voltage has fallen below the set 2.5V and enters the overdischarge state 3, the control signal OD pin is changed from a high potential Turn to a low potential to turn off the MOSFET 11 to ensure that the current of the lithium battery protection device 100 can only flow from the positive terminal VBAT + of the lithium battery protection device 100 to charge and cannot be discharged.

Based on the prior art, under the normal charging and discharging state 2 of the conventional lithium battery protection device 100, the charging and discharging path has the internal resistance of the two MOSFETs of the battery charging and discharging switching device, resulting in additional energy loss. The current on-resistance and total power consumption of two commercial MOSFETs currently suitable for lithium battery supply and discharge switching devices, please refer to the following MOSFET specification table:

In addition, the actual total power consumption may increase due to process drift, actual wiring, and other factors. However, if an ultra-low on-resistance MOSFET is used, it will cost more. Therefore, the battery charge-discharge switching device of the conventional lithium battery protection device 100 has problems of cost efficiency and energy consumption in charge and discharge.

On the other hand, in the same process, if a MOSFET with lower on-resistance is to be manufactured, the circuit layout area must be increased to reduce the MOSFET's on-resistance. However, increasing the layout area will greatly increase the manufacturing cost of the MOSFET. In view of this, it is still not possible to provide a MOSFET suitable for a battery charge-discharge switching device of a lithium battery protection device 100 on the same process and at the same or lower manufacturing cost.

In order to solve the above technical problems, the purpose of the present invention is to provide a lithium battery charge-discharge switch device and a control method thereof, which are compatible with the traditional lithium battery protection status, and achieve the reduction of the equivalent resistance when the lithium battery protection device is turned on and the power consumption To enhance the effect of charge and discharge.

In addition, the lithium battery charge-discharge switch device of the present invention can reduce the equivalent resistance when the lithium battery protection device is turned on without reducing the area (manufacturing cost), and reduce the power consumption to improve the charging and discharging effect.

In addition, the lithium battery charge and discharge switch device and its control method also proposed by the present invention are compatible with the traditional lithium battery protection state, and achieve the reduction of the layout area of the MOSFET without increasing the equivalent resistance. Achieve the effect of reducing manufacturing costs.

In order to achieve the above object, the present invention provides a battery charge-discharge switch device, which is arranged on a charge-discharge path of a battery. The battery charge-discharge switch device has a first end and a second end, wherein the charge switch and the discharge switch are connected in series with each other. The first terminal and the second terminal are electrically connected in series with the charging switch and the discharge switch, and a current channel switch is electrically connected between the first terminal and the second terminal. In addition, when the charging switch is turned off, the current channel switch is used to pass a discharging current and prohibit a charging current from passing; when the discharging switch is turned off, the current channel switch is used to pass the charging current and prohibit the discharging current from passing.

In order to achieve the above object, the present invention further provides a battery charge-discharge switch device for charging and discharging control of a battery. The charge-discharge switch device has a first end and a second end, wherein the charge switch and the discharge switch are connected in series with each other. The first terminal and the second terminal are electrically connected in series with the charging switch and the discharge switch, and the first terminal and the second terminal are electrically connected with a current channel switch. In addition, when the charge switch is turned off, the current channel switch is used to allow a discharge current through the battery, while prohibiting a charge current through the battery; when the discharge switch is turned off, the current channel switch is used to allow the charging through the battery. Current, and the discharge current through the battery is prohibited.

The present invention further provides a battery charge-discharge switch device for controlling a battery voltage. The charge-discharge switch device has a first terminal and a second terminal, wherein a first switch and a second terminal are electrically connected between the first terminal and the second terminal. The discharge switch is connected in series, and a current channel switch is electrically connected between the first end and the second end. In addition, when the battery voltage exceeds a charging threshold, the current channel switch is used to allow the discharge current through the battery and prohibit the charging current through the battery; when the battery voltage is low At a discharge threshold, the current channel switch is used to allow the charging current to pass through the battery, while prohibiting the discharge current to pass through the battery.

The present invention further provides a battery charge-discharge switch device for charging and discharging control of a battery. The battery charge-discharge control device includes a charge control terminal for controlling a charge switch; a discharge control terminal for controlling a discharge switch; And a current channel control terminal for controlling the current channel switch, wherein the current channel switch is connected in parallel with the charge switch and the discharge switch in series. In addition, when the charge control terminal is used to control the charging switch to be turned off, the current channel control terminal is used to control the discharge current of the battery through the current channel switch, and the charging current of the battery is prohibited; when the discharge control terminal is used to control the discharge switch to be closed, the current The channel control terminal is used to control the charging current of the battery through the current channel switch, and the discharge current of the battery is prohibited.

The invention also provides a battery charge-discharge switching device, which is arranged in a battery charge-discharge path. The battery charge-discharge control device has a first end and a second end, wherein the first end and the second end are electrically connected to a charge. The switch is connected in series with a discharge switch, and a current channel switch is electrically connected between the first end and the second end. In addition, when the charge switch and / or the discharge switch are on and the current channel switch is on, a first current flowing through one of the current channel switches is greater than a second current flowing through one of the charge switches and / or discharge switches.

The present invention further provides a battery charge-discharge switch device for charging and discharging control of a battery. The charge-discharge switch device has a first end and a second end, wherein the first end and the second end are electrically connected and charged. The switch is connected in series with the discharge switch, and a current channel switch is electrically connected between the first end and the second end. In addition, when the charging switch, the discharging switch, and the current channel switch are on, the first current flowing through the current channel switch is greater than the second current flowing through the charging switch and / or the discharging switch; when the charging switch and / or the discharging switch are turned off, The current channel switch is closed.

The present invention further provides a battery charge-discharge switch device for controlling a battery voltage. The charge-discharge switch device has a first end and a second end, wherein the first end and the second end are electrically connected between the charge switch and the discharge switch. In series, a current channel switch is electrically connected between the first end and the second end. In addition, when the battery voltage is lower than a charging threshold, the current flowing through the current channel switch is larger than the current flowing through the charging switch; when the battery voltage is higher than a discharging threshold, the current flowing through the current channel switch is larger than Current of the discharge switch.

The present invention further provides a battery charge-discharge switch device for charging and discharging control of a battery. The battery charge-discharge control device includes a charge control terminal for controlling a charge switch; a discharge control terminal for controlling a discharge switch And a current channel control terminal for controlling a current channel switch, wherein the current channel switch is connected in parallel with the charging switch and the discharge switch in series. In addition, when the charge control terminal controls the charge switch to be turned on and / or the discharge control terminal controls the discharge switch to be turned on, and the current channel control terminal controls the current channel switch to be turned on, a first current flowing through the current channel switch is greater than A second current flows through one of the charging switch and / or the discharging switch.

The invention further provides a battery charge-discharge switch device, which is composed of a current channel switch, a charging switch and a discharge switch, wherein the conduction internal resistance of the current channel switch is smaller than the equivalent resistance of the charging switch and the discharge switch in series.

The invention further provides a battery charge-discharge switch device, which is composed of a current channel switch, a charge switch and a discharge switch, wherein the current channel switch is connected in parallel with the charge switch and the discharge switch in series, and the current channel switch integrated circuit The area of circuitization is larger than the circuitization area of the integrated circuit of the charge switch and the discharge switch.

The invention also provides a battery charge-discharge switch device, which is composed of a current channel switch, a charging switch and a discharge switch, and the current channel switch is connected in parallel to be opened. And a series connection of a discharge switch, the current channel switch is a first field-effect transistor and a gate arrangement of the first field-effect transistor is in a square shape, and the charging switch is a second field-effect transistor and the The discharge switch is a third field-effect transistor and a gate arrangement of the second and third field-effect transistors has a gold finger shape. A drain of the second and third field-effect transistors is electrically connected to each other.

The invention further proposes a battery charge-discharge switch device compatible with the protection status of the traditional lithium battery. The battery charge-discharge switch device is composed of a current channel switch, a charge switch and a discharge switch. The channel switch is a first field-effect transistor and a gate arrangement of the first field-effect transistor is gold finger-shaped, the charging switch is a second field-effect transistor and the discharge switch is a third field-effect transistor. The transistor and a gate arrangement of the second and third field-effect transistors are gold finger-shaped, and a drain of the second and third field-effect transistors is electrically connected to each other.

The foregoing aspects and other aspects of the present case will become more clear based on the detailed description of the following non-limiting specific embodiments and with reference to the accompanying drawings.

1‧‧‧ Overcharge protection status

2‧‧‧ Normal charge and discharge status

3‧‧‧ Overdischarge protection status

100, 200‧‧‧ lithium battery protection device

10, 2 0 ‧‧‧ protection circuit

11, 12, 21, 22, 24‧‧‧ MOSFET

13, 23‧‧‧ battery

11a, 12a, 21a, 22a ‧‧‧ equivalent diodes

O, OC, OD‧‧‧ control signals

CSI‧‧‧ Detection voltage terminal

VBAT + ‧‧‧ Positive end of lithium battery protection device

VBAT-‧‧‧ Negative terminal of lithium battery protection device

VDD‧‧‧ Positive terminal of battery

VSS‧‧‧ Negative terminal of battery

R, R _A , R _B ‧‧‧ On-resistance

Sources of S1, S2, S‧‧‧MOSFET

D1, D2, D‧‧‧MOSFET Drain

The first graph shows the voltage change of a conventional lithium battery during charging and discharging.

The second diagram is a conventional circuit diagram of a lithium battery protection device.

The third figure shows the circuit architecture of the lithium battery protection device of the present invention.

The fourth A diagram shows the total equivalent resistance of the conventional circuit architecture.

The fourth diagram B shows the total equivalent resistance of the MOSFET of the lithium battery protection device of the present invention.

The fifth figure is a schematic diagram showing the layout of a MOSFET of a lithium battery charge-discharge switching device according to the present invention.

The sixth diagram is a schematic diagram showing the layout of a MOSFET of another lithium battery charge-discharge switching device according to the present invention.

Please refer to the third figure, which shows the circuit architecture of the lithium battery protection device 200 according to the present invention. Compared with the conventional lithium battery protection device 100 (as shown in the second figure), the lithium battery protection device 200 provided by the present invention further includes The MOSFET 24 and the control signal O, and the lithium battery charge-discharge switching device of the present invention are composed of MOSFETs 21, 22, and 24. The negative terminal VSS of the battery 23 and the negative terminal VBAT- of the lithium battery protection device 200 are connected across the MOSFET 24. And two MOSFETs 21 and 22 connected in series, that is, the MOSFETs 21 and 22 connected in series are connected in parallel with the MOSFET 24, and the control signal O is used to control the MOSFET 24 to be turned on or off, and the control signals OD and OC are respectively used to control the MOSFET 21, 22 to be turned on Or off. Therefore, during normal charging and discharging, a current will flow through the MOSFETs 21, 22, and 24 at the same time to charge or discharge the battery 23.

The battery charge-discharge switch device of the present invention shown in the third figure has a first terminal, a second terminal, a charge control terminal, a discharge control terminal, and a current channel control terminal, wherein the first terminal is electrically connected to the negative terminal of the battery 23 The second terminal is electrically connected to the negative terminal VBAT- of the lithium battery protection device 200, the charging control terminal is electrically connected to the gate of the MOSFET 22, the discharge control terminal is electrically connected to the gate of the MOSFET 21, and the current channel control terminal is electrically The gate of the MOSFET 24 is connected. The charging control terminal, the discharging control terminal, and the current channel control terminal are electrically connected to the protection circuit 20 to receive the control signals OC, OD, and O, respectively.

The lithium battery protection device 200 of the present invention includes a protection circuit 20. In addition to outputting O, OC, and OD control signals, the protection circuit 20 controls the on or off of the MOSFETs 24, 22, and 21 of the battery charge and discharge switch, respectively, and further includes a CSI terminal, VBAT +, VBAT-, VDD, And the VSS terminal, where the CSI terminal is the detection voltage terminal; the VBAT + terminal is the positive terminal of the lithium battery protection device 200; the VBAT- terminal is the negative terminal of the lithium battery protection device 200; the VDD terminal is the positive terminal of the battery 23; and the VSS terminal is The negative terminal of the battery 23.

In one embodiment of the present invention, the MOSFETs 21, 22, and 24 of the battery charge-discharge switching device are completely the same as the MOSFETs 11, 12 of the conventional lithium battery protection device 100, and thus the MOSFETs 11, 12, 21, 22, and 24 are turned on. With the same resistance, the equivalent resistance of MOSFETs 11 and 12 in series will be greater than the equivalent resistance of MOSFET 24 and MOSFETs 21 and 22 in parallel. The equivalent resistance will affect the charging and discharging efficiency of the battery protection device. During the normal charging and discharging process of the battery protection device 200, the equivalent resistance of the charging and discharging switching device between the VSS terminal and the VBAT- terminal is small, and the purpose of improving the charging and discharging efficiency is achieved.

In addition, the substrates of the MOSFETs 21 and 22 are connected to the VSS terminal and the VBAT- terminal, respectively, and the substrates of the MOSFET 24 are floating. When the MOSFETs 21, 22, and 24 are turned on, current is allowed to flow from the VBAT- terminal to the VSS terminal or from the VSS terminal to the VBAT- terminal; however, when the MOSFETs 21, 22, and 24 are turned off, the MOSFET 21 generates an equivalent to the VBAT- terminal. The diode 21a allows the current to the VBAT- terminal to pass, and prohibits the current to the VSS terminal; the MOSFET 22 generates an equivalent diode 22a directed to the VSS terminal, so the current to the VSS terminal is allowed to pass, and the current to the VBAT- terminal is prohibited Pass; in particular, when the MOSFET 24 is turned off, an equivalent diode is not generated, and current in any direction is prohibited from flowing.

In addition, the MOSFET 21 can be used as a discharge switch, the MOSFET 22 can be used as a charge switch, and the MOSFET 24 can be used as a current channel switch. These three switches constitute the battery charge and discharge in the lithium battery protection device 200 The switching device can be adjusted to control the charge switch, discharge switch and current channel according to requirements, so as to be compatible with the traditional lithium battery protection status, such as: Overcharge protection status, overdischarge protection status.

Compared with the conventional battery charge-discharge switching device shown in the second figure, which is composed of MOSFETs 11 and 12, integrated circuitized MOSFETs 11 and 12 can be packaged separately or together. Similarly, the battery charge-discharge switching device of the present invention is composed of MOSFETs 21, 22, and 24. The integrated circuitized MOSFETs 21, 22, and 24 can also be packaged separately or together. In the conventional battery charge-discharge switch device and the battery charge-discharge switch device of the present invention, based on the same integrated circuit design process design, in one embodiment of the present invention, when the MOSFETs 11 and 12 increase the on-resistance R to When 10 times is used to realize MOSFETs 21 and 22, although the equivalent resistance of the MOSFETs 21 and 22 in series is 20R, the layout area of the integrated circuitized MOSFETs 21 and 22 is the same as that of the integrated circuitized MOSFETs 11 and 12. Can be one-tenth (1/10 WL). Therefore, compared with the conventional battery charge-discharge switch device, the battery charge-discharge switch device of the present invention will have an extra layout area to implement the integrated circuitized MOSFET 24.

<Example 1>

Please continue to refer to the third figure. The first embodiment of the present invention includes a settable overcharge voltage threshold and overdischarge voltage threshold, such as 4.3V and 2.5V. When the lithium battery protection device 200 is normally charged and discharged, the battery is charged. In the discharge switching device, the internal resistances of the MOSFETs 21, 22, and 24 are all equal and are normally on (that is, the control signals O, OC, and OD are all high potentials). Since the equivalent resistance of the MOSFETs 21 and 22 in series is greater than that of the MOSFET 24, and The current flowing through the current MOSFET 24 is made larger than the MOSFETs 21 and 22.

However, as a whole, because in the battery charge-discharge switching device of the present invention, the MOSFETs 21 and 22 are connected in series and in parallel with the MOSFET 24, the equivalent of the battery charge-discharge switching device The resistance will be smaller than the traditional two MOSFETs in series, in order to reduce the power consumption and improve the charging and discharging effect. In particular, the lithium battery protection device 200 can further adjust parameters such as the size of the MOSFETs 21, 22, and 24, so that the on-resistance of the MOSFET 24 is smaller than that of the MOSFETs 21 and 22. Therefore, during normal charge and discharge, the MOSFET 24 bears most of the charge The discharge current, that is, the current flowing through the MOSFETs 21, 22 is smaller than the current flowing through the MOSFET 24.

When the voltage of the battery 23 has exceeded 4.3V, the lithium battery protection device 200 enters an overcharge protection state, and the lithium battery protection device 200 will provide a discharge current path for the battery 23 instead of a charge current path for the battery 23. Therefore, the protection circuit 20 changes the MOSFETs 22 and 24 from the on state to the off state (that is, the output control signals OC and O change from a high potential to a low potential), because when the MOSFET 22 is turned off, an equivalent diode is pointed toward the VSS terminal. Therefore, the lithium battery protection device 200 still maintains a discharge current path flowing from the VBAT- terminal to the VSS terminal to discharge the battery 23. In addition, because the MOSFET 24 has no equivalent diode in structure, the MOSFET 24 is open when it is turned off, and Neither bidirectional current can flow, so no charging current path is created.

On the contrary, when the voltage of the battery 23 is lower than 2.5V, the lithium battery protection device 200 enters an over-discharge protection state. The lithium battery protection device 200 will provide a charging current path for the battery 23 instead of a discharging current path for the battery 23. Therefore, the protection circuit 20 changes the MOSFETs 21 and 24 from the on state to the off state (that is, the control signals OD and O change from a high potential to a low potential), because when the MOSFET 21 is turned off, an equivalent diode is pointed to the VBAT- terminal, so The lithium battery protection device 200 still maintains a charging current path flowing from the VSS terminal to the VBAT- terminal to provide charging of the battery 23, and the MOSFET 24 is disconnected when turned off, and bidirectional current cannot pass, so no discharge current path is generated.

The foregoing charge-discharge threshold is an estimated value, and the charge-discharge threshold can be adjusted according to demand. For example, if the delay time is increased and the charge threshold is reduced to 4.25V, the voltage on the battery 23 is substantially Turning off the MOSFET 24 above the charging threshold or below the discharging threshold does not depart from the scope of the present invention.

<Example 2>

Please continue to refer to the third figure. The second embodiment of the present invention is also proposed. In a normal charge-discharge protection state, the operations of the MOSFETs 21, 22, and 24 in the battery charge-discharge switching device can be the same as those in the first embodiment. To repeat.

When the voltage of the battery 23 is higher than 4.3V, the lithium battery protection device 200 enters an overcharge protection state. The battery charge-discharge switch device of the present invention will provide a discharge current path for the battery 23 instead of a charge current path for the battery 23. Therefore, the protection circuit 20 changes the MOSFETs 22 and 24 from the on-state to the off-state (and the control signals OC and O change from a high potential to a low potential), because the MOSFET 22 generates an equivalent diode to the VSS terminal when it is turned off. Only discharge is allowed in this case.

In particular, when the discharge current flows through the MOSFETs 21 and 22, a voltage across is generated, and then the voltage across VBAT- to VSS is detected through the CSI detection voltage terminal. The protection circuit 20 determines whether to turn on the MOSFET 24 (that is, the control signal O is at a low potential). To high potential) to accelerate the discharge of the lithium battery protection device 200.

Conversely, when the battery voltage is lower than 2.5V, the lithium battery protection device enters an overdischarge protection state, and the lithium battery protection device 200 will provide a charging current path for the battery 23 instead of a discharging current path for the battery 23. Therefore, the protection circuit 20 changes the MOSFETs 21 and 24 from the on state to the off state (and the control signals OD and O from high potential to low potential), because when the MOSFET 21 is turned off, an equivalent diode is pointed to the VBAT- terminal. Charging is allowed in this case.

In particular, when the charging current flows through the MOSFETs 21, 22 The voltage across VBAT- to VSS is detected through the CSI detection voltage terminal, and it is determined whether to turn on the MOSFET 24 (that is, the control signal O changes from a low potential to a high potential), so as to accelerate the charging of the lithium battery protection device 200.

Those of ordinary skill in the art can understand that other voltage or current detection mechanisms can be added to determine whether to accelerate the charge and discharge by turning on the MOSFET 24 under an overcharge or overdischarge protection state, without departing from the scope of the present invention. The vocabulary used herein is for description only, and does not limit the scope of the present invention. The functions, steps, and elements described in the description are not limited to a specific number. Those skilled in the art can understand one or more functions, steps, and elements. If the same or similar effects can be achieved, all belong to the scope of the present invention.

In an embodiment of the present invention, as shown in the third figure, the protection circuit 20 implements a control method for controlling a battery charge-discharge switching device, which is arranged in a charge-discharge path of a battery 23, The battery charge-discharge switching device has a first end and a second end, wherein a series connection of a charge switch MOSFET 22 and a discharge switch MOSFET 21 is electrically connected between the first end and the second end, and the first A current channel switch MOSFET 24 is also electrically connected between the terminal and the second terminal. The control method of the present invention includes: when the signal OC controls the charging switch to be turned off, using the signal O to control a discharge current of the current channel switch through the battery 23 and prohibiting a charge current through the battery 23; and when the signal OD controls the discharge When the switch is closed, the charging current of the current channel switch through the battery 23 is controlled by a signal O and the discharging current of the battery is prohibited.

In addition, the control method implemented by the protection circuit 20 further includes: detecting the voltage across VBAT- to VSS by the signal CSI, and when the battery voltage exceeds a charging threshold, controlling the current channel switch through a Discharge current and prohibit a charging current through the battery 23; and the signal CSI detects the voltage across VBAT- to VSS, when the battery voltage is lower than a discharge At the electrical threshold, the charging current of the current channel switch through the battery 23 is controlled with a signal O and the discharging current through the battery is prohibited. The polarity of the signal CSI indicates that the charging current or the discharging current is on the charging and discharging path. In other words, when detecting whether the battery voltage exceeds a charging threshold or falls below a discharging threshold, the polarity of the electrical signal CSI is used to indicate that the charging current or the discharging current is on the charging and discharging path.

Please refer to the fourth diagram A. The fourth diagram A shows the equivalent resistance of the traditional circuit architecture 100 in the second diagram. When the MOSFETs 11 and 12 in the battery charge-discharge switching device have the same channel width W and channel length L, The internal resistance values of the MOSFETs 11 and 12 are R, and the total equivalent resistance of the MOSFETs 11 and 12 in series is 2R. The total layout area of the MOSFET channels is twice the product of W and L.

Please refer to the fourth diagram B. The fourth diagram B shows the total equivalent resistance of the lithium battery protection device 200 in the third diagram. When the MOSFETs 21 and 22 have the same channel width W _B and channel length L _B , they are turned on. The internal resistance is R _B and the layout area is the product of W _B and L _B. When the channel width is W _A and the channel length is L _A , the on-resistance is R _A and the layout area is W _A Product of L _A.

Based on the current formula I _D of the MOSFET and the cross-voltage V _{DS of the} MOSFET, the relationship between the internal resistance R, the channel width W, and the channel length L can be further derived as follows:

Since the MOSFET layout area will be directly affected by the channel width W and channel length L, therefore further assumed that L _A and L _B is equal to L, and the ratio of W and W _A is A: 1, while the proportion of W and W _B of B: 1 That is, the ratio of W _A and W _B is B: A, and the ratio of R _A and R _B is 1 / B: 1 / A. We can obtain the total equivalent resistance value R _T and the total layout area S _{T of the} present invention. The following expressions:

Therefore, the calculation formulas (3) and (4) calculate the total equivalent resistance value R _T of the MOSFETs 21, 22, and 24 of the battery charge-discharge switching device in the lithium battery protection device 200, and the total layout area S _T to protect the lithium battery. The relationship between the total equivalent resistance value R and the total layout area S of the MOSFETs 11 and 12 of the battery charge-discharge switching device in the device 100.

Those skilled in the art can understand that compared with the MOSFETs 11 and 12 of the battery charge-discharge switching device in the conventional lithium battery protection device 100, the MOSFETs 21 and 22 of the battery charge-discharge switching device in the lithium battery protection device 200 of the present invention , 24 can further adjust A and B based on the expressions (3) and (4) to reduce the process area or improve the charge and discharge efficiency.

Therefore, in another embodiment of the present invention, the layout area of the battery charge-discharge switching devices MOSFETs 21, 22, and 24 is equal to the layout of the conventional battery charge-discharge switching devices MOSFETs 11, 12 in consideration of the benefits of charging and discharging energy consumption. Area, and MOSFETs 11 and 12 increase the on-resistance R by 10 times to realize MOSFETs 21 and 22. Although the equivalent resistance of MOSFETs 21 and 22 in series is 20R, it is achieved by 90% of the layout area of MOSFETs 11 and 12. The MOSFET 24 can obtain an on-resistance of 0.555R. Therefore, the battery charge-discharge switching device of the present invention adopts MOSFET 21, The structure of 22 in series and then in parallel with MOSFET 24, as shown in the third figure, enables the battery charge-discharge switching device of the present invention to significantly reduce the on-resistance on the charge-discharge path and reduce power consumption to improve the effect of charge-discharge.

<Example 3>

And based on (4), the present invention further proposes the calculation formula (3), without increasing the overall value of the equivalent resistance R _T is reduced, the total reduction in the layout area S _T to reduce production costs, so the following expression is obtained:

After calculating Expressions (5) and (6) simultaneously, the channel widths W _A and W _B and R _A and R _B of the MOSFETs 21, 22, and 24 of the battery charge-discharge switching device in the lithium battery protection device 200 can be obtained. The relationship is as follows:

B> 1 (8)

When A and B satisfy the relational expressions (7) and (8), the battery charge-discharge switching device in the lithium battery protection device 200 can maintain the total equivalent resistance R _T of the MOSFETs 21, 22, 24 to 2R, but reduce the MOSFETs 21, 22 The total layout area S _{T of} 24 is to achieve the purpose of reducing production costs.

In addition, although the third embodiment reduces the maximum current flow of the charge switch and the discharge switch in the battery charge-discharge switch device, in a normal charge-discharge state, the current path is additionally increased due to the increase of the current channel switch, which compensates for the decrease. Maximum current flow.

<Example 4>

Based on the above expressions (3) and (4), the present invention further proposes to reduce the total equivalent resistance value R _T to increase the charge and discharge efficiency without increasing the total layout area S _T , so the following expressions can be obtained:

By calculating expressions (9) and (10) simultaneously, the relationship between the channel widths W _A and W _B and R _A and R _B of the MOSFETs 21, 22, and 24 of the battery charge-discharge switching device in the lithium battery protection device 200 can be obtained. The formula is as follows:

When A and B satisfy the relational expressions (11) and (12), the total layout area S _T of the MOSFETs 21, 22, and 24 of the battery charge-discharge switching device in the lithium battery protection device 200 can be maintained to 2WL, but the battery charge-discharge switch is reduced. The total equivalent resistance R _T of the MOSFETs 21, 22, and 24 of the device achieves the purpose of reducing power consumption and improving charging and discharging efficiency.

In addition, under normal charge and discharge conditions, the total equivalent resistance R _{T of the} charge switch, the discharge switch, and the current channel switch is reduced, but the overall layout area is not increased to avoid increasing production costs. Therefore, to overcome the current charge-discharge switching device that faces the limitation of lowering the total equivalent resistance, it is bound to take the limitation of higher production costs, such as using a process with low on-resistance or a MOSFET design with a larger channel width.

In addition, in another embodiment of the present invention, considering the benefit of manufacturing cost, the on-resistance of the battery charge-discharge switch device of the present invention is equal to the on-resistance of the conventional battery charge-discharge switch device, and the MOSFETs 11 and 12 will turn on the internal resistance R It is increased to 10 times to realize MOSFETs 21 and 22. Although the equivalent resistance of MOSFETs 21 and 22 in series is 20R and the on-resistance of MOSFET 24 is about 2.222R, the series of MOSFETs 21 and 22 and then connected in parallel with MOSFET 24 etc. The effective resistance is equal to the equivalent resistance of the MOSFETs 11 and 12 in series, so the layout area of the MOSFET 24 is still much smaller than 90% of the layout area of the MOSFETs 11 and 12. Therefore, the layout area of the battery charge-discharge switching device of the present invention for realizing the integrated circuitization of the MOSFET 21, 22, 24 is still far smaller than the layout area of the conventional battery charge-discharge switching device integrated circuitization, so that the battery charge-discharge switching device of the present invention can Achieve lower manufacturing costs and gain the benefits of manufacturing costs.

<Example 5>

Based on the lithium battery protection device 200 in the third figure and the above formulas (3) and (4), the present invention further proposes a layout design structure that reduces the layout area of the battery charge-discharge switch device. The fifth diagram only shows the layout of the MOSFET of the battery charge-discharge switching device in the lithium battery protection device 200 according to the present invention, where S1 can be the source of MOSFET 21, S2 can be the source of MOSFET 22, and MOSFET 21 and The drain of 22 is DB, and the gates of MOSFETs 21 and 22 can be OD and OC, respectively, while the source, drain, and gate of MOSFET 24 are S, D, and O, respectively.

In particular, the MOSFETs 21, 22, and 24 are divided into several smaller MOSFETs in parallel. For example, a MOSFET with a channel width of 30um is divided into two MOSFETs with a channel width of 15um in parallel, and two parallel The effect of a 15um MOSFET approaches that of a 30um channel MOSFET.

In the fifth figure, the MOSFETs 21 and 22 are respectively divided into three MOSFETs, and the channel width is one-third of the original, and the inserts are arranged in parallel. In particular, in order to comply with the connection mode of MOSFETs 21 and 22 in series, the DBs of each of the split MOSFETs 21 and 22 are overlapped, and S1 and S2 are overlapped. Therefore, the gate configuration is sequentially from left to right for MOSFET 21, MOSFET 22, MOSFET 22, MOSFET 21, MOSFET 21, and MOSFET 22 (as shown in the fifth figure).

In addition, this layout method is also referred to as a gold finger layout method. The number of actual layout points is not limited to three, and the placement order is not limited to the fifth figure.

In order to make the layout more square, the MOSFETs 21, 22, and 24 can be divided into several MOSFETs of similar height, as shown in the fifth figure; or, the number of MOSFETs 24 can be divided into MOSFETs 21 and 22. Sum of the number of points to make the layout equal. Take the layout of MOSFETs 21 and 22 in Figure 5 as an example. MOSFET 24 can be split into six MOSFETs of similar height and connected in parallel with each other and placed on MOSFET 21. , 22, where the height of the gold finger layout is related to the channel width of the MOSFETs 21, 22, 24, and the width of the gold finger layout is related Total number of MOSFETs split for MOSFET 21, 22, 24.

<Example 6>

Based on the lithium battery protection device 200 in the third figure and the above-mentioned operation formulas (3) and (4), the present invention further proposes a layout design structure for reducing the layout area of the battery charge-discharge switch device. Please refer to the sixth figure for a schematic illustration. The layout diagram of the MOSFET of the battery charge-discharge switching device proposed by the invention, wherein the MOSFETs 21 and 22 of the battery charge-discharge switching device maintain the gold finger-shaped layout as in the fifth embodiment, and will not be repeated here.

In particular, the MOSFET 24 of the battery charge-discharge switching device is further arranged in a zigzag layout. The source, drain, and gate of the MOSFET 24 of the battery charge-discharge switching device are S, D, and O, respectively, and conform to the MOSFET. The structure must maintain the gate (O) on both sides of the drain (D) and the source (S), so the up, down, left and right directions of the drain (D) are the source (S); and vice versa. Such a layout can improve the symmetry of the MOSFET, reduce the integrated circuit and produce undesirable effects, and reduce the layout area.

In addition, the square shape is not limited to a square. In order to make the layout area square, the square shape and the gold finger shape layout are the same height or width, and the MOSFET 24 can be placed to the left or right of the MOSFETs 21 and 22 as appropriate. Above and below, the height of the gold finger layout is related to the channel width of the MOSFETs 21 and 22, and the width of the gold finger layout is related to the total number of MOSFETs split by the MOSFETs 21 and 22.

Those skilled in the art can understand that the present invention only exemplifies the gate layout of the MOSFET, and the layout diagram is not an actual layout diagram, so other layout details are not limited to the fifth and sixth diagrams.

Claims (32)

A battery charge-discharge switch device has a first end and a second end, wherein the first end and the second end are electrically connected in series with a charge switch and a discharge switch, and the first end and the A current channel switch is electrically connected between the second terminals; wherein when the charging switch is turned off, the current channel switch does not provide a charging current path; and when the discharging switch is turned off, the current channel switch does not provide a discharging current path. A battery charge-discharge switch device is used for charge-discharge control of a battery. The battery charge-discharge switch device has a first end and a second end, and the first end and the second end are electrically connected to a charge. A switch is connected in series with a discharge switch, and a current path switch is electrically connected between the first end and the second end; wherein when the charging switch is turned off, the current path switch does not provide a charging current path through the battery And wherein when the discharge switch is turned off, the current channel switch does not provide a discharge current path through the battery. The battery charge-discharge switch device according to any one of claims 1 to 2, wherein when the charge switch is turned off, the current channel switch provides the discharge current path; and when the discharge switch is turned off, the current channel switch This charging current path is provided. A battery charge-discharge switch device is used to control a battery voltage. The battery charge-discharge switch device includes an overcharge protection state and an overdischarge protection state, and has a first end and a second end, wherein the first end A series connection of a charging switch and a discharge switch is electrically connected to the second terminal, and a current channel switch is electrically connected between the first terminal and the second terminal. In the overcharge protection state, the The current channel switch does not provide a charging current path; and in the over-discharge protection state, the current channel switch does not provide a discharging current path. The battery charge-discharge switching device according to item 4 of the scope of patent application, wherein the current channel switch provides the charging current path during the overdischarge protection state; and the current channel switch provides the Discharge current path. The battery charge-discharge switch device according to item 4 of the scope of patent application, wherein when the battery voltage exceeds a charging threshold, the battery charge-discharge switch device enters the overcharge protection state; and when the battery voltage is lower than a discharge When the threshold value is reached, the battery charge-discharge switch device enters the over-discharge protection state. A battery charge-discharge switch device for charging and discharging control of a battery. The battery charge-discharge control device includes a charge control terminal for controlling a charge switch; a discharge control terminal for controlling a discharge switch; and a current A channel control terminal for controlling a current channel switch, wherein the current channel switch is connected in parallel with the charging switch and a discharge switch in series; wherein when the charging control terminal controls the charging switch to be turned off, the current channel control terminal controls the current channel switch A charging current path through the battery is not provided; and when the discharge control terminal controls the discharge switch to turn off, the current channel control terminal controls the current channel switch to not provide a discharge current path through the battery. The battery charge-discharge switching device according to item 7 of the scope of patent application, wherein when the charge control terminal controls the charge switch to turn off, the current channel control terminal controls the current channel switch to provide the discharge current path; and when the discharge When the control terminal controls the discharge switch to close, the current channel control terminal controls the current channel switch to provide the charging current path. A battery charge-discharge switch device is disposed in a charge-discharge path of a battery. The battery charge-discharge switch device has a first end and a second end, and the first end and the second end are electrically connected to a charge. A switch is connected in series with a discharge switch, and a current path switch is electrically connected between the first end and the second end. When the charging switch and / or the discharge switch are on and the current path switch is on, the current A first current flowing through one of the current channel switches is greater than a second current flowing through the charging switch and / or the discharging switch. A battery charge-discharge switch device is used for charge-discharge control of a battery. The battery charge-discharge switch device has a first end and a second end, and the first end and the second end are electrically connected to a charge. A switch is connected in series with a discharge switch, and a current path switch is electrically connected between the first end and the second end. When the charging switch, the discharge switch, and the current path switch are on, the current path flows through the current path. A first current of one of the switches is greater than a second current flowing through the charging switch and / or the discharging switch; and wherein when the charging switch and / or the discharging switch are turned off, the current channel switch is turned off. A battery charge-discharge switch device is used to control a battery voltage. The battery charge-discharge switch device includes an overcharge protection state and an overdischarge protection state, and has a first end and a second end, wherein the first end A series connection of a charging switch and a discharge switch is electrically connected to the second terminal, and a current channel switch is electrically connected between the first terminal and the second terminal; A first current of one of the current channel switches is greater than a second current of the charging switch; and the first current flowing through the current channel switch is greater than one of the second flowing through the discharge switch when it is not in an overdischarge protection state. Current. The battery charge-discharge switch device according to item 11 of the scope of patent application, wherein when the battery voltage exceeds a charging threshold, the battery charge-discharge switch device enters the overcharge protection state; and when the battery voltage is lower than When a discharge threshold is reached, the battery charge-discharge switch device enters the over-discharge protection state. A battery charge-discharge switch device for charging and discharging control of a battery. The battery charge-discharge control device includes a charge control terminal for controlling a charge switch; a discharge control terminal for controlling a discharge switch; and a current A channel control terminal for controlling a current channel switch, the current channel switch being connected in parallel with the charging switch and the discharging switch in series; wherein when the charging control terminal controls the charging switch to conduct and / or the discharge control terminal controls the discharging switch to conduct, And when the current channel control terminal controls the current channel switch to be turned on, a first current flowing through one of the current channel switches is greater than a second current flowing through the charging switch and / or the discharging switch. A battery charge-discharge switch device is composed of a current channel switch, a charge switch, and a discharge switch. The current channel switch is connected in parallel with the charge switch and the discharge switch in series, and the conduction internal resistance of the current channel switch is less than the charge switch. On-resistance in series with the discharge switch. A battery charge-discharge switch device is composed of a current channel switch, a charge switch and a discharge switch, wherein the current channel switch is connected in parallel with the charge switch and the discharge switch in series, and the area of the current channel switch integrated circuit is larger than the series The area where the charging switch and the discharging switch are integrated. The battery charge-discharge switch device according to any one of claims 1 to 2, 4, 7, 9 to 11, and 13 to 15, wherein the charge switch, the discharge switch, and the current channel switch are field effect transistors. The drain of the charging switch is connected to the drain of the discharging switch, the base of the charging switch is connected to the source, the base of the discharging switch is connected to the source, and the base of the current channel switch is floating. The battery charge-discharge switch device according to any one of claims 1 to 2, 4, 7, 9 to 11, and 13 to 15, wherein the channel width of the charge switch and the discharge switch are the same, and the current channel switch The ratio of the channel width to the channel width of the charging switch is B: A, and the following relationship is satisfied: ; And B> 1. The battery charge-discharge switch device according to any one of claims 1 to 2, 4, 7, 9 to 11, and 13 to 15, wherein the channel width of the charge switch and the discharge switch are the same, and the current channel switch The ratio of the channel width to the channel width of the charging switch is B: A, and the following relationship is satisfied: ; And B> 1. The battery charge-discharge switch device according to any one of claims 1 to 2, 4, 7, 9 to 11, and 13 to 15, wherein the charge switch and the discharge switch have the same on-resistance internal resistance and the current The ratio of the on-resistance of the channel switch to the on-resistance of the charging switch is 1 / B: 1 / A, and the following relationship is satisfied: ; And B> 1. The battery charge-discharge switch device according to any one of claims 1 to 2, 4, 7, 9 to 11, and 13 to 15, wherein the on-resistance of the charge switch and the discharge switch are the same, and the current channel The ratio of the on-resistance of the switch to the on-resistance of the charging switch is 1 / B: 1 / A, and the following relationship is satisfied: ; And B> 1. A battery charge-discharge switch device is composed of a current channel switch, a charge switch and a discharge switch. The current channel switch is connected in parallel with the charge switch and the discharge switch in series. The current channel switch has a first field effect. A transistor and a gate arrangement of the first field-effect transistor has a gold finger shape, the charging switch is a second field-effect transistor and the discharge switch is a third field-effect transistor, and the second and first A gate arrangement of the three field-effect transistors has a gold finger shape, and a drain of the second and third field-effect transistors is electrically connected to each other. The battery charge-discharge switching device according to item 21 of the scope of application, wherein the first, second, and third field-effect transistors can be split into several field-effect transistors with similar channel widths. The battery charge-discharge switching device according to item 21 of the patent application, wherein the first field-effect transistor can be split into several field-effect transistors with similar channel widths, and the second and third field-effect transistors are The crystal is split into several field effect transistors with similar channel widths, and the number of field effect transistor split groups of the current channel switch is the sum of the number of field effect transistor splits in the charge switch and the discharge switch . A battery charge-discharge switch device is composed of a current channel switch, a charge switch and a discharge switch. The current channel switch is connected in parallel with the charge switch and the discharge switch in series. The current channel switch has a first field effect. A transistor and a gate arrangement of the first field-effect transistor is in a zigzag shape, and the charging switch is a second field-effect transistor and the discharge switch is a third field-effect transistor and the second and third fields are A gate arrangement of the effect transistor has a gold finger shape, and a drain of the second and third field effect transistors is electrically connected to each other. The battery charge-discharge switching device according to item 24 of the scope of patent application, wherein the total height of the second and third field-effect transistors in a gold finger layout is similar to the total height of the first field-effect transistors in a square-shaped layout. height. The battery charge-discharge switching device according to item 24 of the scope of patent application, wherein the total width of the second and third field-effect transistors in a gold finger layout is similar to the total width of the first field-effect transistor in a square shape. width. A control method for controlling a battery charge-discharge switch device. The battery charge-discharge switch device is configured in a battery charge-discharge path. The battery charge-discharge switch device has a first end and a second end. A series connection of a charging switch and a discharge switch is electrically connected between the first terminal and the second terminal, and a current channel switch is electrically connected between the first terminal and the second terminal. The control method includes: when controlling the charging When the switch is closed, controlling the current channel switch does not provide a charging current path through the battery; and when controlling the discharge switch to be closed, controlling the current channel switch does not provide a discharge current path through the battery. The control method as described in claim 27, wherein when the charge switch is controlled to be turned off, the current channel switch provides the discharge current path; and when the discharge switch is controlled to be turned off, the current channel switch provides the charging current path. A control method for controlling a battery charge-discharge switch device which controls a battery voltage. The battery charge-discharge switch device includes an overcharge protection state and an overdischarge protection state, and has a first terminal. And a second terminal, wherein the first terminal and the second terminal are electrically connected in series with a charging switch and a discharge switch, and a current channel switch is electrically connected between the first terminal and the second terminal. The control method includes: controlling the current channel switch to not provide a charging current path during the overcharge protection state; and controlling the current channel switch not to provide the discharge current path during the overdischarge protection state. The control method as described in claim 29, wherein in the overcharge protection state, controlling the current channel switch to provide the discharge current path; and in the overdischarge protection state, the current channel switch provides the charging Current path. The control method according to item 29 of the scope of patent application, wherein when detecting that the battery voltage exceeds a charging threshold, controlling the battery charge-discharge switch device to enter the overcharge protection state; and wherein detecting that the battery voltage is lower than one When the discharge threshold is reached, the battery charge-discharge switching device is controlled to enter the over-discharge protection state. The control method according to item 29 of the scope of patent application, wherein in the over-discharge protection state or in the over-discharge protection state, the polarity of the electrical signal of the voltage across the first terminal and the second terminal is used for Represents the charging current or the discharging current.