A charge management circuit for over-discharged lithium batteries

Abstract

The utility model discloses a kind of over-discharge lithium battery's charge management circuit, including charging integrated circuit, with the electric quantity meter of lithium battery electric connection, the output end of charging integrated circuit is electrically connected lithium battery and system mainboard, further include an auxiliary MCU, auxiliary MCU is electrically connected by a voltage stabilizer and adapter, the system mainboard includes main control chip, the high level start pin of one GPIO port of auxiliary MCU and main control chip is connected, the I2C bus of auxiliary MCU is connected after the always-on end of double-channel analog switch with electric quantity meter, auxiliary MCU is connected with the control end of double-channel analog switch, the I2C bus of main control chip is connected after the always-closed end of double-channel analog switch with electric quantity meter, the auxiliary MCU is configured as output switch switching level signal to double-channel analog switch, the I2C bus of control electric quantity meter and auxiliary MCU or main control chip exclusive connection switch, according to the switch of system mainboard of lithium battery current voltage control.

Description

Technical Field

[0001] This utility model relates to the field of battery charging technology, and in particular to a charging management circuit for an over-discharged lithium battery. Background Technology

[0002] Although electronic devices have an automatic shutdown function when the battery is low to prevent over-discharge, the static power consumption of the device will still gradually deplete the lithium battery even when the device is off. Over time, the lithium battery will be completely depleted and enter the over-discharge protection state, at which point the lithium battery will have no output and the voltage value will be zero.

[0003] Currently, charging integrated circuits without path management functions are widely used because they are easy to operate and low in cost. For example... Figure 1 As shown, a charging IC (charging integrated circuit) without path management is used. The maximum constant current charging current is 4A, which we set to 3.2A (leaving some margin). Generally, trickle charging is 1 / 10 of the constant current charging current (i.e., trickle charging current is 320mA). However, our load (system motherboard) requires 350mA for normal startup, exceeding the trickle charging current. Assuming the battery is over-discharged, due to over-discharge protection, there is no voltage output. When the adapter is plugged in, the charging IC detects that the lithium battery voltage is lower than the trickle charging voltage, and the charging IC will output 320mA trickle charging current to charge the lithium battery. However, the existing load (system motherboard) configuration requires immediate startup upon plugging in the adapter to display the charging status to the user. At this time, the current Ic flows to the load, powering the system motherboard, and the lithium battery charging path Icharger receives no current, resulting in the battery's charge remaining almost unchanged for an extended period, failing to charge. Utility Model Content

[0004] The purpose of this invention is to provide a charging management circuit for over-discharged lithium batteries, in order to solve the technical problem that the battery cannot be charged or the charging speed is slow when it is over-discharged.

[0005] This utility model provides a charging management circuit for an over-discharged lithium battery, including a charging integrated circuit whose input terminal is electrically connected to an adapter, a fuel gauge electrically connected to the lithium battery, and an output terminal of the charging integrated circuit electrically connected to the lithium battery and a system motherboard. It also includes an auxiliary MCU, which is electrically connected to the adapter via a voltage regulator. The system motherboard includes a main control chip. One GPIO port of the auxiliary MCU is connected to the high-level start pin of the main control chip. The I2C bus of the auxiliary MCU is connected to the fuel gauge after passing through the normally open terminal of a dual-channel analog switch. The auxiliary MCU is connected to the control terminal of the dual-channel analog switch through another GPIO port. The I2C bus of the main control chip is connected to the fuel gauge after passing through the normally closed terminal of the dual-channel analog switch. The auxiliary MCU is configured to output a switch switching level signal to the dual-channel analog switch, controlling the exclusive connection switching between the fuel gauge's I2C bus and the auxiliary MCU or the main control chip, and controlling the power on / off of the system motherboard based on the current lithium battery voltage.

[0006] In some embodiments, a single-pole double-throw switch is provided on the line connecting the external switch button on the system motherboard and the low-level start pin of the main control chip. The enable terminal of the single-pole double-throw switch is connected to a GPIO port of the auxiliary MCU, and the common terminal of the single-pole double-throw switch is connected to the low-level start pin of the main control chip. The connection and disconnection of the line between the external switch button and the low-level start pin are controlled according to the control signal issued by the auxiliary MCU.

[0007] In some embodiments, a charging indicator light electrically connected to an auxiliary MCU is also included. When the system motherboard is in a powered-off state, if the battery charging current collected by the auxiliary MCU through reading the fuel gauge is greater than a threshold, the charging indicator light is turned on.

[0008] In some embodiments, the dual-channel analog switch includes two parallel single-pole double-throw (SPDT) switches. The control terminals of the two SPDT switches are connected together and then connected to the GPIO port of the auxiliary MCU. The normally closed terminals of the two SPDT switches are respectively connected to two signal lines of the I2C bus of the main control chip, and the normally open terminals of the two SPDT switches are respectively connected to two signal lines of the I2C bus of the auxiliary MCU. The common terminal of the two SPDT switches is respectively connected to two signal lines of the I2C bus of the fuel meter.

[0009] The beneficial effects of this utility model are as follows: After the auxiliary MCU of this utility model is inserted into the adapter, it runs and controls the dual-channel analog switch to realize the switching of the I2C line; the auxiliary MCU reads the battery voltage collected by the fuel gauge through the I2C bus, and controls the power on and off of the system motherboard according to the current voltage of the battery, so as to realize that when the voltage of the battery is very low after over-discharge, the system motherboard (load) is shut down, realizing the adapter to quickly charge the lithium battery, and when the battery voltage rises to a certain value, the system motherboard is started, realizing the purpose of the system motherboard to start up quickly as soon as the power-on conditions are met. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 Here is a block diagram of the principle of an existing charging device; Figure 2 A schematic diagram of the charging management device provided in this embodiment of the utility model; Figure 3 This is a schematic diagram of a dual-channel analog switch. Figure 4 Schematic diagram for controlling an external switch button; Detailed Implementation

[0012] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0013] like Figure 2As shown, this utility model provides a charging management circuit for an over-discharged lithium battery, including a charging integrated circuit whose input terminal is electrically connected to an adapter, a fuel gauge electrically connected to the lithium battery, and an output terminal of the charging integrated circuit electrically connected to the lithium battery and the system motherboard. It also includes an auxiliary MCU, which is electrically connected to the adapter via a voltage regulator. The system motherboard includes a main control chip. One GPIO port of the auxiliary MCU is connected to the high-level start pin of the main control chip. The I2C bus of the auxiliary MCU is connected to the fuel gauge after passing through the normally open terminal of a dual-channel analog switch. The auxiliary MCU is connected to the control terminal of the dual-channel analog switch through another GPIO port. The I2C bus of the main control chip is connected to the fuel gauge after passing through the normally closed terminal of the dual-channel analog switch. The auxiliary MCU is configured to output a switch switching level signal to the dual-channel analog switch, controlling the exclusive connection switching of the fuel gauge's I2C bus with the auxiliary MCU or the main control chip, and controlling the power on / off of the system motherboard according to the current lithium battery voltage.

[0014] The auxiliary MCU of this invention operates after the adapter is inserted and controls the dual-channel analog switch to achieve I2C line switching. When charging without the adapter inserted, the I2C bus of the fuel gauge is exclusively connected to the main control chip, and the main control chip reads the voltage and power and displays it.

[0015] When the adapter is plugged in, the auxiliary MCU starts automatically after being powered on, and outputs the first switch switching level signal to the dual-channel analog switch, so that the I2C bus of the fuel gauge is exclusively connected to the auxiliary MCU; if the voltage of the lithium battery is not lower than the power-on voltage threshold, it outputs the second switch switching level signal to the dual-channel analog switch, disconnects the I2C communication link between the auxiliary MCU and the fuel gauge, and connects the I2C communication link between the main control chip and the fuel gauge.

[0016] The auxiliary MCU reads the battery voltage from the fuel gauge via the I2C bus. Based on the current battery voltage, it controls the power on / off of the mainboard. This allows the mainboard (load) to shut down when the battery voltage is low, enabling the adapter to quickly charge the lithium battery. Conversely, once the battery voltage reaches a certain level, the mainboard is activated, ensuring it powers on quickly and immediately upon meeting the power-on requirements.

[0017] The auxiliary MCU of this invention only runs when the adapter is plugged in for charging, and participates in power monitoring. When the device is not charging, the auxiliary MCU will not run, thus not increasing the power consumption of the device or affecting its usage time.

[0018] In some embodiments, controlling the power on / off of the system motherboard based on the lithium battery voltage specifically includes: If the lithium battery voltage is lower than the power-on voltage threshold, the auxiliary MCU outputs a power-off level signal to the main control chip to control the main control chip to power off. If the lithium battery voltage is not lower than the power-on voltage threshold, the auxiliary MCU outputs a power-on level signal to the main control chip to control the main control chip to power on.

[0019] In some embodiments, such as Figure 4 As shown, a single-pole double-throw switch is installed on the line connecting the external switch button on the system motherboard and the low-level start pin of the main control chip. The external switch button is connected to the normally closed terminal of the single-pole double-throw switch, the enable terminal of the single-pole double-throw switch is connected to a GPIO port of the auxiliary MCU, and the common terminal of the single-pole double-throw switch is connected to the low-level start pin of the main control chip. According to the control signal issued by the auxiliary MCU, the connection and disconnection of the line between the external switch button and the low-level start pin are controlled.

[0020] This invention also restricts the user's external switch button operation, preventing the user from accidentally starting the system motherboard when the battery voltage is insufficient. The specific implementation is as described above: a single-pole double-throw switch is installed on the line connecting the original external switch button to the low-level start pin of the main control chip.

[0021] The adapter or lithium battery outputs 1.8V after voltage regulation and buck conversion to power the dual-channel analog switch and the single-pole double-throw switch. This ensures that the dual-channel analog switch and the single-pole double-throw switch are always powered, guaranteeing that the switch chips are in a working state. Whichever is online, the adapter or lithium battery, powers the switch; if both are online, the one with the higher voltage powers the switch.

[0022] After the auxiliary MCU starts up, it detects that the battery voltage is lower than the power-on voltage threshold through the power meter. It immediately controls the S signal of the single-pole double-throw switch to a high level, and then the signal C switches to the A side (normally open). The external power button is disconnected from the low-level start pin of the main control chip, and the external power button becomes ineffective.

[0023] When the auxiliary MCU detects that the battery voltage is higher than the power-on voltage threshold, the S signal controlling the single-pole double-throw switch is low, and the C signal switches to the B side (normally closed terminal). The external power button is connected to the low-level start pin of the main control chip, and the external power button works normally.

[0024] In some embodiments, the present invention further includes a charging indicator light electrically connected to an auxiliary MCU. When the system motherboard is powered off, if the battery charging current collected by the auxiliary MCU through the fuel gauge is greater than a threshold, the charging indicator light is turned on. During the phase where the adapter is only charging the battery, the display screen on the system motherboard that previously showed the battery level is temporarily not working and cannot display the charging status. The present invention displays the charging status through the charging indicator light electrically connected to the auxiliary MCU.

[0025] In some embodiments, such as Figure 3 As shown, the dual-channel analog switch includes two parallel single-pole double-throw (SPDT) switches. The control terminals of the two SPDT switches are connected together and then connected to the GPIO port of the auxiliary MCU. The normally closed terminals of the two SPDT switches are respectively connected to two signal lines of the I2C bus of the main control chip, and the normally open terminals of the two SPDT switches are respectively connected to two signal lines of the I2C bus of the auxiliary MCU. The common terminal of the two SPDT switches is respectively connected to two signal lines of the I2C bus of the fuel meter.

[0026] The charging management circuit for an over-discharged lithium battery provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

[0027] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

Claims

1. A charging management circuit for an over-discharged lithium battery, comprising a charging integrated circuit whose input terminal is electrically connected to an adapter, and a fuel gauge electrically connected to the lithium battery, wherein the output terminal of the charging integrated circuit is electrically connected to the lithium battery and a system motherboard, characterized in that: It also includes an auxiliary MCU, which is electrically connected to an adapter via a voltage regulator. The system motherboard includes a main control chip. One GPIO port of the auxiliary MCU is connected to the high-level start pin of the main control chip. The I2C bus of the auxiliary MCU is connected to the fuel gauge after passing through the normally open terminal of the dual-channel analog switch. The auxiliary MCU is connected to the control terminal of the dual-channel analog switch through another GPIO port. The I2C bus of the main control chip is connected to the fuel gauge after passing through the normally closed terminal of the dual-channel analog switch. The auxiliary MCU is configured to output a switch switching level signal to the dual-channel analog switch to control the exclusive connection switching between the fuel gauge's I2C bus and the auxiliary MCU or the main control chip, and to control the power on / off of the system motherboard according to the current voltage of the lithium battery.

2. The charge management circuit for over-discharged lithium battery of claim 1, wherein, A single-pole double-throw switch is installed on the line connecting the external switch button on the system motherboard and the low-level start pin of the main control chip. The enable terminal of the single-pole double-throw switch is connected to a GPIO port of the auxiliary MCU, and the common terminal of the single-pole double-throw switch is connected to the low-level start pin of the main control chip. According to the control signal issued by the auxiliary MCU, the connection and disconnection of the line between the external switch button and the low-level start pin are controlled.

3. The charge management circuit for over-discharged lithium battery of claim 1, wherein, It also includes a charging indicator light that is electrically connected to the auxiliary MCU. When the system motherboard is powered off, if the battery charging current collected by the auxiliary MCU through the fuel gauge is greater than the threshold, the charging indicator light will be turned on.

4. The charge management circuit for over-discharged lithium battery of claim 1, wherein, The dual-channel analog switch includes two parallel single-pole double-throw (SPDT) switches. The control terminals of the two SPDT switches are connected together and then connected to the GPIO port of the auxiliary MCU. The normally closed terminals of the two SPDT switches are respectively connected to two signal lines of the I2C bus of the main control chip, and the normally open terminals of the two SPDT switches are respectively connected to two signal lines of the I2C bus of the auxiliary MCU. The common terminal of the two SPDT switches is respectively connected to two signal lines of the I2C bus of the fuel meter.

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