CN201222661Y - Lithium battery protection device with zero discharging function during storage period - Google Patents

Abstract

A lithium battery protection device with a zero-discharge function during the storage period, which includes a charging power supply, a load, a power management chip IC, a charging field effect transistor, and a discharging field effect transistor. The voltage detection pin of the power management chip is in phase with the positive pole of the charging power supply. The charge management pin and discharge management pin of the IC are respectively connected to the charge field effect tube and the discharge field effect tube. The charging power supply is connected to the positive pole of the load, and a switch K is connected in parallel between the voltage detection pin of the power management chip IC and the negative power supply pin. The utility model has a simple circuit, which can be matched with portable electrical appliances, and a switch can be connected in parallel between the voltage detection pin and the load pin of the chip IC of the existing lithium battery protection device, so that the built-in lithium battery not only has the function of overcharging , Over-discharge protection function, and can achieve zero discharge when the device is turned off, prolonging its service life.

Description

Lithium battery protection device with storage period zero discharge function

technical field

The utility model relates to a protection device for a lithium battery, in particular to a circuit for enabling the built-in lithium battery of a portable device to realize zero discharge during transportation and storage, so as to prolong its service life.

Background technique

In recent years, with the development of the electronic industry and the improvement of people's living standards, various portable electrical appliances, such as laptop computers, digital cameras, digital video cameras and mobile phones, portable high-frequency equipment and Bluetooth equipment, etc. Consumer owned, enriching people's lives. Because these portable devices need to have the support of power to work normally, so people often use built-in batteries to solve the power problem of these portable electrical appliances moving freely. Lithium batteries have excellent properties such as small size, high energy density, no memory effect, high cycle life, high voltage battery and low self-discharge rate, and are used as the main power source by many portable appliances. However, when the lithium battery is in the overcharged state, the energy will be surplus after the battery temperature rises, so the electrolyte will decompose to generate gas, and there is a risk of spontaneous combustion or rupture due to the increase in internal pressure; Battery characteristics and durability deteriorate, thereby reducing the number of rechargeable batteries; the protection circuit of lithium batteries is to ensure safety during such overcharge and discharge states, and to prevent characteristic deterioration. The application number of the Chinese patent publication is "200610080792.3", "Lithium battery protection device and method thereof", and the lithium battery protection device includes: an abnormality detection circuit, an optical coupling circuit, a balance circuit and an identification circuit. The battery abnormal detection circuit checks the voltage of the rechargeable battery and outputs a detection signal. If the signal is normal, the charging or discharging operation will continue, and if the signal is abnormal, the charging or discharging operation will be cut off. However, the device is unable to monitor the self-discharge of the battery. The portable device with built-in lithium battery will have static power consumption when it is turned off. It includes the loss of the lithium battery management chip itself, the loss of the PN junction of the field effect transistor and the loss of the load circuit. , Long-term placement can easily cause over-discharge of the lithium battery, resulting in reduced service life or damage to the battery.

Contents of the invention

The purpose of this utility model is to provide a protection device with anti-overcharge, over-discharge and zero-discharge during storage period for the built-in single-cell or multi-cell lithium batteries of portable electrical appliances in view of the defects and deficiencies of the above-mentioned prior art.

In order to achieve the above object, the technical measures taken by the utility model are: the lithium battery protection device with storage period zero discharge function, which includes a charging power supply, a load, a power management chip IC, a charging field effect tube and a discharging field effect tube, a power supply The voltage detection pin of the management chip is connected to the positive pole of the charging power supply, the charging management pin and the discharging management pin of the IC are respectively connected to the charging field effect tube and the discharging field effect tube, the positive power supply pin of the chip IC is connected to the negative power supply The pin is connected to the positive and negative poles of the lithium battery, and is connected to the charging power supply and the positive pole of the load at the same time. It is characterized in that a switch K is connected in parallel between the voltage detection pin of the power management chip IC and the negative power supply pin.

The model of the power management chip IC is S-8232 series, which is a dual-cell lithium battery power management chip, and it includes a voltage detection pin 1 connected to the charging power supply and the positive pole of the load, and a G The discharge management pin 2 connected with the charging FET Q2 and the charging management pin 3 connected with the charging FET Q2, the overcurrent detection pin 4 is connected with the D pin of the charging FET Q2 through the series resistor R3, and the charging field The D pin of the effect tube Q2 is connected with the IC pin 5, the S pin of the charging field effect tube Q2 is connected with the charging power supply, and the capacitor C1 is connected in parallel between the midpoint power input pin 7 and the negative power pin 5 of the management chip IC Between, the capacitor C2 is connected in parallel between the delay capacitor pin 6 of the IC and the negative power supply pin 5, and the capacitor C3 is connected in parallel between the IC pin 7 and the positive power supply input pin 8. After the two lithium batteries BT are connected in series, Its positive pole is connected to the positive pole of the charging power supply and the load, and at the same time connected to the pin 8 of the IC through the resistor R1, the negative pole of the battery is connected to the pin 5 of the chip IC, and a parallel connection between the voltage detection pin 1 and the negative power pin 5 Switch only.

The model of the power management chip IC is SC451 single-cell lithium battery power management chip, which includes a voltage detection pin 1, a discharge management pin 2, a charge management pin 3, an overcurrent detection pin 4, and a negative power supply pin 5 and connect the delay capacitor C2 pin 6, where pin 1 of the IC is connected to the G pin of the discharge FET Q1, and the 2 pins are connected in series with the resistor R3 and the S pin of the charging FET Q2 is connected to the charging power supply and the negative pole of the load Connect, pin 3 of the IC is connected to the pin G of the charge field effect Q2, pin D of the charge field effect tube Q2 is connected to the D pin of the discharge field effect Q1, and pin S of the charge field effect tube Q2 is connected to the negative pole of the lithium battery , the positive pole of the lithium battery is connected to the positive pole of the charging power supply and the load, the 4 pins of the IC are connected to the negative pole of the lithium battery BT through the capacitor C2, the two terminals of the capacitor C3 are connected to the 5 and 6 pins of the chip IC, and the 5 pins of the chip IC are connected in series Resistor R4 is then connected to the positive pole of the lithium battery, pin 6 of the chip IC is directly connected to the negative pole of the lithium battery BT, and a switch K is connected in parallel between the voltage detection pin 5 of the chip IC and the negative power supply pin 6.

The utility model connects a switch K in parallel between the voltage detection pin 1 and the negative power supply pin 5 on the power management chip IC of the conventional lithium battery protection circuit to realize the deep sleep of the lithium battery management chip, thereby realizing that the portable device not only It has over-charging and over-discharging protection functions, and can realize zero discharge when the device is turned off, so that the lithium battery can be stored for a long time to prevent the characteristics of the lithium battery from deteriorating and affecting its service life.

Description of drawings

Fig. 1 is a block diagram of the electric principle of the utility model.

Figure 2 is an electrical schematic diagram of a dual-cell lithium battery protection device.

Figure 3 is an electrical schematic diagram of a single-cell lithium battery protection device.

Detailed ways

Figure 1 is an extended circuit based on a typical application of a lithium battery management chip. The circuit includes a charging power supply, a load, a lithium battery management chip IC, a charging FET and a discharging FET, and the voltage detection pin 1 of the power management chip IC is connected to the charging The positive pole of the power supply is connected, the discharge management pin of the IC is connected to the G pin of the discharge field effect tube, the charge management pin of the IC is connected to the G pin of the charging field effect tube, and the positive power pin of the IC is connected to the charging power supply and the load positive pole respectively. connected, the negative power supply pins of the IC are respectively connected to the negative poles of the charging power supply and the load through charging and discharging field effect tubes, and the positive and negative poles of the lithium battery are respectively fixed on the positive and negative power supply pins. Circuit basis A switch K is connected in parallel between the voltage detection pin 1 of the chip IC and the negative power supply pin 5 . The switch can be selected with a suitable physical switch, which can ensure that the physical switch is closed and then disconnected when there is no charging power input, so as to reduce the static current consumption.

The dual-cell lithium battery protection device shown in Figure 2 is a continuation of the traditional electrical schematic diagram. The model of the power management chip used is S-8232 series, which is a dual-cell lithium battery power management chip (IC for short).

Pin 1 of the power management chip IC - voltage detection pin, pin 2 - discharge management pin, pin 3 - charge management pin, pin 4 - overcurrent detection pin, pin 5 - negative power supply pin, pin 6 - Connect the delay capacitor pin, pin 7-midpoint power input pin, pin 8-positive power input pin. Pin 1 of the IC is connected to the positive pole of the charging power supply and the load through the series resistor R4, pin 2 of the IC is connected to the G pin of the discharge field effect transistor Q1, and pin 3 of the IC is connected to the G pin of the charging field effect transistor Q2 , pin 4 of the IC is connected to pin D of the charging FET Q2 through a series resistor R3, and pin D of the charging FET Q2 is connected to pin 5 of the IC and pin S of the discharging FET Q1. The S pin of the tube Q2 is connected to the negative pole of the charging power supply. Capacitor C1 is connected in parallel between pin 7 and pin 5 of IC, capacitor C2 is connected in parallel between pin 6 and pin 5 of IC, and capacitor C3 is connected in parallel between pin 8 and pin 7 of IC. After the positive and negative of the two-cell lithium battery BT are connected in series, its positive pole is connected to the positive pole of the charging power supply and the load, and at the same time connected to the 8-pin of the IC through the resistor R1, and the negative pole of the battery is connected to the 5-pin of the IC. The series point is connected with pin 7 of IC through series resistance R2. Connect a switch K in parallel between the voltage detection pin 1 of the IC and the negative power supply pin 5.

The electrical principle of the application of the dual-cell lithium battery management chip is described below in conjunction with FIG. 2 .

In Figure 2, the lithium battery management chip S-8232 series, the power management chip IC can monitor the various voltages and discharge currents of the two lithium batteries in the circuit, and control the charging and discharging. The solid arrow indicates the direction of the charging current, and the dashed arrow indicates the direction of the discharging current. When the voltage detection pin 1 of the management chip IC detects that the voltage values of the two batteries are both above the over-discharge detection voltage and below the over-charge detection voltage, and the current flowing through the battery is below the set value, the charge field effect transistor Q2 and the discharge field The effect transistors Q1 are all in the conduction state, and can be charged and discharged freely. When the voltage of any lithium battery exceeds the overcharge detection voltage, the lithium battery management chip will turn off the charging field effect transistor Q2 through the charge management pin to disconnect the charging circuit, thereby realizing overcharge protection; when any When the lithium battery voltage drops from greater than the overcharge detection voltage to less than the overcharge release voltage, and the voltage of the other lithium battery is also lower than the overcharge release voltage, the lithium battery management chip will turn on the charging field effect transistor Q1 through the charge management pin. Realize the conduction of the charging circuit. When the voltage of any lithium battery exceeds the over-discharge detection voltage, the lithium battery management chip will turn off the discharge field effect transistor Q1 through the discharge management pin to realize the disconnection of the discharge circuit, thereby realizing over-discharge protection; when any lithium battery When the battery voltage rises from less than the over-discharge detection voltage to greater than the over-discharge release voltage, and the voltage of another lithium battery is also greater than the over-discharge release voltage, then the lithium battery management chip will turn on the discharge field effect transistor Q1 through the discharge management pin, so that The discharge circuit is turned on.

Figure 3 is an electrical schematic diagram of a single-cell lithium battery protection device.

The model of the power management chip IC used in the figure is SC451. Pin 1 of the chip IC - discharge management pin, pin 2 - overcurrent detection pin, pin 3 - charge management pin, pin 4 - connection delay capacitor pin, pin 5 - voltage detection pin, pin 6 - negative power supply pin.

Among them, pin 1 of the chip IC is connected to the G pin of the discharge FET Q1, pin 3 of the IC is connected to the G pin of the charging FET Q2, and the D pin of the discharging FET Q1 is connected to the D pin of the charging FET Q2. Pins are connected, the 2 pins of the chip IC are connected in series with the resistor R3, and the S pin of the charging field effect tube is connected to the negative pole of the charging power supply and the load. The S pin of Q1 is connected to the negative pole of the lithium battery BT, and the positive pole of the lithium battery is connected to the negative pole of the charging The positive pole of the power supply and the load are connected, the 4 pin of the IC is connected with the negative pole of the lithium battery BT through the capacitor C2, the two terminals of the capacitor C3 are connected to the 5 and 6 pins of the chip IC, and the 5 pin of the chip IC is connected to the positive pole of the lithium battery after being connected in series with the resistor R4 To connect, pin 6 of the chip IC is directly connected to the negative pole of the lithium battery BT, and a switch K is connected in parallel between pin 5 and pin 6 of the chip.

The electrical principle of the single-cell lithium battery protection device will be described in detail below.

When the voltage detection pin (that is, the fifth pin of the SC451 chip in Figure 3) detects that the voltage value of the lithium battery is less than the overcharge detection voltage and greater than the overdischarge detection voltage, then the charging FET Q2 and the discharging FET Q1 are both When it is turned on, charging and discharging can be carried out normally at this time. When the voltage detection pin detects that the lithium battery voltage is greater than the overcharge detection voltage, the charging management pin of the IC chip (pin 3 in the figure) will control the S pole and D pole of the charging field effect transistor Q2 to disconnect, so that the charging and discharging circuit Disconnect to realize overcharge protection. When the lithium battery voltage drops from greater than the overcharge detection voltage to less than the overcharge release voltage, the charging control pin of the IC chip (pin 3 in the figure) will control the S of the charging FET Q2. The pole and the D pole are re-conducted to provide the necessary conditions for the conduction of the charging and discharging circuit. When the voltage detection pin detects that the lithium battery voltage is lower than the over-discharge detection voltage, then the discharge control pin of the IC chip (pin 1 in the figure) will control the S pole and D pole of the discharge field effect transistor Q1 to disconnect, so that the charge and discharge circuit disconnected for overcharge protection. When the lithium battery voltage rises from less than the over-discharge detection voltage to greater than the over-discharge release voltage, the discharge control pin (pin 1) of the IC chip will control the S pole and the D pole of the discharge field effect transistor Q1 to conduct again, which is for charging and discharging. Necessary conditions are provided for the conduction of the circuit.

Based on the above charge and discharge principle, and according to the characteristics of the voltage detection pin, we can reduce the voltage value on the voltage detection pin below the over-discharge detection voltage, and virtualize the lithium battery with normal voltage state into an over-discharge state, thereby Forcibly realizing the dormancy of the lithium battery management chip (that is, in a state of extremely low power consumption), the utility model connects a switch in series with the voltage detection terminal of the lithium battery management chip and then connects it to the negative terminal of the lithium battery to realize the deep sleep of the lithium battery management chip. Steps: 1. Confirm that there is no charging power, that is, no power is introduced into the power port; 2. The lithium battery is in a normal connection state in the circuit; 3. Close the switch K and disconnect it. Through the above three steps, the deep sleep of the lithium battery management chip can be realized, so that the portable device can be stored for a long time in the off state.

The utility model can be used as a supporting built-in lithium battery protection device for portable appliances, and a switch K can be connected in parallel between the voltage detection pin of the power management chip IC and the negative power supply pin of the built-in lithium battery protection device of the portable appliance, so that the lithium The battery has the function of zero discharge during the storage period.

Claims (3)

1. A lithium battery protection device with a zero-discharge function during the storage period, which includes a charging power supply, a load, a power management chip IC, a charging FET and a discharging FET, the voltage detection pin of the power management chip and the charging power supply The positive poles are connected, the charge management pin and the discharge management pin of the chip IC are respectively connected to the charge field effect tube and the discharge field effect tube, the positive power supply pin and the negative power supply pin of the chip IC are connected to the positive and negative poles of the lithium battery, At the same time, it is connected to the charging power supply and the positive pole of the load, and it is characterized in that a switch K is connected in parallel between the voltage detection pin of the power management chip IC and the negative power supply pin. 2. The lithium battery protection device with zero-discharge function during the storage period according to claim 1, characterized in that the model of the power management chip IC is S-8232, which includes a voltage connected to the charging power supply and the positive pole of the load The detection pin 1, the discharge management pin 2 connected with the G pin of the discharge FET Q1 and the charge management pin 3 connected with the charge FET Q2, the overcurrent detection pin 4 is connected to the charge through the series resistor R3 The D pin of the field effect tube Q2 is connected, and the D pin of the charging field effect tube Q2 is connected with the 5 pin of the IC, the S pin of the charging field effect tube Q2 is connected with the charging power supply, and the capacitor C1 is connected in parallel to the center of the management chip IC Point power supply input pin 7 and negative power supply pin 5, capacitor C2 is connected in parallel between IC connection delay capacitor pin 6 and negative power supply pin 5, capacitor C3 is connected in parallel between IC pin 7 and positive power supply input pin Between pin 8, after the two-cell lithium battery BT is connected in series, its positive pole is connected to the charging power supply and the positive pole of the load, and at the same time, it is connected to pin 8 of the IC through resistor R1, and the negative pole of the battery is connected to pin 5 of the chip IC. The voltage detection Connect a switch in parallel between pin 1 and negative supply pin 5. 3. The lithium battery protection device with storage period zero discharge function according to claim 1, characterized in that the model of the power management chip IC is SC451 single-cell lithium battery power management chip, which includes a voltage detection pin 1 , discharge management pin 2, charge management pin 3, overcurrent detection pin 4, negative power supply pin 5, and connection delay capacitor C2 pin 6, where pin 1 of IC is connected to pin G of discharge FET Q1 , the 2-pin series resistor R3 is connected with the S pin of the charging FET Q2 to the charging power supply and the load negative pole, the 3 pin of the IC is connected to the G pin of the charging FET Q2, and the D pin of the charging FET Q2 is connected to the The D pin of the discharge field effect Q1 is connected, the S pin of the charging field effect transistor Q2 is connected with the negative pole of the lithium battery, the positive pole of the lithium battery is connected with the charging power supply and the positive pole of the load, and the 4 pin of the IC is connected with the negative pole of the lithium battery BT through the capacitor C2. Connect, the two ends of the capacitor C3 are connected to the 5th and 6th pins of the chip IC, the 5th pin of the chip IC is connected to the positive pole of the lithium battery after connecting the resistor R4 in series, and the 6th pin of the chip IC is directly connected to the negative pole of the lithium battery BT. A switch K is connected in parallel between the voltage detection pin 5 of the chip IC and the negative power supply pin 6 .

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