Requirements to maintain the performance of integrated circuits

1. High maintenance accuracy of overcharge

When overcharging, in order to prevent the increase of internal pressure caused by temperature rise, the charging state should be stopped. The maintenance IC will detect the battery voltage, and when an overcharge is detected, the overcharge detects the power MOSFEts, causing them to block and stop charging. At present, we should pay attention to the high precision of charging detection voltage. When charging the battery, the user’s primary concern is to keep the battery fully charged and consider safety issues. Therefore, when the allowable voltage is reached, the charging state should be cut off. To combine these two conditions, high-precision detectors are needed. Detector accuracy is now 25mV and needs improvement.

2. Reduce the power consumption of the IC

As time goes by, the voltage of the lithium battery after charging will gradually decrease until it is below the standard value of the specification, at which point the battery needs to be charged. If the battery continues to be used without charging, it may become unusable due to excessive discharge. To prevent excessive discharge of the battery, the maintenance IC tests the battery voltage. When the battery voltage is lower than the overdischarge detection voltage, plug in a power MOSFET to the discharging side to stop discharging. However, the battery itself still has natural discharge and maintains IC consumption current, so keep IC consumption current to a minimum.

3. Overcurrent/short circuit maintenance, low voltage detection, high precision

If the cause of short circuit is unknown, stop the discharge immediately. Overcurrent detection uses Rds(ON) of power MOSFET as inductive impedance to monitor its voltage drop. If the voltage is higher than the overcurrent detection voltage, stop the discharge. In order to make the power MOSFETRds() effective charging current and discharge current application, the impedance value should be as low as possible, the current impedance is about 20m~30m, the current voltage can be low.

4. High pressure resistance

When the battery pack is connected to the charger, high voltage immediately occurs, so the maintenance IC needs to meet the requirements of high voltage resistance.

5. Low battery power consumption

During maintenance, the static power consumption current decreases by 0.1 A.

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During the storage process, some batteries may drop to 0V due to a long time or abnormal reasons, so the maintenance IC needs can also be charged at 0V.

Maintain the development prospects of integrated circuits

As mentioned above, the future maintenance IC will further improve the accuracy of voltage detection, reduce the power consumption of the maintenance IC, improve the prevention of misoperation and other functions. The charger terminal with high voltage resistance is also the focus of research and development. In terms of packaging, SOT23-6 has been gradually transitioning to SON6 packaging, and there will be CSP packaging and even COB products in the future to meet the current requirements for lightweight and shortening.

Functionally, maintaining an IC should not integrate all functions. According to different lithium battery data, a single maintenance IC can be notified, such as overcharge maintenance or overrelease maintenance, which can greatly reduce the cost and scale.

Function module, of course, single crystal are the same goals, such as mobile phone manufacturers are facing now the integrated circuit, charging circuit and power management IC, and other peripheral circuits and logic IC chip constitute a dual chip, but now I want to keep open circuit impedance of the power MOSFET, the autumn with other IC integration, even through specialized skills to the single chip microcomputer, money also is too high, IBe fear. Therefore, it takes some time to solve the maintenance of IC single crystal.