Lithium-ion battery overcharge protection decomposition based on safety standards

ଲେଖକ: ଆଇଫ୍ଲୋପାୱାର - Onye na-ebubata ọdụ ọkụ nwere ike ibugharị

With the arrival of smartphones and the new network age, consumers' requirements for smartphone batteries are more demanding. Due to greater screen sizes, more complex features, it will bring new addresses. In order to ensure proper use of your mobile phone, it is unable to equip high capacity batteries.

From the market, all households play mobile phones, 3000mAh left and right products have been very common. The new 4G network does not use the low power technology, and the consumption of electricity is a big problem, which also brings a need for higher capacity batteries. According to the mobile research and development engineer feedback, in addition to requesting a large-capacity battery to meet the battery life, it also supports higher continuation discharge current and instantaneous current in terms of battery discharge capabilities.

And these high discharge currents use a certain conflict with the safety detection of the battery itself. So, how do you find the balance between them, and it is especially important about battery development designers. In order to better illustrate the relationship between the two, first understand the lithium-ion battery protection circuit, as shown below: 1 level of active protection IC + MOSFET and 2-level passive protector PPTC or MHP-Ta.

Lithium-ion battery protection circuit We all understand the most common standard UL2054 of the battery industry has over-printed requirements. The UL2054 shows the short circuit principles and exception terms of the battery internal components, if it is a non-certified protection device, it will be shorted during the detection process. The FAULT principles are as follows: a.

The device is not fault; b. Any non-certified protection element will be short-circuited by FAULT, usually such as MOSFET, current test resistor during detection; UL2054 overcharge experiment The sample battery for detection is charged with 10 * C5 (2c) (some manufacturers requiring more strict requirements by 1C). Each battery or battery is attached to the heat coupling assembly, and then charge until the battery or The electrical core explosion, leakage, or the temperature of the outer casing is restored to ambient temperature or a stable state.

In the detection, the overcurrent and thermal protection devices do not have to pass the safety certification, and there is no approved protection device. The index requirements of UL2054 are not fire, not exploding. Decompose the above-mentioned safety detection requirements, it can be determined that the selection of the second passive protector is, the lower the device protection point, the more it is conducive to the protection effect.

In this year, the smaller the action current (Itrip) of the device, the easier to detect; the body is in the temperature sensing of the two metal sheets MHP-TA, the lower the device itself, the more it is, the easier action, More easily through detection. However, in the actual use, it is just the opposite, usually requires that the battery can meet the short time to maintain high current power supply, and even maintain a higher current (4A) under high temperature (reaching 60 degrees Celsius). This body is now the protection device itself requires PPTC to have large maintenance currents in high temperature (IHOLD).

The requirements of these two aspects have a certain contradiction, and the one-sided guarantee does not guarantee product safety and actual use. Passive protection devices MHP-TA and PPTC selection and actual use conditions, structural design, reference detection standards, etc., you need to find two balance points.

This requires battery development and designers to communicate with protective device suppliers in the early stage of development, and cooperate with adequate test verification to achieve safety requirements that meet the safety detection, and in line with actual use. TE as a circuit protection industry leader, has been related to related experience in the development and use of lithium-ion battery protection devices, and the PPTC and MHP-TA processed have been used in large numbers of mobile phone battery manufacturers at home and abroad.