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Fast Charge EOS Solution OVP and TVS
EOS stands for Electrical Over Stress in English, which refers to electrical overstress. This occurs when excessive voltage and/or current signals are applied to a device, causing it to fail or become damaged. Hence the term "over." There are three primary ways EOS can occur: high voltage, high current, or a combination of both. While ESD events are essentially short-term high-voltage instances of EOS, dealing with EOS requires considering not only voltage but also current and duration.
With the increasing complexity of mobile phone charging environments—ranging from car chargers and solar chargers to wall chargers and fast chargers—mobile devices face numerous challenges in withstanding diverse charging conditions. Many mobile phones suffer from PMU or charging IC malfunctions due to overvoltage and overcurrent issues in their charging circuits. Developing regions like India and Africa, where the power grid is often unstable, experience the highest rates of EOS incidents. Mobile solution providers have thus developed reliable solutions to address these concerns.
Based on the demands of clients like Huawei and OPPO, Thunder Electronics has designed several reliable solutions tailored to current EOS challenges. Currently, there are no specific overvoltage testing standards in domestic regulations, though export-oriented products often require compliance with certain criteria. Starting from a 300V surge test in 2015, some customers now request tests up to 500V, reflecting their stringent requirements for overvoltage reliability.
Overvoltage protection may seem straightforward, but it poses significant challenges in mobile phones due to space constraints. Designing a chip powerful enough while keeping it compact is a complex task.
The above combination scheme utilizes the properties of three different materials:
PSMFJ24CA is a high-power TVS chip housed in an SOD-123FL package with a power rating of 5000W. It can handle peak currents of up to 250A with a clamping voltage of 30V. Depending on terminal requirements, primary protection options include 7V and 12V variants.
OVP3881 is an overvoltage protection chip whose threshold voltage can be customized based on the main chip's specifications.
The rear-end employs SD4501P4-3, another high-power TVS, featuring a DFN2020 package capable of handling large currents at low voltages. Below is a list of test data for this TVS.
In conclusion, EOS remains a critical issue in modern electronics, especially in mobile devices. As the market evolves, continued innovation and development in overvoltage protection technologies are essential to ensure device reliability and longevity.