Over current protection for charging equipment

In recent years, E-bike has gradually become one of the important means of transportation for urban travel, but at the same time, the fire caused by E-bike is also frequent. Due to improper charging of E-bike, the plastic parts of E-bike are ignited, resulting in huge losses of people and property.

In the process of charging, the intelligent charging equipment of electric bicycle can monitor the charging situation in real time, and has the safety protection functions such as over-current protection and zero current protection. Once it is found that there is a high-power charging refitted car charging, or the electric bicycle charging with aging battery, or there is a short circuit in the charger, it will give an alarm in time. Property, fire and other management departments through the background alarm information for further processing, to achieve fire safety early warning.

The output current of electric bicycle charging device is generally 2-3a, and different current will be output according to different stages of charging. So, how does the device detect the output current and carry out over-current protection?

Due to the limited volume of the charging equipment, in fact, in the charging circuit, a small volume current sensor will be selected to detect the output current and feed it back to the control system in real time. When the set current value is reached, there will be corresponding control methods. Let's take a look at the Hall current sensor which can detect current


Sc8111 is a chip type current sensor based on open-loop hall principle developed by Senko micro. It can be used for AC or DC current measurement and applied in industrial, commercial and communication systems.

The product is packaged in sop-8 package, and the current conductor impedance of 20m Ω is realized on the 4.9mm * 3.9mm * 1.75mm sop-8 package, so that it can be applied to the power system that requires continuous work in measuring up to 6A.

The sc8111 series of Xinggong micro is an isolated current detection chip based on the open-loop Hall sensor detection principle. By introducing the current wire at the high voltage side into the package, based on the magnetic effect of the current, the proportional magnetic field generated around the measured wire is induced by the magnetic sensor of the built-in chip, and then converted into a processable proportional voltage signal. The voltage signal is read and amplified by the built-in high-precision ADC, and the loops such as temperature, noise, hysteresis and nonlinearity are removed with digital calibration technology Environment variable, the final output and measured current value into an ideal ratio of the voltage value, to achieve isolated current measurement.


Isolation measurement, isolation withstand voltage up to 2KV @ 50Hz, 1 minute

It can measure DC and AC current

Current conductor impedance: 20m Ω

Response time as low as 4.5us

Wide working temperature range: - 40 ℃ ~ 125 ℃

Wide range of measured current: 3A ~ 6A

High accuracy: the accuracy error is less than 1% at room temperature

Working temperature range: < 3% accuracy error

Strong driving ability, support output port connected to 2K Ω load

Extremely simple peripheral circuit

Built in IP over-current detection output function

Support wave soldering, automatic chip placement and tape packaging

It is not disturbed by wire magnetic field, external magnetic field and geomagnetic field


Independent research and development without technology dependence

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