PDA is for information collecting, processing, and transmitting in cold chain logistics, including loading, unloading, sorting, packaging, and distribution. It can speed up information integration and circulation in each link, and make fresh food cold chain visualized.
Most PDAs are not suitable for environment of unstable low temperature and high humidity. Operating workers also need PADs designed for low temp to solve the problem. Such PDA device is with low charging current and low cut-off voltage in a cold environment. NTC temperature sensor will be helpful for low-temp charging structure in PDA device. The NTC temperature sensor is usually installed in the battery module, together with the electrothermal film and battery cell.
The NTC temperature sensor is connected to the CPU module and the charging chip. The NTC temperature sensor is used to detect the real-time temperature of the battery cell and send back the information to the CPU module and the charging chip.
If the temperature of the battery cell is ≥0°C, the charging power source of the power adapter supplies power to the charging chip, and the charging chip charges the battery cell until the battery cell is fully charged or the power adapter is unplugged; if the temperature of the battery cell is <0°C, then the charging power supply of the power adapter will supply power to the heating control circuit and the electric heating film.
The heating wire in the electric heating film is energized and generates heat to heat the battery cell, and the charging chip does not charge the battery cell; during the heating process, the NTC temperature sensor continuously detects the battery charge core temperature; if the temperature of the battery cell is ＞0°C, the CPU module controls the charging chip to charge the battery cell; when the NTC temperature sensor detects that the battery cell temperature reaches 5°C, the CPU module controls the heating control circuit to shut down , the heating wire stops heating, and the charging chip continues to charge the battery cells until the battery cells are fully charged or the power adapter is unplugged. When the battery cell temperature ＞ 60°C, the CPU module will help the alarm module to send out an alarm。
The temperature sensor of PDA is an epoxy coated NTC temperature sensor, which is with small size, small volume, better performance, high reliability and high cost performance. Its operating temperature range is -40°C-150°C, which can meet the low temperature requirements of PDA.