The SIM card holder provides the communication interface between the mobile phone and the SIM card in the mobile phone, and contacts the SIM card through the spring sheet on the card holder. Therefore, if the spring sheet is deformed, the SIM card will fail, such as “check card”, “insert card”, etc. There are two types of SIM card power supply: 3V and 5V. In the early days, the SIM card of mobile phone was usually 5V, but now it is mostly 3V. SIM card clock is 3.25mhz; The I / 0 terminal is the data input / output port of the SIM card. When the SIM card circuit is activated, the pulse signal shape can be measured at the SIM card clock and card data port.
Basic knowledge of SIM card holder. The SIM card holder is the SIM card in the mobile phone, which can be distinguished according to the size of different mobile phone models and specifications. The SIM card holder can be divided into large, medium and small cards, and the SIM card holder has several basic SIM card interface terminals: card clock (simclk), card reset (simrst), card power supply (simvcc), ground (simgnd) and card data (Simi / 0 or SIMDAT).
Pin usage characteristics of SIM card holder: 1. Storage capacity of SIM card holder: generally, SIM card holder has 8KB storage capacity, and there are sim card holders with capacity of 16K / 32K / 64K / 128K respectively. 2. Operating temperature of SIM card holder: the standard temperature is – 25 + 70 ℃. Under extreme conditions, each use shall not exceed 4 hours, and the total use shall not exceed 100 times. 3. Service life of SIM card holder: the physical life depends on the number of times the customer plugs in and out, about 10000 times; The life of integrated circuit chip depends on the number of writes of data memory, and its indicators vary from manufacturer to manufacturer.