STM32 pin short circuit to ground analysis

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Analysis of STM32 pin short circuit to ground

The inside of the chip is also a multi-layer structure like PCB. Generally, integrated circuits have at least a dozen layers, and some can reach dozens of layers; but the distance between layers is much smaller than the inter-layer spacing on PCB. The smaller the wire diameter of the chip, the smaller the inter-layer spacing; when a large voltage is introduced from the I/O port, the incoming large current can not only damage the circuit connected to the I/O port, but this large voltage is also likely to break through the insulation between layers, causing an inter-layer short circuit; if the insulation between layers is damaged, it is not surprising that the power supply and ground of the chip are short-circuited. Do not let the I/O load exceed the scope of the document, add driver chips and isolation. Some signal lines are pulled up to 5V, the pull-up resistor value is too small, the input current of the IO port is too large, and the voltage applied to the IO is greater than 3.3V, which will also cause burning. Later I learned that if there is a power short circuit in the STM32 circuit, the first suspect must be it. STM32 uses a 0.18μm process with a high degree of integration. Therefore, compared with other products with lower integration, its overload tolerance is relatively poor, but within the range specified in the data sheet, there is definitely no problem. I once used an oscilloscope to measure the pins and accidentally touched the two pins together with a probe, and it broke. Later, I was afraid and was careful not to make the same mistake again. Add 24V directly to CAN, and then it broke. One piece was broken as a whole, and another piece was broken in the CAN part. I simplified the standard jtag interface into an 8-pin IDC socket. When plugging in the jtag, I was dazzled and only plugged in one row. After discovering it, I plugged it in again, and the chip burned. The burning phenomenon is a power short circuit. The measures taken are to add current limiting resistors to all I/O ports. Consider whether the system design involves wireless communication. It is easy to burn, especially when downloading programs. IO terminal voltage overvoltage/current overload, or even static electricity accumulation (bad grounding) can cause chip burning. Generally, there must be an external voltage and current limiting circuit and short-circuit protection isolation before connecting to the chip's IO terminal. Moreover, for chips that are often fully loaded, heat dissipation is also very important, and an external cooling fan is required (somewhat similar to the CPU of a PC); when applied to industrial control, the separation and control of weak current/strong current must also be considered. It is best to use a PLC with a reasonable cost-effectiveness to connect strong current, and the STM chip will be responsible for weak current signal processing. If the two work together, the failure rate and damage rate of the chip can be effectively reduced.