Overvoltage protection circuit of vehicle-mounted interface

Abstract

The invention discloses an overvoltage protection circuit of a vehicle-mounted interface, which relates to an overload protection circuit. Theovervoltage protection circuit of a vehicle-mounted interface comprises a first diode, a second diode, a signal processing circuit, a VCC end and an embedded circuit which are electrically connected, wherein the embedded circuit comprises a Clamp Hi end and a Clamp Lo end; the positive electrode end and the negative electrode end of the first diode are respectively connected with the detection pin of the protection element and the VCC end; the signal processing circuit receives an input signal and outputs the signal to the protection element; the negative electrode end of the second diode is connected with the detection pin of the protection element, and the positive electrode end of the second diode is connected with the Clamp Lo end; the Clamp Hi end is connected with the VCC end; and the embedded circuit enables the voltage of the protection element to be clamped between 0V and 4.9 V. By adopting the technical scheme provided by the invention, the voltage can be clamped in a voltage range of -0.5 to 5.5 V of the chip when the signal at the input end is overvoltage, and an optimal protection effect is achieved.

Description

technical field [0001] The present application relates to the technical field of overload protection circuits, in particular to an overvoltage protection circuit of a vehicle-mounted structure. Background technique [0002] At present, the on-board electrical environment is relatively harsh, especially for construction machinery vehicles. Due to the harsh working environment and the configuration of many high-power devices, the electrical environment of construction machinery vehicles is also very harsh, and the electrical requirements are very high. There are a large number of external high-power loads (such as relays, horns, light bulbs, etc.) Pressure protection requirements are very high. Therefore, the interface overvoltage protection for the input signal is particularly important, otherwise it is easy to cause circuit overvoltage damage. [0003] See figure 1 , figure 1 It is a traditional input signal overvoltage protection circuit, in which module a is a signal p...

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Problems solved by technology

Therefore, the interface overvoltage protection for the input signal is particularly important, otherwise it is easy to cause circuit overvoltage damage

[0003] See figure 1 , figure 1 It is a traditional input signal overvoltage protection circuit, in which module a is a signal processing circuit. Taking the input voltage of 5V as an example, when the input signal has high voltage noise, it will be higher than 5v after being processed by module a. Due to the conduction voltage drop of diode D1 The characteristic of 0.7V will embed the chip pin voltage at 5.7V, and for the IC chip working voltage of 5V, the detection pin withstand voltage is generally 5.5V, at this time there is a positive withstand voltage higher than the chip pin, There is a risk that the chip should be damaged; when the input signal has negative high-voltage noise, the voltage after processing by module a will be lower than 0V, and the voltage of the chip pin will be clamped at -0.7V, while the working voltage of the IC chip is 5V, and the withstand voltage of the detection pin is generally -0.5V. At this time, there is a voltage higher than the negative withstand voltage of the chip pin, which will cause the risk of damage to the chip and will also affect Chip service life

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