Necessity of lightning protection

With the continuous popularity of automobiles, people's demand for electronic products in automobiles is also increasing.For example: GPRS, video system, TPMS, HID, etc.However,? it will generate a large surge, which will cause damage to automotive electronic products when the car is turned on and does not work normally,. Therefore, the state proposes that the power supply of automotive electronic products needs to pass the surge capability test.

Protection and schematic diagram

Current of Automotive electronics usually is small, but it will general high current and high voltage when an abnormality occurs.We can start by shunting through the TVS tube at a PS level.Then disconnected by PPTC.

Why PTC,Because the response speed of TVS is very fast, but the current capacity of TVS is still very limited. If the TVS works for a long time, it will also cause damage to the TVS. PPTC is needed to disconnect the circuit to more effectively protect the circuit and protect the TVS.(The disconnection time of PPTC is very slow, so tvs also needs to be used, otherwise the back-end circuit will not work because the PPTC is too late to respond).

The Solution Note

Power Supply with 12V

TVS Diode: 5KP20A/CA-5KP33A/CA ( Depending on the clamp voltage of the back-end chip)

Power Supply with 24V?

TVS Diode: 5KP28A/CA-5KP48A/CA? (Depending on the clamp voltage of the back-end chip)

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