The automotive environment is quite harsh for electronic products. Any circuit connected to a 12V power supply must withstand voltage changes that exceed the normal range of 9V to 16V. Other extreme conditions also include load dumps, cold starts, and reverse battery connections, double battery jumper, surge, noise and extremely wide temperature range, etc.
During a load dump, the alternator's output voltage ramps up to 60V or higher; cold cranking, the term used to describe starting a car in cold temperatures, will cause the battery voltage to drop to 6V or lower. Reverse battery polarity is caused by accidentally connecting the wrong polarity of the wires when connecting a dead battery. Many trailers are equipped with two 12V batteries in series to start these vehicles with dead batteries in cold weather. This will increase the entire electrical system to the 28V voltage range and continue until the vehicle is started. The trailer driver removes the jumper wires; and surges and noise are to be expected, because automotive electronic systems include high-current motors, relays, solenoid valves, lights and vibration switch contactors.
Also, the alternator - a three-phase device with chopping voltage regulation - sometimes charges the battery at very high currents; and finally, is a circuit designed to operate in an automotive environment - especially during load dump Circuits that need to withstand high input voltages when connected to double batteries.
| Type of surge | ESD | Surge | Load Dump | EFT | |||
|---|---|---|---|---|---|---|---|
| Application | SEA | STA | MLA | SHV | SHA | MLC | MLA |
| Standard | IEC16750 | IEC61000-4-5 | ISO10605-2 | IEC61000-4-4 | |||
SFI has developed the SHA series of multi-functional overvoltage protectors dedicated to automotive ECU power ports. SHA itself has a large capacitance that can provide better filtering effect on EMI noise. At the same time, SHA provides "ultra-small size SMD patch" packaging, and has "excellent high temperature characteristics" and "highest test standard of resistance to 5a". Compared with In terms of the "disadvantages" of "high temperature characteristic attenuation" and "unable to withstand multiple surge shocks" in TVS currently used in the market, SHA is the best choice for overvoltage components used in the automotive industry.
1.Large size of plug-in packaging (5 Å~14 Å).
2.High suppression voltage.
3.Large leakage current (<50μA).
4.Slow reaction speed (>100ns).
5.Severe deterioration phenomenon.
6.Failure modes may lead to combustion phenomena.
1.SMD package is larger than SHA.
2.Suppression voltage is lower than SHA.
3.Less resistant to continuous impact.
4.Fast reaction speed (<1ns).
5.Not resistant to high temperature environment 125℃.
