Max VCC in automobile-rated IPS

[Rusttree]

I'd like to use the AUIR3313 as high-side switches for the starter, ignition, and accessories circuits in an automobile. Looks like it'll fit the bill, as long as I heat-sink it appropriately.

My one concern is the absolute rating for Vcc-Vout, which is 37V. When the switch is off, it'll feel the full voltage differential of the car's battery. I've read that load dumps can cause voltage spikes of up to 60V for a few ms. This IPS is designed for an automobile environment, so I have to assume it'll survive a load dump. Is that a safe assumption to make, even though the maximum Vcc-Vout is lower?

Thanks!

 

[kubeek]

You can put some kind of EMI filter infront of it. Something along the ways of a transil and inductor/ferrite bead or a resistor. I don´t really have the experience with car power systems, but you should be able to find some ways of overvoltage protection on the internet.

 

[Rusttree]

In the block diagram there's a 43V zener that looks like a voltage clamp. I suspect that would prevent a load dump from damaging the unit. But it doesn't specifically say that anywhere I can find in the datasheet. I'd rather not add any additional protection circuitry if this part has been designed with those concerns in mind already.

 

[Diver300]

Some cars now have central load-dump protection, so that 37 V would be more than they should ever see, even if the battery were disconnected with the engine running.

Also, the zeners would just make the switch turn on if there were to be a larger load dump, so I don't think that there would be a problem.

 

[Rusttree]

Cool, thanks Diver.

 

[Jaguarjoe]

When the car is started, the system voltage droops to a very low voltage, sometimes as low as 6v. Starter relays are special in that regard because they will energize at those low voltages thus allowing the car to start under less than ideal circumstances. Make sure that your device can do the same thing.