RBO40

[Padg]

Hello,

I am trying to build a power supply to power a vehicle tracker.  Can I use two RBO40 in series, so the output of first RBO40 connected to input of second RBO40?  Reason, when a thief steals a vehicle they want to stop the tracker working and sending out GPS coordinates, and quickly.  If they find the tracker's power cable but cannot find tracker because they are quickly working in a public area like a car park they might consider using high voltage like connecting up to 230volts to kill the tracker.  While we can never be sure what actions the attacker will do my thinking is the first RBO40 will be toast and assuming it has created an open circuit, the second RBO40 will continue to ensure nothing bad happens to the battery backed tracker.

Putting the above scenario aside, and it isn't my question because there are too many ifs and buts, my question to ST Community is can I safely use two RBO40 in series for about $2-4 to protect $200-400 of components?

Thanks.

[Peter BENSCH]

Well, your scenario doesn't work because the RBO40 have a peak load dump voltage of 80V. If you apply 230V between two RBO40s connected in series, there will be a big bang and both RBO40 including the tracker will be fried - but also the vehicle that is (or was) connected before the first RBO40.

The more you want to protect the tracker, the more you have to rely on its complete autonomy, e.g. with integrated batteries and a housing that is as burglar-proof as possible and is attached to the vehicle as stably as possible (e.g. welded on?). It would also be conceivable to deactivate the tracker via Bluetooth so that it does not send any coordinates when it detects movement (via MEMS) if it is being used legally. With a stainless steel housing, the thief would have a while to grind or saw it open. But how do you get both the Bluetooth and GSM antennas outside without the thief recognizing and destroying them?

Whatever you do - if the cost of the theft protection is significantly higher than the object to be protected, there is probably no point in doing so.

Hope that helps?

Regards
/Peter

[Padg]

Thanks Peter for getting back to me.  I am glad you thought my scenario was interesting, something a little different from the norm:)  I completely agree the perfect solution would be complete autonomy, but unfortunately for me batteries for trackers still need recharging regularly from the host vehicle to power the wireless bits like mobile 4G/5G.  And yes I am starting to think the same the RBO40 isn't really the solution, building an overvoltage protection circuit would be better way to go.

Getting back to my main question, can two RBO40 be connect in series and work okay, your reply suggest they can be, great. 

Cheers.

[Peter BENSCH · Accepted solution]

You can certainly connect two or more RBO40 in series, but this has no useful function. As mentioned, this does not help against the application of a high voltage in your case.