Using CMOS flip-flops in Automobile application

[holabr]

I've been working on a circuit using CMOS 4013 Flip-Flops. Can I feed power to these circuits directly from a 15 amp circuit in the vehicle without any type of conditioning and/or current limiting circuit? Can I also use a direct connection to a switched power source like the lights or horn to trigger and reset the 4013? I want to make sure I don't fry the circuit.

 

[Pjdd]

The high amp capacity of a power source has nothing to do directly with the safety of using it to supply a low-power load. The 15-amp capacity is simply the maximum load the power source can withstand without being overloaded. That said, it's always a good idea to have some form of fusing or cut-out protection to protect the power source in case the load gets shorted.

Yes, you can trigger a FF directly from such switched circuits. But power in a vehicle is usually very dirty with spikes and fluctuations. It's best to incorporate filters and spike suppressors before feeding them to sensitive CMOS circuits.

---------- Post added at 13:37 ---------- Previous post was at 13:12 ----------

The amp capacity of a power source has nothing to do directly with the safety of using it to supply a low-power load. The 15-amp capacity is simply the maximum load it can safely supply without becoming overloaded. That said, it's always a good idea to have some form of fusing or cut-out provision to protect the source in case the load becomes shorted.

Yes, you can use the switched circuit to trigger the FF. But a vehicle power supply system is usually very dirty, with spikes and fluctuations superimposed on the basic 12V rail which may damage sensitive CMOS devices. It's best to incorporate filtering and spike suppression before applying it to the FF circuit.

(P.S.: I posted my reply some 15-20 minutes ago and it showed up on the thread, but it's gone now. Don't know why. So I'm posting it again.)

 

[holabr]

Is there a simple and cheap way for me to filter the switched circuits that I am using for triggers?