Looking for someone with a bit more experience to recommend me a logic level, SMD (could be through hole if required) MOSFET, for the following application:-
Source voltage would be 7.2-12V, more than likely form AA's, but could be from a 12V SLA or a LiON.
I need to switch that directly across a thermo igniter, essentially an electric match. These igniters are then used to fire pblicly available pyrotechnics, such as a smoke grenade or flashbang.
Now, with AA's in series, maximum current should remain the same so they should not be able to deliver more than a couple of Amps, and it will be for fraction of a second, maybe 200-500ms transient. The igniters are essentially self destroying and go open circuit anyway, but I'll still pulse the output.
I could insert a resistor into the circuit, but I'd need one that could cope with the current, voltage and transient time and continue to operate for 1000's of operations.
My initial thoughts are that a well rated MOSFET could just switch these from AA's, but the complication comes if a battery is being used which can source a higher maximum current.
Measured resistance of e-match is 1.5 Ohms, so a 12v source would give a maximum transient current of 8A, then dependent on the batteries ability to actually deliver that.
It would more typically be 9v (via 6 x AA in series), so theoretical maximum 6A.
The datasheet on Duracell Procell AA's doesn't state maximum discharge, but just says that it could deliver 1A with a discharge curve indicating less than 1 hour. (Datasheet link attached).
Does anyone know typical short circuit currents for different battery types and can you advise on a suitable MOSFET or supplementary circuit to switch this type of transient load?
The same power source will provide 5v and 3.3v to AVR and other items, via linear regulators, so my other concern is voltage dip affecting BOD. Could this be mitigated a little with some large reservoir caps on the input to the regs?
Thanks in advance for any help.