Ematch Drive Circuit

When ematch connected: 
PYRO_SNS is at 0.28V --> indicates ematch continuity
3mA going through ematch (assuming 1ohm from MJG Firewire Initiator specs) --> not enough to blow

After pulling PYRO_CTRL high:
PYRO_SNS pulled up to 3.3V
2.28A going through ematch --> blows

After event:
PYRO_SNS pulled to 3.3V --> indicates no ematch

Can use digital GPIO on VoCore2 for continuity:
VIL =  0.8V, VIH = 2V
Low = ematch connected
High = ematch not connected

LTSPICE Simulations:

 Ematch_Continuity.asc

Ematch_Continuity_Blown.asc