Hi @jbkiwi your right in that the TI part may support up to 18V but there is on board limit also (I believe thermal fuse rated to 15V max) so do not exceed 15V - see here per our earlier exchange in LG191 AU thread
Note also I have found that operation at lower supply limit leaves system prone to issues where (most likely due to brown-out protection mechanisms per exchange with Laird team) when supply applied if voltage ramp isnt fast enough board may not kick in properly - I found feeding supply ‘quickly’ via e.g. a switched relay feed once stable gives fast enough Vin ramp to avoid problems. At slightly higher Vin it doesn’t seem to be a problem. I need to experiment with a couple of systems to find the ‘safe’ operating area/ramp.
Thanks for the heads up. You are correct, it’s a 3A 15V Polyfuse. It’s a large 2920 surface mount device (LittleFuse 2920L300/15) so if you really need that extra 3 volt range you could swap it out, or replace it with a glass fuse.