This MCU is being used for some of the new advanced firmwares. The attiny85 SU has a slightly wider profile, so it won't fit on most existing attiny13a/attiny25 drivers without some modification. The legs can be bent inwards to make this MCU fit on existing drivers, or drivers with a wider pad profile can be used.
This driver can only reliably run down to 2.7V, so set your low voltage protection accordingly (you shouldn't need to ever run much lower than that anyways with a single lithium-ion cell).
FIRMWARE PROGRAMMING OPTIONS (Clicky)
No clicky firmware options currently available.
FET+7135 FIRMWARE PROGAMMING OPTIONS (Momentary / E. Switch)
1. D4 UI V2
This momentary firmware is an offshoot of Narsil, modfied by Tom E. & ToyKeeper especially for the popular Emisar D4 Flashlight. This firmware is open source, available here.
Default Pin Assignments:
2 - E.Switch (other side of switch connects to ground)
5 - 7135 PWM
6 - FET PWM