QLite Driver

QLITE REV.A 7135*8 3.04A LED DRIVER specifications

This is most probably the world's most popular 17mm LED driver, and for good reason: It is super reliable, there is no noticeable PWM AND it features low battery warning and cutoff, among a host of other reasons.
Features:

Input voltage: 2.8V - 4.5V
Default Current: 3.04A
Constant current
PCB diameter: 17mm
PCB thickness: 1.6mm
Components height: 4.7mm
Memory function (sets in after 2 seconds)
No high pitch noises
No visible flicker on any mode
Reverse polarity protection
Gold plated spring
Gold plated contacts
Low voltage protection: At 2.9-3V the light will switch to an emergency low mode. At 2.8V the light will flash 9 times to announce imminent cut-off.