Sofirn SP33S 5000 Lumen Flashlight w/ Battery (5000K or 6500K color temperature) Expired

From what I understand the sc31 uses a sst40 LED which operates at 3v. Budget lights that use 3v emitters usually have a combination driver that's composed of a mosfet and a linear driver. This is commonly labeled as FET+1, or FET+ n, N being the number of AMC7135 linear drivers (they're usually 7135 drivers since they're simple, cheap, and commonly available). The 7135 driver only supplies 350ma so multiples are sometimes implemented for higher current needs. The mosfet portion acts as a light switch that pumps whatever voltage and current the battery is capable of supplying into the led. This is highly inefficient but allows a huge amount of light output with few and inexpensive components.. Dimming is accomplished by PWM. Full brightness pwm can only work so much, so at low brightness levels the linear driver takes over and acts as a variable resister. supplying whatever voltage the brightness is set at to the led while bleeding off the rest of the voltage as heat. For example if the brightness is set to supply 2.8v to the LED and the battery is currently at 3.5v, the linear driver supplies the 2.8v to the LED and burns off the excess 0.7v as heat. It's inefficient but cheap and reliable. Though depending on implementation the 7135 drivers may use PWM also, effectively acting like a mini reduced brightness FET of sorts.

The SP33S flashlight uses a XHP70.2 LED which operates at either 6v or 12v (not sure which for this particular flashlight, I know the Acebeam L35 uses a xhp70.2 in 6v configuration). This necessitates a boost driver that is capable of boosting the 2.7v-4.2v of the Li-ion battery to the operating 6v or 12v. These drivers are much more complex and expensive, but they have the advantage of being very efficient (upwards of 96% vs around 70% for linear drivers). And they are capable of maintaining constant brightness until the battery is empty. A FET driver, as usually implemented in more budget flashlights, can't do this as it is pumping whatever voltage the battery cell is at into the LED. So as the cell lowers in voltage, so does the light output of the LED. A fully regulated driver like a boost circuit doesn't care what voltage your battery is at, it'll just boost it to whatever voltage you set it to.

Now some more expensive implementation of linear drivers don't use PWM and instead use large high current capable mosfet in linear mode. Where any setting below full brightness, as previously explained, it supplies whatever voltage it is set at to the LED and bleeds off the excess as heat. And at full brightness lets the battery pump whatever it's capable of into the LED. This can result in some hilariously impractical but fun lights like the Emisar DT8. Which is a light slightly larger than a safety razor that can blow out 8000 lumens at startup...for like 10 seconds before it thermal throttles.

This should help. https://www.olightstore.com/blog/...emperature

The "6500k" and "5000k" refer to the color (kelvin) of the light. A 6500k is going to have a tint of blue while 5000k will be more white with a tinge of blue. Really a preference thing.