Driver: Difference between revisions

Though people call this type of driver a linear regulator, linear regulators regulate the voltage. However these drivers have a number of AMC7135 current regulating chips installed. Each chip allows 350mA of current through and when wired in parallel, the current adds, so 700mA from 2 chips, 1050mA from 3 chips, and 1400mA from 4 (some drivers have higher binned regulator chips that allow 380mA through). Wiring 2 boards with 4 chips each gives 2800mA which is ideal for P7, MC-E, and XM-L LED's. Constrained to a particular current, the LED will settle in at its [[Terminology#Vf|Vf]] for that current and the rest of the voltage from the battery will be converted to heat by the regulator chips. Because any voltage beyond the required amount is wasted as heat, supplying a higher voltage is less efficient and the board becomes more efficient as the input voltage approaches the output voltage. As the voltage supplied drops below the Vf of the LED plus some overhead for the chips, the driver drops out of regulation and goes into direct drive and the light will start to dim. These drivers can also have modes by using a microcontroller utilizing [[Terminology#PWM|PWM]] for lower modes and flashing modes.