FAN5608

The FAN5608 LED driver generates regulated output currents from a battery with input voltage varying between 2.7V to 5V. An internal NMOS switch drives an external inductor, and a Schottky diode delivers the inductor's stored energy to the load. Proprietary internal circuitry continuously monitors the currrent on both strings and automatically adjusts the generated output DC voltage to the lowest minimum value required by the LEDs string with the highest summarized forward voltage. This adaptive nature of the FAN5608 ensures operation at the highest possible efficiency. Soft start circuitry prevents excessive current drawn from the supply during power on. Any number of LEDs can be connected in series as long as the summed forward voltages do not exceed the specified operating output voltage range. Although it is not required to have an equal number of LEDs connected in series within each branch, the highest efficiency and best current regulation is always achieved when an equal number of LEDs are serially connected.

In the FAN5608 device, two internal two-bit D/A converters provide independent programmability of each output channel current. Analog programming of the output current is also possible in the FAN5608. To do this, ground the "B" pins and connect a resistor between the "A" pins and a fixed supply voltage. The output current can then be programmed to any desired value within its specified range. The FAN5608DMPX/FAN5608MPX version uses a single