I'm trying to design an efficient circuit that is able to drive 4 independent (ie, connected in parallel) white LEDs and to control their intensity independently as well, through PWM. The thing is: most of the circuits I find were designed either for 3 "strings" (rows of LEDs), which is cool if you use RGB LEDs, or don't provide a way to control the intensity of each string.
Using multiple driver ICs, each one controlling a single row, would destroy the efficiency of the whole circuit.
The white LED I'm using: http://www.mouser.com/ds/2/311/LW%20Y1SG%20-%20Micro%20SIDELED-335725.pdf Forward voltage (max): 3.6V Current: 30mA
Also, two other requirements are: it should have low quiescent current (ideally < 1uA) and Vin(min) > 1.6V since the circuit may be powered by two alkaline batteries.
This is the first time I'm designing such circuit, so I'm very looking forward to hear some tips from those who have done this before. Thanks in advance!