Various embodiments include a voltage adjusting block (VAB) coupled to a light emitting diode (LED) string. The VAB includes a first switch having a first lead connected to a voltage input, and having a second lead, the first switch having a controllable duty cycle, a first diode having a cathode connected to the second lead of the first switch, and having an anode, a first inductor having a first lead connected to the cathode of the first diode, and having a second lead, and a first capacitor having a first lead connected to the anode of the first diode and having a second lead connected to the second lead of the first inductor. The VAB may provide a variable voltage across the anode of the first diode and the second lead of the first capacitor dependent upon a number of LEDs in the LED string being turned on.