This design note shows the ZXLD1100 and ZXLD1101 driving series connected LEDs. The input
voltage range is 2.5V to 5.5V. The same circuit can be used for up to 6 LEDs.
The ZXLD1100 contains onchip open circuit LED protection. This function would require an
additional Zener and resistor with the ZXLD1101.