The PAM2804 is a step-down constant current LED driver. When the input voltage down to lower than LED forward voltage, then PAM2804 run into LDO mode. The PAM2804 supports a range of input voltages from 2.5V to 6.0V, allowing the use of a single Li+/Li-polymer cell, 3AA or 4AA cell, USB, and other standard power sources. The FB voltage is only 0.1V to achieve high efficiency. PAM2804 employ internal power switch and synchronous rectifier to minimize external part count and realize high efficiency. During shutdown, the input is disconnected from the output and the shutdown current is less than 1μA. Other key features include undervoltage lockout to prevent deep battery discharge of the Li+ battery.