I need to drive a single led (Vf=3.3v, If=750mA) with a lipo cell (from 2.7 to 4v).
From what I've read, a buck driver will regulate the output current with a maximum output voltage of roughly Vin. This device will be suitable when the battery voltage is within 3.3v and 4v but not within 2.7v and 3.3v.
On the other hand, a boost driver will regulate the output current with a minimum output voltage of roughly Vin and a maximum which depends on the device (and some other stuffs). This device will be suitable when the battery voltage is within 2.7v and 3.3v but not within when it is more than 3.3v.
None of the above solution works over the full input voltage range (2.7 to 4v).
Did I understood somehing wrong? What's the good solution?