A 1.2A 2MHz tri-mode Buck-Boost LED driver with feed-forward duty cycle correction

A flash LED Buck-Boost driver employs a dual duty cycle control and feed-forward duty cycle correction to achieve high efficiency over the entire Li-On battery voltage range of 3.0 to 5.2V. Fabricated in a 0.5μm CMOS process, the converter uses an external 1μH inductor and a 10μF capacitor and operates at 2MHz switching frequency. The measured peak efficiency is 83% and 87% at 1.2A and 0.6A LED currents, respectively. This achieved efficiency represents an improvement of more than 10% over conventional approaches.