The ISL6227 dual PWM controller delivers high efficiency precision voltage regulation from two synchronous buck DC/DC converters. It was designed especially to provide power regulation for DDR memory, chipsets, graphics and other system electronics in Notebook PCs. The ISL6227's wide input voltage range capability allows for voltage conversion directly from AC/DC adaptor or Li-Ion battery pack. Automatic mode transition of constant-frequency synchronous rectification at heavy load, and hysteretic (HYS) diode-emulation at light load, assure high efficiency over a wide range of conditions. The HYS mode of operation can be disabled separately on each PWM converter if constant-frequency continuous-conduction operation is desired for all load levels. Efficiency is further enhanced by using the lower MOSFET rDS(ON) as the current sense element. Voltage-feed-forward ramp modulation, current mode control, and internal feedback compensation provide fast response to input voltage and load transients. Input current ripple is minimized by channel-to-channel PWM phase shift of 0, 90 or 180 (determined by input voltage and status of the DDR pin).