60 V current mode synchronous step-down controller has onboard start-up regulator

Linear Technology Corporation has introduced the LT3800, a current mode, high-voltage step-down controller said to offer excellent line and load regulation as well as fast transient response that operates without the need for an auxiliary dc/dc regulator for startup. An integrated regulator provides IC power directly from input supply.

The LT3800 operates from 4 V to 60 V supplies and regulates output voltages ranging from 1.23 V to 36 V at load currents up to 10 A. By driving N-channel MOSFETs synchronously with maximum gate-source “ON” voltage, the controller operates at 94% efficiency while converting 60 V input to 12 V at 36 W output. Burst mode operation reduces no load quiescent current to less than 100 ìA, as required in automotive maintenance power supplies. The LT3800 has applications in 12 V and 42 V automotive systems, according to the company.