The TPS54540B is a 42-V, 5-A step-down regulator with an integrated high side MOSFET. Current-mode control provides simple external compensation and flexible component selection. A low-ripple pulse-skip mode reduces no-load-supply current to 146 µA. Shutdown supply current is reduced to 2 µA when the EN (enable) pin is pulled low. Undervoltage lockout is internally set at 4.3 V but can be increased using the EN pin. Output voltage start-up ramp is internally controlled to provide a controlled start-up and eliminate overshoot. A wide switching frequency range allows either efficiency or external component size to be optimized. Output current is limited cycle-by-cycle. Frequency foldback and thermal shutdown protects internal and external components during an overload condition. The TPS54540B is available in an 8-pin thermally enhanced HSOIC PowerPAD package.