The MAX1843 uses a unique current-mode, constant-offtime, PWM control scheme, which includes Idle ModeTM to maintain high efficiency during light-load operation. The programmable constant-off-time architecture sets switching frequencies up to 1MHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1843 features an adjustable soft-start to limit surge currents during startup, a 100% duty-cycle mode for low dropout operation, and a low-power shutdown mode that disconnects the input from the output and reduces supply current below 1A. The MAX1843 is available in a 28pin QFN package with an exposed backside pad.