The MAX1692 is a low-noise, pulse-width-modulated (PWM), DC-DC step-down converter. It powers logic and transmitters in small wireless systems such as cellular phones, communicating PDAs, and handy-terminals. The device features an internal synchronous rectifier for high efficiency; it requires no external Schottky diode. Excellent noise characteristics and fixed-frequency operation provide easy post-filtering. The MAX1692 is ideally suited for Li-Ion battery applications. It is also useful for +3V or +5V fixed input applications. The device operates in one of four modes. Forced PWM mode operates at a fixed frequency regardless of the load. Synchronizable PWM mode allows an external switching frequency to control and minimize harmonics. Idle ModeTM (PWM/PFM) extends battery life by switching to a PFM pulse-skipping mode during light loads. Shutdown mode places the device in standby, reducing quiescent supply current to under 0.1A.