The LM3673 step-down DC-DC converter is optimized for powering low voltage circuits from a single Li-Ion cell battery and input voltage rails from 2.7 V to 5.5 V. It provides up to 350-mA load current over the entire input voltage range. There are several different fixed voltage output options available, as well as an adjustable output voltage version ranging from 1.1 V to 3.3 V. The device offers superior features and performance for mobile phones and similar portable systems. The LM3673 uses intelligent automatic switching between pulse width modulation (PWM) and pulse frequency modulation (PFM) for better efficiency. During PWM mode, the device operates at a fixed-frequency of 2 MHz (typical). Hysteretic PFM mode extends the battery life by reducing the quiescent current to 16 µA (typical) during light load and standby operation. Internal synchronous rectification provides high efficiency during PWM mode operation. In shutdown mode, the device turns off and reduces battery consumption to 0.01 µA (typical). The LM3673 is available in a tiny 5-pin DSBGA package. A high switching frequency of 2 MHz (typical) allows the use of three tiny surface-mount components: an inductor and two ceramic capacitors. For all available packages, see the orderable addendum at the end of the data sheet.