STMicroelectronics' STBB2 is a fixed frequency, high efficiency, buck-boost DC-DC converter, able to provide output voltages from 1.2 V to 4.5 V starting from input voltage of 2.3 V to 5.5 V. The device can operate with input voltages higher than, equal to, or lower than the output voltage making the product suitable for single Li-Ion, multi-cell alkaline, or NiMH applications where the output voltage is within the battery voltage range. The low-RDSon N-channel and P-channel MOSFET switches are integrated and contribute to achieving high efficiency. The MODE pin allows selection between auto mode and forced PWM mode, therefore benefiting from either lower power consumption or best dynamic performance. The bypass function allows battery power saving. In this operating mode, the high-side switches are turned on so that the output voltage is equal to the input voltage; in this condition, the current consumption is reduced to a maximum of 5 μA. The device includes also soft-start control, thermal shutdown, and current limit. The STBB2 is packaged in Flip Chip 20 bumps with 0.4 mm pitch.