The TPS62745 is a high efficiency ultra low power synchronous step down converter optimized for low power wireless applications. It provides a regulated output voltage consuming only 400-nA quiescent current. The device operates from two rechargeable Li-Ion batteries, Li-primary battery chemistries such as Li-SOCl2, Li-SO2, Li-MnO2 or four to six cell alkaline batteries. The input voltage range up to 10 V allows also operation from a USB port and thin-film solar modules. The output voltage is set with four VSEL pins between 1.8 V and 3.3 V for TPS62745 or 1.3 V and 2.8 V for TPS627451. TPS62745 features low output ripple voltage and low noise with a small output capacitor. An internal input voltage switch controlled by pin ENVINSW connects the supply voltage to pin VINSW. The switch is intended to be used for an external voltage divider, scaling down the input voltage for an external ADC. The switch is automatically opened when the supply voltage is below the undervoltage lockout threshold. The TPS62745 is available in a small 12 pin 3 mm × 2 mm WSON package.