The TPS61023 synchronous step-up converter is designed to operate from an input voltage supply range between 0.5 V and 5.5 V with 3.7-A (typical) valley switch current limit. The TPS61023 typically operates at a quasi-constant frequency pulse width modulation (PWM) at moderate to heavy load currents. The switching frequency is 1 MHz when the input voltage is above 1.5 V. The switching frequency reduces down to 0.5 MHz gradually when the input voltage goes down from 1.5 V to 1 V and keeps at 0.5 MHz when the input voltage is below 1 V. At light load conditions, the TPS61023 converter operates in power-save mode with pulse frequency modulation (PFM). During PWM operation, the converter uses adaptive constant on-time valley current mode control scheme to achieve excellent line regulation and load regulation and allows the use of a small inductor and ceramic capacitors. Internal loop compensation simplifies the design process while minimizing the number of external components.