The MAX38656 is an ultra-low IQ (420nA) buck converter that steps down from an input voltage range of 1.8V to 5.5V to a wide range of output voltages between 0.7V to 3.3V using a single resistor at the RSEL pin for the MAX38656A or factory-preprogrammed fixed output voltage versions from 0.7V to 5V for the MAX38656B. For the MAX38656B, the RSEL pin can be left floating. The MAX38656 buck converter offers robust performance features. To optimize efficiency and transient response across the load range, the buck converter automatically switches between ultra-low-power mode (ULPM), low-power mode (LPM) and high-power mode (HPM) to service the load better, depending on the load current. The buck converter overregulates in ULPM to allow the output capacitor to handle the transient load currents. See Figure 1 for the MAX38656 mode transitions. The device supports 100% duty-cycle operation. In applications where the ambient temperature is more than +85°C, make sure that the load current is always more than 10μA at the output of buck converter. The active discharge resistor in the MAX38656A/MAX38656B pulls OUT to ground when the part is in shutdown. Key Applications * Portable Space-Constrained Consumer Products * Wearable Devices, Ultra-Low-Power Internet of Things (IoT), Narrowband IoT, and Bluetooth Low Energy * Single Li-Ion and Coin Cell Battery Products * Wired, Wireless Industrial Products * Extends Battery Life * 420nA Ultra-Low Quiescent Supply Current * 5nA Shutdown Current * 95% Peak Efficiency and over 85% at 10μA * Easy to Use—Addresses Popular Operation * 1.8V to 5.5V Input Range * Single Resistor-Adjustable VOUT from 0.7V to 3.3V (MAX38656A) * Preprogrammed VOUT from 0.7V to 5V (MAX38656B) in Steps of 50mV * 100% Duty-Cycle Mode for Low-Dropout Operation * ±1.5% Output Voltage Accuracy * Up to 1.5A Load Current