General Description
The MAX20356 is a highly integrated and programmable power-management solution designed for ultra-low-power wearable applications. It is optimized for size and efficiency to enhance the value of the end product by extending battery life and shrinking the overall solution size. A flexible set of power-optimized voltage regulators including multiple buck converters, a buck-boost converter, and linear regulators provide a high level of integration and the ability to create a fully optimized power architecture. The quiescent current of each regulator is ultra-low to extend battery life in always-on applications.
The MAX20356 includes a complete battery-management solution with battery seal, charger, power path, and fuel gauge. Both thermal management and input protection are built into the charger. The device also includes a factory-programmable button controller with multiple inputs that are customizable to fit specific product user requirements.
A low-noise, 1.5W buck-boost converter provides highly efficient and clean power conversion required for the LEDs used in optical heart-rate systems such as PPG and SPO2 measurements. The MAX20356 is also equipped with a nano IQ fast transient LDO, optimized for use in analog front-end (AFE) sensors. The MAX20356 is configurable through an I2C interface that allows for programming various functions and reading the device status, including the ability to read temperature and supply voltages through the monitor multiplexer.
The MAX20356 is available in a 63-bump, 0.5mm pitch, 3.71mm x 4.48mm, wafer-level package (WLP) and operates over the -40°C to +85°C extended temperature range.

Benefits and Features
• Extend Time Between Charges
• 3 x Nano-IQ, 400mA Buck Regulators (IQ = 400nA typ)
- 0.500V to 1.130V in 10mV Steps
- 0.500V to 2.075V in 25mV Steps
- 0.500V to 3.650V in 50mV Steps
• 2 x Micro-IQ LDO/Load Switches (IQ = 1μA typ)
- 1.71V to 5.5V Input-Voltage Range
- 100mA Output-Current Capability
- 0.900V to 4.0V in 100mV Steps
• Nano-IQ Fast Transient LDO (IQ = 820nA typ)
- Optimized for use with Sensor AFEs
- 1.71V to 5.5V Input-Voltage Range
- 100mA Output-Current Capability
- 0.900V to 4.075V in 25mV Steps
• Nano-IQ Real-Time Clock LDO (IQ = 200nA typ)
- Always-On Configurable for RTCs in μC Timers
- 1.2V [+25mV, +50mV] and 1.8V [+25mV, +50mV]
• Micro-IQ Buck-Boost Regulator (IQ = 2μA typ)
- 1.5W Output
- 2.6V to 5.5V in 50mV Steps
- Dynamic Voltage Scaling
• 3 x Nano-IQ, Low On-Resistance Load Switches (IQ = 260nA typ)
- Low 0.25Ω (typ) On-Resistance
- Short-Circuit Protection
- Soft-Start Feature
• Easy-to-Implement Li+ Battery Charging
• Wide Fast Charge Current Range: 4mA to 500mA
• +28V/-5.5V Tolerant Input
• Programmable JEITA Current/Voltage Profiles
• Programmable Automatic Step-Charging
• Seamless Interaction with MAX20361 Solar Energy Harvester
• Multiple-Purpose Control Pins are Provided for Flexible Control
• Minimize Solution Footprint Through High Integration
• Programmable Push-Button Controller
• Programmable Supply Sequencing
• Battery Seal Shipping Mode
• On-Chip Voltage/Charge Current Monitor Mux

Applications
• Wearable Devices
• IoT