TI BQ25121AYFPR

The BQ25121A is a highly integrated battery charging management IC that integrates the most commonly used functions for wearable devices: a linear charger, regulated output, load switch, manual reset (with the help of a timer), and battery voltage monitoring. This integrated buck converter is a high-efficiency, low-I₀ switch that uses DCS-Control™ to extend light-load efficiency with load currents as low as 10 μA. The low quiescent current during operation and shutdown helps extend battery life. The device supports charging currents from 5 mA to 300 mA. Parameters such as input current limit, charging current, buck converter output voltage, and LDO output voltage can all be programmed via the I²C interface. The device charges the battery in three stages using a standard lithium-ion charging curve: pre-charge, constant current, and constant voltage. The device includes a voltage-based JEITA-compliant battery pack thermistor monitoring input (TS) that can monitor the battery temperature and automatically change the charging parameters to prevent the battery from charging at temperatures outside its safe temperature range. This charger is optimized for a 5V USB input and can withstand 20V line transient voltages. The buck converter is powered by the input or the battery. When in battery-only mode, the device can operate on a battery with a voltage up to 4.65V. With the configurable load switch, the device can disconnect from infrequently used devices to optimize the system. The timer manual reset function enables various different configuration options for optimized wake-up and reset. A simple voltage-based monitor provides the host with battery charge information, with a unit increment of 2% in the 60% to 100% charge range of the programmed V(BATREG).

• Extended system runtime after charging
• Configurable 300mA buck regulator (default voltage 2.5V)
• 700nA (typical) Iq with buck converter enabled (no load)
• Configurable load switch or 100mA LDO output (load switch enabled by default)
• Up to 300mA charge current for fast charging
• 0.5% battery regulation accuracy (configurable voltage range 3.6V to 4.65V, 10mV step)
• Configurable termination current as low as 500μA
• Voltage-based simple battery monitor
• Watchdog timer disabled
• Highly integrated solution in compact package
• 2.5mm x 2.5mm WCSP package with 6 external components for minimum footprint solution
• Push-button wake-up and reset via adjustable timer
• Power path management for system power supply and battery charging
• Power path management enables <50nA ship mode battery quiescent current to maximize shelf life
• Battery charger operating voltage 3.4V–5.5V VIN (5.5V OVP / 20V withstand voltage)
• Dedicated pins for input current limit, charge current, termination current, and status output
• I²C communication control: charge voltage and current, termination threshold, input current limit, VINDPM threshold, timer options, load switch control, fault interrupt and status control, system output voltage regulation, LDO output voltage regulation

• Smartwatches and other wearable devices
• Fitness accessories
• Health monitoring medical accessories
• Rechargeable toys