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Texas Instruments bq25121

bq2512x 700nA Low Iq Highly Integrated Battery Charge Management Solution for Wearables and IoT


TopologyBuck Converter
Input voltage3.4-5.5 V
Output 13.6 V / 0.3 A
IC revisionC


The bq2512x is a highly integrated battery charge management IC that integrates the most common functions for wearable devices: Linear charger, regulated output, load switch, manual reset with timer, and battery voltage monitor. The integrated buck converter is a high efficiency, low IQ switcher using DCS control that extends light load efficiency down to 10-µA load currents. The low quiescent current during operation and shutdown enables maximum battery life. The device supports charge currents from 5 mA to 300 mA. The input current limit, charge current, buck converter output voltage, LDO output voltage, and other parameters are programmable through the I2C interface.The battery is charged using a standard Li-Ion charge profile with three phases: precharge, constant current and constant voltage. A voltage-based JEITA compatible battery pack thermistor monitoring input (TS) is included that monitors battery temperature and automatically changes charge parameters to prevent the battery from charging outside of its safe temperature range. The charger is optimized for 5-V USB input, with 20-V tolerance to withstand line transients. The buck converter is run from the input or battery. When in battery only mode, the device can run from a battery up to 4.65 V.A configurable load switch allows system optimization by disconnecting infrequently used devices. The manual reset with timer allows mutliple different configuration options for wake are reset optimization. A simple voltage based monitor provides battery level information to the host in 2% increments from 60% to 100% of the programmed V(BATREG).


Increases System Operation Time Between ChargesConfigurable 300-mA Buck Regulator(1.8-V Default)700 nA (typical) Iq with Buck Converter Enabled (No Load)Configurable Load Switch or 100mA LDO Output (Load Switch by Default)Up to 300-mA Charge Current for Fast Charging0.5% Accurate Battery Voltage Regulation (Configurable from 3.6 V to 4.65 V in 10-mV Steps)Configurable Termination Current Down to500 µASimple Voltage Based Battery Monitor

Highly Integrated Solution with Small Footprint 2.5 mm × 2.5 mm WCSP Package and 6 External Components for Minimal SolutionPush-Button Wake-Up and Reset with Adjustable TimersPower Path Management for Powering the System and Charging the BatteryPower Path Management enables <50 nA Ship Mode Battery Quiescent Current for Longest Shelf LifeBattery Charger Operates from 3.4 V – 5.5 VIN (5.5-V OVP / 20-V Tolerant)Dedicated Pins for Input Current Limit, Charge Current, Termination Current, and Status Output

I2C Communication ControlCharge Voltage and CurrentTermination ThresholdInput Current LimitVINDPM ThresholdTimer OptionsLoad Switch ControlControls for Interrupts for Faults and StatusSystem Output Voltage AdjustmentLDO Output Voltage Adjustment

Typical applications

  • Fitness Accessories
  • Health Monitoring Medical Accessories
  • Rechargeable Toys
  • Smart Watches and other Wearable Devices