The BQ25619 integrates charging, boost converter and voltage protection in a single device. It provides ultra-low termination current for switch-mode chargers, enabling full battery-capacity charging of wearables. The low quiescent current of the BQ25619 reduces battery leakage to 6 μA in shipping mode, saving battery energy and multiplying the shelf life of the device. The device is a highly integrated 1.5 A switch-mode battery charge management and system power path management device for single-cell Li-Ion and Li-polymer batteries. It features fast charging with high input voltage support for a wide range of applications such as wearables and earphone charging cases. The low-impedance power path optimizes switch-mode operation efficiency, reducing battery charging time and extending battery life during the discharge phase. Input voltage and current regulation, low termination current, and battery remote sensing provide maximum battery charging power. This highly integrated solution features a reverse blocking field effect transistor (RBFET, Q1), high-side switching FET (HSFET, Q2), low-side switching FET (LSFET, Q3), and battery FET (BATFET) between system and battery , Q4). It integrates a cathode load diode for high-side gate drive to simplify system design. The I2C serial interface with charging and system setup makes this device a truly flexible solution.

The BQ25619 supports a variety of input sources, including standard USB host ports, USB charging ports, USB-compatible high-voltage adapters, and wireless power. Complies with USB 2.0 and USB 3.0 power specifications with input current and voltage regulation. The device obtains results from detection circuitry in the system, such as a USB PHY device. The BQ25619 integrates a buck charger and boost regulator into a single inductor solution. Boost mode provides 5 V on the PMID pin (adjustable 4.6 V/4.75 V/5 V/5.15 V) for reducing the BOM and charging another battery under the control of PMID_GOOD. The PMID_GOOD pin is used to drive an external PMOS FET to disconnect the boost output PMID from connected accessories. Power path management uses an adapter to regulate the system to a level slightly above the battery voltage, but does not drop below the minimum system voltage (programmable) of 3.5 V. With this feature, the system will continue to operate even if the battery is completely drained or removed. When the input current limit or voltage limit is reached, power path management automatically reduces the charge current to zero. As the system load continues to increase, the power path discharges the battery until the system power requirements are met. This supplemental mode prevents overloading of the input source.

The entire process of the BQ25619 starting and completing a charge cycle requires no software control. It detects the battery voltage and charges the battery in three stages: preconditioning, constant current and constant voltage. At the end of the charging cycle, the charger automatically terminates when the charging current is below a preset limit and the battery voltage is above the charging threshold. If the battery level falls below the charging threshold when fully charged, the charger will automatically start another charging cycle. The charger provides various safety features for battery charging and system operation, including battery NTC thermistor monitoring, charge safety timer, overvoltage and overcurrent protection. Thermal regulation reduces charge current when the junction temperature exceeds +110°C. Status registers report charging status and fault conditions. With I2C, the VBUS_GD bit indicates whether a good power supply is present, and the INT output immediately informs the host in the event of a fault. The device provides a QON pin for enable and reset control of the BATFET to exit low power ship mode or full system reset functionality. The BQ2619 device is available in a 24-pin 4 mm × 4 mm × 0.75 mm thin WQFN package to simplify layout.

characteristic

Single-chip solution to charge wearable accessories via adapter or battery

High Efficiency, 1.5 MHz, Synchronous Switch Mode Buck Charger

Boost Mode Output 4.6 V to 5.15 V

Single input supports USB, high voltage adapter or wireless power

Narrow VDC (NVDC) Power Path Management

Flexible I2C configuration and automatic charging for optimal system performance

Highly integrated, including MOSFETs, current sense and loop compensation

Low RDS(ON) 19.5 mΩ BATFET minimizes charging losses and extends battery life

Low battery leakage current (7 μA) and system standby current (9.5 μA) in shipping mode

High-precision battery charging curve

application

Consumer wearables, smart watches

Personal Care and Fitness

Headphones/Headphones with Microphone

Earbuds (true wireless or TWS) charging case

Hearing aid charging case

BQ25619EVM