TheBQ25618/619 integrates charge, boost converter and voltage protection in a single device. It offersthe industrys lowest termination current for switching chargers to charge wearable devices by fullbattery capacity. The BQ25618/619 best-in-class low quiescent current reduces battery leakage downto 6 uA in ship mode, which conserves battery energy to double the shelf life for the device.BQ25619 is in 4x4 QFN package for easy layout. BQ25618 is in 2.0x2.4mm2 WCSP package for spacelimited design.
The BQ25619/618 is a highly integrated1.5-A switch-mode battery charge management and system PowerPath management device for Li-Ion and Li-polymer battery. It features fast charging with high inputvoltage support for a wide range of applications including wearables, and earphone charging case. Its lowimpedance power path optimizes switch-mode operation efficiency, reduces battery charging time andextends battery run time during discharging phase. Its input voltage and current regulation,low termination current, and battery remotesensing deliver maximum charging power to the battery. The solution is highly integratedwith input reverse-blocking FET (RBFET, Q1), high-side switching FET (HSFET, Q2), low-sideswitching FET (LSFET, Q3), and battery FET (BATFET, Q4) between system and battery. It alsointegrates the bootstrap diode for the high-side gate drive for simplified system design.TheI2C serial interface with charging and system settings makes the device a truly flexible solution.
The device supports a wide range of input sources, including standard USB host port, USBcharging port, USB compliant high voltage adapter and wireless power. It is compliant with USB 2.0and USB 3.0 power spec with input current and voltage regulation. The device takes the resultfrom detection circuit in the system, such as USB PHY device.
The device integrates the buck charger and boost regulator into one solution with singleinductor. Theboost mode supplies 5V (adjustable 4.6 V/4.75 V/5 V/5.15 V) on PMID pin. The boost mode is used tosave BOM and charge another battery by the control of PMID_GOOD.The PMID_GOOD pin is used to drivethe external PMOS FET to disconnect boost output PMID from the attached accessories.
The Power Path management regulates the system slightly above battery voltage but doesnot drop below 3.5-V minimum system voltage (programmable) with adapter applied. With this feature, thesystem maintains operation even when the battery is completely depleted or removed. When the inputcurrent limit or voltage limit is reached, the Power Path management automatically reduces thecharge current. As the system load continues to increase, the battery starts to discharge thebattery until the system power requirement is met. This supplement mode prevents overloading theinput source.
The device initiates and completes a charging cycle without software control. It sensesthe battery voltage and charges the battery in three phases: pre-conditioning, constant current andconstant voltage. At the end of the charging cycle, the charger automatically terminates when thecharge current is below a preset limit and the battery voltage is higher than the rechargethreshold. If the fully charged battery falls below the recharge threshold, the chargerautomatically starts another charging cycle.
The charger provides various safety features for battery charging and system operations,including battery negative temperature coefficient thermistor monitoring, charging safety timer andovervoltage and over-current protections. Thermal regulation reduces charge current when thejunction temperature exceeds 110°C. The status register reportsthe charging status and any fault conditions.WithI2C, the VBUS_GD bit indicates if a good power source is present, andthe INT output immediately notifies host when a fault occurs.
The device also providesthe QON pin for BATFET enable and reset control to exit low power ship modeor full system reset function.
The BQ2619 device is available in 24-pin, 4 mm × 4 mm x 0.75 mm thin WQFN package andBQ25618 is available in 30-ball, 2.0 mm × 2.4 mm WCSP package.