BQ25619RTWR

The BQ25618/619 integrates charging, boost converter, and voltage protection functions in a single device. It features the industry's lowest termination current for a switching charger, enabling maximum battery capacity charging for wearable devices. Its excellent low quiescent current reduces battery leakage to 6uA in shipping mode, conserving battery power and doubling the device's shelf life. The BQ25619/618 is a highly integrated 1.5A switch-mode battery charge management and system power path management device for lithium-ion and lithium-polymer batteries. It provides fast charging capability and high input voltage for various applications such as wearable devices and earphone charging cases. Its low-impedance power path optimizes switch-mode operating efficiency, reducing battery charge time and extending battery runtime during the discharge phase. Input voltage and current regulation, low termination current, and battery remote sensing deliver maximum charging power to the battery. The solution highly integrates an input reverse blocking FET (RBFET, Q1), high-side switching FET (HSFET, Q2), low-side switching FET (LSFET, Q3), and battery FET (BATFET, Q4) between the system and battery. It also integrates a bootstrap diode for high-side gate drive, simplifying system design. An I2C serial interface with charging and system settings makes this device a truly flexible solution. The device supports multiple input sources, including standard USB host ports, USB charging ports, USB-compatible high-voltage adapters, and wireless power. The device complies with USB 2.0 and USB 3.0 power specifications with input current and voltage regulation capability. The device obtains results from system detection circuits such as USB PHY devices. The device integrates a buck charger and boost regulator in a single solution through a single inductor. Boost mode provides 5V on the PMID pin (adjustable: 4.6V/4.75V/5V/5.15V). Boost mode is used to save BOM cost and can charge another battery by controlling PMID_GOOD. The PMID_GOOD pin drives an external PMOS FET to disconnect the boost output PMID from connected accessories. When an adapter is present, power path management regulates the system voltage to a level slightly above the battery voltage, but not below the minimum system voltage of 3.5V (programmable). This feature keeps the system operational even when the battery is completely depleted or removed. When the input current or voltage limit is reached, the power path management system automatically reduces the charging current. As system load continues to increase, the battery begins to discharge until the system power demand is met. This supplemental mode prevents the input source from being overloaded. The device initiates and completes a charge cycle without software control. It senses the battery voltage and charges the battery through three phases: pre-charge, constant current, and constant voltage. At the end of the charge cycle, the charger automatically terminates when the charge current falls below a preset threshold and the battery voltage is above the recharge threshold. If a fully charged battery drops below the recharge threshold, the charger automatically initiates another charge cycle. The charger provides multiple safety features for battery charging and system operation, including battery NTC thermistor monitoring, charge safety timer, and overvoltage and overcurrent protection. Thermal regulation reduces the charge current when the junction temperature exceeds 110℃. Status registers report the charge status and any fault conditions. Via I2C, the VBUS_GD bit indicates whether the power supply is valid, and the INT output immediately notifies the host upon a fault occurrence. The device also provides a QON pin for BATFET enable and reset control, used to exit low-power shipping mode or perform a full system reset.

Applications

• Consumer wearables, smartwatches
• Personal care and fitness
• Headsets/headphones
• Earbuds (true wireless or TWS) charging cases
• Hearing aid charging cases

Key features

• Single-chip solution for charging wearable accessories via adapter or battery
• High-efficiency 1.5MHz synchronous switch-mode buck charger
• 95.5% charging efficiency at 0.5A, 94.5% at 1A
• ±0.5% charge voltage regulation (10mV step)
• I²C-programmable JEITA profile for charge voltage, current, and temperature thresholds
• High-accuracy low termination current 20mA±10mA
• Compact inductor size 2.5×2.0×1.0mm³
• Boost mode output range 4.6V to 5.15V
• 94% boost efficiency at 1A output
• Integrated control for seamless switching between charge mode and boost mode
• PMID_GOOD pin controls external PMOS FET for fault protection
• Single input supporting USB input, high-voltage adapter, or wireless power
• 4V to 13.5V input voltage range, 22V absolute maximum input rating
• Programmable input current limit (IINDPM) via I2C (100mA to 3.2A, 100mA/step)
• Maximum power point tracking via input voltage limit (VINDPM) up to 5.4V
• Automatic battery voltage tracking via VINDPM threshold
• Narrow VDC (NVDC) power path management enables instant system startup without battery or with deeply discharged battery
• Flexible I²C configuration and autonomous charging for superior system performance
• High integration includes all MOSFETs, current sensing, and loop compensation
• Low RDSON 19.5mΩ BATFET for reduced charging losses and extended battery runtime
• BATFET control for ship mode with full system reset capability with and without adapter
• 7μA low battery leakage current in ship mode
• 9.5μA low battery leakage current during system standby
• High-accuracy battery charging profile
• ±6% charge current regulation
• ±7.5% input current regulation
• Remote battery sense for faster charging
• Programmable charge termination timer for battery full charge
• IEC 62368-1 CB certified