BQ25895M_15 Datasheet, PDF (3/12 Pages) Texas Instruments – bq25895M I2C Controlled Single Cell Fast Charger with MaxChargeTM Technology for High Input Voltage

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bq25895M
SLUSCC8 – JULY 2015
5 Description (Continued)
The bq25895M is a highly-integrated 5-A switch-mode battery charge management and system power path
management device for single cell Li-Ion and Li-polymer battery. It features fast charging with high input voltage
support for a wide range of smartphone, tablet and portable devices. Its low impedance power path optimizes
switch-mode operation efficiency, reduces battery charging time and extends battery life during discharging
phase. It also integrates Input Current Optimizer (ICO) and Resistance Compensation (IRCOMP) to deliver
maximum charging power to battery. The solution is highly integrated with input reverse-blocking FET (RBFET,
Q1), high-side switching FET (HSFET, Q2), low-side switching FET (LSFET, Q3), and battery FET (BATFET, Q4)
between system and battery. It also integrates the bootstrap diode for the high-side gate drive and battery
monitor for simplified system design. The I²C 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, USB charging port, and
USB compliant adjustable high voltage adapter. To support fast charging using adjustable high voltage adapter,
the bq25895M provides support MaxCharge^TM handshake using D+/D- pins and DSEL pin for USB switch
control. In addition, the device includes interface to support adjustable high voltage adapter using input current
pulse protocol. To set the default input current limit, device uses the built-in USB interface. The device is
compliant with USB 2.0 and USB 3.0 power spec with input current and voltage regulation. In addition, the Input
Current Optimizer (ICO) supports the detection of maximum power point detection of the input source without
overload. The device supports battery boost operation by supplying adjustable 4.5V-5.5V on PMID pin with up to
3.1A with integrated charge and boost mode detection
The power path management regulates the system slightly above battery voltage but does not drop below 3.5V
minimum system voltage (programmable). With this feature, the system maintains operation even when the
battery is completely depleted or removed. When the input current limit or voltage limit is reached, the 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 requirement is met. This operation prevents
overloading the input source.
The device initiates and completes a charging cycle without software control. It automatically detects the battery
voltage and charges the battery in three phases: pre-conditioning, constant current and constant voltage. At the
end of the charging cycle, the charger automatically terminates when the charge current is below a preset limit in
the constant voltage phase. When the full battery falls below the recharge threshold, the charger will
automatically start another charging cycle.
The charger provides various safety features for battery charging and system operations, including battery
temperature negative thermistor monitoring, charging safety timer and overvoltage/overcurrent protections. The
thermal regulation reduces charge current when the junction temperature exceeds 120°C (programmable). The
STAT output reports the charging status and any fault conditions. The INT immediately notifies host when fault
occurs.
The device also provides a 7-bit analog-to-digital converter (ADC) for monitoring charge current and
input/battery/system (VBUS, BAT, SYS, TS) voltages. The QON pin provides BATFET enable/resôet control to
exit low power ship mode or full system reset function.
The device family is available in 24-pin, 4 x 4 mm² x 0.75 mm thin WQFN package.
Copyright © 2015, Texas Instruments Incorporated
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