Stand Alone 1cell 3A Fast charger with High input voltage and Power Path

The BQ25606 is

a highly-integrated standalone 3.0-A switch-mode battery charge management

and system power path management device for single cell Li-ion and Li-polymer

batteries. 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. The low impedance power path

optimizes switch-mode operation efficiency, reduces battery charging time, and

extends battery life during discharging phase.

The BQ25606 features fast

charging with high input voltage support for a wide range of

standalone chargers and portable devices. Its

input voltage and current regulation deliver maximum charging power to the battery. It also integrates a

bootstrap diode for the high-side gate drive for simplified system design.

The device supports a wide range of input sources,

including standard USB host port, USB charging port, and USB compliant high voltage

adapter. The device sets the default input current limit based on the built-in

USB interface.

The device is compliant with the USB 2.0

and USB 3.0 power specs with input current and voltage regulation. When the built-in USB interface identifies the

input adaptor is unknown, the input current limit of the device is determined by

the ILIM pin setting resistor value. The device also meets the USB

On-the-Go (OTG) operation power rating specification by supplying 5.15 V on VBUS

with a constant current limit up to 1.2 A.

The power path management regulates the system

slightly above battery voltage but does not drop below the 3.5-V minimum system

voltage. 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. As the system load continues to increase, the power path

discharges the battery until the system power requirement is met. This Supplement

mode prevents overloading the input source.

The device initiates and completes a charging

cycle without software control. It senses 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 and the battery voltage is higher than the recharge

threshold. If the fully charged battery falls below the recharge threshold, the

charger automatically 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, and overvoltage and

overcurrent protections. The thermal regulation reduces charge current when the

junction temperature exceeds 110°C. The STAT output reports charging status and any fault

conditions. Other safety features include battery temperature sensing for charge and

boost mode, thermal regulation and thermal shutdown, and input UVLO and overvoltage

protection.

The device is available

in a 24-pin, 4 mm x 4 mm QFN package.