1 Features

• Charging

– 1% Charge voltage accuracy

– 10% Charge current accuracy

– Pin selectable USB 100 mA and 500 mA

maximum input current limit

– Programmable termination and precharge

threshold, BQ24040 and BQ24045

– High voltage (4.35 V) chemistry support with

BQ24045

• Protection

– 30V Input rating; with 6.6 V or 7.1 V input

overvoltage protection

– Input voltage dynamic power management

– 125°C thermal regulation; 150°C thermal

shutdown protection

– OUT Short-circuit protection and ISET short

detection

– Operation over JEITA range via battery NTC –

1/2 fast-charge-current at Cold, 4.06V at Hot,

BQ24040 and BQ24045

– Fixed 10 hour safety timer, BQ24040 and

BQ24045

• System

– Automatic termination and timer disable mode

(TTDM) for absent battery pack with thermistor,

BQ24040 and BQ24045

– Status indication – charging and done

– Available in small 2 × 2 mm2 DFN-10 package

– Integrated auto start function for production line

testing, BQ24041

• Functional Safety-Capable (BQ24040)

– Documentation available to aid functional safety

system design

• Safety-Related Certifications:

– IEC 62368-1 CB Certification (BQ24040,

BQ24045)

2 Applications

• TWS Headsets and headphones

• Smartwatches and wristbands

• Wireless speakers

• Mobile POS

• Portable medical devices

3 Description

The BQ2404x series of devices are highly integrated

Li-Ion and Li-Pol linear chargers devices targeted at

space-limited portable applications. The devices

operate from either a USB port or AC adapter. The

high input voltage range with input overvoltage

protection supports low-cost unregulated adapters.

The BQ2404x has a single power output that charges

the battery. A system load can be placed in parallel

with the battery as long as the average system load

does not keep the battery from charging fully during

the 10 hour safety timer.

The battery is charged in three phases: conditioning,

constant current and constant voltage. In all charge

phases, an internal control loop monitors the IC

junction temperature and reduces the charge current

if an internal temperature threshold is exceeded.

The charger power stage and charge current sense

functions are fully integrated. The charger function

has high accuracy current and voltage regulation

loops, charge status display, and charge termination.

The pre-charge current and termination current

threshold are programmed through an external

resistor on the BQ24040 and BQ24045. The fast

charge current value is also programmable through an

external resistor.