1 Features
• Input voltage up-to 30-V tolerant
• Automatic Sleep Mode for low power consumption
– 350-nA battery leakage current
– 85-μA input leakage current when charge
disabled
• Supports 1-cell Li-Ion, Li-Poly, and LiFePO4
• External resistor programmable operation
– VSET to set battery regulation voltage:
• Li-Ion: 4.05 V, 4.1 V, 4.2 V, 4.35 V, 4.4 V
• LiFePO4: 3.5 V, 3.6 V, 3.7 V
– ISET to set charge current from 10 mA to 800
mA
• High accuracy
– ±0.5% charge voltage accuracy
– ±10% charge current accuracy
• Charging features
– Precharge current 20% of ISET
– Termination current 10% of ISET
– NTC thermistor input to monitor battery
temperature
– TS pin for charging function control
– Open-drain output for status and fault indication
– Open-drain output for power good indication
• Integrated fault protection
– 6.6-V IN overvoltage protection
– VSET based OUT overvoltage protection
– 1000-mA overcurrent protection
– 125°C thermal regulation; 150°C thermal
shutdown protection
– OUT short-circuit protection
– VSET, ISET pins short/open protection

2 Applications
• True wireless headsets
• Wearable accessories, smart band
• Beauty and grooming
• Electric toothbrush
• Fleet management, asset tracking

3 Description
The BQ25170 is an integrated 800-mA linear charger
for 1-cell Li-Ion, Li-Polymer, and LiFePO4 batteries
targeted at space-limited portable applications. The
device has a single power output that charges the
battery. The system load can be placed in parallel
with the battery, as long as the average system load
does not prevent the battery from charging fully within
the safety timer duration. When the system load is
placed in parallel with the battery, the charge current
is shared between the system and the battery.
The device has three phases for charging a Li-Ion
battery: precharge to recover a fully discharged
battery, fast-charge constant current to supply the
bulk of the charge, and voltage regulation to reach
full capacity.
In all charge phases, an internal control loop monitors
the IC junction temperature and reduces the charge
current if an internal temperature threshold, TREG, 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 automatic charge
termination. The charge voltage and fast charge
current are programmable through external resistors.
The precharge and termination current threshold track
the fast charge current setting.