BQ24171_15 Datasheet, PDF (3/39 Pages) Texas Instruments – bq24171 JEITA-Compliant Stand-Alone, Switched-Mode Li-Ion and Li-Polymer Battery Charger With Integrated MOSFETs and Power Path Selector

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bq24171
SLUSAF2C – FEBRUARY 2011 – REVISED APRIL 2015
5 Description (Continued)
The bq24171 charges the battery in three phases: preconditioning, constant current, and constant voltage. The
device is adjustable for up to three series Li+ cells.
Charge is terminated when the current reaches 10% of the fast charge rate. A programmable charge timer offers
a safety backup. The bq24171 automatically restarts the charge cycle if the battery voltage falls below an internal
threshold, and enters a low-quiescent current sleep mode when the input voltage falls below the battery voltage.
The bq24171 features Dynamic Power Management (DPM) to reduce the charge current when the input power
limit is reached to avoid overloading the adapter. A highly accurate current-sense amplifier enables precise
measurement of input current from adapter to monitor overall system power.
The bq24171 device provides power path selector gate driver ACDRV/CMSRC on input NMOS pair ACFET (Q1)
and RBFET (Q2), and BATDRV on a battery PMOS device (Q3). When the qualified adapter is present, the
system is directly connected to the adapter. Otherwise, the system is connected to the battery. In addition, the
power path prevents battery from boosting back to the input.
The bq24171 charges battery from DC source as high as 17 V, including car battery. The input overvoltage limit
is adjustable through the OVPSET pin. The AVCC, ACP and ACN pins are 30-V rating. When a high-voltage DC
source is inserted, Q1 and Q2 remain off to avoid high voltage damage to the system.
For 1-cell applications, if the battery is not removable, the system can be directly connected to the battery to
simplify the power path design and reduce the cost. With this configuration, the battery can automatically
supplement the system load if the adapter is overloaded.
The bq24171 is available in a 24-pin, 5.5-mm × 3.5-mm thin QFN package.
6 Device Comparison Table
bq24133
bq24170
bq24171
bq24172
INPUT VOLTAGE
4.5 V to 17 V
MAX CHARGE RATE
2.5 A
4A
BATTERY VOLTAGE
4.2 V/cell
4.2 V/cell
Adjustable
Adjustable
JEITA
No
No
Yes
No
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