TI BQ24171RGYT

The bq24171 is a highly integrated, standalone lithium-ion and lithium-polymer switch-mode battery charger featuring two integrated N-channel power MOSFETs. The device provides a constant-frequency synchronous PWM controller with high-accuracy regulation of input current, charge current, and voltage. The bq24171 closely monitors battery pack temperature and permits charging only within a JEITA-compliant window — with a lower charge rate at low temperatures and a lower charge voltage at high temperatures. The bq24171 charges batteries in three phases: pre-charge, constant-current charge, and constant-voltage charge. The bq24171 regulates battery voltage and supports charging of up to 3 cells. The bq24171 charges batteries in three phases: pre-charge, constant-current charge, and constant-voltage charge. The device supports regulation for up to 3 series-connected lithium-ion cells. Charge termination occurs when the current drops to 10% of the fast-charge rate. A programmable charge timer provides a safety backup. If the battery voltage falls below an internal threshold, the bq24171 automatically restarts the charge cycle and enters a low quiescent current sleep mode when the input voltage drops below the battery voltage. The bq24171 features Dynamic Power Management (DPM), which reduces charge current when the input power limit is reached to prevent overloading the adapter. A high-accuracy current-sense amplifier precisely measures adapter input current to monitor total system power. The bq24171 provides power path selector gate drivers ACDRV/CMSRC for the input NMOS pair (ACFET (Q1) and RBFET (Q2)), and BATDRV for the battery PMOS device (Q3). When a qualified adapter is connected, the system connects directly to the adapter. Otherwise, the system connects to the battery. In addition, the power path prevents reverse boost from the battery to the input. The bq24171 charges batteries from DC power supplies with voltages up to 17V, including automotive batteries. The input overvoltage limit is adjustable via the OVPSET pin. The AVCC, ACP, and ACN pins are rated at 30V. When a high-voltage DC supply is connected, Q1 and Q2 remain off to protect the system from high-voltage damage. For single-cell applications with non-removable batteries, the system can be connected directly to the battery to simplify the power path design and reduce cost. With this configuration, the battery can automatically supplement system load power when the adapter is overloaded. The bq24171 is available in a 24-pin 5.5mm×3.5mm thin QFN package.

• 30V rated input voltage with adjustable overvoltage protection
• Input operating voltage range: 4.5V to 17V
• High integration for battery charge voltage
• Automatic power path selector between adapter and battery
• Dynamic power management
• Integrated 20V switching MOSFET
• Integrated bootstrap diode
• Internal loop compensation
• Internal digital soft-start
• Current reduction via thermal regulation loop, limiting T_J to 120°C
• Thermal shutdown
• Battery thermistor for high/low temperature charge suspension detection
• Input overvoltage protection with programmable threshold
• Cycle-by-cycle current limiting
• ±0.5% charge voltage regulation
• ±4% charge current regulation
• ±4% input current regulation
• Battery current below 15μA after adapter removal
• Input current below 1.5mA when adapter connected but charger disabled
• Small QFN package
• 24-pin 5.5mm×3.5mm QFN package

• Tablet PCs, netbooks, and ultra-portable computers
• Portable data acquisition terminals
• Portable printers
• Medical diagnostic equipment
• Desktop battery chargers
• Backup battery systems