SLUSDK0A August   2020  – March 2021 BQ25171-Q1


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Device Power Up from Input Source
        1. ISET Pin Detection
        2. CHM_TMR Pin Detection
        3. VSET Pin Detection
        4. Charger Power Up
      2. 7.3.2 Battery Charging Features
        1. Lithium-Ion Battery Charging Profile
          1. NiMH Battery Charging Profile
        2. Charge Termination and Battery Recharge
        3. Charging Safety Timers
        4. Battery Cold, Hot Temperature Qualification (TS Pin)
      3. 7.3.3 Status Outputs (STAT1, STAT2)
        1. Charging Status Indicator (STAT1, STAT2)
      4. 7.3.4 Protection Features
        1. Input Overvoltage Protection (VIN OVP)
        2. Output Overvoltage Protection (BAT OVP)
        3. Output Overcurrent Protection (BAT OCP)
        4. Thermal Regulation and Thermal Shutdown (TREG and TSHUT)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown or Undervoltage Lockout (UVLO)
      2. 7.4.2 Sleep Mode
      3. 7.4.3 Active Mode
        1. Standby Mode
      4. 7.4.4 Fault Mode
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 1s LiFePO4 Charger Design Example
        1. Design Requirements
        2. Detailed Design Procedure
          1. Program the Fast Charge Current, ISET:
          2. TS Function
        3. Application Curves
      2. 8.2.2 2s Li-Ion Charger with Power Path Design Example
        1. Design Requirements
      3. 8.2.3 4s NiMH Charger Design Example
        1. Design Requirements
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information


The BQ25171-Q1 is an automotive rated, 800-mA linear charger for 1-cell and 2-cell Li-Ion, Li-Polymer, and LiFePO4, in addition to 1-cell up to 6-cell NiMH battery 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.

The device charges a NiMH in constant current mode only, and terminates the charge cycle when the programmable timer expires or the battery voltage exceeds the VOUT_OVP threshold. 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.

Device Information
BQ25171-Q1 VSON (10) 3.0 mm x 3.0 mm
For all available packages, see the orderable addendum at the end of the data sheet.
GUID-20210503-CA0I-G0ZM-53WL-0PPVNBZV8DL7-low.gif Simplified Schematic