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

Charging Safety Timers

The device has built-in safety timers to prevent an extended charging cycle due to abnormal battery conditions. The precharge timer is fixed at 30 minutes. The user can program or disable the fast charge safety timer through the CHM_TMR pin. When safety timer expires, the charge cycle ends. A toggle on the input supply or CE pin is required to restart a charge cycle after the safety timer has expired.

During thermal regulation, the safety timer counts at half clock rate as the actual charge current is likely to be below the ISET setting. For example, if the charger is in thermal regulation throughout the whole charging cycle, and the safety timer is 10 hours, then the timer will expire in 20 hours.

During faults which disable charging, such as VIN OVP, BAT OVP, TSHUT or TS faults, the timer is suspended. Once the fault goes away, charging and the safety timer resumes. If the charging cycle is stopped and started again, the timer gets reset (toggle CE pin restarts the timer).

The safety timer restarts counting for the following events:

  1. Charging cycle stop and restart (toggle CE pin, charged battery falls below recharge threshold, or toggle input supply)
  2. OUT pin voltage crosses the VBAT_LOWV threshold in either direction

The precharge safety timer (fixed counter that runs when VOUT < VBAT_LOWV), follows the same rules as the fast-charge safety timer in terms of getting suspended, reset, and counting at half-rate.