ZHCSQ82 September   2022 BQ25176M

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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. 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. 7.3.1.1 ISET Pin Detection
        2. 7.3.1.2 VSET Pin Detection
        3. 7.3.1.3 Charger Power Up
      2. 7.3.2 Battery Charging Features
        1. 7.3.2.1 Lithium-Ion Battery Charging Profile
        2. 7.3.2.2 Input Voltage Based Dynamic Power Management (VINDPM)
        3. 7.3.2.3 Charge Termination and Battery Recharge
      3. 7.3.3 Status Outputs ( PG, STAT)
        1. 7.3.3.1 Power Good Indicator (PG Pin)
        2. 7.3.3.2 Charging Status Indicator (STAT)
      4. 7.3.4 Protection Features
        1. 7.3.4.1 Input Overvoltage Protection (VIN_OV)
        2. 7.3.4.2 Output Overvoltage Protection (VOUT_OVP)
        3. 7.3.4.3 Output Overcurrent Protection (IOUT_OCP)
        4. 7.3.4.4 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. 7.4.3.1 Standby Mode
      4. 7.4.4 Fault Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Li-Ion Charger Design Example
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 LiFePO4 Charger Design Example
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 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 第三方产品免责声明
    2. 11.2 接收文档更新通知
    3. 11.3 支持资源
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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7.1 Overview

The BQ25176M is an integrated 800-mA linear solar charger for 1-cell Li-Ion, Li-Polymer, and LiFePO4 batteries. The device has a single power output that charges the battery. The system load can be placed in parallel with the battery. When the system load is placed in parallel with the battery, the output current is shared between the system and the battery.

The device has four phases for charging a Li-Ion/Li-Poly battery: trickle charge to bring the battery voltage up to VBAT_SHORT, 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 charger includes flexibility in programming of the fast-charge current and regulation voltage. This charger is designed to work with a standard USB connection or dedicated charging adapter (DC output).

The charger also comes with a full set of safety features: overvoltage protection, and configuration pin (VSET, ISET) short and open protection. All of these features and more are described in detail below.

The charger is designed for a single path from the input to the output to charge the battery. Upon application of a valid input power source, the configuration pins are checked for short/open circuit.

If the battery voltage is below the VBAT_LOWV threshold, the battery is considered discharged and a preconditioning cycle begins. If the battery voltage is below VBAT_SHORT, the charge current is IBAT_SHORT.If the battery voltage is higher than VBAT_SHORT but lower than VBAT_LOWV, the amount of precharge current is 20% of the programmed fast-charge current via the ISET pin.

Once the battery has charged to the VBAT_LOWV threshold, Fast Charge Mode is initiated. The fast charge constant current is programmed using the ISET pin. The constant current phase provides the bulk of the charge. Power dissipation in the IC is greatest in fast charge with a lower battery voltage. If the IC temperature reaches TREG, the IC enters thermal regulation. Figure 7-1 shows the typical lithium battery charging profile with thermal regulation. Under normal operating conditions, the IC junction temperature is less than TREG and thermal regulation is not entered.

Once the battery has charged to the regulation voltage, the voltage loop takes control and holds the battery at the regulation voltage until the current tapers to the termination threshold. The termination threshold is 10% of the programmed fast-charge current.

Further details are described in Section 7.3.

GUID-20220315-SS0I-LD2T-SS1J-JHMP1P2LFC7K-low.gifFigure 7-1 Lithium-Ion Battery Charging Profile with Thermal Regulation