SLUSFH5A May   2024  – October 2024 BQ25856-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Device Power-On-Reset
      2. 7.3.2  Device Power-Up From Battery Without Input Source
      3. 7.3.3  Device Power Up From Input Source
        1. 7.3.3.1 VAC Operating Window Programming (ACUV and ACOV)
        2. 7.3.3.2 REGN Regulator (REGN LDO)
        3. 7.3.3.3 Compensation-Free Buck-Boost Converter Operation
          1. 7.3.3.3.1 Light-Load Operation
        4. 7.3.3.4 Switching Frequency and Synchronization (FSW_SYNC)
        5. 7.3.3.5 Device HIZ Mode
      4. 7.3.4  Battery Charging Management
        1. 7.3.4.1 Autonomous Charging Cycle
          1. 7.3.4.1.1 Charge Current Programming (ICHG pin and ICHG_REG)
        2. 7.3.4.2 Li-Ion Battery Charging Profile
        3. 7.3.4.3 LiFePO4 Battery Charging Profile
        4. 7.3.4.4 Charging Termination for Li-ion and LiFePO4
        5. 7.3.4.5 Charging Safety Timer
        6. 7.3.4.6 Thermistor Qualification
          1. 7.3.4.6.1 JEITA Guideline Compliance in Charge Mode
          2. 7.3.4.6.2 Cold/Hot Temperature Window in Reverse Mode
      5. 7.3.5  Power Management
        1. 7.3.5.1 Dynamic Power Management: Input Voltage and Input Current Regulation
          1. 7.3.5.1.1 Input Current Regulation
            1. 7.3.5.1.1.1 ILIM_HIZ Pin
          2. 7.3.5.1.2 Input Voltage Regulation
      6. 7.3.6  Switching Frequency Dithering Feature
      7. 7.3.7  Reverse Mode Power Direction
        1. 7.3.7.1 Auto Reverse Mode
      8. 7.3.8  Integrated 16-Bit ADC for Monitoring
      9. 7.3.9  Status Outputs (PG, STAT1, STAT2, and INT)
        1. 7.3.9.1 Power Good Indicator (PG)
        2. 7.3.9.2 Charging Status Indicator (STAT1, STAT2 Pins)
        3. 7.3.9.3 Interrupt to Host (INT)
      10. 7.3.10 Protections
        1. 7.3.10.1 Voltage and Current Monitoring
          1. 7.3.10.1.1 VAC Over-voltage Protection (VAC_OVP)
          2. 7.3.10.1.2 VAC Under-voltage Protection (VAC_UVP)
          3. 7.3.10.1.3 Battery Over-voltage Protection (BAT_OVP)
          4. 7.3.10.1.4 Battery Over-current Protection (BAT_OCP)
          5. 7.3.10.1.5 Reverse Mode Over-voltage Protection (REV_OVP)
          6. 7.3.10.1.6 Reverse Mode Under-voltage Protection (REV_UVP)
          7. 7.3.10.1.7 DRV_SUP Under-voltage and Over-voltage Protection (DRV_OKZ)
          8. 7.3.10.1.8 REGN Under-voltage Protection (REGN_OKZ)
        2. 7.3.10.2 Thermal Shutdown (TSHUT)
      11. 7.3.11 Serial Interface
        1. 7.3.11.1 Data Validity
        2. 7.3.11.2 START and STOP Conditions
        3. 7.3.11.3 Byte Format
        4. 7.3.11.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 7.3.11.5 Target Address and Data Direction Bit
        6. 7.3.11.6 Single Write and Read
        7. 7.3.11.7 Multi-Write and Multi-Read
    4. 7.4 Device Functional Modes
      1. 7.4.1 Host Mode and Default Mode
      2. 7.4.2 Register Bit Reset
    5. 7.5 BQ25856-Q1 Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 ACUV / ACOV Input Voltage Operating Window Programming
          2. 8.2.1.2.2 Charge Voltage Selection
          3. 8.2.1.2.3 Switching Frequency Selection
          4. 8.2.1.2.4 Inductor Selection
          5. 8.2.1.2.5 Input (VAC) Capacitor
          6. 8.2.1.2.6 Output (VBAT) Capacitor
          7. 8.2.1.2.7 Sense Resistor (RAC_SNS and RBAT_SNS) and Current Programming
          8. 8.2.1.2.8 Power MOSFETs Selection
          9. 8.2.1.2.9 Converter Fast Transient Response
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Typical Application (4s LiFePO4 car battery configuration)
        1. 8.2.2.1 Design Requirements
      3. 8.2.3 Typical Application (Capacitor Backup)
        1. 8.2.3.1 Design Requirements
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  12. 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
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RRV|36
Thermal pad, mechanical data (Package|Pins)
Orderable Information
8.2.1.2.4 Inductor Selection

Higher switching frequency allows the use of smaller inductor and capacitor values. Inductor saturation current should be higher than the inductor current (IL) plus half the ripple current (IRIPPLE):

Equation 11. ISAT≥IL+12IRIPPLE

The inductor ripple current in buck operation depends on input voltage (VAC), duty cycle (DBUCK = VBAT/VAC), switching frequency (fSW) and inductance (L):

Equation 12. IRIPPLE_BUCK=VAC×DBUCK×1-DBUCKfSW×L

During boost operation, the duty cycle is: DBOOST = 1 – (VAC/VBAT). The inductor ripple current is:

Equation 13. IRIPPLE_BOOST=VAC×DBOOSTfSW×L

The maximum inductor ripple current happens with D = 0.5 or close to 0.5. Ripple calculations should be analyzed for both forward and reverse operating modes if applicable.

Usually inductor ripple is designed in the range of (20 – 40%) maximum inductor current (in either forward or reverse mode) as a trade-off between inductor size and efficiency for a practical design.