SLUSFH5 May   2024 BQ25856-Q1

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Device Power-On-Reset
      2. 6.3.2  Device Power-Up From Battery Without Input Source
      3. 6.3.3  Device Power Up from Input Source
        1. 6.3.3.1 VAC Operating Window Programming (ACUV and ACOV)
        2. 6.3.3.2 REGN Regulator (REGN LDO)
        3. 6.3.3.3 Compensation-Free Buck-Boost Converter Operation
          1. 6.3.3.3.1 Light-Load Operation
        4. 6.3.3.4 Switching Frequency and Synchronization (FSW_SYNC)
        5. 6.3.3.5 Device HIZ Mode
      4. 6.3.4  Battery Charging Management
        1. 6.3.4.1 Autonomous Charging Cycle
          1. 6.3.4.1.1 Charge Current Programming (ICHG pin and ICHG_REG)
        2. 6.3.4.2 Li-Ion Battery Charging Profile
        3. 6.3.4.3 LiFePO4 Battery Charging Profile
        4. 6.3.4.4 Charging Termination for Li-ion and LiFePO4
        5. 6.3.4.5 Charging Safety Timer
        6. 6.3.4.6 Thermistor Qualification
          1. 6.3.4.6.1 JEITA Guideline Compliance in Charge Mode
          2. 6.3.4.6.2 Cold/Hot Temperature Window in Reverse Mode
      5. 6.3.5  Power Management
        1. 6.3.5.1 Dynamic Power Management: Input Voltage and Input Current Regulation
          1. 6.3.5.1.1 Input Current Regulation
            1. 6.3.5.1.1.1 ILIM_HIZ Pin
          2. 6.3.5.1.2 Input Voltage Regulation
      6. 6.3.6  Switching Frequency and Dithering Feature
      7. 6.3.7  Reverse Mode Power Direction
      8. 6.3.8  Integrated 16-Bit ADC for Monitoring
      9. 6.3.9  Status Outputs (PG, STAT1, STAT2, and INT)
        1. 6.3.9.1 Power Good Indicator (PG)
        2. 6.3.9.2 Charging Status Indicator (STAT1, STAT2 Pins)
        3. 6.3.9.3 Interrupt to Host (INT)
      10. 6.3.10 Protections
        1. 6.3.10.1 Voltage and Current Monitoring
          1. 6.3.10.1.1 VAC Over-voltage Protection (VAC_OVP)
          2. 6.3.10.1.2 VAC Under-voltage Protection (VAC_UVP)
          3. 6.3.10.1.3 Battery Over-voltage Protection (BAT_OVP)
          4. 6.3.10.1.4 Battery Over-current Protection (BAT_OCP)
          5. 6.3.10.1.5 Reverse Mode Over-voltage Protection (REV_OVP)
          6. 6.3.10.1.6 Reverse Mode Under-voltage Protection (REV_UVP)
          7. 6.3.10.1.7 DRV_SUP Under-voltage and Over-voltage Protection (DRV_OKZ)
          8. 6.3.10.1.8 REGN Under-voltage Protection (REGN_OKZ)
        2. 6.3.10.2 Thermal Shutdown (TSHUT)
      11. 6.3.11 Serial Interface
        1. 6.3.11.1 Data Validity
        2. 6.3.11.2 START and STOP Conditions
        3. 6.3.11.3 Byte Format
        4. 6.3.11.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 6.3.11.5 Target Address and Data Direction Bit
        6. 6.3.11.6 Single Write and Read
        7. 6.3.11.7 Multi-Write and Multi-Read
    4. 6.4 Device Functional Modes
      1. 6.4.1 Host Mode and Default Mode
      2. 6.4.2 Register Bit Reset
    5. 6.5 BQ25856-Q1 Registers
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Typical Application
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 ACUV / ACOV Input Voltage Operating Window Programming
          2. 7.2.1.2.2 Charge Voltage Selection
          3. 7.2.1.2.3 Switching Frequency Selection
          4. 7.2.1.2.4 Inductor Selection
          5. 7.2.1.2.5 Input (VAC) Capacitor
          6. 7.2.1.2.6 Output (VBAT) Capacitor
          7. 7.2.1.2.7 Sense Resistor (RAC_SNS and RBAT_SNS) and Current Programming
          8. 7.2.1.2.8 Power MOSFETs Selection
          9. 7.2.1.2.9 Converter Fast Transient Response
      2. 7.2.2 Typical Application (4s LiFePO4 car battery configuration)
        1. 7.2.2.1 Design Requirements
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Packaging Information
    2. 12.2 Tape and Reel Information
    3. 12.3 Mechanical Data

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RRV|36
Thermal pad, mechanical data (Package|Pins)
7.2.1.2.7 Sense Resistor (RAC_SNS and RBAT_SNS) and Current Programming

The battery current sense resistor between SRP and SRN is fixed at 5 mΩ; using a different value is not recommended. The input current sense resistor between ACP and ACN is typically 2 mΩ, but can be increased to achieve better accuracy at lower sensed currents. In USB-PD EPR applications, a 5-mΩ sense resistor is recommended to achieve programmability in 50 mA/step. In addition, if input current limit function is not desired, ACP and ACN may be shorted together. For both of these sense resistors, a filter network is recommended as shown in the Typical Application.

For both the input current and the output current, the limits may be programmed using the I2C interface or an external programming resistor on ILIM_HIZ and ICHG pins, respectively.

PARAMETERFORMULAVALUE
Input Current Hardware LimitUnused Pull ILIM_HIZ pin to GND
Input Current Software LimitUnusedREG06 = 0x00A0 (5A) with 5-mΩ RAC_SNS
Output Current Hardware LimitUnused Pull ICHG pin to GND
Output Current Software LimitICHG = 5 AREG02 = 0x0190 (5A)

The default input sense resistor (RAC_SNS) is 2 mΩ, and the register allows for a range of up-to 50-A input current limit. If lower currents are desired, it is possible to use a higher resistor, such as 5 mΩ. In this case, the IAC_DPM register value should be multiplied by a factor of 2/5 to program the correct current. For example, if a 5-mΩ RAC_SNS is used, and the register is programmed to a value of 0x60, the true maximum current across the RAC_SNS will be: 12A * 2/5 = 4.8 A. Similarly, the KILIM parameter used to set the ILIM_HIZ pull-down resistor should be scaled by 2/5. For example, with a 5-mΩ RAC_SNS resistor, a 6-A current limit would be achieved as: RILIM = KILIM * (2/5) / 6A = 3.3 kΩ.