SLUSCM3K June   2016  – July 2020 BQ77904 , BQ77905

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
      1. 8.1.1 Device Functionality Summary
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Protection Summary
      2. 8.3.2  Fault Operation
        1. 8.3.2.1  Operation in OV
        2. 8.3.2.2  Operation in UV
        3. 8.3.2.3  Operation in OW
        4. 8.3.2.4  Operation in OCD1
        5. 8.3.2.5  Operation in OCD2
        6. 8.3.2.6  Operation in SCD
        7. 8.3.2.7  Overcurrent Recovery Timer
        8. 8.3.2.8  Load Removal Detection
        9. 8.3.2.9  Load Removal Detection in UV
        10. 8.3.2.10 Operation in OTC
        11. 8.3.2.11 Operation in OTD
        12. 8.3.2.12 Operation in UTC
        13. 8.3.2.13 Operation in UTD
      3. 8.3.3  Protection Response and Recovery Summary
      4. 8.3.4  Configuration CRC Check and Comparator Built-In-Self-Test
      5. 8.3.5  Fault Detection Method
        1. 8.3.5.1 Filtered Fault Detection
      6. 8.3.6  State Comparator
      7. 8.3.7  DSG FET Driver Operation
      8. 8.3.8  CHG FET Driver Operation
      9. 8.3.9  External Override of CHG and DSG Drivers
      10. 8.3.10 Configuring 3-S, 4-S, or 5-S Mode
      11. 8.3.11 Stacking Implementations
      12. 8.3.12 Zero-Volt Battery Charging Inhibition
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power Modes
        1. 8.4.1.1 Power-On Reset (POR)
        2. 8.4.1.2 FAULT Mode
        3. 8.4.1.3 SHUTDOWN Mode
        4. 8.4.1.4 Customer Fast Production Test Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Recommended System Implementation
        1. 9.1.1.1 CHG and DSG FET Rise and Fall Time
        2. 9.1.1.2 Protecting CHG and LD
        3. 9.1.1.3 Protecting CHG FET
        4. 9.1.1.4 Using Load Detect for UV Fault Recovery
        5. 9.1.1.5 Temperature Protection
        6. 9.1.1.6 Adding Filter to Sense Resistor
        7. 9.1.1.7 Using a State Comparator in an Application
          1. 9.1.1.7.1 Examples
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Design Example
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Links
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2.8 Load Removal Detection

The load removal detection feature is implemented with the LD pin (see Table 8-2). When no undervoltage fault and current fault conditions are present, the LD pin is held in an open-drain state. Once any UV, OCD1, OCD2, or SCD fault occurs and load removal is selected as part of the recovery conditions, a high impedance pull-down path to VSS is enabled on the LD pin. With an external load still present, the LD pin will be externally pulled high: It is internally clamped to VLDCLAMP and should also be resistor-limited through RLD externally to avoid conducting excessive current. If the LD pin exceeds VLDT, this is interpreted as a load present condition. When the load is eventually removed, the internal high-impedance path to VSS should be sufficient to pull the LD pin below VLDT for tLD_DEG. This is interpreted as a load removed condition and is one of the recovery mechanisms selectable for undervoltage and overcurrent faults.

GUID-A7EAA0E1-FC28-47EA-AFD1-F21E0472417C-low.gifFigure 8-3 Load Detection Circuit for Current Faults Recovery
Table 8-2 Load State
LD PINLOAD STATE
≥ VLDTLoad present
< VLOT for tLD_DEGLoad removed