SLUSCU0I March   2018  – September 2020 BQ77915


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (continued)
  6. Device Comparison Table
  7. Pin Configuration and Functions
    1.     Pin Functions
  8. Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Table
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
  9. Detailed Description
    1. 9.1 Overview
      1. 9.1.1 Device Functionality Summary
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1  Protection Summary
      2. 9.3.2  Fault Operation
        1.  Operation in OV
        2.  Operation in UV
        3.  Operation in OW
        4.  Operation in OCD1
        5.  Operation in OCD2
        6.  Programming the OCD1/2 Delay Using the OCDP Pin
        7.  Operation in SCD
        8.  Operation in OCC
        9.  Overcurrent Recovery Timer
        10. Load Detection and Load Removal Detection
        11. Operation in OTC
        12. Operation in OTD
        13. Operation in UTC
        14. Operation in UTD
      3. 9.3.3  Protection Response and Recovery Summary
      4. 9.3.4  Cell Balancing
      5. 9.3.5  HIBERNATE Mode Operation
      6. 9.3.6  Configuration CRC Check and Comparator Built-In-Self-Test
      7. 9.3.7  Fault Detection Method
        1. Filtered Fault Detection
      8. 9.3.8  State Comparator
      9. 9.3.9  DSG FET Driver Operation
      10. 9.3.10 CHG FET Driver Operation
      11. 9.3.11 External Override of CHG and DSG Drivers
      12. 9.3.12 Configuring 3-Series, 4-Series, or 5-Series Modes
      13. 9.3.13 Stacking Implementations
      14. 9.3.14 Zero-Volt Battery Charging Inhibition
    4. 9.4 Device Functional Modes
      1. 9.4.1 Power Modes
        1. Power On Reset (POR)
        2. NORMAL Mode
        3. FAULT Mode
        4. HIBERNATE Mode
        5. SHUTDOWN Mode
        6. Customer Fast Production Test Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Recommended System Implementation
        1. CHG and DSG FET Rise and Fall Time
        2. Protecting CHG and LD
        3. Protecting the CHG FET
        4. Using Load Detect for UV Fault Recovery
        5. Temperature Protection
        6. Adding RC Filters to the Sense Resistor
        7. Using the State Comparator in an Application
          1. Examples
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. Design Example
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Support Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

DSG FET Driver Operation

The DSG pin is driven high only when no related faults (UV, OW, OTD, UTD, OCD1, OCD2, SCD, OCC, and CTRD disabled) are present and the device is not in HIBERNATE mode of operation. It is a fast switching driver with a target on resistance of about 15 Ω–20 Ω and an off resistance of RDSGOFF. It is designed to enable customers to select the optimized RGS value to archive the desirable FET rise and fall time per the application requirement and the choice of FET characteristics. When the DSG FET is turned off, the DSG pin drives low and all discharge overcurrent protections (OCD1, OCD2, SCD) are disabled to better conserve power. These resume operation when the DSG FET is turned on. The device provides FET body diode protection through the state comparator if one FET driver is on and the other FET driver is off.

The DSG driver may be turned on to prevent FET damage if the battery pack is charging while a discharge inhibit fault condition is present. This is done by the state comparator. The state comparator (with VSTATE_C threshold and VSTATE_C_HYS hysteresis) remains on for the entire duration of a DSG fault with no CHG fault event.

  • If (SRP–SRN) ≤ (VSTATE_C – VSTATE_C_HYS) and no charge event is detected, the DSG FET output will remain OFF due to the presence of a DSG fault.
  • If (SRP–SRN) > VSTATE_C and a charge event is detected, the DSG FET output will turn ON for body diode protection.

See the Section 9.3.8 section for details.

The presence of any related faults, as shown in Figure 9-8, results in the DSGFET_OFF signal.

GUID-8BA65CBB-1882-411F-976E-0A5E4F899C33-low.gifFigure 9-8 Faults that Can Qualify DSGFET_OFF