SLUSBU9I March   2014  – August 2024 BQ2970 , BQ2971 , BQ2972 , BQ2973

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
    1. 5.1 Pin Descriptions
      1. 5.1.1 Supply Input: BAT
      2. 5.1.2 Cell Negative Connection: VSS
      3. 5.1.3 Voltage Sense Node: V–
      4. 5.1.4 Discharge FET Gate Drive Output: DOUT
      5. 5.1.5 Charge FET Gate Drive Output: COUT
  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 DC Characteristics
    6. 6.6 Programmable Fault Detection Thresholds
    7. 6.7 Programmable Fault Detection Timer Ranges
    8. 6.8 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Timing Charts
    2. 7.2 Test Circuits
    3. 7.3 Test Circuit Diagrams
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation
      2. 8.4.2 Overcharge Status
      3. 8.4.3 Over-Discharge Status
      4. 8.4.4 Discharge Overcurrent Status (Discharge Overcurrent, Load Short-Circuit)
      5. 8.4.5 Charge Overcurrent Status
      6. 8.4.6 0V Charging Function Enabled
      7. 8.4.7 0V Charging Inhibit Function
      8. 8.4.8 Delay Circuit
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Performance Plots
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Related Documentation
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.4.2 Overcharge Status

This mode is detected when the battery voltage measured is higher than the overcharge detection threshold (VOVP) during charging. If this condition exists for a period greater than the overcharge detection delay (tOVPD) or longer, the COUT output signal is driven low to turn OFF the charging FET to prevent any further charging of the battery.

The overcharge condition is released if one of the following conditions occurs:

  • If the V– pin is higher than the overcharge detection voltage (VOCC_Min), the device releases the overcharge status when the battery voltage drops below the overcharge release voltage (VOVP-Hys).
  • If the V– pin is higher than or equal to the over-discharge detection voltage (VOCD), the device releases the overcharge status when the battery voltage drops below the overcharge detection voltage (VOVP).

The discharge is initiated by connecting a load after the overcharge detection. The V– pin rises to a voltage greater than VSS due to the parasitic diode of the charge FET conducting to support the load. If the V– pin voltage is higher than or equal to the discharge overcurrent detection threshold (VOCD), the overcurrent condition status is released only if the battery voltage drops lower than or equal to the overcharge detection voltage (VOVP).

CAUTION:
  1. If the battery is overcharged to a level greater than overcharge detection (VOVP) and the battery voltage does not drop below the overcharge detection voltage (VOVP) with a heavy load connected, the discharge overcurrent and load short-circuit detection features do not function until the battery voltage drops below the overcharge detection voltage (VOVP). The internal impedance of a battery is in the order of tens of mΩ, so application of a heavy load on the output should allow the battery voltage to drop immediately, enabling discharge overcurrent detection and load short-circuit detection features after an overcharge release delay.
  2. When a charger is connected after an overcharge detection, the overcharge status does not release even if the battery voltage drops below the overcharge release threshold. The overcharge status is released when the V– pin voltage exceeds the overcurrent detection voltage (VOCD) by removing the charger.