SLUUCY9 November   2023 BQ76905

 

  1.   1
  2.   Description
  3.   Get Started
  4.   Features
  5.   Applications
  6.   6
  7. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  8. 2Hardware
    1. 2.1 Before You Begin
    2. 2.2 Required Equipment
    3. 2.3 BQ76905 Circuit Module Use
      1. 2.3.1 Cell Simulator
      2. 2.3.2 Evaluating with Load Current
      3. 2.3.3 Evaluating Charge and Discharge Currents
      4. 2.3.4 Evaluating with Simulated Current
      5. 2.3.5 Reducing the Cell Count
      6. 2.3.6 Connecting Cells
      7. 2.3.7 Connecting to a Host
      8. 2.3.8 Hardware Configuration
        1. 2.3.8.1 Configuration Jumpers
      9. 2.3.9 Configuration Register Programming
  9. 3Quick Start Guide
  10. 4Software
    1. 4.1 Battery Management Studio Software
      1. 4.1.1 System Requirements
      2. 4.1.2 Installing BQStudio
      3. 4.1.3 BQ76905 bqz File Installation
      4. 4.1.4 BQStudio Operation and Registers View
      5. 4.1.5 Commands
      6. 4.1.6 Data Memory
        1. 4.1.6.1 Entering, Saving, and Loading Configuration
      7. 4.1.7 Command Sequences
  11. 5Hardware Design Files
    1. 5.1 Schematic
    2. 5.2 Board Layout
    3. 5.3 Bill of Materials
  12. 6Additional Information
    1.     Trademarks

Reducing the Cell Count

The BQ76905 must have the top and bottom cells used for proper operation. Cell count can be reduced by shorting the unused cell inputs from the next-to-top down. Cell count can be reduced for basic evaluation by shorting unused cells at the input terminal block. Follow the recommendations in the data sheet for which cells to short. This works for both operation with the cell simulator and cells, but can have some side effects in transient tests because the shorted resistors are parallel to the cell IC where the capacitor provides a signal path to the used input. See Figure 3-4 for an example of simple reduced cell configuration for 3 cells. For the best evaluation with reduced cells in a transient environment, short the VCx pins at the capacitor and remove the unused input resistor. When using the cell simulator, shorting the unused cell at the terminal block is still required to eliminate the simulated cell voltage. Shorting the cell inputs at the terminal block screw terminals is suggested since the cell inputs are apparent if the board is re-used for a different cell count. Table 3-1 shows configuration recommendations for reduced cell count, this table assumes the board has been set-up as detailed in Section 3.

Attention: By default, the BQ76905 EVM has VC4A/B and VC3A/B shorted at the IC inputs. However, the user must make sure to also short CELL6 to CELL5 and CELL4 to CELL3 on the cell input terminals prior to making any cell reduction, as explained in Section 3.
Table 2-1 Reducing Cell Count
Unused cell
(numbered from bottom cell 1)
Short cell input terminalsInput resistor to removeReplace capacitor with 0 ohmIC inputs shorted
Cell 4CELL5 to CELL4R8C7VC4A/B to VC3A/B
Cell 3CELL3 to CELL2R11C9VC3A/B to VC2
GUID-20231117-SS0I-VJXV-ZFMC-H89S492Q9D1Z-low.svgFigure 2-4 Example 3 Cell Simple Evaluation Configuration