Texas Instruments bq76930 - Reducing the Cell Count; Simulating Current Setup; Reducing Cell Count

DC Power Supply
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DC Power Supply
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bq769x0 Circuit Module Use www.ti.com
Figure 17. Simulating Current Setup
The power supply technique can also be used with the bq78350 to provide current for calibration or to
show current flow. However the simulated current will not provide good gauging evaluation.
6.4 Reducing the Cell Count
Cell count can be reduced for basic evaluation by shorting unused cells at the input terminal block. Follow
the recommendations in the datasheet for which cells to short. This works for both operation with the cell
simulator and with cells, but can have some side effects in transient tests because it parallels the input
and balance FET gate resistors of the used and unused inputs to the IC where the capacitor provides a
signal path to the used input. For the best evaluation with reduced cells in a transient environment, short
the VCx pins at the capacitor or VCx test points and remove the unused cell's input resistor and balance
FET gate resistor. When using the cell simulator, shorting the unused cell input terminals is still required to
eliminate the simulated cell voltage. Shorting the cell inputs at the terminal block screw terminals is
suggested since it should be apparent if the board is reused for a different cell count.
Table 3. Reducing Cell Count
Unused Cell (Numbered
Input and Balance FET Gate
from Bottom, Bottom = Cell Short Cell Terminals Short AFE Inputs
Resistors to Remove
1)
Cell 14 C14 to C13 R65, R70 VC14 to VC13
Cell 13 C13 to C12 R66, R71 VC13 to VC12
Cell 9 C9 to C8 R23, R33 VC9 to VC8
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bq76930 and bq76940 Evaluation Module User's Guide SLVU925B–April 2014–Revised July 2014
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