BQ29200_16 Datasheet, PDF (10/24 Pages) Texas Instruments – Voltage Protection with Automatic Cell Balance

bq29200, bq29209
SLUSA52C – SEPTEMBER 2010 – REVISED MARCH 2016
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Feature Description (continued)
8.3.5 Cell Balance Configuration
The cell balancing current may be calculated as follows:
For Cell 1 (VC1–GND) balancing current, I_CB1:
VC1
I_CB1 = _{RCB + RCB1}
(1)
For Cell 2 (VC2–VC1) balancing current, I_CB2:
I_CB2
=
(VC2 - VC1)
(R_CB+ R_VD )+ R_CB2
(2)
Where:
RCB = resistor connected between the top of Cell 1 and the VC1_CB
RCB1 = resistor connected between the top of Cell 1 and the VC1
RCB2 = resistor connected between the top of Cell 2 and the VC2
RVD = resistor connected between the top of Cell 2 and the VDD
8.3.6 Cell Imbalance Auto-Detection (Via Cell Voltage)
The V_{MM_DET_ON} and V_{MM_DET_OFF} specifications are calibrated where VDD = VC2 = 7.6 V and VC1 = 3.8 V. The
recommended range of cell balancing is VC2 and VDD between 6.0 V and 8.4 V, and VC1 between 3 V and 4.2
V. Below VDD = 6 V, it is recommended to pull CB_EN high to disable the cell balancing function.
111%
100%
79%
VC2
6V
7.6 V
8.4 V
Figure 5. V_{MM_DET_ON} and V_{MM_DET_OFF} Threshold
8.3.7 Customer Test Mode
Customer Test Mode (CTM) helps to greatly reduce the overvoltage detection delay time and enable quicker
customer production testing. This mode is intended for quick-pass board-level verification tests, and, as such,
individual cell overvoltage levels may deviate slightly from the specifications (V_PROTECT, V_OA). If accurate
overvoltage thresholds are to be tested, use the standard delay settings that are intended for normal use.
To enter CTM, VDD should be set to approximately 9.5 V higher than VC2. When CTM is entered, the device
switches from the normal overvoltage delay time scale factor, X_DELAY, to a significantly reduced factor of
approximately 0.08, thereby reducing the delay time during an overvoltage condition.
10
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