8.2.2 Detailed Design Procedure

8.2.2.1 Step-by-Step Design Procedure

8.2.2.1.1 STEP 1: Review and Modify the Data Flash Configuration Data.

While many of the default parameters in the data flash are suitable for most applications, the following should

first be reviewed and modified to match the intended application.

• Design Capacity: Enter the value in mAh divided by CurrScale() for the battery, even from the “design

energy” point of view.

• Design Energy: Enter the value in cWh divided by EnergyScale() .

• Cell Charge Voltage Tx-Ty: Enter the desired cell charge voltage for each JEITA temperature range.

8.2.2.1.2 STEP 2: Review and Modify the Data Flash Configuration Registers.

• LED_Comm Configuration: See in the BQ34Z100-R2 Technical Reference Manual to aid in selection of an

LED mode. Note that the pin used for the optional Alert signal is dependent upon the LED mode selected.

• Alert Configuration: See the BQ34Z100-R2 Technical Reference Manual to aid in selection of which faults

trigger the ALERT pin.

• Number of Series Cells

• Pack Configuration: Ensure that the VOLSEL bit is set for multicell applications and cleared for single-cell

applications.

8.2.2.1.3 STEP 3: Design and Configure the Voltage Divider.

If the battery contains more than 1-s cells, a voltage divider network is required. Design the divider network,

based on the formula below. The voltage division required is from the highest expected battery voltage, down to

approximately 900 mV. For example, using a lower leg resistor of 16.5 KΩ where the highest expected voltage is

32000 mV:

Rseries = 16.5 KΩ (32000 mV – 900 mV)/900 mV = 570.2 KΩ

Based on price and availability, a 600-K resistor or pair of 300-K resistors could be used in the top leg along with

a 16.5-K resistor in the bottom leg.

Set the Voltage Divider in the Data Flash Calibration section of the Evaluation Software to 32000 mV with

VoltScale() =1.

Use the Evaluation Software to calibrate to the applied nominal voltage; for example, 24000 mV. After

calibration, a slightly different value appears in the Voltage Divider parameter, which can be used as a default

value for the project. For the applications with voltage higher than 65535 mV, please refer to the BQ34Z100-R2

Technical Reference Manual.

Following the successful voltage calibration, calculate and apply the value to Flash Update OK Cell Volt as:

Flash Update OK Cell Volt = 2800 mV × Number Of Series Cells × 5000 / Voltage Divider /VoltScale() .

8.2.2.1.4 STEP 4: Determine the Sense Resistor Value.

To ensure accurate current measurement, the input voltage generated across the current sense resistor should

not exceed +/–125 mV. For applications with a very high dynamic range, it is allowable to extend this range to

absolute maximum of +/–300 mV for overload conditions where a protector device will be taking independent

protective action. In such an overloaded state, current reporting and gauging accuracy will not function correctly.

The value of the current sense resistor should be entered into both CC Gain and CC Delta parameters in the

Data Flash Calibration section of the Evaluation Software.

8.2.2.1.5 STEP 5: Review and Modify the Data Flash Gas Gauging Configuration, Data, and State.

• Load Select: See Current Model Used When Load Mode = 0 and Constant-Power Model Used When Load

Mode = 1 in the BQ34Z100-R2 Technical Reference Manual.

• Load Mode: See Current Model Used When Load Mode = 0 and Constant-Power Model Used When Load

Mode = in the BQ34Z100-R2 Technical Reference Manual.

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BQ34Z100-R2

SLUSF37 – DECEMBER 2022

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