ZHCSD75D March 2014 – January 2018
PRODUCTION DATA.
Several key parameters must be updated to align with a given application's battery characteristics. For highest accuracy gauging, it is important to follow-up this initial configuration with a learning cycle to optimize resistance and maximum chemical capacity (Qmax) values prior to sealing and shipping packs to the field. Successful and accurate configuration of the fuel gauge for a target application can be used as the basis for creating a "golden" gas gauge (.GG) file that can be written to all production packs, assuming identical pack design and Li-Ion cell origin (chemistry, lot, and so on). Calibration data can be included as part of this golden GG file to cut down on battery pack production time. If going this route, it is recommended to average the calibration data from a large sample size and use these in the golden file. Ideally, it is recommended to calibrate all packs individually as this will lead to the highest performance and lowest measurement error in the end application on a per-pack basis. In addition, the integrated protection functionality should be correctly configured to ensure activation based on the fault protection needs of the target pack design, or else accidental trip could be possible if using defaults. Table 11, Key Data Flash Parameters for Configuration, shows the items that should be configured to achieve reliable protection and accurate gauging with minimal initial configuration.
| NAME | DEFAULT | UNIT | RECOMMENDED SETTING |
|---|---|---|---|
| Design Capacity | 1000 | mAh | Set based on the nominal pack capacity as interpreted from cell manufacturer's datasheet. If multiple parallel cells are used, should be set to N * Cell Capacity. |
| Design Energy | 3800 | mWh | Set based on the nominal pack energy (nominal cell voltage * nominal cell capacity) as interpreted from the cell manufacturer's datasheet. If multiple parallel cells are used, should be set to N * Cell Energy. |
| Design Energy Scale | 1 | — | Set to 10 to convert all power values to cWh or to 1 for mWh. Design Energy is divided by this value. |
| Reserve Capacity | 0 | mAh | Set to desired runtime remaining (in seconds/3600) * typical applied load between reporting 0% SOC and reaching Terminate Voltage, if needed. |
| Design Voltage | 3800 | mV | Set to nominal cell voltage per manufacturer datasheet. |
| Cycle Count Threshold | 900 | mAh | Set to 90% of configured Design Capacity |
| Device Chemistry | 0354 | hex | Should be configured using TI-supplied Battery Management Studio software. Default open-circuit voltage and resistance tables are also updated in conjunction with this step. Do not attempt to manually update reported Device Chemistry as this does not change all chemistry information! Always update chemistry using the appropriate software tool (that is, BMS). |
| Load Mode | 1 | — | Set to applicable load model, 0 for constant current or 1 for constant power. |
| Load Select | 1 | — | Set to load profile which most closely matches typical system load. |
| Qmax Cell 0 | 1000 | mAh | Set to initial configured value for Design Capacity. The gauge will update this parameter automatically after the optimization cycle and for every regular Qmax update thereafter. |
| V at Chg Term | 4350 | mV | Set to nominal cell voltage for a fully charged cell. The gauge will update this parameter automatically each time full charge termination is detected. |
| Terminate Voltage | 3000 | mV | Set to empty point reference of battery based on system needs. Typical is between 3000 and 3200 mV. |
| Ra Max Delta | 43 | mΩ | Set to 15% of Cell0 R_a 4 resistance after an optimization cycle is completed. |
| Charging Voltage | 4350 | mV | Set based on nominal charge voltage for the battery in normal conditions (25°C, for example). Used as the reference point for offsetting by Taper Voltage for full charge termination detection. |
| Taper Current | 100 | mA | Set to the nominal taper current of the charger + taper current tolerance to ensure that the gauge will reliably detect charge termination. |
| Taper Voltage | 100 | mV | Sets the voltage window for qualifying full charge termination. Can be set tighter to avoid or wider to ensure possibility of reporting 100% SOC in outer JEITA temperature ranges that use derated charging voltage. |
| Dsg Current Threshold | 60 | mA | Sets threshold for gauge detecting battery discharge. Should be set lower than minimal system load expected in the application and higher than Quit Current. |
| Chg Current Threshold | 75 | mA | Sets the threshold for detecting battery charge. Can be set higher or lower depending on typical trickle charge current used. Also should be set higher than Quit Current. |
| Quit Current | 40 | mA | Sets threshold for gauge detecting battery relaxation. Can be set higher or lower depending on typical standby current and exhibited in the end system. |
| Avg I Last Run | –299 | mA | Current profile used in capacity simulations at onset of discharge or at all times if Load Select = 0. Should be set to nominal system load. Is automatically updated by the gauge every cycle. |
| Avg P Last Run | –1131 | mW | Power profile used in capacity simulations at onset of discharge or at all times if Load Select = 0. Should be set to nominal system power. Is automatically updated by the gauge every cycle. |
| Sleep Current | 15 | mA | Sets the threshold at which the fuel gauge enters SLEEP Mode. Take care in setting above typical standby currents else entry to SLEEP may be unintentionally blocked. |
| Shutdown V | 0 | mV | If auto-shutdown of fuel gauge is required prior to protect against accidental discharge to undervoltage condition, set this to desired voltage threshold for completely powering down the fuel gauge. Recovery occurs when a charger is connected. |
| T1 Temp | 0 | °C | Sets the boundary between charging inhibit/suspend and charging with T1-T2 parameters. Defaults set based on recommended values from JEITA standard. |
| T2 Temp | 10 | °C | Sets the boundary between charging with T1-T2 or T2-T3 parameters. Defaults set based on recommended values from JEITA standard. |
| T3 Temp | 45 | °C | Sets the boundary between charging with T2-T3 or T3-T4 parameters. Defaults set based on recommended values from JEITA standard. |
| T4 Temp | 50 | °C | Sets the boundary between charging with T4-T5 or T4-T5 parameters. Also serves as charge inhibit boundary if initiating new charging event. Defaults set based on recommended values from JEITA standard. |
| T5 Temp | 60 | °C | Sets the boundary between charging suspend and charging with T4-T5 parameters. Refer to JEITA standard for compliance. |
| Temp Hys | 1 | °C | Adds temperature hysteresis for boundary crossings to avoid oscillation if temperature is changing by a degree or so on a given boundary. |
| T1-T2 Chg Voltage | 4350 | mV | Sets reported charge voltage when inside of T1 Temp and T2 Temp range. Defaults set based on recommended values from JEITA standard. |
| T2-T3 Chg Voltage | 4350 | mV | Sets reported charge voltage when inside of T2 Temp an d T3 Temp range. Defaults set based on recommended values from JEITA standard. |
| T3-T4 Chg Voltage | 4300 | mV | Sets reported charge voltage when inside of T3 Temp and T4 Temp range. Defaults set based on recommended values from JEITA standard. |
| T4-T5 Chg Voltage | 4250 | mV | Sets reported charge voltage when inside of T4 Temp and T5 Temp range. Defaults set based on recommended values from JEITA standard. |
| T1-T2 Chg Current | 50 | % | Sets reported charge current when inside of T1 Temp and T2 Temp range. Defaults set based on recommended values from JEITA standard. |
| T2-T3 Chg Current | 80 | % | Sets reported charge current when inside of T2 Temp and T3 Temp range. Defaults set based on recommended values from JEITA standard. |
| T3-T4 Chg Current | 80 | % | Sets reported charge current when inside of T3 Temp and T4 Temp range. Defaults set based on recommended values from JEITA standard. |
| T4-T5 Chg Current | 80 | % | Sets reported charge current when inside of T4 Temp and T5 Temp range. Defaults set based on recommended values from JEITA standard. |
| OV Prot Threshold | 4390 | mV | Set to maximum allowable cell voltage due to overcharge in normal operation. |
| OV Prot Delay | 1 | s | Set to required OVP duration prior to fault detection and FET disable. Setting of 0 disables firmware-based OVP feature. Default of 1s is recommended. |
| OV Prot Recovery | 4290 | mV | Set to desired OVP recovery threshold. 100 to 200 mV below OVP trip threshold is common. |
| OV Prot Threshold | 2800 | mV | Set to minimum allowable cell voltage due to overdischarge in normal operation. |
| OV Prot Delay | 1 | s | Set to required UVP duration prior to fault detection and FET disable. Setting of 0 disables firmware-based UVP feature. Default of 1s is recommended. |
| OV Prot Recovery | 2900 | mV | Set to desired UVP recovery threshold. 100 to 200 mV above UVP trip threshold is common. |
| Body Diode Current Threshold | 60 | mA | Varies based on FET selection. Use the max DC current for the forward-biased body diode from the FET datasheet and derate based on the operating temperature range to arrive at the minimum current value (and add some margin) that the fuel gauge should use to re-enable FET when disabled during a fault condition. |
| OT Chg | 55.0 | °C | Set to desired temperature at which charging is prohibited to prevent cell damage due to excessive ambient temperature. |
| OT Chg Time | 5 | s | Set to desired time before CHG FET is disabled based on overtemperature. Since temperature changes much more slowly than other fault conditions, the default setting is sufficient for most application. |
| OT Chg Recovery | 50.0 | °C | Set to the temperature threshold at which charging is no longer prohibited. |
| OT Dsg | 60.0 | °C | Set to desired temperature at which discharging is prohibited to prevent cell damage due to excessive ambient temperature. |
| OT Dsg Time | 5 | s | Set to desired time before DSG FET is disabled based on overtemperature. Since temperature changes much more slowly than other fault conditions, the default setting is sufficient for most application. |
| OT Dsg Recovery | 55.0 | °C | Set to the temperature threshold at which cell discharging is no longer prohibited. |
| Prot OC Config | 0A | hex | Set based on required trip thresholds for overcurrent in charge, overcurrent in discharge, and short-circuit in discharge. When setting this parameter, be sure to account for charger tolerance and maximum load spikes expected in the end system to avoid accidental trip of these fault conditions |
| Prot OV Config | 07 | hex | Set to maximum tolerable cell voltage before cell is permanently damaged. Serves as a second level OVP protection mechanism. |
| Prot Checksum | 11 | hex | Set to sum of Prot OC Config and Prot OV Config. Improper setting will cause FETs to open and warning flag assertion in SafetyStatus(), until corrected. |
| CC Gain | 5 | mΩ | Calibrate this parameter using TI-supplied BMS software and calibration procedure in the TRM. Determines conversion of coulomb counter measured sense resistor voltage to current. |
| CC Delta | 5.074 | mΩ | Calibrate this parameter using TI-supplied BMS software and calibration procedure in the TRM. Determines conversion of coulomb counter measured sense resistor voltage to passed charge. |
| CC Offset | 6.874 | mA | Calibrate this parameter using TI-supplied BMS software and calibration procedure in the TRM. Determines native offset of coulomb counter hardware that should be removed from conversions. |
| Board Offset | 0.66 | uA | Calibrate this parameter using TI-supplied BMS software and calibration procedure in the TRM. Determines native offset of the printed circuit board parasitics that should be removed from conversions. |
| Pack V Offset | 0 | mV | Calibrate this parameter using TI-supplied BMS software and calibration procedure in the TRM. Determines voltage offset between cell tab and ADC input node to incorporate back into or remove from measurement, depending on polarity. |