The BQ2083-V1P3 SBS standard fuel gauge IC is installed and maintained in a battery pack or system to accurately record the available charge in Li-ion or Li-polymer cells. The bq2083-V1P3 monitors key parameters of the battery pack such as capacity and reports the information communication bus provided to the system host controller via the serial port. It is designed to maximize functionality and safety with the bq29311 analog front-end (AFE) protection IC minimizing component count and cost of smart battery circuits. Using information from the bq2083-V1P3, the host controller can manage the remaining battery power to extend system runtime as much as possible.

block diagram

feature

Provides accurate available measurements for Li-ion and Li-polymer battery charging

Support Smart Battery Specification SBS) V1.1

Compatible with TI bq29311 Analog Front End AFE) Protection IC Provides a Complete Package for 10.8 V or 14.4 V Battery Pack Electronics with Few External Components

Based on a powerful low-power RISC CPU core and high-performance peripherals

Integrated flash memory eliminates need for external configuration EEPROM

16-bit integrating converter for measuring charge flow using high voltage resolution

- Better than 3-nVh resolution

- Self-calibration

- Offset error less than 1-µV

Accurate voltage and temperature measurements using 16-bit Delta Sigma converters

Programmable Cell Modeling Maximizes Battery Fuel Gauge Accuracy

3-segment, 4-segment or 5-segment LED display for the driver

Remaining capacity indication

38-pin TSSOP (DBT)

application

laptop

Medical and Test Equipment

Portable Meter

The bq2083-V1P3 uses an integrating converter to continuously sample and measure battery charge and discharge current. Optimized for coulomb counting in portable applications, the resolution of the self-calibrating integrating converter is better than 3-nVh offset measurement error is less than 1-µV (typical). For voltage and temperature reporting, the bq2083-V1P3 uses a 16-bit A/D converter. The use of the bq29311 in conjunction with the on-board ADC to monitor the individual cell voltages in the battery pack allows the bq2083-V1P3 to generate the control signals necessary for cell balancing and safety chemicals required for Li-ion and Li-polymer batteries. The bq2083-V1P3 supports Smart Battery Data (SBData) commands and charge control functions. It transmits data using the System Management Bus (SMBus) 2-wire protocol. Available data includes remaining battery capacity, temperature, voltage, current and remaining runtime forecast. The bq2083-V1P3 provides LED drivers and pushbutton inputs to change remaining battery capacity from full to empty in 20%, 25% or 33% increments with 3, 4 or 3 5-segment displays.

The bq2083-V1P3 contains 512 bytes of internal data flash to store configuration information. This information includes nominal capacity and voltage, self-discharge rate, rate compensation factor, etc. Programmable cell modeling factors are used to accurately adjust remaining capacity based on usage conditions

time, speed and temperature. The bq2083-V1P3 also automatically calibrates or learns the true battery capacity during programmable discharge cycles near full to near empty levels.

The bq29311 AFE protection IC supplies power from the bq2083-V1P3 of the 3- or 4-series Li-Ion battery stack without the need for an external voltage regulator circuit.

Function Description:

General Operation: The bq2083-V1P3 determines battery capacity by monitoring the amount of power input or removed from a rechargeable battery. In addition to quantitative charge and discharge, the bq2083-V1P3 measures battery voltage, temperature, and current to estimate battery self-discharge, and monitor the battery's low-voltage threshold. The bq2083-V1P3 measures the resistance between the negative terminal of the charging and discharging active cell and the negative terminal of the battery pack by monitoring the voltage across a small value series inductance. Available batteries determine charge conditions by monitoring this voltage and correcting for measurement environment and operation.

The bq2083-V1P3 interfaces with the bq29311 to perform cell protection, cell balancing and voltage translation functions.

The bq2083-V1P3 can accept any NTC thermistor (Semitec 103AT by default) for temperature measurement or can be configured to use its internal temperature sensor. The bq2083-V1P3 uses temperature to monitor the battery pack and compensate for self-discharge estimates.

Measurements: The bq2083-V1P3 uses an integrated sigma-delta analog-to-digital converter (ADC) for current measurements and a second sigma delta ADC for battery voltage and temperature measurements. Voltage, current and temperature are measured every second. charge and discharge count

The integrating ADC measures the charge and discharge flow of the battery by monitoring the small sense of the resistance between the SR1 and SR2 pins as shown in the schematic. The integrating ADC measures bipolar signals from -0.3 to 1.0 V. The bq2083-V1P3 detects charging activity when VSR = V(SR1)-V(SR2) is positive and discharging when VSR = V(SR1)-V(SR2 ) is negative for the activity. The bq2083-V1P3 uses a time-continuous integral signal internal counter. The base rate of the counter is 2.6 nVh. The bq2083-V1P3 updates the remaining capacity to accumulate charge or discharge every second in this internal counter.

Offset Calibration: The bq2083-V1P3 provides an auto-calibration feature that removes voltage offset errors on SR1 and SR2 for maximum charge measurement accuracy. When the SMBus line is stuck, the bq2083-V1P3 performs an auto-calibration low for at least 20 seconds. The bq2083-V1P3 is capable of automatic offset calibration down to 1 μV.

Digital Filter: The bq2083-V1P3 does not measure charge or discharge counts below the digital filter threshold. The digital filter threshold is programmed in Digital Filter DF 0x2b and should be set high enough to prevent false positive detection without charging or discharging current through the sense resistor.

Voltage: While monitoring the charge and discharge currents of SR1 and SR2, the bq2083-V1P3 monitors the individual series battery voltages through the bq29311. The bq2083-V1P3 configures the bq29311 to present the selected cell to the bq29311's VCELL pin should be connected to the bq2083-V1P3's VIN. The bq2083-V1P3 of the internal ADC then measures the voltage and adjusts it appropriately. The bq2083-V1P3 then reports the voltage and the individual cell voltages in VCELL1, VCELL2, VCELL3 and VCELL4 located at 0x3c-0x3f.

The current bq2083-V1P3 uses the SR1 and SR2 inputs to measure and calculate the battery charge and discharge current as shown in the data register Current.

Temperature: The TS input of the bq2083-V1P3 works with an NTC thermistor to measure the battery temperature as shown in the schematic. bq2083-V1P3 reports temperature for temperature. The bq2083-V1P3 can also be configured to configure DF 0x2a with its internal temperature sensor by setting the IT bit in Misc. Data flash locations DF 0xa4 to DF 0xad must also be changed to the specified value if the internal temperature sensor option is selected.

Operation diagram of gas meter of bq2083-V1P3

The bq2083-V1P3 accumulates a measure of charge and discharge current and estimates the self-discharged battery. The bq2083-V1P3 compensates temperature and state-of-charge for charge current measurement of batteries. The bq2083-V1P3 also adjusts self-discharge estimates based on temperature.

The main charge counter RemainingCapacity (RM) represents the available capacity or energy of the battery at any given time. The bq2083-V1P3 regulates the charge, self-discharge and other compensation factors of the RM. The information in this RM register can be accessed through the SMBus interface and can also be indicated by LEDs. The FullChargeCapacity (FCC) register indicates that the battery was fully discharged at the last measurement. It is used as a reference for battery full charge as a relative capacity indication. The bq2083-V1P3 experienced a qualifying discharge from almost complete to low battery level after battery update FCC. The FCC is accessible through the SMBus interface. The Discharge Count Register (DCR) is an inaccessible register that tracks the discharge of the battery. The bq2083-V1P3 uses the DCR register to update the FCC register if the battery has undergone a qualifying discharge and the battery is almost full. In this way, the bq2083-V1P3 can learn the true discharge capacity of the battery under system usage conditions.

Primary Gas Metering Register

The gas meter register function is shown in the figure above. RM represents the remaining capacity of the battery. bq2083-V1P3 calculates RM in mAh or mA

10 mWh depends on the selected mode. See Battery Mode (0x03) for device configuration. M counts to a maximum value FCC during charge and drops to a minimum during discharge and self-discharge In addition to charge and self-discharge compensation, the bq2083-V1P3 calibrates RM to 3 low battery voltage thresholds, EDV2, EDV1 and EDV0 and three programmable IFs Thresholds VOC25, VOC50 and VOC75. This provides voltage-based calibration for the RM counter. is the user-specified full capacity of the battery. It is calculated from Pack Capacity DF 0x31-0x32

Expressed in mAh or 10mWh. It also represents the full battery reference for absolute display mode. FCC is the last measured battery discharge capacity. It is expressed in mAh or 10 mWh, depending on the selected mode. On initialization, the bq2083-V1P3 sets the FCC to the value stored in Last Measured to discharge DF 0x35-0x36. During subsequent discharges, the bq2083-V1P3 updates the FCC battery discharge capacity at the last measurement. The last measured battery discharge is based on the value in the DCR register after a qualified discharge occurs. After the update, the bq2083-V1P3 flashes the new FCC value in mAh to the last measured discharge. FCC stands for complete battery reference charge calculation for relative display mode and relative status. Discharge Count Register (DCR) The DCR register counts up during discharge regardless of RM. DCR calculates discharge activity, battery load estimates and self-discharge increments. The bq2083-V1P3 initializes DCR to FCC at start of discharge - RM when RM is within the programmed value in near full DF 0x2f. The DCR initial value of the FCC-RM is reduced if SC = 1 (bit 5 in the meter configuration), then passes FCC/128, and if SC = 0, it is not reduced. When the battery is on, the DCR stops counting

The voltage reaches the EDV2 threshold during discharge. Capacity Learning (FCC Update) and Qualifying Discharge If a qualifying discharge occurs, the bq2083-V1P3 updates the FCC based on the value in the DCR. The new FCC value is equal to the DCR value plus programmable near full and low battery levels