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Texas Instruments BQ2085DBT
- Part No.:
- BQ2085DBT
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 38-TFSOP (0.173", 4.40mm Width)
- Datasheet:
-
BQ2085DBT.pdf
- Description:
- IC GAS GAUGE FOR BQ29311 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,635
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Product details
Overview
BQ2085DBT from Texas Instruments is a Smart Battery Specification (SBS) v1.1–compliant gas gauge IC designed for Li-ion and Li-polymer battery packs. It performs coulomb counting with better than 3-nVh resolution, integrates a 16-bit delta-sigma ADC for voltage/temperature sensing, and interfaces via SMBus 2-wire protocol with the bq29311 AFE to deliver complete pack electronics for 10.8-V or 14.4-V systems.
For engineers reviewing the BQ2085DBT datasheet, BQ2085DBT pinout, BQ2085DBT application, or BQ2085DBT equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, SBS-compliant implementation guidance, and confirmed alternative options for smart battery fuel gauging in notebook PCs and portable instrumentation.
Technical Context
The BQ2085DBT implements a self-calibrating integrating ADC for high-accuracy coulomb counting (offset error < 1 µV, resolution better than 3-nVh), paired with a separate 16-bit delta-sigma ADC for simultaneous voltage and temperature measurement. It operates with the bq29311 analog front-end to monitor individual cell voltages, enable cell balancing, and execute safety protection logic without external regulators.
Its RISC CPU core executes programmable cell modeling using 512 bytes of on-chip FLASH memory, enabling runtime compensation for temperature, discharge rate, and self-discharge-updating RemainingCapacity( ) every second and learning FullChargeCapacity( ) during qualified discharges from near-full to EDV2 threshold.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gas Gauge Compliance | SBS v1.1 compliant; supports SBData commands and charge-control functions over SMBus |
| Coulomb Counting Resolution | Better than 3-nVh; enables sub-mAh accuracy in capacity tracking for multi-hour runtime estimation |
| ADC Architecture | Dual 16-bit delta-sigma converters: one for current (integrating), one for voltage/temperature |
| Offset Error (Current ADC) | < 1 µV typical; ensures minimal drift-induced capacity error during low-current standby or trickle charge |
| Internal Time Base | Integrated 32.768-kHz oscillator; eliminates need for external crystal and reduces BOM count |
| FLASH Memory | 512 bytes configuration EEPROM; stores nominal capacity, self-discharge rate, and cell-modeling coefficients |
| Operating Temp Range | –20°C to +85°C; validated for industrial-grade notebook and medical equipment environments |
Pinout & Package
38-pin TSSOP (DBT) package with exposed thermal pad; RoHS-compliant, lead-free finish; 0.65-mm pitch; body size 9.7 mm × 4.4 mm × 1.2 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Cell voltage input | Accepts scaled single-cell voltage from bq29311 VCELL output; used for pack-level voltage reporting |
| SR1 / SR2 | Current sense differential inputs | Monitor voltage across external sense resistor (10–20 mΩ); bipolar range –0.3 V to +1.0 V enables bidirectional coulomb counting |
| TS | Thermistor input | Supports NTC thermistors (e.g., Semitec 103AT) or internal sensor; enables temperature-compensated self-discharge modeling |
| SMBC / SMBD | SMBus interface | Open-drain bidirectional clock/data lines; compatible with 10–100 kHz SMBus slave timing |
| LED1–LED5 | LED segment drivers | Push-pull outputs capable of driving 10 mA each; support 3-/4-/5-segment LED display for 20%/25%/33% remaining capacity steps |
| RBI | Register backup supply | Accepts capacitor or battery backup; preserves data registers during main supply brownout or removal |
Key Features
| Feature | Design Value |
|---|---|
| Glueless AFE Interface | Direct level-translated control and data exchange with bq29311-no external logic or voltage translators required |
| Auto Offset Calibration | Performs full offset cancellation on SR1/SR2 when SMBus idle ≥20 s; maintains ≤1-µV residual error without manual calibration |
| Programmable EDV Thresholds | Three user-configurable end-of-discharge voltages (EDV0/EDV1/EDV2) with automatic temperature/current compensation |
| Learning-Based FCC Update | Updates FullChargeCapacity( ) only after qualified discharge meeting 7 criteria-including no charge activity, bounded self-discharge, and temperature compliance |
| Digital Filter Threshold | Configurable via DF 0x2b to suppress noise-induced false counts below user-defined current level |
Applications
| Notebook PC Battery Management | Medical Portable Instrumentation |
|---|---|
Use Scenario: Integrated into removable Li-ion battery packs for Windows-based laptops requiring SBS-compliant runtime prediction and LED state-of-charge indication. IC Role / Device Role / Timing Role: Primary fuel gauge IC performing real-time coulomb counting, voltage/temperature sampling, and SMBus communication with host EC/BIOS. Use Value: Enables accurate "minutes remaining" estimates and prevents unexpected shutdown by triggering OS-level low-battery warnings at precise EDV thresholds. | Use Scenario: Embedded in sealed battery modules for handheld ultrasound or patient monitors where calibration stability and long-term capacity retention are critical. IC Role / Device Role / Timing Role: Standalone gas gauge managing capacity learning, self-discharge compensation, and midrange voltage corrections under varying ambient temperatures. Use Value: Maintains ±2% SoC accuracy over 500+ cycles by adapting to aging via FCC updates and temperature-dependent self-discharge modeling. |
| Industrial Test Equipment | Portable Data Acquisition Systems |
Use Scenario: Used in rechargeable battery packs for benchtop multimeters and oscilloscope accessories operating across –20°C to +70°C ambient ranges. IC Role / Device Role / Timing Role: Core SBS-compliant gauge interfacing with bq29311 for cell-level monitoring and safety enforcement during high-current test loads. Use Value: Delivers stable capacity reporting despite wide temperature swings by applying real-time thermal derating to self-discharge and EDV thresholds. | Use Scenario: Deployed in field-deployable environmental sensors powered by 3S/4S Li-ion packs requiring >1-year shelf life and reliable wake-from-sleep capacity recall. IC Role / Device Role / Timing Role: Fuel gauge with RBI-supplied register retention and configurable sleep timer (DF 0xE7) for ultra-low-power periodic self-discharge correction. Use Value: Preserves RemainingCapacity( ) integrity during 6-month storage by applying temperature-scaled self-discharge rates (e.g., 1/4Y% per day below 10°C). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar smart battery fuel gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ2084DBT | No LED drivers; lacks DISP, LED1–LED5 pins; identical coulomb counting, SMBus, and FLASH architecture | Requires external LED driver circuitry; suitable for space-constrained designs where visual indication is handled off-chip | Select BQ2084DBT when LED display is unnecessary and PCB area must be minimized. |
| BQ20Z75-V150 | Enhanced 32-bit RISC core; integrated 24-bit ADC; supports Impedance Track™ algorithm; higher accuracy and extended temperature range (–40°C to +85°C) | Targets premium notebooks and EV auxiliary batteries; requires different firmware and calibration flow | Choose BQ20Z75-V150 for next-gen designs needing <1% SoC error and impedance-based health monitoring. |
Compared with BQ2085DBT, BQ2084DBT removes LED functionality while retaining identical gas gauge accuracy and SBS compliance, whereas BQ20Z75-V150 upgrades core architecture and metrology for higher precision and broader environmental operation-requiring firmware rework but delivering superior long-term aging compensation.
Availability
BQ2085DBT is available at Aetrix Electronics and suitable for notebook PC battery packs, medical portable instrumentation, and industrial test equipment requiring stable component supply, long-lifecycle support, and SBS v1.1 interoperability.
Supply support for BQ2085DBT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of leadership in battery management ICs.
The BQ2085DBT belongs to TI's Smart Battery Gas Gauge product line, engineered specifically to simplify SBS-compliant battery pack design by integrating coulomb counting, cell monitoring, and SMBus communication in a single IC working seamlessly with the bq29311 AFE.
FAQ
What is the primary function of the BQ2085DBT in a smart battery system?
The BQ2085DBT serves as the core SBS v1.1–compliant fuel gauge IC, performing real-time coulomb counting, voltage/temperature measurement, and SMBus communication to report RemainingCapacity( ), FullChargeCapacity( ), and runtime estimates. It works exclusively with the bq29311 AFE to manage cell balancing and safety functions-making BQ2085DBT essential for accurate, standards-compliant battery state-of-charge tracking in 3S/4S Li-ion packs.
Does the BQ2085DBT require an external crystal oscillator?
No, the BQ2085DBT integrates a factory-trimmed 32.768-kHz oscillator with ±2% frequency error over –20°C to +85°C, eliminating the need for an external crystal. Its ROSC pin connects to a precision 113-kΩ resistor (±0.1%, ±50 ppm) for biasing, and CLKOUT provides the clock signal directly to the bq29311-reducing component count and board space versus crystal-based solutions.
How does the BQ2085DBT handle battery self-discharge compensation?
The BQ2085DBT applies temperature-scaled self-discharge compensation using a programmable base rate (Y% per day at 25°C) stored in DF 0x2c. It adjusts RM( ) every 250 ms when awake and periodically in sleep mode, halving the rate per 10°C drop below 25°C (e.g., 1/4Y% per day below 10°C) and doubling it per 10°C rise-ensuring accurate capacity holdover during storage without external intervention.
Can the BQ2085DBT operate without the bq29311 analog front-end?
No-the BQ2085DBT is architecturally dependent on the bq29311 for cell voltage monitoring, safety control signals (SAFE, EVENT), and power regulation. Its VIN, SCLK, SDATA, and SAFE pins are designed for direct glueless interface with bq29311; standalone operation is not supported, and no internal voltage regulation or cell protection logic exists within BQ2085DBT itself.
What is the role of the RBI pin on the BQ2085DBT?
The RBI (Register Backup Input) pin on the BQ2085DBT accepts a backup capacitor or small battery to maintain data register integrity-including RemainingCapacity( ), FullChargeCapacity( ), and configuration settings-during main supply dropout or pack removal. With VRB ≥ 1.3 V and I(RBI) ≤ 100 nA, RBI ensures seamless capacity continuity across hot-swap events and brownout conditions critical for medical and industrial applications.
BQ2085DBT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width)
- Packaging:
- Tray
- Product Status:
- Active
- Function:
- Battery Monitor
- Battery Chemistry:
- Lithium Ion/Polymer
- Number of Cells:
- -
- Fault Protection:
- -
- Interface:
- SMBus
- Operating Temperature:
- -20°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP
BQ2085DBT FAQ
1.How can I place an order for BQ2085DBT through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ2085DBT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BQ2085DBT reliable?
The price and inventory of BQ2085DBT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ2085DBT is usually 5 days.
3.What payment methods are accepted for BQ2085DBT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ2085DBT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ2085DBT?
BQ2085DBT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ2085DBT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BQ2085DBT?
For technical support, including BQ2085DBT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ2085DBT requirements.
6.How does Aetrix verify that BQ2085DBT is sourced from the original manufacturer or authorized distributors?
All BQ2085DBT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BQ2085DBT meets industry standards.
7.What is the process for return or replacement of BQ2085DBT?
All BQ2085DBT units undergo pre-shipment inspection (PSI). If there is an issue with BQ2085DBT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BQ2085DBT part is unused and in its original packaging.
Return procedure for BQ2085DBT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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