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Texas Instruments BQ2085DBT-TI
- Part No.:
- BQ2085DBT-TI
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 38-TFSOP (0.173", 4.40mm Width)
- Datasheet:
-
BQ2085DBT-TI.pdf
- Description:
- IC BATT MONITOR LI-ION 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,687
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Product details
Overview
BQ2085DBT-TI from Texas Instruments is an SBS-compliant gas gauge IC for Li-ion/Li-polymer battery packs, integrating a 16-bit integrating ADC (≤1-µV offset), 16-bit delta-sigma ADC for voltage/temperature, 512-byte flash memory, SMBus 2-wire interface, and LED drivers for 3–5-segment displays. It operates with the bq29311 AFE to deliver complete smart battery electronics for 10.8-V or 14.4-V packs in notebook PCs.
For engineers reviewing the BQ2085DBT-TI datasheet, BQ2085DBT-TI pinout, BQ2085DBT-TI application, or BQ2085DBT-TI equivalent, key selection considerations include coulomb counting resolution (<3-nVh), self-calibrating current sensing, programmable cell modeling, SMBus compliance per SBS v1.1, and integrated time base eliminating external crystals.
Technical Context
The BQ2085DBT-TI implements dual sigma-delta ADC architecture: one integrating converter for high-precision charge/discharge current measurement (SR1/SR2 inputs, ±0.3 V to 1.0 V range), and a second for simultaneous voltage (VIN) and temperature (TS) sampling every second. It uses internal RISC CPU with flash-based configuration to execute fuel-gauge algorithms including dynamic self-discharge compensation, EDV-based RM correction, and FCC learning during qualified discharges.
Communication occurs exclusively via SMBus 2-wire protocol (SMBC/SMBD), supporting Smart Battery Data commands and charge-control functions. The device interfaces gluelessly with the bq29311 AFE-receiving cell voltage data through VIN, issuing safety control signals via SAFE, and synchronizing via SCLK/SDATA-enabling full pack protection, cell balancing, and power-FET control without external logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Current Sensing | 16-bit integrating ADC with ≤1-µV offset error and <3-nVh resolution enables accurate coulomb counting over full discharge cycles |
| Voltage/Temperature Sensing | 16-bit delta-sigma ADC measures pack voltage (VIN) and thermistor voltage (TS) every second for real-time state-of-charge updates |
| SMBus Interface | Complies with SBS v1.1; supports 10–100 kHz clock rate, 25–35 ms timeout, and full register access (e.g., RemainingCapacity at 0x0F, FullChargeCapacity at 0x10) |
| Internal Memory | 512-byte flash stores nominal capacity, self-discharge rate, rate/temperature compensation factors, and learned FCC values for autonomous calibration |
| Operating Range | –20°C to 85°C ambient; 3.0–3.6 V supply (VDDA/VDDD); supports NTC thermistors or internal temperature sensor |
| LED Drive | Five open-drain outputs (LED1–LED5) drive external LEDs in 3-/4-/5-segment configurations for 20%/25%/33% remaining capacity indication |
| Power Consumption | 450 µA typical operating current; 1 µA hibernate mode current extends shelf life during storage |
Pinout & Package
38-pin TSSOP (DBT) package with exposed thermal pad; 0.65 mm pitch; 12.5 mm × 6.1 mm footprint; RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Cell voltage input | Receives scaled individual cell voltage from bq29311 VCELL output for accurate per-cell monitoring |
| TS (2) | Temperature sense input | Connects to NTC thermistor divider network (e.g., Semitec 103AT) for battery temperature measurement |
| OC (3) | Offset calibration input | Connected to VSSA to enable auto-zeroing of SR1/SR2 amplifier offset before current measurement |
| SCLK (6) | AFE clock output | Provides synchronous clock signal to bq29311 for coordinated ADC sampling and safety control timing |
| RBI (9) | Register backup input | Accepts capacitor or auxiliary battery to retain RAM contents during main supply brownout or removal |
| SDATA (10) | AFE data I/O | Half-duplex serial link with bq29311 for cell voltage readback and safety command transmission |
| SAFE (12) | Safety control output | Drives external fuse or latch circuit upon overvoltage/overcurrent detection for hardware-level protection escalation |
| SMBC/SMBD (15/16) | SMBus interface | Open-drain bidirectional lines compliant with SMBus v1.1 for host communication (address 0x0B default) |
| DISP (17) | Display control input | Configures LED segment count (3/4/5) and update rate via external pull-up/pull-down resistor |
| EVENT (18) | AFE alert input | Interrupts BQ2085DBT-TI on XALERT assertion from bq29311 indicating critical fault (e.g., cell imbalance) |
| MRST (26) | Master reset input | Active-high asynchronous reset forcing full initialization and register reload from flash memory |
| SR1/SR2 (27/28) | Current sense inputs | Differential pair measuring voltage across 10–20 mΩ sense resistor for bidirectional charge/discharge current calculation |
| LED1–LED5 (20–24) | LED driver outputs | Open-drain outputs sinking up to 10 mA each; support direct connection to common-anode LED arrays |
Key Features
| Feature | Design Value |
|---|---|
| Self-calibrating integrating ADC | Automatically nulls SR1/SR2 amplifier offset to ≤1 µV during SMBus idle periods ≥20 s, eliminating manual calibration steps |
| Programmable cell modeling | Uses 512-byte flash to store temperature-, rate-, and time-dependent compensation coefficients (DF 0x2c–0x2f, 0x84–0x8d) for adaptive fuel-gauge accuracy |
| Qualified discharge learning | Updates FullChargeCapacity only after verified discharge from near-full to EDV2 threshold with no charge activity, enabling true capacity tracking under real usage |
| EDV-based capacity correction | Applies voltage-triggered RM adjustments at three thresholds (EDV0=0%, EDV1=3%, EDV2=Battery Low%) to correct drift without requiring full discharge cycles |
| Integrated time base | On-chip oscillator with ±2% frequency error (32.768 kHz) removes need for external crystal, reducing BOM count and PCB area |
Applications
| Notebook PC Battery Packs | Medical Portable Devices |
|---|---|
Use Scenario: Integrated into removable Li-ion battery packs for Windows/Linux laptops to report remaining runtime, health, and safety status to OS power management. IC Role / Device Role / Timing Role: Primary gas gauge IC performing coulomb counting, voltage/temperature sampling, SMBus communication, and LED capacity indication. Use Value: Enables precise battery runtime prediction (±5% error) and prevents unexpected shutdowns by triggering OS hibernation before EDV2 threshold. | Use Scenario: Embedded in sealed battery modules for portable ultrasound, infusion pumps, or defibrillators requiring FDA-compliant battery health logging and fail-safe discharge cutoff. IC Role / Device Role / Timing Role: Fuel gauge and safety monitor interfacing with microcontroller host via SMBus to log cycle count, self-discharge history, and thermal profiles. Use Value: Supports regulatory traceability with flash-stored manufacturing date, serial number, and calibrated capacity data accessible via ManufacturerAccess (0x00) and SpecificationInfo (0x1a). |
| Test & Measurement Equipment | Industrial Handheld Instruments |
Use Scenario: Powering battery-backed data loggers, spectrum analyzers, or oscilloscope probes that operate unattended for hours and require accurate low-power estimation. IC Role / Device Role / Timing Role: Autonomous fuel gauge executing self-discharge compensation every 250 ms in sleep mode while maintaining SMBus responsiveness. Use Value: Extends usable runtime by 12–18% versus fixed-model gauges through temperature-adaptive self-discharge estimation (e.g., 4× faster decay at 45°C vs 25°C). | Use Scenario: Used in ruggedized barcode scanners, gas detectors, or multimeters where battery replacement is infrequent and capacity degradation must be tracked over 3+ years. IC Role / Device Role / Timing Role: Long-term capacity learner updating FullChargeCapacity during field discharges and storing historical data in nonvolatile flash. Use Value: Delivers >95% capacity estimation accuracy after 200 cycles by combining FCC learning, midrange VOC corrections, and EDV-based RM trimming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar gas gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ20Z75-V165 | Higher integration: includes integrated AFE, 32-bit CPU, and enhanced SBS v1.1 compliance; requires different firmware and layout | Targets newer designs needing higher accuracy (±1% SOC) and extended diagnostics (impedance tracking) | Select for new 3–4 cell Li-ion systems requiring drop-in upgrade path with TI's Impedance Track™ algorithm |
| MAX17043 | Standalone fuel gauge with ModelGauge™ m3 algorithm; no SMBus-uses I²C; smaller 8-pin µDFN package | Used in space-constrained consumer devices (wearables, Bluetooth headsets) where AFE integration is handled externally | Select when board area is critical and system already includes discrete protection IC; not compatible with bq29311 glueless interface |
Compared with BQ2085DBT-TI, the BQ20Z75-V165 offers superior accuracy and embedded protection but demands full firmware migration, while the MAX17043 reduces footprint and cost at the expense of AFE co-design and SMBus compatibility-making BQ2085DBT-TI optimal for legacy notebook battery packs using bq29311.
Availability
BQ2085DBT-TI is available at Aetrix Electronics and suitable for notebook PC battery packs, medical portable devices, test equipment, and industrial handheld instruments requiring stable component supply and long-lifecycle support.
Supply support for BQ2085DBT-TI 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions across industrial, automotive, and personal electronics markets.
The BQ2085DBT-TI belongs to TI's Smart Battery Solutions product line, engineered specifically for SBS-compliant Li-ion/Li-polymer fuel gauging in multi-cell portable systems where integration with analog front-end protection ICs is required.
FAQ
What is the primary function of the BQ2085DBT-TI in a smart battery system?
The BQ2085DBT-TI serves as the core gas gauge IC in smart battery systems, performing real-time coulomb counting via its integrating ADC, measuring voltage and temperature, executing fuel-gauge algorithms (including FCC learning and EDV correction), and reporting battery parameters-including RemainingCapacity, FullChargeCapacity, and Temperature-over SMBus to the host system. It works exclusively with the bq29311 AFE to form a complete, glueless battery management solution.
Does the BQ2085DBT-TI require an external crystal oscillator?
No, the BQ2085DBT-TI does not require an external crystal oscillator. It integrates an on-chip 32.768-kHz oscillator with ±2% frequency accuracy, which drives internal timing functions and provides CLKOUT to the bq29311 AFE. This eliminates the need for external timing components, reducing bill-of-materials cost and PCB layout complexity in battery pack designs.
How does the BQ2085DBT-TI achieve accurate fuel gauging without periodic full discharges?
The BQ2085DBT-TI achieves accurate fuel gauging through multiple complementary mechanisms: (1) self-calibrating integrating ADC minimizes offset drift; (2) programmable cell modeling compensates for temperature, rate, and aging effects; (3) EDV-based RM corrections at three voltage thresholds (EDV0/EDV1/EDV2) adjust capacity without full discharge; and (4) qualified discharge learning updates FullChargeCapacity only after verified deep discharges, ensuring long-term accuracy without user intervention.
What safety features does the BQ2085DBT-TI provide in conjunction with the bq29311?
The BQ2085DBT-TI provides layered safety by generating control signals to the bq29311 AFE-including SAFE output for hardware fuse activation-and receiving real-time alerts via the EVENT pin (connected to bq29311's XALERT). It also monitors cell voltages through VIN, triggers EDV-based shutdowns, and coordinates cell balancing commands-all while maintaining independent SMBus communication for host visibility into fault conditions such as overvoltage, overcurrent, or thermal runaway.
Can the BQ2085DBT-TI operate with internal temperature sensing instead of an external NTC thermistor?
Yes, the BQ2085DBT-TI can operate using its internal temperature sensor by setting bit 7 (IT) in the Misc Configuration data flash location 0x2a. When enabled, internal sensor readings replace TS input measurements, and data flash constants (DF 0xa4–0xad) must be updated to predefined values per the datasheet. This mode simplifies design in cost-sensitive applications where ±3°C accuracy suffices, though external NTC thermistors (e.g., Semitec 103AT) remain preferred for medical or high-precision use cases.
BQ2085DBT-TI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- 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-TI FAQ
1.How can I place an order for BQ2085DBT-TI through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ2085DBT-TI 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-TI reliable?
The price and inventory of BQ2085DBT-TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ2085DBT-TI is usually 5 days.
3.What payment methods are accepted for BQ2085DBT-TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ2085DBT-TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ2085DBT-TI?
BQ2085DBT-TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ2085DBT-TI 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-TI?
For technical support, including BQ2085DBT-TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ2085DBT-TI requirements.
6.How does Aetrix verify that BQ2085DBT-TI is sourced from the original manufacturer or authorized distributors?
All BQ2085DBT-TI 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-TI meets industry standards.
7.What is the process for return or replacement of BQ2085DBT-TI?
All BQ2085DBT-TI units undergo pre-shipment inspection (PSI). If there is an issue with BQ2085DBT-TI, 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-TI part is unused and in its original packaging.
Return procedure for BQ2085DBT-TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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