Texas Instruments BQ2085DBTR

Overview

BQ2085DBTR from Texas Instruments is a Smart Battery Specification (SBS) v1.1–compliant gas gauge IC for Li-ion and Li-polymer battery packs. It performs coulomb counting via a self-calibrating 16-bit integrating ADC (<1-µV offset, >3-nVh resolution), measures voltage/temperature with a 16-bit delta-sigma ADC, integrates 512-byte FLASH for programmable cell modeling, and drives up to 5-segment LED displays. It operates in notebook PC battery packs with the bq29311 AFE.

For engineers reviewing the BQ2085DBTR datasheet, BQ2085DBTR pinout, BQ2085DBTR application, or BQ2085DBTR equivalent, key selection criteria include SMBus 2-wire interface compliance, integrated time base eliminating external crystal, coulomb-counting accuracy under dynamic load, LED display segment control, and seamless glueless interfacing with the bq29311 analog front end.

Technical Context

The BQ2085DBTR implements dual sigma-delta ADC architecture: one dedicated to high-resolution current sensing across SR1/SR2 (±0.3 V input range, <1 µV offset), and another for simultaneous voltage and temperature measurement. Its RISC CPU executes fuel-gauge algorithms-including capacity learning, EDV-based RM correction, and temperature-compensated self-discharge estimation-using configuration data stored in on-chip 512-byte FLASH.

It interfaces exclusively via SMBus 2-wire protocol (10–100 kHz slave mode), supports SBS v1.1 command set (e.g., RemainingCapacity, FullChargeCapacity, Temperature), and relies on the bq29311 for cell voltage monitoring, safety control, and power delivery-enabling full pack electronics with minimal external components.

Key Specifications

Pinout & Package

38-pin TSSOP (DBT) package with exposed thermal pad; lead-free and RoHS-compliant per TI specification.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar gas gauge applications.

Compared with BQ2085DBTR, BQ2084DBTR removes LED drive capability but retains identical gauging accuracy and SMBus interface, while BQ20Z75-V156 upgrades core architecture and measurement precision for applications demanding sub-1% capacity error and adaptive learning.

Availability

BQ2085DBTR is available at Aetrix Electronics and suitable for notebook PC battery packs, portable medical devices, and industrial instrumentation requiring stable component supply, long-lifecycle support, and SBS v1.1 compliance.

Supply support for BQ2085DBTR 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 expertise in battery management solutions.

The BQ2085DBTR belongs to TI's Smart Battery Gas Gauge IC product line, designed specifically to deliver SBS-compliant, high-accuracy fuel gauging for multi-cell Li-ion/Li-polymer battery packs in portable computing and professional equipment.

FAQ

What is the primary function of the BQ2085DBTR in a battery management system?

The BQ2085DBTR serves as the core SBS-compliant gas gauge IC, performing real-time coulomb counting, voltage/temperature monitoring, capacity learning, and SMBus-based data reporting. It works in tandem with the bq29311 AFE to form a complete smart battery solution. The BQ2085DBTR itself handles all fuel-gauge calculations, stores learned parameters in on-chip FLASH, and drives LED indicators-making it essential for accurate runtime estimation in notebook and portable equipment battery packs.

Does the BQ2085DBTR require an external crystal oscillator?

No, the BQ2085DBTR integrates an internal oscillator with ±2% frequency accuracy, eliminating the need for an external 32.768-kHz crystal. Its time base is configured via the ROSC pin (pin 33) and a precision 113-kΩ resistor to VSSA, enabling compact, low-BOM designs. This internal timing source directly feeds the coulomb counter and SMBus interface, ensuring synchronization without external components.

How does the BQ2085DBTR achieve high-accuracy current measurement?

The BQ2085DBTR achieves high-accuracy current measurement using a self-calibrating 16-bit integrating ADC with better than 3-nVh resolution and less than 1-µV offset error. It samples the differential voltage across an external sense resistor (10–20 mΩ) connected to SR1/SR2 pins, continuously integrating charge flow. Auto-offset calibration occurs when SMBus lines remain low for ≥20 seconds, ensuring long-term accuracy without manual trimming or external calibration circuitry.

Can the BQ2085DBTR operate independently without the bq29311 AFE?

No-the BQ2085DBTR is designed for glueless operation with the bq29311 AFE and relies on it for critical functions including cell voltage monitoring (via VIN), power supply generation, safety control signaling (SAFE, EVENT), and level translation. While basic SMBus communication may initialize, full gas-gauge functionality-including accurate per-cell voltage reporting, protection coordination, and learned capacity updates-requires the bq29311. The BQ2085DBTR lacks internal high-voltage analog front-end circuitry needed for standalone multi-cell operation.

What type of memory does the BQ2085DBTR use for configuration storage, and what is its endurance?

The BQ2085DBTR uses 512 bytes of on-chip FLASH memory to store configuration data-including nominal capacity, self-discharge rate, temperature compensation coefficients, and learned FullChargeCapacity values. This FLASH supports 10⁵ write cycles and guarantees 10 years of data retention under normal operating conditions. Configuration is retained during power loss via the RBI pin, which accepts a backup capacitor or auxiliary supply to preserve register contents during brownout events.