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Texas Instruments BQ20851DBT-TI
- Part No.:
- BQ20851DBT-TI
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 38-TFSOP (0.173", 4.40mm Width)
- Datasheet:
-
BQ20851DBT-TI.pdf
- Description:
- IC BATT MON LI-ION 3-4CL 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:200
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Product details
Overview
BQ20851DBT-TI from Texas Instruments is an SBS-compliant gas gauge IC designed for Li-ion/Li-polymer battery packs, providing coulomb counting with <1-µV offset error, 3-nVh resolution, and integrated 16-bit delta-sigma ADCs for voltage/temperature measurement. It operates with the bq29311 AFE to enable complete smart battery electronics for 10.8-V or 14.4-V notebook PC battery packs.
For engineers reviewing the BQ20851DBT-TI datasheet, BQ20851DBT-TI pinout, BQ20851DBT-TI application, or BQ20851DBT-TI equivalent, this page delivers verified technical context, SMBus 2-wire interface timing, LED display drive capability, self-calibrating integrating ADC performance, and flash-based cell modeling parameters critical for accurate fuel gauging in portable systems.
Technical Context
The BQ20851DBT-TI implements a dual-ADC architecture: a high-resolution 16-bit integrating converter for current sensing (SR1/SR2) with continuous sampling and auto-calibration, and a separate 16-bit delta-sigma ADC for voltage (VIN) and temperature (TS) measurements. It uses an internal RISC CPU with 512 bytes of on-chip FLASH for configuration storage and runtime learning.
It interfaces gluelessly with the bq29311 AFE via dedicated control lines (SCLK, SDATA, EVENT, SAFE), supports SMBus 2.0 protocol at up to 100 kHz, and drives 3–5 segment LED displays directly via LED1–LED5 outputs. Its internal oscillator eliminates external crystal requirements, with frequency stability dependent on the 113-kΩ ROSC resistor tolerance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0 V to 3.6 V - powers analog (VDDA) and digital (VDDD) domains independently |
| Operating Current | 350 µA typical - enables low-power operation during active fuel gauging |
| Integrating ADC Resolution | <3-nVh - achieves sub-microampere-level current measurement accuracy over time |
| Offset Error | <1 µV - ensures minimal baseline drift in coulomb counting without manual calibration |
| SMBus Frequency | 10–100 kHz - supports standard system management bus communication with host controllers |
| LED Drive Outputs | 5 segments (LED1–LED5) - directly drives external LEDs for 20%/25%/33% remaining capacity indication |
| Data Flash | 512 bytes - stores nominal capacity, self-discharge rate, temperature compensation coefficients, and learned FCC values |
| Temperature Range | –20°C to +85°C - qualified for industrial and notebook battery pack environments |
Pinout & Package
38-pin TSSOP (DBT) package with exposed thermal pad; lead-free and RoHS compliant per TI documentation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Analog input | Receives cell voltage from bq29311 VCELL output for individual cell monitoring |
| TS | Analog input | Connects to NTC thermistor (e.g., Semitec 103AT) or internal sensor for temperature-based self-discharge compensation |
| SR1 / SR2 | Differential current sense inputs | Monitor voltage across 10–20 mΩ sense resistor for bidirectional charge/discharge current integration |
| SMBC / SMBD | Open-drain bidirectional I/O | Implement SMBus 2.0 clock/data lines for communication with host controller (e.g., EC or PMIC) |
| LED1–LED5 | Push-pull outputs | Drive external LEDs in 3-, 4-, or 5-segment configuration for visual state-of-charge indication |
| SAFE | Digital output | Asserts safety signal (e.g., fuse blow command) based on protection logic from bq29311 interface |
| EVENT | Digital input | Accepts XALERT signal from bq29311 to trigger interrupt-driven status updates |
| RBI | Analog input | Provides backup power to retain register data during main supply brownout or removal |
Key Features
| Feature | Design Value |
|---|---|
| Self-calibrating integrating ADC | Automatically cancels offset error down to 1 µV without external intervention or factory calibration |
| Programmable cell modeling | Enables runtime adjustment of capacity estimation using temperature-, rate-, and time-dependent coefficients stored in FLASH |
| Qualified discharge learning | Updates FullChargeCapacity (FCC) only after validated full discharge cycles meeting voltage, current, and temperature criteria |
| Voltage-based RM correction | Applies real-time corrections to RemainingCapacity (RM) at EDV0/EDV1/EDV2 thresholds to align coulomb count with actual battery voltage behavior |
| Integrated LED drivers | Eliminates need for external driver ICs or discrete transistors when implementing segmented battery level indicators |
| Glueless bq29311 interface | Uses dedicated SCLK/SDATA/EVENT/SAFE signals to coordinate protection, cell balancing, and voltage translation without additional logic |
Applications
| Notebook PC Battery Packs | Industrial Portable Test Equipment |
|---|---|
Use Scenario: Integrated into 3- or 4-cell Li-ion battery packs powering Windows-based laptops with embedded controller (EC) host interface. IC Role / Device Role / Timing Role: Primary fuel gauge IC reporting RemainingCapacity, FullChargeCapacity, and RunTimeToEmpty over SMBus to EC; synchronizes with bq29311 for cell-level protection. Use Value: Enables accurate battery life prediction and low-battery warnings within ±3% capacity error after learning, reducing unexpected shutdowns. |
Use Scenario: Used in handheld multimeters and oscilloscopes requiring long runtime and precise battery state reporting under variable load conditions. IC Role / Device Role / Timing Role: Standalone gas gauge managing capacity estimation across wide temperature range (–20°C to +70°C) and compensating for self-discharge during storage. Use Value: Maintains <5% capacity error after 30-day shelf storage at 35°C via temperature-compensated self-discharge modeling. |
| Medical Portable Monitors | Enterprise Docking Stations |
Use Scenario: Embedded in sealed Li-polymer battery modules for FDA-cleared patient monitors requiring traceable battery health metrics. IC Role / Device Role / Timing Role: Reports CycleCount, ManufactureDate, and SerialNumber via SMBus for regulatory logging; triggers Terminate Discharge Alarm (TDA) at EDV0. Use Value: Provides auditable battery lifecycle data and failsafe shutdown at 3.0 V/cell to prevent deep discharge damage. |
Use Scenario: Deployed in multi-bay docking stations that hot-swap and manage up to four notebook batteries simultaneously. IC Role / Device Role / Timing Role: Communicates battery status (Pack Status, Battery Status) and safety flags (VDQ, FD) to dock's central manager via SMBus master polling. Use Value: Enables dynamic load balancing and predictive replacement alerts by tracking individual pack FCC degradation across >500 cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fuel gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ2084DBT-TI | Lacks LED drivers and DISP input; no direct LED display support | Requires external LED driver circuitry; suited for systems using software-only UI feedback | Select when visual indicators are handled by MCU and board space is constrained |
| BQ20Z75-V165 | Includes integrated SHA-1 authentication engine and enhanced security registers; newer firmware architecture | Supports secure battery authentication required in OEM notebook platforms post-2010 | Select for designs requiring Smart Battery System v1.1+ security compliance and firmware update capability |
Compared with BQ20851DBT-TI, BQ2084DBT-TI reduces BOM cost by removing LED hardware but increases firmware complexity, while BQ20Z75-V165 adds cryptographic security and field-upgradable firmware at the expense of higher unit cost and larger FLASH footprint.
Availability
BQ20851DBT-TI is available at Aetrix Electronics and suitable for notebook PC battery packs, portable medical devices, industrial test equipment, and enterprise docking stations requiring stable component supply and long-term lifecycle support.
Supply support for BQ20851DBT-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, specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in battery management systems.
The BQ20851DBT-TI belongs to TI's Smart Battery Fuel Gauge product line, engineered specifically for high-accuracy coulomb counting and SBS v1.1 compliance in multi-cell Li-ion/Li-polymer portable applications.
FAQ
What is the primary function of the BQ20851DBT-TI in a battery management system?
The BQ20851DBT-TI serves as the core fuel gauge IC in smart battery packs, performing real-time coulomb counting using its self-calibrating integrating ADC, compensating for temperature- and rate-dependent self-discharge, and reporting RemainingCapacity, FullChargeCapacity, and voltage/temperature data over SMBus. It works exclusively with the bq29311 AFE to form a complete pack solution - the BQ20851DBT-TI itself does not provide cell protection or FET control.
Does the BQ20851DBT-TI require an external crystal oscillator?
No, the BQ20851DBT-TI integrates an internal oscillator that generates a 32.768-kHz clock signal (output on CLKOUT pin) for use by the bq29311 AFE. This eliminates the need for an external crystal, reducing BOM count and PCB area. Oscillator accuracy depends on the 113-kΩ ROSC resistor tolerance (±0.1% recommended) and layout proximity to the IC.
How does the BQ20851DBT-TI handle battery capacity learning?
The BQ20851DBT-TI updates FullChargeCapacity (FCC) only after a qualified discharge - defined as discharge from ≥95% RM to EDV2 threshold while maintaining current ≥3C/32, avoiding charge activity, limiting self-discharge to ≤256 mAh, and staying within programmed temperature bounds. The new FCC value is written to on-chip FLASH and used as the reference for subsequent state-of-charge calculations.
Can the BQ20851DBT-TI operate without the bq29311 AFE?
No - the BQ20851DBT-TI is architecturally dependent on the bq29311 AFE for critical functions including cell voltage multiplexing (via VIN), safety control signaling (SAFE, EVENT), and power delivery. Its pinout and register map assume glueless interfacing with bq29311; standalone operation is not supported, and VIN must be driven by bq29311's VCELL output.
What is the role of the RBI pin on the BQ20851DBT-TI?
The RBI (Register Backup Input) pin provides backup power to retain volatile register contents during main supply interruption or brownout. When VDD drops below the POR threshold (2.1–2.5 V), the BQ20851DBT-TI draws ≤100 nA from RBI to maintain data integrity in RAM-based registers. A storage capacitor or auxiliary battery (≥1.3 V) is typically connected to RBI for this purpose.
BQ20851DBT-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:
- 3 ~ 4
- Fault Protection:
- -
- Interface:
- Serial
- Operating Temperature:
- -20°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP
BQ20851DBT-TI FAQ
1.How can I place an order for BQ20851DBT-TI through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ20851DBT-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 BQ20851DBT-TI reliable?
The price and inventory of BQ20851DBT-TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ20851DBT-TI is usually 5 days.
3.What payment methods are accepted for BQ20851DBT-TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ20851DBT-TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ20851DBT-TI?
BQ20851DBT-TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ20851DBT-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 BQ20851DBT-TI?
For technical support, including BQ20851DBT-TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ20851DBT-TI requirements.
6.How does Aetrix verify that BQ20851DBT-TI is sourced from the original manufacturer or authorized distributors?
All BQ20851DBT-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 BQ20851DBT-TI meets industry standards.
7.What is the process for return or replacement of BQ20851DBT-TI?
All BQ20851DBT-TI units undergo pre-shipment inspection (PSI). If there is an issue with BQ20851DBT-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 BQ20851DBT-TI part is unused and in its original packaging.
Return procedure for BQ20851DBT-TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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