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Texas Instruments BQ2040SN-C408TR
- Part No.:
- BQ2040SN-C408TR
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
BQ2040SN-C408TR.pdf
- Description:
- IC BATTERY GAS GAUGE 16-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,458
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Product details
Overview
BQ2040SN-C408TR from Texas Instruments is a Smart Battery System (SBS) v1.0–compliant gas gauge IC designed for embedded battery-pack integration. It delivers accurate remaining capacity, state-of-charge, and remaining time estimation for NiCd, NiMH, and Li-Ion chemistries using SMBus 2-wire interface, integrated temperature sensing, and sense-resistor-based current integration. It drives a four-segment LED display and supports SBS charge control commands in portable medical devices, power tools, and two-way radios.
For engineers reviewing the BQ2040SN-C408TR datasheet, BQ2040SN-C408TR pinout, BQ2040SN-C408TR application, or BQ2040SN-C408TR equivalent, key selection considerations include its 16-pin narrow SOIC package, ±75 µV SR input offset, EEPROM-programmable self-discharge rate (0–25%/day), SMBus broadcast of ChargingVoltage/ChargingCurrent, and support for ∆T/∆t (NiMH/NiCd) and current-taper (Li-Ion) charge termination.
Technical Context
The BQ2040SN-C408TR implements coulomb counting with temperature-compensated current integration via the SR–VSS sense resistor path, using an internal 16-bit ADC with ±75 µV typical offset. Its firmware applies programmable charge efficiency compensation (0.75–1.0) based on state-of-charge, temperature, and chemistry.
It embeds a digital magnitude filter (VSRD threshold configurable via EEPROM) to suppress noise-induced false counts, and performs autonomous capacity learning by updating FullChargeCapacity (FCC) only after a qualified full-to-empty discharge validated by Discharge Count Register (DCR), EDV1 detection, and low-temperature fault absence.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 3.0–6.5 V - Supports direct operation from 3-cell NiCd/NiMH packs; REF output enables external FET regulator for higher-voltage Li-Ion configurations. |
| SR Input Offset (VOS) | ±75 µV typical - Enables accurate low-current monitoring down to ~10 mA with 10 mΩ sense resistor; layout-critical single-point ground required. |
| SMBus Interface | 2-wire open-drain (SMBC/SMBD) - Implements SBS v1.0 protocol including Read/Write Word, supports broadcast charge commands to smart chargers every 10 s. |
| Self-Discharge Rate | Programmable 0–25%/day at 20–30°C - Temperature-compensated estimation stored in EEPROM address 0x4f; doubles per +10°C up to 70°C. |
| LED Display Control | Four independent LED1–LED4 outputs - Drives 25% increment segments in relative mode (vs FCC) or absolute mode (vs DesignCapacity); DISP pin enables 4-s manual activation or auto-on-charge ≥100 mA. |
| Charge Termination | Li-Ion: Current taper (VSRO < programmed threshold for ≥100 s at VSB within 128 mV of ChargingVoltage); NiMH/NiCd: ∆T/∆t (programmable step: 1.6–4.6°C / 20–320 s). |
| EEPROM Dependency | External serial EEPROM required - Stores 100+ configuration parameters including DesignCapacity (0x10/0x11), ChargingVoltage (0x0a/0x0b), EDVF (0x5e/0x5f), and self-discharge rate (0x4f); integrity verified via check bytes 0x01=0x5b and 0x64=0xb5. |
Pinout & Package
Package: 16-pin narrow SOIC (5.3 mm × 10.2 mm, 1.27 mm pitch), RoHS-compliant, surface-mount.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Supply voltage input | Primary power rail (3.0–6.5 V); powers internal circuitry and VOUT/REF outputs. |
| VSS | System ground | Single-point analog/digital return; critical for SR measurement accuracy - must not share high-current paths. |
| SR | Sense resistor input | Differential input measuring voltage drop across external sense resistor; integrates charge/discharge current with ±75 µV offset. |
| SB | Battery sense input | High-impedance divider input for pack voltage monitoring; used for EDV1/EDVF detection and charging voltage alarm. |
| PSTAT | Protector status input | Logic input (≥1.5 V = overvoltage fault) - triggers charge suspension when Li-Ion protection circuit asserts. |
| DISP | Display control input | Three-state control: high = LED disabled; floating = auto-enable on charge ≥100 mA; low = forced 4-s activation. |
| LED1–LED4 | LED segment outputs | Open-drain drivers for 25% capacity increments; support both relative (FCC-based) and absolute (DesignCapacity-based) display modes. |
| SMBD / SMBC | SMBus data/clock | Open-drain bidirectional pins compliant with SMBus v1.0; require external pull-ups; enable SBS register access and charge command broadcast. |
| ESDA / ESCL | EEPROM data/clock | Bidirectional serial interface to external configuration EEPROM; transfers calibration data, thresholds, and chemistry settings at power-up. |
| REF | Voltage reference output | Stable reference for external FET-based micro-regulator; enables VCC generation from >3-cell battery packs. |
| VOUT | EEPROM supply output | Provides regulated 5 V (typ.) to external EEPROM; eliminates need for separate EEPROM supply rail. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated temperature sensor | Eliminates external thermistor; provides real-time compensation for charge efficiency, self-discharge, and ∆T/∆t termination without added BOM cost or layout area. |
| Autonomous capacity learning | Updates FullChargeCapacity (FCC) only after validated full discharge (RM = 0 → EDV1), preventing drift from partial cycles and adapting to battery aging. |
| Programmable digital magnitude filter | Configurable VSRD threshold (via EEPROM) rejects sub-threshold noise - e.g., DMF = 0xC8 sets VSRD = 0.23 mV, blocking false counts below ~23 mA with 10 mΩ resistor. |
| SBS-compliant charge control | Broadcasts ChargingCurrent and ChargingVoltage over SMBus every 10 s; enables coordination with smart chargers while supporting maintenance-rate fallback on fault conditions. |
| Low-power LED interface | Four dedicated open-drain outputs with DISP-triggered activation - delivers intuitive 25% capacity visualization without MCU intervention or additional driver ICs. |
Applications
| Portable Medical Devices | Power Tools |
|---|---|
Use Scenario: Rechargeable battery packs in handheld ultrasound scanners and infusion pumps requiring precise runtime prediction and regulatory-compliant low-battery warnings. IC Role / Device Role / Timing Role: Gas gauge IC performing real-time coulomb counting, self-discharge estimation, and SMBus-reporting of RemainingCapacity and RemainingTime to host MCU. Use Value: Enables FDA-aligned battery health reporting and prevents unexpected shutdown during critical procedures via programmable RemainingCapacityAlarm and EDVF thresholds. | Use Scenario: High-drain 12–18 V NiMH/NiCd packs in cordless drills and impact drivers subject to rapid temperature rise and deep discharge cycles. IC Role / Device Role / Timing Role: Battery management unit executing ∆T/∆t charge termination, overtemperature suspension (PSTAT-linked), and FCC learning across repeated full discharges. Use Value: Extends tool runtime and battery life by adapting charge profiles to actual cell aging and thermal behavior, reducing capacity overestimation by up to 15% vs fixed-gain gauges. |
| Two-Way Radios | Emergency Lighting Systems |
Use Scenario: Mission-critical handheld radios used in public safety where battery state must be communicated reliably over long idle periods and intermittent high-current transmit bursts. IC Role / Device Role / Timing Role: Smart battery subsystem providing SBS v1.0–compliant state-of-charge, cycle count, and manufacturer data to radio host via SMBus. Use Value: Delivers field-serviceable battery health metrics (e.g., FullChargeCapacity decay) and enables predictive replacement scheduling without opening sealed packs. | Use Scenario: UL924-compliant emergency exit signs and egress lighting with sealed NiCd backup batteries requiring decades-long reliability and infrequent maintenance. IC Role / Device Role / Timing Role: Standalone gas gauge monitoring self-discharge, end-of-discharge voltage (EDVF), and calendar life via EEPROM-stored manufacture date and cycle count. Use Value: Reduces annual inspection labor by 40% through automated low-capacity alarms and tamper-proof capacity history logged in external EEPROM. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar gas gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ2060A | Enhanced SBS v1.1 compliance; integrated 10-bit ADC; supports Li-Ion, NiCd, NiMH, and SLA; includes built-in EEPROM (no external required). | Reduces BOM count and layout complexity; suitable for new designs targeting higher integration and broader chemistry support. | Select BQ2060A when eliminating external EEPROM and adding SLA support are priorities; not drop-in due to different pinout and EEPROM architecture. |
| MAX17043 | ModelGauge™ m3 algorithm; no SMBus - uses I²C; no LED drivers; lower quiescent current (24 µA vs 120 µA); no charge control broadcast capability. | Optimized for ultra-low-power wearables and IoT sensors where SMBus infrastructure is absent and LED indication is handled externally. | Choose MAX17043 for space-constrained, battery-life–critical applications without SMBus host or LED display needs; requires firmware adaptation for SBS register mapping. |
Compared with BQ2040SN-C408TR, the BQ2060A simplifies design by embedding EEPROM and extending chemistry coverage, while the MAX17043 trades SMBus compatibility and LED drive for superior energy efficiency and model-based accuracy - making each suitable for distinct system architectures rather than direct substitution.
Availability
BQ2040SN-C408TR is available at Aetrix Electronics and suitable for portable medical devices, power tools, two-way radios, and emergency lighting systems requiring stable component supply, long-lifecycle support, and legacy battery gauge compatibility.
Supply support for BQ2040SN-C408TR 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.
The BQ2040SN-C408TR belongs to TI's Smart Battery Fuel Gauge product line, engineered specifically for SBS v1.0–compliant battery packs needing accurate capacity tracking, charge control interoperability, and minimal external components in space-constrained applications.
FAQ
What battery chemistries does the BQ2040SN-C408TR support?
The BQ2040SN-C408TR supports NiCd, NiMH, and Li-Ion battery chemistries. It implements chemistry-specific charge termination algorithms - ∆T/∆t for nickel-based cells and current taper detection for Li-Ion - and stores chemistry identification in EEPROM address 0x40–0x45. It does not support lead-acid or lithium-polymer as standalone chemistries unless configured identically to Li-Ion in the EEPROM.
Is an external EEPROM mandatory for BQ2040SN-C408TR operation?
Yes, an external EEPROM is mandatory for BQ2040SN-C408TR operation. The device reads critical configuration data-including DesignCapacity, ChargingVoltage, EDVF, self-discharge rate, and calibration values-from external EEPROM via ESDA/ESCL pins at power-up. Without it, the BQ2040SN-C408TR cannot initialize valid capacity estimates or execute charge control, resulting in undefined RM and FCC register behavior.
How does the BQ2040SN-C408TR handle battery self-discharge compensation?
The BQ2040SN-C408TR estimates self-discharge using an internal temperature sensor and a user-programmable rate stored in EEPROM address 0x4f (0–25%/day at 20–30°C). The rate scales exponentially with temperature-doubling per +10°C up to 70°C-and decrements RemainingCapacity (RM) and increments Discharge Count Register (DCR) continuously when the discharge flag is active.
Can the BQ2040SN-C408TR drive LEDs directly without external transistors?
Yes, the BQ2040SN-C408TR can drive standard low-current LEDs directly via its LED1–LED4 open-drain outputs. Each output supports typical 5–10 mA sink current; external current-limiting resistors (e.g., 330 Ω for 5 V VCC) are required. For high-brightness or multiplexed displays, external FET drivers are recommended to avoid exceeding total package current limits.
What is the function of the PSTAT pin on the BQ2040SN-C408TR?
The PSTAT pin on the BQ2040SN-C408TR receives overvoltage status signals from an external Li-Ion protection IC. When PSTAT ≥1.5 V, the BQ2040SN-C408TR suspends charging by setting requested current to zero and asserting Terminate_Charge_Alarm in BatteryStatus. The alarm clears only when PSTAT falls below 1.0 V or the Discharging flag is set, ensuring coordinated safety response with the protector circuit.
BQ2040SN-C408TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Battery Monitor
- Battery Chemistry:
- Multi-Chemistry
- Number of Cells:
- -
- Fault Protection:
- Over Current, Over Temperature, Over/Under Voltage
- Interface:
- SMBus
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
BQ2040SN-C408TR FAQ
1.How can I place an order for BQ2040SN-C408TR through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ2040SN-C408TR 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 BQ2040SN-C408TR reliable?
The price and inventory of BQ2040SN-C408TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ2040SN-C408TR is usually 5 days.
3.What payment methods are accepted for BQ2040SN-C408TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ2040SN-C408TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ2040SN-C408TR?
BQ2040SN-C408TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ2040SN-C408TR 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 BQ2040SN-C408TR?
For technical support, including BQ2040SN-C408TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ2040SN-C408TR requirements.
6.How does Aetrix verify that BQ2040SN-C408TR is sourced from the original manufacturer or authorized distributors?
All BQ2040SN-C408TR 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 BQ2040SN-C408TR meets industry standards.
7.What is the process for return or replacement of BQ2040SN-C408TR?
All BQ2040SN-C408TR units undergo pre-shipment inspection (PSI). If there is an issue with BQ2040SN-C408TR, 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 BQ2040SN-C408TR part is unused and in its original packaging.
Return procedure for BQ2040SN-C408TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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