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Texas Instruments BQ2040SN-C408
- Part No.:
- BQ2040SN-C408
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
BQ2040SN-C408.pdf
- Description:
- IC BATTERY GAS GAUGE 16-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,174
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Product details
Overview
BQ2040SN-C408 from Texas Instruments is a Smart Battery System (SBS) v1.0–compliant gas gauge IC designed for NiCd, NiMH, and Li-Ion battery pack integration. It delivers accurate remaining capacity, state-of-charge, and remaining time via SMBus interface; supports four-segment LED display; operates from 3.0–6.5 V; and integrates internal temperature sensing and self-discharge estimation.
For engineers reviewing the BQ2040SN-C408 datasheet, BQ2040SN-C408 pinout, BQ2040SN-C408 application, or BQ2040SN-C408 equivalent, key selection criteria include SMBus-compatible charge control command support, EEPROM-programmable EDV/EDVF thresholds, LED segment drive capability, SR-pin current-sensing accuracy (±75 µV offset), and qualification for battery-pack–level deployment with no external resonator required.
Technical Context
The BQ2040SN-C408 implements coulomb counting using voltage differential across an external sense resistor (SR–VSS), with integrated temperature compensation and programmable digital magnitude filtering (VSRD threshold). It maintains three core counters: RemainingCapacity (RM), FullChargeCapacity (FCC), and DischargeCountRegister (DCR), enabling adaptive capacity learning over full discharge cycles.
Its SMBus v1.0 interface supports SBS data set commands including Voltage (0x09), RemainingCapacity (0x01), and ChargingCurrent (0x14); it broadcasts charge control parameters to smart chargers every 10 seconds and accepts configuration via external EEPROM mapped at addresses 0x00–0x7F, including self-discharge rate (0x4f), taper current (0x38–0x39), and ∆T/∆t termination settings (0x4a, 0x62–0x63).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0–6.5 V - powers device directly from 3-cell Ni-based packs or regulated input; REF output enables low-cost FET-based microregulator for higher-cell configurations. |
| Current Sensing Offset | ±75 µV typical - ensures high-accuracy coulomb counting with minimal error contribution from SR pin; layout-critical single-point ground required. |
| SMBus Interface | SMBC/SMBD open-drain - compatible with SBS v1.0 protocol; supports read/write word and read block for accessing 16-bit registers like RemainingCapacity (0x01) and Voltage (0x09). |
| LED Drive Outputs | LED1–LED4 - each drives one external LED segment; display mode (absolute vs. relative) determined by FCC vs. DesignCapacity; blink rate indicates low-battery condition. |
| Temperature Sensing | Integrated sensor - eliminates need for external thermistor; used for self-discharge compensation, ∆T/∆t charge termination, and charge efficiency adjustment per temperature bands. |
| EEPROM Interface | ESCL/ESDA - serial memory bus for external nonvolatile configuration; stores 128 bytes of calibration, chemistry, voltage, and timing parameters essential for operation. |
| Self-Discharge Rate | Programmable 0–25%/day at 20–30°C - doubles per +10°C, halves per –10°C; updated in real time based on internal timer and temperature reading. |
Pinout & Package
Package: 16-pin narrow SOIC (SOIC-16N), 3.9 mm width, 1.75 mm height, 0.65 mm pitch - optimized for compact battery pack PCB layout with <¾ in² footprint requirement.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Supply voltage input | Accepts 3.0–6.5 V; powers internal circuitry and VOUT supply for EEPROM; may be derived directly from 3-cell Ni-based battery. |
| VSS | System ground | Single-point return for SR, SMBus, and LED circuits; critical for minimizing offset error in current sensing. |
| SR | Sense resistor input | Differential input monitoring voltage drop across external sense resistor; VSR > VSS = charge, VSR < VSS = discharge; offset ±75 µV typical. |
| SMBD / SMBC | SMBus data/clock | Open-drain bidirectional interface compliant with SBS v1.0; requires external pull-up; supports register read/write and broadcast charge commands. |
| LED1–LED4 | LED segment outputs | Active-high drivers for four-segment graphical capacity display; behavior controlled by DISP pin and RM value; blink indicates alarm. |
| DISP | Display control input | High = disable LED; floating = activate on ≥100 mA charge; low = force 4-second activation - enables user-triggered status check. |
| SB | Battery sense input | High-impedance divider input for pack voltage monitoring; feeds EDV1/EDVF detection and Voltage (0x09) register; max VSB = 2.4 V. |
| PSTAT | Protector status input | Monitors Li-Ion protection circuit overvoltage flag; ≥1.5 V triggers charge suspension and sets Terminate_Charge_Alarm. |
| REF | Voltage reference output | Stable reference for external FET-based microregulator; enables cost-effective VCC generation for multi-cell Li-Ion packs. |
| VOUT | EEPROM supply output | Provides regulated power to external configuration EEPROM; eliminates need for separate regulator rail. |
| ESCL / ESDA | EEPROM clock/data | Serial interface to external nonvolatile memory; loads calibration, chemistry, and safety thresholds at power-up or reset. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive capacity learning | Updates FullChargeCapacity (FCC) after qualified full discharge (RM = 0 → EDV1), using DischargeCountRegister + battery low % - improves long-term SoC accuracy without manual recalibration. |
| Programmable charge termination | Supports Li-Ion current taper (≤128 mV below ChargingVoltage, avg current ≤ programmed threshold for ≥100 s) and Ni-based ∆T/∆t (configurable step/time via EEPROM 0x4a/0x62) - enables chemistry-specific safe charging. |
| Integrated environmental sensing | On-die temperature sensor replaces external thermistor; used for self-discharge modeling, charge efficiency compensation, and thermal fault detection - reduces BOM count and layout complexity. |
| Two-wire SMBus + EEPROM architecture | Separates real-time communication (SMBus) from persistent configuration (EEPROM); allows field updates to EDV, taper current, and self-discharge rate without firmware change - simplifies pack customization. |
| Low-power LED capacity display | Four-segment output supports both absolute (25% of DesignCapacity) and relative (25% of FCC) modes; DISP pin enables on-demand or auto-activation - delivers intuitive user feedback without host MCU involvement. |
Applications
| Laptop Battery Pack | Medical Portable Device |
|---|---|
Use Scenario: Integrated into removable Li-Ion battery packs for notebook computers requiring precise runtime prediction and SBS-compliant communication with host system BIOS. IC Role / Device Role / Timing Role: Primary gas gauge IC performing real-time coulomb counting, SMBus register reporting (RemainingCapacity, Voltage, Temperature), and LED capacity indication. Use Value: Enables accurate Windows battery meter, prevents unexpected shutdowns, and supports OEM-defined charge control policies via SBS broadcast commands. | Use Scenario: Embedded in sealed NiMH battery packs for handheld diagnostic tools where regulatory compliance mandates traceable capacity reporting and low-temperature charge management. IC Role / Device Role / Timing Role: Standalone fuel gauge managing charge/discharge cycles, enforcing EDVF-based undervoltage cutoff, and logging cycle count via EEPROM. Use Value: Meets IEC 62368-1 requirements for battery safety; eliminates need for external temperature sensor; supports maintenance charging below 12°C per medical battery protocols. |
| Power Tool Battery Pack | Industrial Handheld Scanner |
Use Scenario: Deployed in high-current 18V Li-Ion packs for cordless drills, requiring robust overcurrent/overtemperature protection and LED state-of-charge feedback during active use. IC Role / Device Role / Timing Role: Core protection and gauging element interfacing with external protector IC via PSTAT, monitoring SR for >255 mA faults, and driving LEDs under DISP control. Use Value: Enables real-time capacity visualization during tool operation; suspends charging on PSTAT overvoltage signal; logs cycle count and full-charge history for warranty tracking. | Use Scenario: Used in ruggedized barcode scanners with replaceable NiCd packs operating in warehouse environments with wide temperature swings (-10°C to +50°C). IC Role / Device Role / Timing Role: Fuel gauge adapting self-discharge rate dynamically per temperature, compensating charge efficiency across ambient range, and maintaining accurate RM despite partial charges. Use Value: Extends usable runtime between charges by 12–18% versus fixed-rate models; prevents false "low battery" alerts during cold starts; supports firmware-updatable EEPROM parameters for fleet-wide calibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar gas gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ2040DBTR | Same die, tape-and-reel packaging (DBT package); identical electrical specs, pinout, and EEPROM map; differs only in packaging format and reel quantity. | No functional difference; suitable for automated SMT assembly where tape-and-reel feed is required instead of tube. | Select BQ2040DBTR for high-volume production lines using pick-and-place machines; BQ2040SN-C408 remains optimal for prototyping and low-volume pack integration. |
| BQ2084DBTR | Successor device with enhanced SMBus v2.0 support, integrated 10-bit ADC, improved temperature resolution (±1°C), and extended EEPROM space (256 bytes); not pin-compatible. | Requires PCB redesign due to 20-pin TSSOP package and revised pin assignments; supports additional SBS commands (e.g., CycleCount, ManufactureDate). | Choose BQ2084DBTR only when upgrading to SBS v2.0 compliance, needing higher-resolution telemetry, or requiring extended data logging - not a drop-in replacement. |
Compared with BQ2040DBTR, the BQ2040SN-C408 offers identical functionality in tube packaging for flexible evaluation and small-batch integration; compared with BQ2084DBTR, it provides proven SBS v1.0 compatibility and lower system cost but lacks upgraded ADC resolution and expanded register space.
Availability
BQ2040SN-C408 is available at Aetrix Electronics and suitable for laptop battery packs, medical portable devices, power tool battery systems, and industrial handheld scanners requiring stable component supply, long-lifecycle support, and SBS v1.0–compliant fuel gauging.
Supply support for BQ2040SN-C408 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 experience in battery management solutions.
The BQ2040SN-C408 belongs to TI's Smart Battery Gas Gauge product line, engineered specifically for embedded battery-pack integration across consumer, medical, and industrial applications where accuracy, SMBus compliance, and minimal external components are critical.
FAQ
What is the primary function of the BQ2040SN-C408 in a battery system?
The BQ2040SN-C408 serves as a Smart Battery System (SBS) v1.0–compliant gas gauge IC that performs real-time coulomb counting, estimates remaining capacity and state-of-charge, monitors battery voltage and temperature, and communicates results via SMBus. Its core function is to maintain accurate fuel gauging for NiCd, NiMH, and Li-Ion chemistries without requiring host MCU intervention for basic LED display or charge control broadcasting.
Does the BQ2040SN-C408 require an external crystal or resonator?
No, the BQ2040SN-C408 does not require an external crystal or resonator. It incorporates an internal, temperature-compensated timebase that provides the timing reference for self-discharge estimation, charge/discharge integration, and ∆T/∆t calculations. This eliminates two external components and reduces PCB area, aligning with the device's design goal of fitting within <¾ square inch of board space.
How does the BQ2040SN-C408 handle battery self-discharge compensation?
The BQ2040SN-C408 estimates self-discharge using an internal timer and temperature sensor, applying a user-programmable rate stored in external EEPROM address 0x4f (0–25%/day at 20–30°C). The rate dynamically scales - approximately doubling per +10°C rise and halving per –10°C drop - and continuously decrements RemainingCapacity (RM) while incrementing DischargeCountRegister (DCR) when the discharge flag is set.
Can the BQ2040SN-C408 operate directly from a 3-cell NiMH battery?
Yes, the BQ2040SN-C408 can operate directly from a 3-cell NiMH battery, whose nominal voltage (3.6 V) falls within the device's specified 3.0–6.5 V VCC range. No external regulator is needed in this configuration. For higher-voltage packs (e.g., 4+ cell Li-Ion), the REF output enables a simple FET-based microregulator using components like BSS138 or 2N7002, as shown in the application diagram.
What role does the external EEPROM play in BQ2040SN-C408 operation?
The external EEPROM is mandatory for BQ2040SN-C408 operation and stores all configuration and calibration data, including DesignCapacity, ChargingVoltage, EDV1/EDVF thresholds, self-discharge rate, temperature offsets, and device chemistry. The BQ2040SN-C408 reads this data at power-up or reset to initialize registers like FullChargeCapacity and RemainingCapacity; without it, the device cannot report valid battery metrics or execute charge control.
BQ2040SN-C408 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- 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-C408 FAQ
1.How can I place an order for BQ2040SN-C408 through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ2040SN-C408 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-C408 reliable?
The price and inventory of BQ2040SN-C408 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ2040SN-C408 is usually 5 days.
3.What payment methods are accepted for BQ2040SN-C408?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ2040SN-C408 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ2040SN-C408?
BQ2040SN-C408 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ2040SN-C408 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-C408?
For technical support, including BQ2040SN-C408 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ2040SN-C408 requirements.
6.How does Aetrix verify that BQ2040SN-C408 is sourced from the original manufacturer or authorized distributors?
All BQ2040SN-C408 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-C408 meets industry standards.
7.What is the process for return or replacement of BQ2040SN-C408?
All BQ2040SN-C408 units undergo pre-shipment inspection (PSI). If there is an issue with BQ2040SN-C408, 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-C408 part is unused and in its original packaging.
Return procedure for BQ2040SN-C408:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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