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Texas Instruments BQ2018SN-E1TR
- Part No.:
- BQ2018SN-E1TR
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
BQ2018SN-E1TR.pdf
- Description:
- IC BATT MON MULT-CHEM 1-4C 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,959
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Product details
Overview
BQ2018SN-E1TR from Texas Instruments is a multifunction charge/discharge counter IC for rechargeable battery state-of-charge (SoC) estimation. It measures voltage drop across a sense resistor with 12.5µV resolution, integrates internal temperature sensing for self-discharge compensation, and provides 1024-bit NVRAM (128 × 8) for capacity and status storage. It operates in battery packs for portable electronics requiring precise coulomb counting.
For engineers reviewing the BQ2018SN-E1TR datasheet, BQ2018SN-E1TR pinout, BQ2018SN-E1TR application, or BQ2018SN-E1TR equivalent, key selection considerations include its single-wire HDQ interface, ±200mV differential current-sense input range, <80µA operating current, REG-regulated 3.7V output, and 8-pin TSSOP package optimized for compact battery pack integration.
Technical Context
The BQ2018SN-E1TR implements a dynamically balanced voltage-to-frequency converter (VFC) architecture to integrate current flow over time, using SR1/SR2 differential inputs to distinguish charge (VSR1 > VSR2) from discharge (VSR1 < VSR2) with ±200mV full-scale range. Its internal 1.5% accurate oscillator eliminates external timing components.
It features dual-mode operation-<80µA active mode and <10µA sleep mode-with wake-up triggered by HDQ high transition or |VSRO| exceeding programmable WOE threshold (0.549–3.84mV). The OFR offset register enables host-calibrated cancellation of up to ±500µV input offset for improved measurement fidelity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 2.8V to 5.5V; supports direct Li-ion or Ni-based cell stacks without external regulator when REG not used. |
| Current Sense Resolution | 12.5µV per hour; enables precise coulomb counting at low currents (e.g., 100mV = 8000 counts/hour). |
| Operating Current | <80µA; minimizes parasitic drain on battery during active SoC monitoring. |
| Sleep Current | <10µA; extends pack shelf life during storage via automatic low-power suspension. |
| REG Output | 3.7V ±200mV; drives external n-JFET for low-cost microregulated VCC supply. |
| Temperature Sensing | ±2°C typical accuracy at 25°C; enables self-discharge rate doubling every 10°C above 25°C for accurate long-term SoC hold. |
| NVRAM Size | 128 × 8 bits; upper 13 bytes store capacity, status, and calibration data; retains values via RBI backup input. |
| Interface | Single-wire HDQ (open-drain); asynchronous return-to-one protocol at ≤5 kbps; requires external pull-up/down. |
Pinout & Package
Package: 8-pin TSSOP (SN suffix) - 3.0 mm × 4.4 mm footprint, suitable for integration between A-size cylindrical cells or within prismatic cell width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| REG | Regulator output | Drives external n-JFET to generate regulated 3.7V supply; eliminates need for dedicated LDO in cost-sensitive packs. |
| VCC | Supply voltage input | Accepts 2.8–5.5V unregulated input; when REG is used, VCC is clamped to 3.7V ±200mV. |
| VSS | Ground reference | Common return for all analog and digital circuitry; must be low-impedance connection to pack ground. |
| HDQ | Data I/O | Single-wire serial interface; open-drain requires external pull-up; controls sleep/wake and register access. |
| WAKE | Wake-up output | Open-drain signal asserts low when |VSRO| exceeds programmed WOE threshold; informs host of activity onset. |
| SR1 / SR2 | Differential current sense inputs | Measure voltage drop across external sense resistor; polarity determines charge/discharge direction (VSR1 > VSR2 = charge). |
| RBI | Register backup input | Maintains NVRAM contents during VCC dropout (e.g., shorted battery); draws <100nA from capacitor or auxiliary cell. |
Key Features
| Feature | Design Value |
|---|---|
| Internal offset calibration | Stores 8-bit two's complement offset (OFR) to cancel up to ±500µV sensor path error, enabling sub-mV-level current resolution. |
| Self-discharge estimation | Uses integrated temperature sensor (±2°C typical) to scale SCR count rate-doubling per 10°C above 25°C-to improve long-term SoC retention accuracy. |
| Dual power modes | Automatic transition to <10µA sleep mode after 10s of HDQ low + low |VSRO|; resumes full operation on HDQ high or WAKE assertion. |
| Nonvolatile register backup | RBI pin sustains RAM during VCC loss (e.g., pack removal or deep discharge); backup current <100nA enables multi-year capacitor hold-up. |
| Programmable wake threshold | WOE bits (MODE/WOE[3:1]) set VWOE from 0.549mV to 3.84mV in 7 steps; allows tuning sensitivity to detect micro-leakage or trickle charge. |
Applications
| Laptop Battery Pack | Power Tool Battery Pack |
|---|---|
|
Use Scenario: Integrated into multi-cell Li-ion packs to report real-time state-of-charge to host SMBus controller during charging, discharging, and storage. IC Role / Device Role / Timing Role: Coulomb counter providing accumulated charge/discharge counts (DCR/CCR), time-in-state (DTC/CTC), and temperature-compensated self-discharge (SCR) to host MCU. Use Value: Enables accurate fuel-gauge reporting with <80µA active current and <10µA sleep current-extending pack runtime and shelf life without adding system-level power overhead. |
Use Scenario: Embedded in high-current 18V/20V Li-ion packs for cordless drills and impact drivers, where rapid charge/discharge cycles demand robust current sensing. IC Role / Device Role / Timing Role: Differential sense amplifier and integrator converting mV-level resistor drop into digital counts; WAKE output alerts host MCU to initiate protection or logging upon load activation. Use Value: ±200mV input range and 12.5µV/h resolution support accurate SoC tracking even at high C-rates; REG output simplifies power delivery using low-cost JFET instead of discrete LDO. |
| Medical Portable Monitor Battery | Consumer Bluetooth Headset Battery |
|
Use Scenario: Used in sealed medical-grade battery modules requiring traceable SoC history, long-term self-discharge modeling, and fail-safe register retention during sterilization or storage. IC Role / Device Role / Timing Role: NVRAM-backed SoC estimator with RBI-supplied register backup; internal temperature sensor feeds SCR scaling for predictive capacity decay modeling. Use Value: 128×8 NVRAM stores calibration, serial number, and manufacturing date; RBI input ensures critical registers survive VCC interruption during device cleaning or battery replacement. |
Use Scenario: Deployed in ultra-compact earbud cases and headset batteries where PCB space is constrained and power efficiency is critical for multi-day operation. IC Role / Device Role / Timing Role: Low-power coulomb counter with 8-pin TSSOP footprint fitting between AAA/AA cells; single-wire HDQ minimizes interconnect pins and routing complexity. Use Value: 3.0×4.4mm TSSOP package enables mechanical integration in tight form factors; <10µA sleep current prevents measurable drain during weeks of idle storage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery fuel-gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ2019SN | Same pinout and core architecture; adds EEPROM write-protection and enhanced WAKE debounce logic. | Preferred for new designs requiring higher data integrity in high-noise environments (e.g., power tools). | Select BQ2019SN if write-protection of NVRAM and improved wake glitch immunity are required; otherwise BQ2018SN-E1TR remains optimal for cost-sensitive, volume-constrained applications. |
| BQ2022APWR | 14-pin TSSOP; integrates SMBus physical layer and command parser; eliminates need for host-side HDQ bit-banging. | Suitable for systems with existing SMBus infrastructure but incompatible with single-wire HDQ-only host firmware. | Choose BQ2022APWR only when migrating to standardized SMBus communication and board layout allows larger 14-pin footprint; BQ2018SN-E1TR retains advantage in minimal pin count and legacy HDQ compatibility. |
Compared with BQ2019SN and BQ2022APWR, the BQ2018SN-E1TR offers the smallest footprint and lowest BOM cost for basic coulomb counting, while maintaining identical accuracy, resolution, and power performance-making it ideal for high-volume consumer battery packs where pin count and layout simplicity are prioritized.
Availability
BQ2018SN-E1TR is available at Aetrix Electronics and suitable for laptop battery packs, power tool battery modules, medical portable monitors, and consumer Bluetooth headsets requiring stable component supply and long-term production continuity.
Supply support for BQ2018SN-E1TR 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 leadership in battery management ICs.
The BQ2018SN-E1TR belongs to TI's Power Minder™ family of battery fuel-gauge ICs, designed specifically for cost-effective, high-accuracy state-of-charge estimation in rechargeable Li-ion and Ni-based battery packs.
FAQ
What is the primary function of the BQ2018SN-E1TR?
The BQ2018SN-E1TR is a dedicated coulomb-counting fuel-gauge IC that measures battery charge/discharge current via a sense resistor, accumulates counts in DCR/CCR registers, compensates for self-discharge using temperature data, and reports results over a single-wire HDQ interface. It does not perform voltage-based SoC estimation or protection functions-those are handled by the host controller.
How does the BQ2018SN-E1TR achieve high current-sense accuracy?
The BQ2018SN-E1TR achieves high accuracy through 12.5µV/h resolution integration, internal offset calibration (OFR register cancels up to ±500µV), temperature-compensated self-discharge counting, and a precision 1.5% oscillator eliminating external timing components. Its ±200mV differential input range and 10MΩ input impedance minimize loading errors on the sense resistor path.
Can the BQ2018SN-E1TR operate without an external microcontroller?
No-the BQ2018SN-E1TR requires an intelligent host controller to read registers (DCR, CCR, SCR, etc.), reset counters via TMP/CLR, perform offset calibration, interpret temperature steps, and calculate final state-of-charge. It provides raw measurement data and timing primitives but performs no autonomous SoC computation or decision-making.
What is the role of the REG pin on the BQ2018SN-E1TR?
The REG pin on the BQ2018SN-E1TR outputs a 3.7V ±200mV regulated voltage to drive an external n-channel JFET, forming a low-cost microregulator for VCC. This allows the BQ2018SN-E1TR to operate from unregulated battery stacks (e.g., 3–4 NiCd/NiMH or 1 Li-ion cell) without adding a separate LDO, reducing BOM cost and PCB area in battery pack designs.
How does the RBI pin preserve data during battery removal or deep discharge?
The RBI pin on the BQ2018SN-E1TR accepts backup voltage (e.g., from a storage capacitor or auxiliary cell) to maintain NVRAM contents when VCC drops below 2.4V. In this mode, the BQ2018SN-E1TR draws less than 100nA, enabling multi-year data retention with a modest capacitor-critical for preserving calibration, serial number, and usage history across battery servicing or storage periods.
BQ2018SN-E1TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- Power Minder™
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Battery Monitor
- Battery Chemistry:
- Multi-Chemistry
- Number of Cells:
- 1 ~ 4
- Fault Protection:
- -
- Interface:
- HDQ
- Operating Temperature:
- -20°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
BQ2018SN-E1TR FAQ
1.How can I place an order for BQ2018SN-E1TR through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ2018SN-E1TR 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 BQ2018SN-E1TR reliable?
The price and inventory of BQ2018SN-E1TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ2018SN-E1TR is usually 5 days.
3.What payment methods are accepted for BQ2018SN-E1TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ2018SN-E1TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ2018SN-E1TR?
BQ2018SN-E1TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ2018SN-E1TR 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 BQ2018SN-E1TR?
For technical support, including BQ2018SN-E1TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ2018SN-E1TR requirements.
6.How does Aetrix verify that BQ2018SN-E1TR is sourced from the original manufacturer or authorized distributors?
All BQ2018SN-E1TR 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 BQ2018SN-E1TR meets industry standards.
7.What is the process for return or replacement of BQ2018SN-E1TR?
All BQ2018SN-E1TR units undergo pre-shipment inspection (PSI). If there is an issue with BQ2018SN-E1TR, 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 BQ2018SN-E1TR part is unused and in its original packaging.
Return procedure for BQ2018SN-E1TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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