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Texas Instruments BQ26221PWG4
- Part No.:
- BQ26221PWG4
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 8-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
BQ26221PWG4.pdf
- Description:
- IC BATT MON LI-ION 1CELL 8TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,910
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Product details
Overview
BQ26221PWG4 from Texas Instruments is a single-wire HDQ battery gas gauge IC designed for integration into rechargeable Li-ion/Li-polymer battery packs. It performs coulometric charge/discharge current integration (3.0 µVH resolution), 11-bit battery voltage measurement (2.44 mV LSB), and internal die temperature sensing (±4 K accuracy), enabling precise state-of-charge estimation in portable electronics.
For engineers reviewing the BQ26221PWG4 datasheet, BQ26221PWG4 pinout, BQ26221PWG4 application, or BQ26221PWG4 equivalent, key selection considerations include its 8-pin TSSOP package, 1 µA sleep current, integrated VFC with auto-offset compensation, HDQ serial interface timing compliance, and flash-backed RAM for battery parameter retention during deep discharge.
Technical Context
The BQ26221PWG4 implements a precision voltage-to-frequency converter (VFC) for differential current sensing across SRP/SRN, with gain stability of ±0.5%/V over supply and ±0.005%/°C over temperature. Its internal 11-bit ADC digitizes BAT voltage with gain/offset correction applied via factory-stored calibration data in ID ROM (addresses 0x78–0x7F).
Operation relies on host-controlled register access via HDQ: all counters (DCR, CCR, SCR, DTC, CTC) are maintained externally, while self-discharge rate adapts dynamically-doubling per +10°C above 25°C-and hibernate mode sustains RAM via RBI backup at 600 nA when VCC drops below 1.9 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.8 V to 4.5 V - supports direct operation from single-cell Li-ion without external regulator |
| Current Sensing | Differential VSR input (±100 mV), 3.0 µVH resolution - enables accurate capacity tracking down to microampere-hour levels |
| Battery Voltage ADC | 11-bit, 2.44 mV LSB, ±15 LSB max error - calibrated via on-chip offset/gain correction stored in ID ROM |
| Temperature Sensing | Internal sensor, ±4 K accuracy, 0.25 K resolution - eliminates need for external thermistor in pack design |
| Power Modes | 30 µA active, 1 µA sleep, 600 nA hibernate - extends pack shelf life and reduces standby drain |
| Memory | 32 bytes RAM (flash-backed), 96 bytes flash (64 user + 32 shadow), 8-byte ID ROM - retains SOC, chemistry, and warranty data across power loss |
| Interface | Single-wire HDQ, ≤5 kbps, break-recoverable protocol - minimizes PCB routing and connector pins vs. I²C/SMBus |
Pinout & Package
Package: 8-lead TSSOP (PW), 3.0 mm × 4.4 mm, 0.65 mm pitch, moisture sensitivity level 2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BAT (Pin 5) | Battery voltage sense input | Direct connection to cell anode; feeds 11-bit ADC with gain/offset correction for accurate SOC calculation |
| RBI (Pin 1) | Register backup input | Accepts capacitor or auxiliary supply to retain RAM contents during VCC dropout below 1.9 V POR threshold |
| VCC (Pin 2) | Supply voltage input | Primary power rail (2.8–4.5 V); powers analog front-end, digital core, and HDQ transceiver |
| VSS (Pin 3) | Ground reference | Common return for all analog and digital circuits; must be low-impedance connection to pack negative |
| HDQ (Pin 4) | Single-wire HDQ interface | Bidirectional communication port requiring external pull-up; handles command/data exchange with host controller |
| GPIO (Pin 8) | Programmable digital I/O | Configurable as input or open-drain output via HDQ registers; usable for pack status signaling or external control |
| SRP (Pin 7) | Current sense positive input | Connects to high-side of sense resistor; polarity determines charge (VSRP > VSRN) vs. discharge (VSRP < VSRN) |
| SRN (Pin 6) | Current sense negative input | Connects to low-side of sense resistor; differential pair drives VFC for coulometric integration |
Key Features
| Feature | Design Value |
|---|---|
| Auto-compensated VFC offset | Eliminates host-initiated calibration cycles; maintains <±20 µV offset drift over life and temperature |
| Flash-backed RAM | 32 bytes retained across VCC loss using RBI-supplied energy; preserves runtime SOC and cycle count |
| Temperature-adaptive self-discharge | SCR increments at 1 count/hour @25°C, doubles per +10°C - enables accurate shelf-life prediction |
| Integrated precision oscillator | Replaces external crystal; provides stable timebase for DTC/CTC counters with no additional BOM cost |
| HDQ break-recovery protocol | Enables robust communication recovery after bus glitches or host reset without hardware intervention |
Applications
| Smartphone Battery Pack | PDA Power Management |
|---|---|
|
Use Scenario: Integrated into sealed Li-ion battery pack for Android/iOS smartphones requiring accurate remaining runtime estimation under dynamic load. IC Role / Device Role / Timing Role: Gas gauge IC performing real-time coulometric integration and voltage/temperature sampling; provides host with corrected SOC via HDQ every 10 seconds. Use Value: Enables <±2% SOC error over full discharge cycle by combining auto-calibrated VFC, ADC offset correction, and temperature-compensated self-discharge modeling. |
Use Scenario: Embedded in enterprise-grade PDA battery module where firmware must report battery health, cycle count, and safe shutdown thresholds. IC Role / Device Role / Timing Role: Nonvolatile battery monitor storing chemistry ID, manufacturing date, and warranty data in flash; maintains integrity during storage or accidental short-circuit. Use Value: Guarantees traceability and warranty enforcement via 8-byte ID ROM and 96-byte flash - survives 5-year data retention and 10,000 write cycles. |
| Wearable Device Battery | Bluetooth Headset Power System |
|
Use Scenario: Ultra-low-power fitness tracker battery pack needing minimal quiescent current to maximize shelf life before first use. IC Role / Device Role / Timing Role: Sleep-mode gas gauge drawing only 1 µA while maintaining self-discharge counter; wakes on HDQ activity to update host. Use Value: Extends pre-shipment shelf life by >3× vs. comparable ICs due to 600 nA hibernate current and RBI-assisted RAM retention. |
Use Scenario: Compact Bluetooth headset with space-constrained battery compartment requiring minimal component count and footprint. IC Role / Device Role / Timing Role: Single-chip solution replacing discrete ADC, temp sensor, crystal, and EEPROM - housed in 8-pin TSSOP (3.0 × 4.4 mm). Use Value: Reduces bill-of-materials by 4 components and PCB area by >25 mm² versus discrete implementation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar battery gas gauge applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ26200PW | No internal temperature sensor; requires external thermistor; identical HDQ interface and VFC architecture | Suitable only when pack-level thermal monitoring is handled externally; lacks die-temp reporting for self-discharge adaptation | Select when cost reduction outweighs need for autonomous temperature compensation and board space permits external sensor |
| BQ27200YZFT | Uses I²C interface instead of HDQ; includes enhanced algorithm engine for impedance-track fuel gauging | Requires two PCB traces (SCL/SDA) and pull-ups; supports advanced aging compensation not available in BQ26221PWG4 | Choose when host MCU has I²C support and higher accuracy (<±1% SOC) across aging cycles is required |
Compared with BQ26221PWG4, BQ26200PW omits die temperature sensing and thus cannot autonomously adjust self-discharge rates, while BQ27200YZFT trades HDQ simplicity for I²C complexity and adds impedance-based modeling - making BQ26221PWG4 optimal for cost-sensitive, space-constrained Li-ion packs needing proven coulometric accuracy with minimal external components.
Availability
BQ26221PWG4 is available at Aetrix Electronics and suitable for smartphone battery packs, PDA power modules, wearable device batteries, and Bluetooth headset power systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for BQ26221PWG4 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 BQ26221PWG4 belongs to TI's dedicated battery fuel gauge product line, engineered specifically for high-accuracy, low-power, single-wire integration into portable Li-ion battery packs - prioritizing coulometric fidelity, nonvolatile parameter retention, and host-agnostic HDQ interoperability.
FAQ
What is the primary function of the BQ26221PWG4 in a battery system?
The BQ26221PWG4 serves as a standalone coulometric gas gauge IC that measures battery charge/discharge current via differential VFC, monitors cell voltage and die temperature, and reports processed data to a host controller over HDQ. It does not perform charging or protection functions - those remain in external controllers. Its core value lies in delivering accurate state-of-charge estimation with minimal external components and ultra-low quiescent current.
How does the BQ26221PWG4 handle voltage measurement accuracy?
The BQ26221PWG4 uses an 11-bit ADC with 2.44 mV LSB to digitize battery voltage at the BAT pin. Accuracy is enhanced by factory-programmed gain correction (stored in ID ROM byte 0x79) and 5-bit signed-magnitude offset (bits 3–7 of BATH register), both applied by the host processor. This achieves ±15 LSB maximum error across 2.6–4.5 V, enabling reliable SOC calculation even as cell voltage sags under load.
Can the BQ26221PWG4 operate without an external crystal or oscillator?
Yes. The BQ26221PWG4 integrates a high-accuracy internal timebase that eliminates the need for an external crystal oscillator. This precision oscillator drives the charge/discharge time counters (CTC/DTC) and self-discharge counter (SCR), ensuring consistent timing for coulometric integration and temperature-adaptive calculations without adding BOM cost or PCB area.
What memory resources does the BQ26221PWG4 provide for battery data storage?
The BQ26221PWG4 provides 32 bytes of flash-backed RAM (retained via RBI during VCC loss), 96 bytes of flash memory (64 bytes user-accessible, 32 bytes shadowing RAM), and 8 bytes of factory-programmed ID ROM. This allows storage of calibrated parameters, chemistry identifiers, manufacturing dates, cycle counts, and warranty information - all preserved for ≥5 years with 10,000 write cycles.
How does the BQ26221PWG4 manage power consumption in low-use scenarios?
The BQ26221PWG4 offers three power states: 30 µA active operation, 1 µA sleep mode (with periodic wake-ups to update SCR), and 600 nA hibernate mode (activated when VCC falls below 1.9 V). In hibernate, it draws current from the RBI pin to maintain RAM contents - enabling full state retention during shipping, storage, or accidental deep discharge without data loss.
BQ26221PWG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Function:
- Battery Monitor
- Battery Chemistry:
- Lithium Ion
- Number of Cells:
- 1
- Fault Protection:
- -
- Interface:
- HDQ
- Operating Temperature:
- -20°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-TSSOP
BQ26221PWG4 FAQ
1.How can I place an order for BQ26221PWG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ26221PWG4 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 BQ26221PWG4 reliable?
The price and inventory of BQ26221PWG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ26221PWG4 is usually 5 days.
3.What payment methods are accepted for BQ26221PWG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ26221PWG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ26221PWG4?
BQ26221PWG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ26221PWG4 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 BQ26221PWG4?
For technical support, including BQ26221PWG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ26221PWG4 requirements.
6.How does Aetrix verify that BQ26221PWG4 is sourced from the original manufacturer or authorized distributors?
All BQ26221PWG4 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 BQ26221PWG4 meets industry standards.
7.What is the process for return or replacement of BQ26221PWG4?
All BQ26221PWG4 units undergo pre-shipment inspection (PSI). If there is an issue with BQ26221PWG4, 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 BQ26221PWG4 part is unused and in its original packaging.
Return procedure for BQ26221PWG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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