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Texas Instruments BQ27421YZFR-G1B
- Part No.:
- BQ27421YZFR-G1B
- Manufacturer:
- Texas Instruments
- Category:
- Battery Management
- Package:
- 9-UFBGA, DSBGA
- Datasheet:
-
BQ27421YZFR-G1B.pdf
- Description:
- IC BATT FUEL GAUGE LICO2 9DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:5,999
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Product details
Overview
BQ27421YZFR-G1B from Texas Instruments is a system-side single-cell Li-ion fuel gauge IC with integrated 7 mΩ sense resistor, Impedance Track™ algorithm, and I²C interface. It resides on the host board (not in battery pack), supports embedded or removable batteries, and delivers real-time state-of-charge (%), remaining capacity (mAh), voltage (mV), and state-of-health estimation. Used in space-constrained portable electronics requiring accurate battery runtime prediction.
For engineers reviewing the BQ27421YZFR-G1B datasheet, BQ27421YZFR-G1B pinout, BQ27421YZFR-G1B application, or BQ27421YZFR-G1B equivalent, key selection criteria include integrated sense resistor value (7 mΩ), LDO-regulated 1.8 V output, ±0.1% voltage accuracy, 16-bit coulomb counter resolution, and support for 400-kHz I²C fast-mode communication with configurable GPOUT interrupt.
Technical Context
The BQ27421YZFR-G1B implements Texas Instruments' patented Impedance Track™ algorithm to model battery impedance, enabling high-accuracy SOC estimation across temperature (–40°C to 85°C), aging, self-discharge, and load-rate variations. It uses an internal 15-bit ADC for cell voltage (2.45–4.5 V range) and a dedicated 16-bit integrating ADC for current sensing via the SRX–BAT differential path.
Power management includes five operational modes-NORMAL (93 µA), SLEEP (21 µA), HIBERNATE (9 µA), SHUTDOWN (0.6 µA), and INITIALIZATION-with automatic transitions and host-controlled entry/exit. The integrated LDO accepts 2.45–4.5 V input at BAT and regulates to stable 1.8 V at VDD for internal circuitry, eliminating need for external regulator.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Input Range | 2.45 V to 4.5 V at BAT pin - powers device directly from battery without external supply rail |
| LDO Output | 1.8 V at VDD - internally regulated, decoupled by 0.47 µF capacitor, not intended to power external loads |
| Integrated Sense Resistor | 7 mΩ (typical) - enables direct current measurement without external shunt; firmware-compensated for tempco |
| Coulomb Counter Resolution | 16-bit - provides high-precision accumulated charge/discharge tracking over full operating range |
| Voltage Measurement Accuracy | ±0.1% - ensures reliable remaining capacity calculation under varying load and temperature conditions |
| I²C Interface Speed | Up to 400 kHz - supports fast-mode communication for responsive host polling and configuration updates |
| Operating Temperature | –40°C to +85°C - validated for industrial and consumer portable applications including smartphones and tablets |
Pinout & Package
Package: DSBGA-9 (YZF), 1.62 mm × 1.58 mm, 0.5 mm pitch, NanoFree™ chip-scale package optimized for ultra-compact PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BAT (C3) | LDO input & coulomb counter reference | Connects to PACK+; supplies power and serves as current-sense reference; requires 1 µF decoupling to VSS |
| SCL (A3) | I²C clock line | Open-drain, requires external 10 kΩ pullup; supports 100/400 kHz timing; must avoid floating via pulldown if pullups disabled |
| SDA (A2) | I²C data line | Open-drain, requires external 10 kΩ pullup; bidirectional communication path for command/data exchange |
| SRX (C2) | Coulomb counter analog input | Differential input referenced to BAT; measures voltage drop across integrated 7 mΩ resistor to compute current |
| GPOUT (A1) | Configurable open-drain output | Default: SOC interrupt pulse; configurable as BAT_LOW warning; must use 10 kΩ pullup; toggling exits SHUTDOWN |
| BIN (B1) | Battery insertion detection input | Logic input with internal BIE bit control; used with pulldown resistor on pack to detect removable battery presence |
| VDD (B3) | LDO-regulated output | 1.8 V supply for internal logic; decoupled with 0.47 µF ceramic cap; not for powering external components |
| VSS (B2, C1) | Ground reference | B2 is primary ground; C1 is floating but usable as board ground bridge; recommended trace routing between B2→C1→PCB GND |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 7 mΩ sense resistor | Eliminates external shunt, reduces BOM count and layout area, and avoids placement-induced measurement errors |
| Impedance Track™ algorithm | Delivers <±2% SOC error across battery life, temperature, and load profiles without user calibration |
| Configurable GPOUT interrupt | Reduces host polling overhead by signaling SOC threshold crossings or low-battery events asynchronously |
| Multi-mode power management | Enables <1 µA quiescent draw in SHUTDOWN mode while retaining configuration and volatile state |
| On-chip temperature sensor | Provides real-time thermal data for SOC correction; eliminates need for external thermistor in many designs |
Applications
| Smartphones | Tablets |
|---|---|
|
Use Scenario: Real-time battery level display and low-power shutdown triggering during active UI usage and standby. IC Role / Device Role / Timing Role: System-side fuel gauge providing smoothed SOC % and remaining capacity (mAh) via I²C every 1–5 seconds. Use Value: Enables accurate "hours remaining" estimates and prevents unexpected shutdowns by detecting true end-of-discharge under dynamic load. |
Use Scenario: Runtime prediction during video playback, web browsing, and background sync across varying screen brightness and CPU load. IC Role / Device Role / Timing Role: Host-attached coulomb counter and voltage monitor feeding adaptive power management firmware. Use Value: Achieves ±2% SOC accuracy over 300+ cycles, supporting consistent user-facing battery indicators and optimized charging algorithms. |
| Digital Cameras | Handheld Terminals |
|
Use Scenario: Power budgeting for burst-mode image capture, flash charging, and LCD preview with intermittent high-current draws. IC Role / Device Role / Timing Role: High-resolution current integrator (16-bit) capturing transient load spikes up to 3.5 A peak. Use Value: Prevents premature "low battery" warnings during flash operation by distinguishing between momentary surge and actual energy depletion. |
Use Scenario: Reliable battery status reporting in warehouse scanners and field service devices subjected to wide ambient temperature swings (–20°C to 60°C). IC Role / Device Role / Timing Role: Temperature-compensated fuel gauge using internal sensor and Impedance Track™ to maintain accuracy across operating range. Use Value: Extends usable runtime per charge in cold environments by correcting OCV-based SOC drift without external calibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fuel gauging applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BQ27421YZFT-G1B | Same die, 0.4-mm pitch DSBGA-9 (YZF vs YZFT); identical electrical specs and firmware | Requires tighter PCB assembly tolerance due to smaller pad pitch; same footprint area | Select YZFT-G1B only when board assembly process supports 0.4-mm pitch; otherwise YZFR-G1B preferred for manufacturability |
| BQ27441YZFR-G1 | Higher-accuracy variant with extended temperature compensation; 15-bit voltage ADC (vs 15-bit), same 16-bit coulomb counter | Targeted at premium portable devices requiring <±1% SOC error; higher cost and same pinout | Choose BQ27441YZFR-G1 only when sub-1.5% SOC error is required across full lifecycle; BQ27421YZFR-G1B suffices for mainstream applications |
Compared with BQ27421YZFR-G1B, the YZFT-G1B alternative demands finer-pitch assembly capability without functional gain, while the BQ27441YZFR-G1 offers measurable accuracy improvement at higher cost-making BQ27421YZFR-G1B the optimal balance of precision, integration, and production readiness for mid-tier portable electronics.
Availability
BQ27421YZFR-G1B is available at Aetrix Electronics and suitable for smartphones, tablets, and handheld terminals requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for BQ27421YZFR-G1B 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 specializing in analog, embedded processing, and power management technologies, with leadership in battery management ICs since 2005.
The BQ27421YZFR-G1B belongs to TI's bq27xxx fuel gauge family, designed specifically for system-side, single-cell Li-ion battery monitoring in space-constrained portable electronics where accuracy, integration, and low power are critical.
FAQ
What is the function of the BIN pin on the BQ27421YZFR-G1B?
The BIN pin on the BQ27421YZFR-G1B serves as a battery insertion detection input. When Operation Configuration bit [BIE] = 1 (default), a logic-low signal on BIN indicates battery presence-typically implemented with a 10-kΩ pulldown on the pack and 1.8-MΩ pullup on the system board. If [BIE] = 0, the host must explicitly notify the BQ27421YZFR-G1B of insertion/removal via BAT_INSERT/BAT_REMOVE subcommands. Direct shorting of BIN to VCC or VSS is prohibited.
Does the BQ27421YZFR-G1B require an external sense resistor?
No, the BQ27421YZFR-G1B does not require an external sense resistor. It integrates a precision 7 mΩ sense resistor between the SRX and BAT pins, enabling direct current measurement without additional components. This resistor is firmware-compensated for temperature coefficient, and its typical resistance is validated across –40°C to 85°C. External shunts are unnecessary and would conflict with the internal sensing architecture.
What I²C address does the BQ27421YZFR-G1B use?
The BQ27421YZFR-G1B uses a fixed 7-bit I²C slave address of 0x55 (binary 1010101). In standard I²C transactions, this translates to write address 0xAA (0x55 << 1 | 0) and read address 0xAB (0x55 << 1 | 1). The device supports standard-mode (100 kHz) and fast-mode (400 kHz) timing, with all command protocols-including Control(), Temperature(), and StateOfCharge()-accessed via this address.
How does the BQ27421YZFR-G1B handle battery temperature measurement?
The BQ27421YZFR-G1B incorporates an internal temperature sensor for autonomous cell temperature estimation, which feeds directly into the Impedance Track™ algorithm for SOC correction. Alternatively, the host MCU can provide external temperature data via the HostTemperature() command. The internal sensor achieves ±5°C accuracy over –40°C to 85°C, and its readings are automatically applied to voltage and impedance models-eliminating manual calibration in most portable applications.
What power modes does the BQ27421YZFR-G1B support, and how are they controlled?
The BQ27421YZFR-G1B supports five power modes: NORMAL (93 µA), SLEEP (21 µA), HIBERNATE (9 µA), SHUTDOWN (0.6 µA), and INITIALIZATION. Transitions occur automatically based on activity (e.g., I²C inactivity triggers SLEEP), but the host can force mode changes using Control() subcommands like SET_HIBERNATE, SHUTDOWN_ENABLE, and SHUTDOWN. Wake-up from SHUTDOWN is triggered by toggling GPOUT or applying power to BAT.
BQ27421YZFR-G1B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- Impedance Track™
- Package/Case:
- 9-UFBGA, DSBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Battery Monitor
- Battery Chemistry:
- Lithium Ion
- Number of Cells:
- 1
- Fault Protection:
- -
- Interface:
- I2C
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 9-DSBGA
BQ27421YZFR-G1B FAQ
1.How can I place an order for BQ27421YZFR-G1B through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ27421YZFR-G1B 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 BQ27421YZFR-G1B reliable?
The price and inventory of BQ27421YZFR-G1B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ27421YZFR-G1B is usually 5 days.
3.What payment methods are accepted for BQ27421YZFR-G1B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ27421YZFR-G1B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ27421YZFR-G1B?
BQ27421YZFR-G1B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ27421YZFR-G1B 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 BQ27421YZFR-G1B?
For technical support, including BQ27421YZFR-G1B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ27421YZFR-G1B requirements.
6.How does Aetrix verify that BQ27421YZFR-G1B is sourced from the original manufacturer or authorized distributors?
All BQ27421YZFR-G1B 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 BQ27421YZFR-G1B meets industry standards.
7.What is the process for return or replacement of BQ27421YZFR-G1B?
All BQ27421YZFR-G1B units undergo pre-shipment inspection (PSI). If there is an issue with BQ27421YZFR-G1B, 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 BQ27421YZFR-G1B part is unused and in its original packaging.
Return procedure for BQ27421YZFR-G1B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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