Product details

Rating Automotive Features AEC-Q100 Automotive Qual, ASIL-D, Battery Management Unit, Battery Monitoring, High precision, Integrated ADC, Overtemperature protection, Overvoltage protection, Stackable (built-in interface), Undertemperature protection, Undervoltage protection Communication interface Daisy chain, SPI Operating temperature range (°C) to TI functional safety category Functional Safety-Compliant Operating current (typ) (μA) 5000
Rating Automotive Features AEC-Q100 Automotive Qual, ASIL-D, Battery Management Unit, Battery Monitoring, High precision, Integrated ADC, Overtemperature protection, Overvoltage protection, Stackable (built-in interface), Undertemperature protection, Undervoltage protection Communication interface Daisy chain, SPI Operating temperature range (°C) to TI functional safety category Functional Safety-Compliant Operating current (typ) (μA) 5000
HTQFP (PHP) 48 81 mm2 9 x 9
  • Two fast pack voltage measurements
    • Dedicated single-ended measurements; ASIL-D
    • HV Measurement Accuracy <0.4% ; 0.3-5v single ended
    • 0uS VI sync within BQ79881; fast 5uS typical VI Sync with cell measurements
  • Accurate Single-Ended Measurements
    • Up to 18 single ended ADC inputs; ASIL-D
    • HV Measurement Accuracy <0.4%; 0-5V single ended
    • Usable as ratiometric temperature sense inputs
    • Configurable 1.8V/2.5V/3.3V reference for HV measurements
  • Four Current Sense ADCs
    • Measure up to two separate currents; ASIL-D
    • Input range = +/-275mV differential, +/-750mV common mode; ASIL-D
    • 0.1% accuracy. 10mA (50u Rshunt)
  • Over Current Comparators
    • Dedicated fast overcurrent digital comparator per CS ADC; ASIL-D
    • Response : 100uS to 1mS. Accuracy: 1%
    • Thresholds: 0mV to +/-300mV.
    • OC response on GPIO pins.
    • Majority voting option
  • Upgraded Daisy Chain Interface
    • 2x parallel SPI ports to MCU to support split chain with single bridge device
    • 2-wire isolated interface, SPI to MCU
    • 2Mbps single chain/ring, 4Mbps split chain for up to 4x speed improvement
    • Closed Loop BCI: 200mA; Open Loop BCI: 300mA
    • Isolation: Transformer or capacitor-only
    • FDTI Time: <100ms for 800V packs or 250 cells
    • Support for ring architecture
    • Reverse wakeup available without ring architecture
  • Smart EIS Engine
    • Integrated Electrochemical Impedance Spectroscopy measurement engine
    • Impedance Accuracy: 1% with 1A excitation, >200uΩ impedance
    • Excitation frequency: 0.01Hz – 3.5kHz
    • < 5us I/V synchronization from device to device
    • Support for global excitation
  • Other
    • 12V switch drive pins to drive NMOSFET or Opto-MOS switches
    • Package: 48-pin QFN, 0.5mm pitch
    • Meets AEC-Q100 and ISO26262 ASIL-D Functional Safety
    • Power Consumption
      • Active mode: < 100mW
      • Sleep mode: < 0.5mW
      • Deep sleep mode: < 0.05mW
  • Two fast pack voltage measurements
    • Dedicated single-ended measurements; ASIL-D
    • HV Measurement Accuracy <0.4% ; 0.3-5v single ended
    • 0uS VI sync within BQ79881; fast 5uS typical VI Sync with cell measurements
  • Accurate Single-Ended Measurements
    • Up to 18 single ended ADC inputs; ASIL-D
    • HV Measurement Accuracy <0.4%; 0-5V single ended
    • Usable as ratiometric temperature sense inputs
    • Configurable 1.8V/2.5V/3.3V reference for HV measurements
  • Four Current Sense ADCs
    • Measure up to two separate currents; ASIL-D
    • Input range = +/-275mV differential, +/-750mV common mode; ASIL-D
    • 0.1% accuracy. 10mA (50u Rshunt)
  • Over Current Comparators
    • Dedicated fast overcurrent digital comparator per CS ADC; ASIL-D
    • Response : 100uS to 1mS. Accuracy: 1%
    • Thresholds: 0mV to +/-300mV.
    • OC response on GPIO pins.
    • Majority voting option
  • Upgraded Daisy Chain Interface
    • 2x parallel SPI ports to MCU to support split chain with single bridge device
    • 2-wire isolated interface, SPI to MCU
    • 2Mbps single chain/ring, 4Mbps split chain for up to 4x speed improvement
    • Closed Loop BCI: 200mA; Open Loop BCI: 300mA
    • Isolation: Transformer or capacitor-only
    • FDTI Time: <100ms for 800V packs or 250 cells
    • Support for ring architecture
    • Reverse wakeup available without ring architecture
  • Smart EIS Engine
    • Integrated Electrochemical Impedance Spectroscopy measurement engine
    • Impedance Accuracy: 1% with 1A excitation, >200uΩ impedance
    • Excitation frequency: 0.01Hz – 3.5kHz
    • < 5us I/V synchronization from device to device
    • Support for global excitation
  • Other
    • 12V switch drive pins to drive NMOSFET or Opto-MOS switches
    • Package: 48-pin QFN, 0.5mm pitch
    • Meets AEC-Q100 and ISO26262 ASIL-D Functional Safety
    • Power Consumption
      • Active mode: < 100mW
      • Sleep mode: < 0.5mW
      • Deep sleep mode: < 0.05mW

The device can be used to measure divided down high voltage nodes in a battery system. It can measure voltages across Fuses and Contactors, and it can check isolation voltages in battery junction box (BJB) systems. The device has four integrated current sense paths supporting low side shunt resistors. Coulomb counting is available for accurate SOC calculation. There are 18 GPIOs/auxiliary inputs that can be used for HV measurements, thermistor measurements and driving relays. There are 4 SW outputs that can be used to drive MOSFET switches in the measurement path. The device can function as a SPI and I2C HUB and interface with up to 8 separate SPI devices/groups. Over current protection response can be achieved autonomously using OC Pins for fast reaction in dangerous over current events. The isolated bi-directional daisy chain ports support both capacitor and transformer based isolation. The device can also communicate with MCU over SPI.

The device can be used to measure divided down high voltage nodes in a battery system. It can measure voltages across Fuses and Contactors, and it can check isolation voltages in battery junction box (BJB) systems. The device has four integrated current sense paths supporting low side shunt resistors. Coulomb counting is available for accurate SOC calculation. There are 18 GPIOs/auxiliary inputs that can be used for HV measurements, thermistor measurements and driving relays. There are 4 SW outputs that can be used to drive MOSFET switches in the measurement path. The device can function as a SPI and I2C HUB and interface with up to 8 separate SPI devices/groups. Over current protection response can be achieved autonomously using OC Pins for fast reaction in dangerous over current events. The isolated bi-directional daisy chain ports support both capacitor and transformer based isolation. The device can also communicate with MCU over SPI.
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* Data sheet BQ79881-Q1 UIR Sensor with Pack-Level EIS and Voltage, Current and Insulation Resistance Monitoring in EV/BMS HV Automotive Applications datasheet PDF | HTML 24 Sep 2025

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Driver or library

BQ79826-Q1-DESIGN — BQ79826-Q1 design resources

BQ79826-Q1 Document Repository
Supported products & hardware

Supported products & hardware

Products
Battery monitors & balancers
BQ79881-Q1 — Automotive battery junction box pack monitor with Electrochemical Impedance Spectroscopy
Driver or library

BQ79881-Q1-DESIGN — BQ79881-Q1 design resources

BQ79881-Q1 documentation repository
Supported products & hardware

Supported products & hardware

Products
Battery monitors & balancers
BQ79881-Q1 — Automotive battery junction box pack monitor with Electrochemical Impedance Spectroscopy
Driver or library

BQ79881-Q1-FS — Functional Safety documentation for BQ79881-Q1

This secure folder stores Functional Safety document for BQ79881-Q1
Supported products & hardware

Supported products & hardware

Products
Battery monitors & balancers
BQ79881-Q1 — Automotive battery junction box pack monitor with Electrochemical Impedance Spectroscopy
Driver or library

EIS-BQ798XX-Q1-DESIGN — BQ798XX-Q1 Electrochemical Impedance Spectroscopy Design resources

EIS design secure folder for BQ798XX-Q1
Supported products & hardware

Supported products & hardware

Products
Battery monitors & balancers
BQ79826Z-Q1 — Automotive 26-S battery monitor and balancer with Electrochemical Impedance Spectroscopy engine BQ79881-Q1 — Automotive battery junction box pack monitor with Electrochemical Impedance Spectroscopy
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HTQFP (PHP) 48 Ultra Librarian

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