1 Features

• AEC-Q100 qualified –40°C to +125°C

• Functional safety compliant

– Documentation to aid ISO 26262 system design

– Systematic capability up to ASIL D

– Hardware capability up to ASIL D

• 17 single-ended voltage channels

– High voltage pack, link, charge measurement

accuracy update to 0.2%

– Pack and cell VI sync to 64μS

• 2 independent current sense ADCs

– ±0.15% gain error drift

– Input range = ±275mV

• 2 Over current detect comparators

– ±1% accuracy

– Selectable bi-directional thresholds

– Programmable OC

• Integrated Coulomb counting

• 15 GPIO inputs as IO, I2C, SPI, ADC and temp

sense

• Dedicated MOSFET switch drive pins

• Intelligent SPI contoller HUB

– Support multiple SPI peripheral devices

– HW pin to trigger contactor drivers and Pyro

Fuse drivers

• Stackable and register map compatible with

BQ7971x-Q1 cell monitors

2 Applications

• Full Electric, Plug-In Hybrid, Hybrid Vehicles

3 Description

BQ79731B-Q1 can be used to measure divided down

high voltage nodes in a battery system. The device

can measure voltage across Fuse, Contactors and

check isolation voltage in a battery junction box (BJB)

system. The device has two integrated current sense

paths supporting low-side shunt resistor. Coulomb

counting function is available for accurate SOC

calculation. There are 15 GPIOs/auxiliary inputs

that can be used for HV measurements, thermistor

measurements, and driving relays. There are four SW

outputs that can be used to drive MOSFET switches

in the measurement path. The device can function as

a SPI HUB and interface with up to eight separate

SPI devices/groups. Over current protection response

can be achieved autonomously using HW pins for

fast protection 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 and UART.