Texas Instruments BQ79600-Q1 | First Look

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Modern EVs, HEVs, and energy storage systems require sophisticated battery management systems that can effectively monitor battery packs that can be 800 volts or greater and consist of hundreds of lithium ion cells stacked in series in each pack. Each pack also has a high accuracy battery monitor to provide diagnostic information and identify faults.

In a conventional system, this distributed batter management solution requires the MCU in the battery management unit to periodically wake up, check the battery monitors, then go back to sleep. The BMU is powered by the car’s 12V battery, which remains on to power functions such as security and keyless entry, but the constant cycling by the BMU can cause premature discharge of the 12V battery.

Texas Instruments’ BQ79600 is a functional-safety compliant communication IC that eliminates the MCU cycling, preserving battery life while enabling high accuracy battery monitoring. The BQ79600 provides an interface between the MCU in the battery management unit and TI BQ79600 series battery monitor ICs in each cell management unit. It enables revere host wake up functionality, which allows the MCU and its PMIC to remain in sleep mode, while the BQ79600 waits for a fault tone from the battery monitors. Once a fault tone is received, the BQ79600 wakes up, checks for a valid fault, then wakes up the PMIC and MCU so the system can respond accordingly.

The BQ79600 is robust and easy to use. It can operate from a 4.75V to 40V supply and is compatible with 3.3V and 5V logic. It communicates with the host MCU through SPI or UART and with the battery monitors through an isolated differential daisy chain interface. A single device supports the ring architecture required for reverse host wake-up, and it supports transformer or capacitor isolation between the battery and cell management units.

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