The BQ79631-Q1 device is a UIR monitor that measures divided down voltages from various HV nodes. The device also has a precision current measurement that measures voltage across a low-side shunt resistor. The device can be used to measure insulation resistance by utilizing the ADC for voltage measurement and GPIO logic to control switches in this scheme. The device is also capable of measuring temperatures by reading the voltages from thermistors.

The ADCs in the daisy-chained devices can be configured to align the start of voltage measurements and all voltages can be measured within 128 μs. Each VS sensing channel includes a post-ADC digital low-pass filter (LPF) for noise reduction as well as providing moving average measurement results. The device has eight GPIOs, all of which are configurable for thermistor connections. All eight GPIOs can be measured within 1.6 ms.

The eight GPIOs can be configured as general purpose I/O. These I/O pins can be used to drive and receive logic level signals. Additionally, some of these GPIO pins can be configured as master-SPI device in order to control and communicate with external SPI peripheral devices such as an EEPROM and others.

The BQ79631-Q1 communicates over daisy-chain. It has a pair of high (north) and low (south) differential communication ports, requiring only one twisted pair cable. The device supports either capacitive only, capacitive and choke, or transformer isolation. Multiple devices can be connected in a daisy-chain. Communication is reclocked on each daisy-chained device, ensuring communication integrity for long distances. An optional RING connection is supported to reverse the daisy-chain communication direction in case of cable failure. Each device includes a SPI master configured through the GPIOs.

The device includes a hardware OVUV comparator with user configurable thresholds. These can be used for overcurrent detection independent of ADC measurements. This method of overcurrent detection will need an external amplifier between the current sensing inputs and the OVUV comparator input.

The device provides an option to embed fault status information to the communication frame. The device can be configured to trigger an NFAULT pin as an interrupt signal to the system. This provides a way to reduce communication overhead without adding an additional twisted pair cable and isolation for faster fault detection.

The device has SLEEP and SHUTDOWN modes for lower power consumption. All functions work in ACTIVE mode; a hardware comparator for OVUV works in SLEEP mode. While in SHUTDOWN, all active functions are turned off. A HW reset function is available and can be activated by the host MCU. The HW reset provides a POR-like event to the device without actual power supply removal. This provides a reliable, low cost, and recoverable option to improve overall system robustness.