[FAQ] BQ76952: How do I RESET the BQ769x2 device?

The BQ769x2 family of devices can undergo 2 types of RESET: partial and full.

Partial:

The partial RESET can be performed by driving the RST_SHUT pin HIGH for < 1 second.  This resets most of the digital logic, including that associated with the serial communications bus.  However, it does not reset the registers of the device or the logic that holds the state of the protection FETs and FUSE.  These remain as they were before the pin was driven HIGH.

If the RST_SHUT pin is driven HIGH for > 1 second, the device will transition into SHUTDOWN mode, which involves disabling external protection FETs, and powering off the internal oscillators, REG18 LDO, on-chip pre-regulator, and REG1 & REG2 LDOs.

Special Considerations:

• If a HIGH signal < 1 second at the RST_SHUT pin is used to wake the device from SLEEP mode, a partial RESET will be performed. To wake from sleep and avoid a partial RESET, use the SLEEP_DISABLE command followed by the SLEEP_ENABLE enable command, or use WAKE current detection.
• If the RST_SHUT pin is asserted while the device is updating something in RAM, the RAM integrity check could fail and trigger a full RAM RESET.

Full:

The full RESET resets all of the digital logic as well as the logic that holds the state of the protection FETs and FUSE.  After a full RESET is performed, the BQ769x2 device settings will return to their default state, and every register value that is not programmed to OTP will have to be reconfigured.

The full RESET can only be performed in one of 2 ways: sending the 0x0012 RESET() subcommand or entering and exiting SHUTDOWN mode.

Sending the 0x0012 RESET() Command:

This subcommand can be sent via an MCU through the I2C/SPI/HDQ communication lines.  More information about the RESET subcommand can be found in Section 2.4 of the Software Development Guide (https://www.ti.com/lit/pdf/sluaa11).

Entering and Exiting SHUTDOWN Mode:

Although SHUTDOWN mode will fully RESET the device, it is not recommended to SHUTDOWN and WAKE your device just to accomplish a device RESET.  SHUTDOWN mode should normally only be used for shipping the battery or long-term storage. 

Entering SHUTDOWN mode can be accomplished by lowering battery voltage below VPORA – VPORA_HYS, sending a SHUTDOWN subcommand, or through protection settings.  More information on SHUTDOWN mode can be found in Section 13.5 SHUTDOWN Mode in the BQ76952 datasheet (https://www.ti.com/lit/gpn/bq76952).

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