ZHCSTD7A December 2021 – November 2023 BQ79631-Q1
PRODUCTION DATA
In SLEEP mode, the following fault detections are still active:
Because communication is not available in SLEEP mode, the device provides an option to transmit the fault status through Heartbeat (device in no fault state) and Fault (device in fault state) Tones. These tones are transmitted in the same direction as a communication command frame, which is based on the CONTROL1[DIR_SEL] setting. For the tone signal to return back to the base device (so NFAULT can be triggered if needed), a Ring architecture must be used to support transmitting fault status in SLEEP mode.
Both the Heartbeat and Fault Tones are a type of tone similar to the communication tone. One main difference is a communication tone only transmits with a single burst of couplets, but Heartbeat and Fault Tones are sent with a burst of couplets periodically. See Section 8.3.5.2.3.3 for details.