SLUSBV4B June 2018 – September 2020 BQ40Z80
PRODUCTION DATA
The chemical fuse (Dexerials, Uchihashi, and so on) is ignited under command from either the bq771800 secondary voltage protection IC or from the FUSE pin of the gas gauge. Either of these events applies a positive voltage to the gate of Q9, which then sinks current from the third terminal of the fuse, causing it to ignite and open permanently.
It is important to carefully review the fuse specifications and match the required ignition current to that available from the N-CH FET. Ensure that the proper voltage, current, and Rds(on) ratings are used for this device. The fuse control circuit is discussed in detail in Section 9.2.2.3.5.