BQ40Z50-R1 Datasheet, PDF (30/55 Pages) Texas Instruments – Li-Ion Battery Pack Manager

bq40z50-R1
SLUSCB3 – JULY 2015
www.ti.com
Figure 22. bq40z50-R1 Protection FETs
9.2.2.1.2 Chemical Fuse
The chemical fuse (Dexerials, Uchihashi, and so forth) is ignited under command from either the bq294700
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 Q5, shown in Figure 23, 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-channel 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 FUSE Circuitry.
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