SLUSE13A January 2020 – May 2021 BQ76952
The FUSE pin on the BQ76952 device can be used to blow a chemical fuse in the presence of a Permanent Fail (PF), as well as to determine if an external secondary protector in the system has detected a fault and is attempting to blow the fuse itself. The pin can drive the gate of an NFET, which can be combined with the drive from an external secondary protector, as shown in Figure 12-1. When the FUSE pin is not asserted by the BQ76952 device, it remains in a high-impedance state and detects a voltage applied at the pin by a secondary protector. The device can be configured to generate a PF if it detects a high signal at the FUSE pin.
The device can be configured to blow the fuse when a PF occurs. In this case, the device will only attempt to blow the fuse if the stack voltage is above a programmed threshold, based on a system configuration with the fuse placed between the top of stack and the high-side protection FETs. If instead the fuse is placed between the FETs and the PACK+ connector, then the device bases its decision on the PACK pin voltage (based on configuration setting). This voltage threshold check may be disregarded under certain special cases, as described in the BQ76952 Technical Reference Manual (SLUUBY2).