4.5V threshold — where it lands in the system
The ROHM BD48E45G-MTR is a single-channel voltage detector from the automotive-grade BD48Exx series. It asserts a reset (active-low, open-drain output) when the monitored supply drops below 4.5V, and releases it when the supply recovers above that threshold.
AEC-Q100 and the 105°C ceiling
The 105°C upper limit suits engine-bay-adjacent locations and transmission control modules, though not direct exhaust- or brake-mounted spots that see sustained 125°C+ junction temperatures. For those, the BU4921G-TR sibling (rated to 125°C) is the correct grade.
Open-drain output — pull-up resistor required
This allows the reset output to be shared across multiple detectors or pulled to a different voltage than the monitored rail, which is common in mixed-voltage automotive architectures.
Housed in a 5-pin SC-74A / SOT-753 package, also designated as 5-SSOP. The small footprint (roughly 2.9 mm x 1.6 mm) fits space-constrained ECU layouts. Surface-mount assembly is standard; no special reflow profile beyond the usual lead-free solder requirements.