What this dual comparator does in a BOM
The LM2903YQ3T is a dual, general-purpose voltage comparator from STMicroelectronics, part of the Automotive AEC-Q100 series. It compares two analog voltages and outputs a digital logic level indicating which is higher, making it a fundamental building block for threshold detection, zero-crossing detectors, and window comparators in automotive and industrial control boards.
Parametric fit for the signal chain
Input offset voltage is 7 mV maximum at 30 V supply — this sets the smallest detectable voltage difference between the inputs. For a 0.25 V threshold, the offset contributes about 2.8% error, which is acceptable for most switch-point applications but worth derating for precision window detectors. Quiescent current maxes at 2.5 mA for both comparators, and each output can sink 16 mA at 5 V — enough to drive a logic input or a small LED directly, but not a relay coil without a buffer transistor.
Housed in an 8-WFDFN exposed-pad package (2x2 mm body), the LM2903YQ3T uses a wettable flank design — the side of the package has a solderable metal finish, enabling automated optical inspection (AOI) of the solder joint after reflow. This is a requirement for many automotive tier-1 assembly lines.
The base product number is LM2903, and several package variants exist (LM2903YPT in TSSOP-8, LM2903BYDT in SO-8, LM2903DT in SO-8). All share the same electrical core — the difference is the package footprint and the wettable flank option. If the board layout is fixed for a 2x2 DFN, the YQ3T is the only drop-in; the others require a different land pattern.