Differential comparator with strobe — 8-SOIC, industrial temp grade
The LM211QDR is a single-channel differential comparator from Texas Instruments, offered in an 8-SOIC package (0.154" width, 3.90 mm body) for surface-mount assembly. It is classified as a general-purpose type, meaning it is designed for standard comparator functions without specialized rail-to-rail or high-speed optimization.
Output stage and signal compatibility
The output stage supports multiple logic families — DTL, MOS, open-collector, open-emitter, RTL, and TTL — giving the designer flexibility to interface with both bipolar and CMOS digital inputs without an external level translator. Typical output current is 50 mA, sufficient to drive a logic input or a small relay coil directly when pulled up to the appropriate rail. Quiescent current maxes at 6 mA, which is modest for a general-purpose comparator; the device draws this regardless of output state, so it is best suited for continuously powered applications rather than battery-operated duty-cycled designs.
Input precision — offset and bias at ±15 V
Maximum input offset voltage is 3 mV at ±15 V supplies — a typical figure for a general-purpose comparator. This sets the threshold for the smallest detectable differential signal; applications requiring sub-millivolt resolution should budget an external offset-nulling network or select a precision-grade comparator. Maximum input bias current is 0.1 µA at ±15 V, which is low enough that high-impedance sources (e.g., 10 kΩ sensors) introduce less than 1 mV of additional offset error from bias current alone. The bias current doubles roughly every 10°C, so at 125°C the effective bias may approach 1 µA — a consideration for very-high-impedance front-ends.