What this comparator does and where it fits
The AD8561ARUZ from Analog Devices is a single-channel, general-purpose comparator built for speed. Its headline rating is a maximum propagation delay of 9.8 ns, which means it can resolve a signal transition and present a valid output in under ten nanoseconds — fast enough for pulse-width discriminator circuits, zero-crossing detectors in high-frequency power stages, or clock-recovery thresholding in data links. The output stage is CMOS and TTL-compatible, with complementary outputs available, so it can drive logic families directly without an external level shifter. Supply flexibility covers single-rail operation from 3 V to 10 V or split supplies from ±1.5 V to ±5 V, suiting it for mixed-signal boards where the analog rail is higher than the digital core voltage.
Supply range and input offset — what they mean for your BOM
The 3 V to 10 V single-supply range lets the AD8561ARUZ sit on a 5 V or 3.3 V rail without a separate analog regulator, though the 7 mV maximum input offset at 5 V means the comparator's switching threshold can be off by that much — fine for digital thresholding, but something to budget for if you are sensing a tight analog window. The 6 µA maximum input bias current at 5 V is low enough that high-impedance sources (like a photodiode transimpedance amplifier output) will not be loaded significantly. Typical CMRR of 85 dB and PSRR of 65 dB give reasonable rejection of supply ripple and common-mode shifts, though the PSRR figure is modest compared to precision comparators — expect some threshold wander if the rail is noisy.
Package and temperature grade
Housed in an 8-lead TSSOP (4.40 mm width), the AD8561ARUZ is a surface-mount part suited for compact PCB layouts. The operating temperature range of -40°C to 85°C covers industrial environments — outdoor telecom cabinets, factory-floor sensor interfaces, and benchtop instrumentation — but not automotive under-hood or extended-temperature industrial beyond 85°C. The part is marked as RoHS3 compliant, so it meets current European and global restriction-of-hazardous-substances requirements.
Lifecycle and sourcing
That means it is suitable for new designs and production BOMs without an imminent last-time-buy risk. The closest functional sibling is the AD8561ARZ, which shares the same die and specifications but ships in an SOIC-8 package; the ARUZ variant is the TSSOP-8 option for space-constrained layouts.