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Renesas Electronics 74FCT521ATSOG — Analog & Data Acquisition

74FCT521ATSOG 8-Bit Identity Comparator, 20-SOIC, Active

MPN74FCT521ATSOG
End of Life

Renesas 74FCT521ATSOG, 8-bit identity comparator, active-low output, 7.2 ns propagation delay at 5V, 50 pF, industrial temperature -40°C to 85°C, 20-SOIC package.

$2.92Ref. price · indicative, final on quote
Renesas Electronics 74FCT521ATSOG datasheet (PDF)
Packaging20-SOIC (0.295", 7.50mm Width)
RoHSROHS3 Compliant
Series74FCT
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

74FCT521ATSOG specifications
ParameterValue
TypeIdentity Comparator
Series74FCT
MountingSurface Mount
Voltage4.75V ~ 5.25V
Current - quiescent10 µA
Current - output high, low15mA, 48mA
Operating temperature-40°C ~ 85°C
OutputActive Low
PackageTube
Number of bits8
Case20-SOIC (0.295\", 7.50mm Width)
Output functionA=B
Max propagation delay @ v, max CL7.2ns @ 5V, 50pF

Product details

8-bit identity comparator in 20-SOIC

The Renesas 74FCT521ATSOG is an 8-bit identity comparator from the 74FCT series. It compares two 8-bit words and asserts the output when they match. The output is active-low, so a low signal on the A=B pin indicates equality. This part is used in address decoding, data bus matching, and parity-check circuits where a fast, glitch-free match signal is needed. Output drive capability is 15 mA sinking and 48 mA sourcing, enough to feed a standard TTL input or drive an LED indicator through a series resistor.

Supply and timing — what matters for the bus

Quiescent current is only 10 µA, so the part adds negligible draw to the 5V rail when idle. The active current will be higher when inputs toggle, but for a glue-logic comparator this is rarely a power-budget concern.

Frequently asked questions

Is 74FCT521ATSOG RoHS compliant?

Yes, it is ROHS3 compliant.

What is the closest pin-compatible alternative to 74FCT521ATSOG?

Within the 74FCT series, other 8-bit identity comparators in 20-SOIC with active-low output share the same footprint and function. The key difference is propagation delay and supply range — verify the timing and voltage tolerance against your specific BOM before substituting.