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Texas Instruments SN74ALS27AD — Logic ICs

SN74ALS27AD TI 74ALS Triple 3-Input NOR Gate, 15 ns SOIC-14

MPNSN74ALS27AD
End of Life

Texas Instruments SN74ALS27AD, Series 74ALS, Logic Type NOR Gate, 3 Circuits, 3 Inputs, 14-SOIC (0.154", 3.90mm Width), Surface Mount, 0°C ~ 70°C, 15ns @ 5V, 50pF max propagation delay.

$1.58Ref. price · indicative, final on quote
Texas Instruments SN74ALS27AD datasheet (PDF)
Packaging14-SOIC (0.154", 3.90mm Width)
RoHSROHS3 Compliant
Series74ALS
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

SN74ALS27AD specifications
ParameterValue
Series74ALS
Logic typeNOR Gate
MountingSurface Mount
Supply voltage4.5V ~ 5.5V
Current - output high, low400µA, 8mA
I/O channels3
Operating temperature0°C ~ 70°C
PackageTube
Case14-SOIC (0.154\", 3.90mm Width)
Number of circuits3
Input logic level - low0.8V
Input logic level - high2V
Max propagation delay @ v, max CL15ns @ 5V, 50pF

Product details

What the 15 ns propagation delay means for your bus

The SN74ALS27AD is a triple 3-input NOR gate from TI's 74ALS family, in a 14-SOIC package. The headline number is 15 ns max propagation delay at 5 V and 50 pF load.

Output drive and what it can actually sink

The output is rated for 400 µA source and 8 mA sink. That 8 mA sink is enough to drive four standard LSTTL loads but won't directly light an LED or drive a relay coil without a transistor buffer.

Supply and temperature — where it fits

Runs on a 4.5 V to 5.5 V supply, so it's strictly a 5 V rail part.

Frequently asked questions

How does SN74ALS27AD compare to the 74LS27?

The ALS series is faster (15 ns vs about 18-22 ns for LS) and uses less power per gate. Pin-compatible and a direct drop-in replacement for most 74LS27 sockets, provided the supply is 5 V.

Is there a direct replacement for SN74ALS27AD?

No official TI second-source is listed, but the SN74F27NSR (74F27) is a pin-compatible, faster alternative (5 ns propagation delay) with the same logic function and supply range.

What is the pinout of SN74ALS27AD?

Standard 14-pin SOIC pinout for a triple 3-input NOR gate. Pins 1, 2, 13 are inputs for gate 1; pin 12 is output. Pins 3, 4, 5 for gate 2; pin 6 output. Pins 9, 10, 11 for gate 3; pin 8 output. Pin 7 is GND, pin 14 is VCC. The datasheet has the full diagram.