Functional Description

The FCT138T is a 1-of-8 decoder. The FCT138T accepts three binary weighted inputs (A0, A1, A2) and, when enabled, provides eight mutually exclusive active LOW outputs (O0–O7). The FCT138T features three enable inputs, two active LOW (E1, E2) and one active HIGH (E3).

All inputs will be HIGH unless E1 and E2 are LOW and E3 is HIGH. This multiple enable function allows easy parallel expansion of the device to a 1-of-32 (5 lines to 32 lines) decoder with just four FCT138T devices and one inverter.

The outputs are designed with a power-off disable feature to allow for live insertion of boards.

Features

• Function, pinout, and drive compatible with FCT and F logic

• FCT-C speed at 5.0 ns max. (Com’l), FCT-A speed at 5.8 ns max. (Com’l)

• Reduced VOH (typically = 3.3V) versions of equivalent FCT functions

• Edge-rate control circuitry for significantly improved noise characteristics

• Power-off disable feature

• ESD > 2000V

• Matched rise and fall times

• Fully compatible with TTL input and output logic levels

• Extended commercial range of −40°C to +85°C

• Sink current 64 mA (Com’l), 32 mA (Mil)