74F240 Octal inverting buffer (3-state)

Category: Electronics, Logic ICS, NXP

The 74F240 datasheet describes an octal inverting buffer designed with 3-state outputs, appropriate for bus line driving, specifically in buffer memory address registers. The device is highlighted for its robust output current capabilities, managing to sink up to 64 mA and source up to 15 mA.

Features

This integrated circuit is recognized for its octal bus interface and 3-state buffer outputs, and is part of the product catalogue of Philips Semiconductors. As an improvement upon its predecessors (data of 2002 Mar 18), this update was provided on 2004 Feb 25.

Description & Ordering Information

Philips’ 74F240 offers two output enables, each governing four 3-state outputs. Notably, typical propagation delay is measured at 4.3 nanoseconds while the typical supply current is 37 mA when the supply voltage Vcc is at 5 V ±10%, and the ambient temperature (Tamb) ranges from 0°C to +70°C.

Ordering options for this buffer include 20-pin plastic DIP (N74F240N), 20-pin plastic SOL (N74F240D), and 20-pin plastic SSOP (N74F240DB), delineated by corresponding package drawing numbers SOT146-1, SOT163-1, and SOT339-1 respectively.

Input and Output Loading and Fan Out Table

The datasheet provides an important table outlining the input and output loading parameters, as well as fan out information for the various pins of the 74F240 device. These details include:

Data inputs (Ian, Ibn): 1.0/1.67 UL high/low
Output enable inputs (Active-LOW OEa, OEb): 1.0/0.33 UL high/low
Data outputs (Yan, Ybn): 750/106.7 UL high/low

Here, UL refers to FAST unit loads, with one FAST unit load equating to 20 μA in the HIGH state and 0.6 mA in the LOW state. This offers clear insight into the buffer’s logical performance parameters.

Pin Configuration & Logic Symbol

The datasheet includes detailed diagrams that express the pin configuration and logic symbol (SF00320, SF00321), which incorporate critical aspects of the device, highlighting the distribution of the 20 pins with labeled voltage supply (Vcc) and ground (GND) connections, as well as data inputs/outputs and output enable inputs.