74HC/HCT259

General description

The 74HC/HCT259 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.

The 74HC/HCT259 are high-speed 8-bit addressable latches designed for general purpose storage applications in digital systems. The '259' are multifunctional devices capable of storing single-line data in eight addressable latches, and also 3-to-8 decoder and demultiplexer, with active HIGH outputs (Q₀ to Q₇), functions are available.

The '259' also incorporates an active LOW common reset (MR) for resetting all latches, as well as, an active LOW enable input (LE).

The '259' has four modes of operation as shown in the mode select table. In the addressable latch mode, data on the data line (D) is written into the addressed latch. The addressed latch will follow the data input with all non-addressed latches remaining in their previous states. In the memory mode, all latches remain in their previous states and are unaffected by the data or address inputs.

In the 3-to-8 decoding or demultiplexing mode, the addressed output follows the state of the D input with all other outputs in the LOW state. In the reset mode all outputs are LOW and unaffected by the address (A₀ to A₂) and data (D) input. When operating the '259' as an addressable latch, changing more than one bit of address could impose a transient-wrong address. Therefore, this should only be done while in the memory mode. The mode select table summarizes the operations of the '259'.

Features

• Combines demultiplexer and 8-bit latch
• Serial-to-parallel capability
• Output from each storage bit available
• Random (addressable) data entry
• Easily expandable
• Common reset input
• Useful as a 3-to-8 active HIGH decoder
• Output capability: standard
• I_CC category: MSI

Products/packages

Pricing/ordering/availability

Applications

• High-speed disc or tape controller
• Communications buffer.

Related applications
50-60 Hz CRT integrated DTV (TV210D)
Mid-range integrated DTV (TV810)

Design support

Support Documents

HCT_USER_GUIDE; HC/T User Guide (1997-11-01)

Parametrics/similar products

Similar products
74HC/HCT259 links to the similar products page containing an overview of products that are similar in function or related to the type number(s) as listed on this page. The similar products page includes products from the same catalog tree(s), relevant selection guides and products from the same functional category.

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