74AHCT259D データシートの表示（PDF） - NXP Semiconductors.

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74AHCT259D

8-bit addressable latch

NXP Semiconductors. 

74AHC259; 74AHCT259

8-bit addressable latch

Rev. 02 — 15 May 2008

Product data sheet

1. General description

The 74AHC259; 74AHCT259 is a high-speed Si-gate CMOS device and is pin compatible

with Low-power Schottky TTL (LSTTL). It is specified in compliance with JEDEC standard

No. 7-A.

The 74AHC259; 74AHCT259 is a high-speed 8-bit addressable latch designed for general

purpose storage applications in digital systems. It is a multifunctional device capable of

storing single-line data in eight addressable latches and providing a 3-to-8 decoder and

multiplexer function with active HIGH outputs (Q0 to Q7). It also incorporates an active

LOW common reset (MR) for resetting all latches as well as an active LOW enable input

(LE).

The 74AHC259; 74AHCT259 has four modes of operation:

• 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 data input (D) with all other outputs in the LOW state.

• In the reset mode, all outputs are LOW and unaffected by the address inputs

(A0 to A2) and data input (D).

When operating the 74AHC259; 74AHCT259 as an address latch, changing more than

one bit of the address could impose a transient-wrong address. Therefore, this should

only be done while in the memory mode.

2. Features

I Balanced propagation delays

I All inputs have Schmitt-trigger actions

I Combines demultiplexer and 8-bit latch

I Serial-to-parallel capability

I Output from each storage bit available

I Random (addressable) data entry

I Easily expandable

I Common reset input

I Useful as a 3-to-8 active HIGH decoder

I Inputs accept voltages higher than VCC

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