SN74ALS648A

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Octal Bus Transceivers/Registers With 3-State Outputs

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Product details

Parameters

Technology Family ALS VCC (Min) (V) 4.5 VCC (Max) (V) 5.5 Bits (#) 8 Voltage (Nom) (V) 5 F @ nom voltage (Max) (MHz) 75 ICC @ nom voltage (Max) (mA) 88 Propagation delay (Max) (ns) 17 IOL (Max) (mA) 24 IOH (Max) (mA) -15 Operating temperature range (C) 0 to 70 open-in-new Find other Registered transceiver

Package | Pins | Size

SOIC (DW) 24 160 mm² 15.5 x 10.3 open-in-new Find other Registered transceiver

Features

  • Independent Registers for A and B Buses
  • Multiplexed Real-Time and Stored Data
  • Choice of True or Inverting Data Paths
  • Choice of 3-State or Open-Collector Outputs
  • Package Options Include Plastic Small-Outline (DW) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (NT) and Ceramic (JT) 300-mil DIPs

 

 

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Description

These devices consist of bus-transceiver circuits with 3-state or open-collector outputs, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the data bus or from the internal storage registers. Data on the A or B bus is clocked into the registers on the low-to-high transition of the appropriate clock (CLKAB or CLKBA) input. Figure 1 illustrates the four fundamental bus-management functions that can be performed with the octal bus transceivers and registers.

Output-enable () and direction-control (DIR) inputs control the transceiver functions. In the transceiver mode, data present at the high-impedance port may be stored in either or both registers.

The select-control (SAB and SBA) inputs can multiplex stored and real-time (transparent mode)

data. The circuitry used for select control eliminates the typical decoding glitch that occurs in a multiplexer during the transition between stored and real-time data. DIR determines which bus receives data when is low. In the isolation mode ( high), A data may be stored in one register and/or B data may be stored in the other register.

When an output function is disabled, the input function is still enabled and can be used to store and transmit data. Only one of the two buses, A or B, may be driven at a time.

The -1 version of the SN74ALS646A is identical to the standard version, except that the recommended maximum IOL in the -1 version is increased to 48 mA. There are no -1 versions of the SN54ALS646, SN54ALS648, or SN74ALS648A.

The SN54ALS646, SN54ALS648, and SN54AS646 are characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS646A, SN74ALS648A, SN74AS646, and SN74AS648 are characterized for operation from 0°C to 70°C.

 

 

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Technical documentation

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Type Title Date
* Datasheet Octal Bus Transceivers & Registers With 3 -State Outputs datasheet (Rev. F) Jan. 01, 1995
Selection guides Logic Guide (Rev. AB) Jun. 12, 2017
Application notes Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) Dec. 02, 2015
User guides LOGIC Pocket Data Book (Rev. B) Jan. 16, 2007
Application notes Semiconductor Packing Material Electrostatic Discharge (ESD) Protection Jul. 08, 2004
More literature Logic Cross-Reference (Rev. A) Oct. 07, 2003
Application notes TI IBIS File Creation, Validation, and Distribution Processes Aug. 29, 2002
Application notes Bus-Interface Devices With Output-Damping Resistors Or Reduced-Drive Outputs (Rev. A) Aug. 01, 1997
Application notes Designing With Logic (Rev. C) Jun. 01, 1997
Application notes Input and Output Characteristics of Digital Integrated Circuits Oct. 01, 1996
Application notes Live Insertion Oct. 01, 1996
Application notes Advanced Schottky (ALS and AS) Logic Families Aug. 01, 1995

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Hardware development

EVALUATION BOARDS Download
document-generic User guide
$10.00
Description
This EVM is designed to support any logic device that has a D, DW, DB, NS, PW, P, N, or DGV package in a 14 to 24 pin count.
Features
  • Board design allows for versatility in evaluation
  • Supports a wide-range of logic devices

CAD/CAE symbols

Package Pins Download
SOIC (DW) 24 View options

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