Product details

Supply voltage (min) (V) 4.5 Supply voltage (max) (V) 5.5 Number of channels 8 IOL (max) (mA) 32 IOH (max) (mA) -12 Input type TTL Output type TTL Features Over-voltage tolerant inputs, Very high speed (tpd 5-10ns) Technology family AS Rating Military Operating temperature range (°C) -55 to 125
Supply voltage (min) (V) 4.5 Supply voltage (max) (V) 5.5 Number of channels 8 IOL (max) (mA) 32 IOH (max) (mA) -12 Input type TTL Output type TTL Features Over-voltage tolerant inputs, Very high speed (tpd 5-10ns) Technology family AS Rating Military Operating temperature range (°C) -55 to 125
CDIP (JT) 24 221.44 mm² 32 x 6.92
  • 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

 

 

  • 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

 

 

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.

 

 

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
* Data sheet Octal Bus Transceivers & Registers With 3 -State Outputs datasheet (Rev. F) 01 Jan 1995
* SMD SN54AS646 SMD 5962-87595 21 Jun 2016
Selection guide Logic Guide (Rev. AB) 12 Jun 2017
Application note Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) 02 Dec 2015
User guide LOGIC Pocket Data Book (Rev. B) 16 Jan 2007
Application note Semiconductor Packing Material Electrostatic Discharge (ESD) Protection 08 Jul 2004
Application note TI IBIS File Creation, Validation, and Distribution Processes 29 Aug 2002
Application note Designing With Logic (Rev. C) 01 Jun 1997
Application note Advanced Schottky Load Management 01 Feb 1997
Application note Input and Output Characteristics of Digital Integrated Circuits 01 Oct 1996
Application note Live Insertion 01 Oct 1996
Application note Advanced Schottky (ALS and AS) Logic Families 01 Aug 1995

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