Product details

Supply voltage (min) (V) 2 Supply voltage (max) (V) 6 Number of channels 8 IOL (max) (mA) 7.8 IOH (max) (mA) -7.8 Input type CMOS Output type CMOS Features Balanced outputs, High speed (tpd 10-50ns), Positive input clamp diode Technology family HC Rating Catalog Operating temperature range (°C) -40 to 85
Supply voltage (min) (V) 2 Supply voltage (max) (V) 6 Number of channels 8 IOL (max) (mA) 7.8 IOH (max) (mA) -7.8 Input type CMOS Output type CMOS Features Balanced outputs, High speed (tpd 10-50ns), Positive input clamp diode Technology family HC Rating Catalog Operating temperature range (°C) -40 to 85
SOIC (DW) 24 159.65 mm² 15.5 x 10.3
  • Wide Operating Voltage Range of 2 V to 6 V
  • High-Current 3-State Outputs Can Drive Up To 15 LSTTL Loads
  • Low Power Consumption, 80-µA Max ICC
  • Typical tpd = 11 ns
  • ±6-mA Output Drive at 5 V
  • Low Input Current of 1 µA Max
  • Independent Registers for A and B Buses
  • Multiplexed Real-Time and Stored Data
  • True Data Paths

  • Wide Operating Voltage Range of 2 V to 6 V
  • High-Current 3-State Outputs Can Drive Up To 15 LSTTL Loads
  • Low Power Consumption, 80-µA Max ICC
  • Typical tpd = 11 ns
  • ±6-mA Output Drive at 5 V
  • Low Input Current of 1 µA Max
  • Independent Registers for A and B Buses
  • Multiplexed Real-Time and Stored Data
  • True Data Paths

The ’HC646 devices consist of bus-transceiver circuits with 3-state outputs, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal 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 ’HC646 devices.

Output-enable (OE)\ 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. DIR determines which bus receives data when OE\ is active (low). In the isolation mode (OE\ high), A data may be stored in one register and/or B data may be stored in the other register.

To ensure the high-impedance state during power up or power down, OE\ should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

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

The ’HC646 devices consist of bus-transceiver circuits with 3-state outputs, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal 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 ’HC646 devices.

Output-enable (OE)\ 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. DIR determines which bus receives data when OE\ is active (low). In the isolation mode (OE\ high), A data may be stored in one register and/or B data may be stored in the other register.

To ensure the high-impedance state during power up or power down, OE\ should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

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

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Technical documentation

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Type Title Date
* Data sheet SN54HC646, SN74HC646 datasheet (Rev. C) 18 Mar 2003
Application note Implications of Slow or Floating CMOS Inputs (Rev. E) 26 Jul 2021
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
User guide Signal Switch Data Book (Rev. A) 14 Nov 2003
Application note TI IBIS File Creation, Validation, and Distribution Processes 29 Aug 2002
Application note CMOS Power Consumption and CPD Calculation (Rev. B) 01 Jun 1997
Application note Designing With Logic (Rev. C) 01 Jun 1997
Application note Input and Output Characteristics of Digital Integrated Circuits 01 Oct 1996
Application note Live Insertion 01 Oct 1996
Application note SN54/74HCT CMOS Logic Family Applications and Restrictions 01 May 1996
Application note Using High Speed CMOS and Advanced CMOS in Systems With Multiple Vcc 01 Apr 1996

Design & development

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Evaluation board

14-24-LOGIC-EVM — Logic product generic evaluation module for 14-pin to 24-pin D, DB, DGV, DW, DYY, NS and PW packages

The 14-24-LOGIC-EVM evaluation module (EVM) is designed to support any logic device that is in a 14-pin to 24-pin D, DW, DB, NS, PW, DYY or DGV package,

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SOIC (DW) 24 View options

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