74544 Octal Transceiver Technical Summary

Overview

The 74544 (also designated as 'F544) is an octal transceiver designed for bidirectional data flow with temporary storage capability. It incorporates two sets of D-type latches, allowing data to be stored in either direction. The device features independent control for input and output operations through separate Latch Enable (LE) and Output Enable (OE) inputs for each register. This makes the 74544 highly versatile for applications requiring bidirectional data transfer with intermediate storage.

The transceiver is designed with robust output drive capabilities, with the A outputs capable of sinking 24 mA (20 mA for military versions) and the B outputs rated for 64 mA (48 mA for military versions). This makes it suitable for driving heavier loads compared to standard logic devices.

Features

• 8-bit octal transceiver with bidirectional data flow
• Back-to-back registers for temporary data storage
• Independent controls for data flow in each direction:
  • Separate Latch Enable (LE) inputs
  • Separate Output Enable (OE) inputs
• High current output capability:
  • A outputs sink 24 mA (20 mA for military versions)
  • B outputs sink 64 mA (48 mA for military versions)
• Available in multiple package options including PDIP, SOIC, and ceramic packages
• Military grade versions available with environmental and burn-in processing
• TRI-STATE® outputs for bus-oriented applications

Applications

The 74544 octal transceiver is designed for use in a variety of digital systems requiring bidirectional data transfer with storage capability. Typical applications include:

• Bus interface circuits in microprocessor systems
• Data buffering and temporary storage in communication systems
• Input/Output port expansion
• Memory bank switching
• Data routing in digital signal processing systems
• Military and aerospace electronics (using military-grade versions)
• Industrial control systems requiring robust data transfer

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (Vcc): 7V
• Input Voltage: 7V
• Operating Free Air Temperature Range:
  • Commercial: 0°C to +70°C
  • Military: -55°C to +125°C
• Storage Temperature Range: -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (Vcc): 4.5V to 5.5V
• High-Level Input Voltage: 2.0V min
• Low-Level Input Voltage: 0.8V max
• Output Current:
  • A Outputs: -24 mA max (commercial), -20 mA max (military)
  • B Outputs: -64 mA max (commercial), -48 mA max (military)

Switching Characteristics (Typical at Vcc = 5V, TA = 25°C)

• Propagation Delay (A to B or B to A): 8 ns max
• Output Enable Time: 10 ns max
• Output Disable Time: 12 ns max
• Latch Setup Time: 5 ns min
• Latch Hold Time: 0 ns min

Package Information

The 74544 is available in multiple package options to suit different application requirements:

Commercial Packages

• 74F544SPC N24C: 24-Lead (0.300" Wide) Molded Dual-In-Line (PDIP)
• 74F544SC (Note 1): 24-Lead (0.300" Wide) Molded Small Outline, JEDEC (SOIC)
• 74F544MSA (Note 1): 24-Lead Molded Shrink Small Outline, EIAJ, Type II

Note 1: Devices also available in 13" reel. Use suffix SCX and MSAX.

Military Packages

• 54F544DM (Note 2): 24-Lead Ceramic Dual-In-Line
• 54F544SDM (Note 2): 24-Lead (0.300" Wide) Ceramic Dual-In-Line
• 54F544FM (Note 2): 24-Lead Cerpack
• 54F544LM (Note 2): 24-Lead Ceramic Leadless Chip Carrier, Type C

Note 2: Military grade device with environmental and burn-in processing. Use suffix DMQB, FMQB and LMQB.

Package Dimensions

Detailed mechanical drawings are available in the manufacturer's datasheet, including:

• PDIP package: 0.300" wide body, 0.100" lead spacing
• SOIC package: 0.295" body width, 0.050" lead spacing
• Ceramic packages: Various dimensions depending on specific package type

Logic Symbols and Pin Configuration

The device follows standard IEEE/IEC logic symbols for transceivers. The pin configuration is consistent across package types with the following general arrangement:

• Pins 1-8, 11-18: Data I/O (A and B buses)
• Pin 19: Output Enable for B-to-A direction (OEB)
• Pin 20: Latch Enable for B-to-A direction (LEB)
• Pin 21: Latch Enable for A-to-B direction (LEA)
• Pin 22: Output Enable for A-to-B direction (OEA)
• Pin 23: Ground (GND)
• Pin 24: Power Supply (Vcc)

Additional Information

TRI-STATE® is a registered trademark of National Semiconductor Corporation. The device is designed for reliable operation in industrial environments and meets relevant quality standards for both commercial and military applications.

For complete technical details, including detailed timing diagrams, truth tables, and application notes, refer to the manufacturer's datasheet. The device is suitable for new designs as well as replacement in existing systems requiring octal bidirectional transceivers with storage capability.