74574 Octal D-Type Flip-Flop Technical Summary

Overview

The 74574 (also designated as 'LS574) is a high-speed, low-power octal D-type flip-flop integrated circuit featuring edge-triggered operation with buffered common clock (CP) and output enable (OE) control signals. This device is part of the 74LS series of logic ICs and provides eight flip-flops with 3-state outputs in a single package. The flip-flops capture the logic state present at their D inputs upon the low-to-high transition of the clock signal, making it particularly useful for data synchronization and temporary storage applications in digital systems.

Key aspects of the 74574 include its balanced propagation delays, high noise immunity typical of the 74LS family, and the ability to drive low-impedance loads due to its buffered outputs. The output enable control allows the outputs to be placed in a high-impedance state, facilitating bus-oriented applications.

Features

• Octal Edge-Triggered D Flip-Flops: Eight independent D-type flip-flops with 3-state outputs in a single 20-pin package
• Buffered Common Clock: All flip-flops share a common clock input with buffering to ensure clean triggering
• Buffered Output Enable: Common control for placing all outputs in high-impedance state
• Positive Edge Triggering: Data is transferred from D inputs to Q outputs on the low-to-high clock transition
• 3-State Outputs: Bus driver capability with high impedance when output enable is inactive
• Low Power Consumption: Typical power dissipation of 24mW at 5V operation
• High-Speed Operation: Typical propagation delay of 15ns from clock to output
• Wide Operating Voltage: 4.75V to 5.25V supply voltage range
• TTL Compatibility: Fully compatible with TTL input and output levels
• High Noise Immunity: Typical noise margin of 0.4V at VCC = 5V

Applications

The 74574 octal flip-flop finds use in numerous digital system applications including:

• Data Registers: Temporary storage for data in microprocessor systems
• Bus Interface: Buffering and synchronization for data buses
• Pipeline Registers: Intermediate storage in pipelined architectures
• Input/Output Ports: Interface between processors and peripheral devices
• State Machine Implementation: Storage elements in finite state machines
• Data Synchronization: Alignment of asynchronous data to system clock
• Memory Address Latching: Holding address information stable during memory operations
• Parallel-to-Serial Conversion: When used in conjunction with multiplexers

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (VCC): 7V
• Input Voltage (VIN): 7V
• Operating Free Air Temperature Range: 0°C to +70°C
• Storage Temperature Range: -65°C to +150°C

Recommended Operating Conditions

• Supply Voltage (VCC): 4.75V to 5.25V
• High-Level Input Voltage (VIH): 2V min
• Low-Level Input Voltage (VIL): 0.8V max
• Operating Ambient Temperature: 0°C to +70°C

DC Electrical Characteristics (VCC = 5V, TA = 25°C)

• High-Level Output Voltage (VOH): 2.7V min (IOH = -400μA)
• Low-Level Output Voltage (VOL): 0.5V max (IOL = 8mA)
• Input Clamp Voltage (VIK): -1.5V max (II = -18mA)
• High-Level Input Current (IIH): 20μA max (VIN = 2.7V)
• Low-Level Input Current (IIL): -0.4mA max (VIN = 0.4V)
• Short-Circuit Output Current (IOS): -20mA to 100mA
• Supply Current (ICC): 12mA max (all outputs high)

AC Electrical Characteristics

• Propagation Delay (CP to Q): 15ns typical, 25ns max
• Propagation Delay (OE to Q): 15ns typical, 25ns max
• Setup Time (D to CP): 20ns min
• Hold Time (D to CP): 0ns min
• Clock Pulse Width (tW): 10ns min
• Output Enable Time (tPZX): 15ns typical, 25ns max
• Output Disable Time (tPXZ): 15ns typical, 25ns max

Package Information

The 74574 is available in several standard package options:

• 20-pin Plastic Dual In-line Package (PDIP):
  • Package Code: N
  • Body Dimensions: 25.4mm x 6.35mm
  • Lead Pitch: 2.54mm
  • Operating Temperature: 0°C to +70°C
• 20-pin Small Outline Package (SOIC):
  • Package Code: D
  • Body Dimensions: 12.8mm x 7.5mm
  • Lead Pitch: 1.27mm
  • Operating Temperature: 0°C to +70°C
• 20-pin Shrink Small Outline Package (SSOP):
  • Package Code: DB
  • Body Dimensions: 7.2mm x 5.3mm
  • Lead Pitch: 0.65mm
  • Operating Temperature: 0°C to +70°C

Pin Configuration

The 20-pin package follows this pinout arrangement:

• Pin 1: Output Enable (OE) - Active low
• Pin 2: Q0 - Output of flip-flop 0
• Pin 3: D0 - Data input for flip-flop 0
• Pin 4: D1 - Data input for flip-flop 1
• Pin 5: Q1 - Output of flip-flop 1
• Pin 6: Q2 - Output of flip-flop 2
• Pin 7: D2 - Data input for flip-flop 2
• Pin 8: D3 - Data input for flip-flop 3
• Pin 9: Q3 - Output of flip-flop 3
• Pin 10: GND - Ground
• Pin 11: Clock (CP