Octal D-Type Flip-Flop with 3-STATE Outputs# 74F573 Octal Transparent Latch with 3-State Outputs - Technical Documentation
Manufacturer : FAIRCHILD
## 1. Application Scenarios
### Typical Use Cases
The 74F573 is an octal transparent latch specifically designed for temporary data storage and bus-oriented applications. Key use cases include:
Data Buffering and Storage
- Acts as an intermediate storage element between asynchronous and synchronous systems
- Holds data from microprocessors during peripheral device access cycles
- Maintains stable output while input data changes
- Essential in pipeline architectures where data must be held for specific clock cycles
Bus Interface Applications
- Serves as a bidirectional bus driver when used in pairs
- Isolates CPU from bus loading during write operations
- Prevents bus contention in multi-master systems
- Enables time-multiplexed address/data bus systems
I/O Port Expansion
- Extends microcontroller I/O capabilities
- Creates latched output ports in embedded systems
- Interfaces low-power microcontrollers with higher-current peripherals
- Forms the basis for programmable I/O subsystems
### Industry Applications
Computing Systems
- Memory address latching in x86 and other microprocessor systems
- Bus interface units in motherboard designs
- Peripheral controller interfacing (disk controllers, network interfaces)
- Graphics card memory interfacing
Industrial Automation
- PLC input/output modules for signal conditioning
- Motor control interface circuits
- Sensor data acquisition systems
- Process control instrumentation
Communications Equipment
- Data routing in network switches and routers
- Telecom switching matrix control
- Serial-to-parallel conversion systems
- Protocol conversion interfaces
Consumer Electronics
- Display driver circuits in TVs and monitors
- Audio system control interfaces
- Gaming console I/O expansion
- Set-top box control systems
### Practical Advantages and Limitations
Advantages:
- High-Speed Operation : Typical propagation delay of 5.5ns enables operation up to 100MHz
- 3-State Outputs : Allows direct bus connection and bus sharing
- High Drive Capability : 64mA output current drives multiple TTL loads
- Low Power Consumption : 85mA typical ICC reduces system power requirements
- Wide Operating Voltage : 4.5V to 5.5V operation with TTL compatibility
- Latch Enable Control : Transparent latch operation simplifies timing design
Limitations:
- Limited Voltage Range : Restricted to 5V systems without level shifting
- TTL Input Levels : May require interface circuits for CMOS systems
- Power Dissipation : Higher than CMOS equivalents in static conditions
- Output Skew : Up to 2ns output skew may affect high-speed timing margins
- Simultaneous Switching Noise : Can generate ground bounce in multi-output switching
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Timing Violations
- Pitfall : Latch enable (LE) timing violations causing metastability
- Solution : Maintain LE active time > tWL min (10ns) and ensure setup/hold times are met
- Implementation : Use synchronized clock domains and proper timing analysis
Bus Contention
- Pitfall : Multiple 74F573 outputs enabled simultaneously on shared bus
- Solution : Implement strict output enable (OE) control sequencing
- Implementation : Use decoder circuits with guaranteed break-before-make timing
Power Supply Decoupling
- Pitfall : Inadequate decoupling causing signal integrity issues
- Solution : Place 100nF ceramic capacitors within 0.5" of VCC pins
- Implementation : Use multiple capacitor values (100nF, 10μF) for broadband decoupling
Simultaneous Switching Noise
- Pitfall : Ground bounce exceeding 0.8V
