8-Bit Serial-In/Parallel-Out Shift Register# CD74ACT164M Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The CD74ACT164M serves as an 8-bit serial-in/parallel-out shift register with asynchronous reset functionality. Common implementations include:
Data Serialization Systems
- Converts serial data streams to parallel outputs in communication interfaces
- Enables efficient data transfer in microcontroller-based systems with limited I/O pins
- Typical data rates: up to 100 MHz in ACT logic family applications
Display Driver Circuits
- Drives LED arrays and seven-segment displays in multiplexed configurations
- Enables scanning display systems with reduced wiring complexity
- Supports cascading for larger display matrices (16, 24, or 32-bit displays)
Digital Signal Processing
- Implements simple delay lines and digital filters
- Forms basic building blocks for more complex digital signal processing chains
- Used in timing recovery circuits and synchronization systems
### Industry Applications
Industrial Automation
- PLC input/output expansion modules
- Sensor data acquisition systems
- Motor control interface circuits
- *Advantage*: High noise immunity (400 mV typical) suitable for industrial environments
- *Limitation*: Requires proper decoupling in electrically noisy settings
Consumer Electronics
- Remote control signal processing
- Keyboard scanning matrices
- Audio equipment display drivers
- *Advantage*: Low power consumption (4 μA typical ICC) for battery-operated devices
- *Limitation*: Limited drive capability for high-current loads
Automotive Systems
- Instrument cluster displays
- Body control module interfaces
- Lighting control systems
- *Advantage*: Wide operating temperature range (-55°C to +125°C)
- *Limitation*: Requires additional protection circuits for automotive transients
### Practical Advantages and Limitations
Advantages
- High-Speed Operation : 4.5 ns typical propagation delay at 5V
- CMOS Technology : Low static power consumption
- Wide Voltage Range : 2V to 6V operating supply voltage
- Robust Inputs : Standard CMOS input structure with high impedance
- Cascadable Design : Multiple devices can be connected for expanded functionality
Limitations
- Limited Output Current : 24 mA maximum output current per pin
- Simultaneous Switching Noise : Requires careful PCB layout when multiple outputs switch simultaneously
- Power Sequencing : CMOS inputs require proper power-up sequencing to prevent latch-up
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Uncontrolled Power-Up States
- *Problem*: Outputs may enter undefined states during power-up
- *Solution*: Implement proper reset circuitry using the MR (Master Reset) pin
- *Implementation*: Connect MR to VCC through RC circuit (10 kΩ resistor, 100 nF capacitor)
Simultaneous Switching Noise
- *Problem*: Multiple outputs switching simultaneously cause ground bounce
- *Solution*: Use multiple decoupling capacitors distributed around the device
- *Implementation*: Place 100 nF ceramic capacitor within 10 mm of VCC pin, plus bulk 10 μF capacitor
Signal Integrity Issues
- *Problem*: Long trace lengths cause signal degradation at high frequencies
- *Solution*: Implement proper termination and controlled impedance routing
- *Implementation*: Series termination resistors (22-33Ω) for clock and data lines
### Compatibility Issues
Mixed Logic Level Systems
- TTL Compatibility : ACT family provides TTL-compatible inputs while maintaining CMOS output levels
- 3.3V Systems : Can interface directly with 3.3V logic when operated at 3.3V VCC
- Level Translation : For mixed-voltage systems, ensure proper level shifting for control signals
Timing Constraints
- Setup/Hold Times : 3 ns setup time,
