74ACT843SC

Latches Overview

The onsemi 74ACT843SC is a 9-bit transparent latch featuring TTL-compatible inputs and 3-STATE outputs. It operates within a supply voltage range of 4.5V to 5.5V and supports an operating temperature range from -40°C to +85°C. The device utilizes a 24-Lead Small Outline Integrated Circuit (SOIC) package, designated as M24B. Key electrical characteristics include a maximum propagation delay of 10.0 ns at 5.0V with 50 pF load, ensuring high-speed data handling. Quiescent supply current is limited to 80.0 µA, while output drive capability reaches ±24 mA.

Latches Feature Summary

• Provides nine D-type latches for buffering existing logic and expanding address/data path width.
• Features asynchronous operation where outputs follow data transitions when Latch Enable is HIGH.
• Includes dedicated Clear and Preset pins optimized for parity bus interfacing in high-performance systems.

Latches Applications

• Parity bus interfacing
• High-performance system data buffering
• Address/data path expansion

Latches Procurement Notes

Verify the specific ordering suffix against the manufacturer's documentation to confirm packaging type. The standard SC designation indicates SOIC packaging, while appending 'X' denotes Tape and Reel availability. Confirm RoHS compliance status through official material composition documents prior to integration into final assemblies.

Latches Selection Notes

Select this component when designing circuits requiring wide data path buffering with transparent latch functionality. Ensure the design accommodates the specified 4.5V to 5.5V supply voltage range. Verify that the 24-pin SOIC footprint aligns with the PCB layout constraints and thermal requirements for the target operating environment.

Latches Part Context

This component belongs to the ACT logic family, characterized by CMOS technology compatible with TTL input levels. It serves as a bus interface latch designed to replace multiple discrete packages, simplifying board layouts for wider data buses. The device integrates control signals for precise data latching and tri-state bus management.

Latches Replacement Considerations

Check for equivalent 9-bit transparent latches from other manufacturers offering identical pinouts and electrical specifications. Verify compatibility with existing system timing constraints and voltage levels before substitution.

Latches FAQ

How does the Latch Enable pin affect data transparency?

When the Latch Enable (LE) pin is HIGH, the flip-flops appear transparent, allowing the output transition to follow the data input transition immediately.

What is the function of the Output Enable pin?

Data appears on the bus when the Output Enable (OE) pin is LOW. When OE is HIGH, the bus output enters a high impedance state.

Which control signal takes precedence between Clear and Preset?

The Preset signal overrides the Clear signal. If PRE is LOW, the outputs go HIGH (assuming OE is LOW), regardless of the Clear pin state.