74F579PC

Overview

The onsemi 74F579PC is an 8-bit bidirectional binary counter featuring multiplexed 3-STATE I/O ports for bus-oriented applications. It supports parallel loading and carry lookahead for cascading. The device operates within a supply voltage range of +4.5V to +5.5V and functions at temperatures from 0°C to +70°C. Key electrical parameters include a typical count frequency of 100 MHz, maximum clock frequency of 80 MHz, and propagation delays ranging from 3.0 ns to 13.5 ns depending on the signal path. Supply current typically ranges from 70 mA to 120 mA.

Feature Summary

• Multiplexed 3-STATE I/O ports enable shared bus connections.
• Built-in carry lookahead capability facilitates easy cascading.
• Fully synchronous operation with rising edge clock initiation.

Applications

• Bus-oriented data storage systems
• Cascaded counting circuits
• Programmable counters

Procurement Notes

Verify component authenticity through official manufacturer channels or authorized distributors. Confirm package type matches the N20A designation for 20-Lead Plastic Dual-In-Line Package. Review datasheet specifications for absolute maximum ratings to ensure operational safety. Check for RoHS compliance documentation if required by project standards.

Selection Notes

Select this component for designs requiring high-speed bidirectional counting with integrated bus interface capabilities. Ensure power supply stability within the 4.5V to 5.5V range to maintain specified timing characteristics. Consider thermal management due to typical supply currents exceeding 70 mA. Verify that the 3-STATE output impedance meets system bus requirements.

Part Context

This part belongs to the 74F logic family, known for high-speed performance in standard TTL-compatible applications. The 74F579 specifically addresses needs for complex counting operations with flexible input/output configurations. It serves as a specialized solution for digital systems requiring precise synchronization and direction control.

Replacement Considerations

Direct substitutes may include other 8-bit bidirectional counters with 3-STATE outputs from compatible logic families. Verify pin compatibility and electrical characteristics before substitution. Consult manufacturer cross-reference guides for equivalent parts with similar functionality and package dimensions.

FAQ

What controls the counting direction?

The U/D (Up/Down) input determines the counting direction. A HIGH level enables up-counting, while a LOW level enables down-counting.

How is parallel data loaded?

Parallel data is loaded when both PE (Parallel Enable) and CS (Chip Select) inputs are LOW, triggered by the rising edge of the clock pulse.

What is the function of the TC output?

The TC (Terminal Count) output indicates when the counter reaches its terminal value. It goes LOW when the count limit is reached, useful for cascading multiple counters.