74F779SC

Overview

The onsemi 74F779SC is an 8-bit bidirectional binary counter featuring multiplexed 3-STATE I/O ports, designed for bus-oriented applications. It operates within a supply voltage range of +4.5V to +5.5V and supports a maximum clock frequency of 100 MHz at +25°C. The device utilizes two mode pins (S0, S1) to control synchronous functions including hold, count up, count down, and parallel load, all triggered by the rising edge of the clock. It includes built-in carry lookahead for cascading and is housed in a 16-Lead Small Outline Integrated Circuit (SOIC) package.

Feature Summary

• Multiplexed 3-STATE I/O ports enable efficient bus-oriented data handling.
• Built-in lookahead carry capability facilitates easy cascading of multiple units.
• Fully synchronous operation with control functions managed via two mode pins.

Applications

• Bus-oriented digital systems requiring bidirectional counting
• Cascaded counter configurations utilizing carry lookahead
• Synchronous logic circuits operating at high clock frequencies

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm RoHS compliance status as indicated in official documentation. Check for obsolescence notices, as this part may be discontinued. Ensure the specific SOIC package variant matches design requirements. Review datasheet specifications for absolute maximum ratings to prevent operational damage.

Selection Notes

Select this component for designs requiring an 8-bit synchronous counter with tri-state outputs. Verify that the 100 MHz typical count frequency meets system timing constraints. Ensure the 16-SOIC package fits the PCB layout. Confirm power supply stability within the 4.5V to 5.5V range. Consider the 80 mA typical supply current for thermal management planning.

Part Context

This device belongs to the 74F series of high-speed logic integrated circuits. It serves as a specialized counter IC within the broader family of standard logic components. The 74F779 specifically addresses applications needing bidirectional counting with bus interface capabilities, distinguishing it from standard unidirectional counters.

Replacement Considerations

Check for equivalent parts from other manufacturers offering similar 8-bit bidirectional counter functionality with 3-STATE outputs. Verify pin compatibility and electrical characteristics such as supply voltage and propagation delay. Ensure the replacement supports the required 100 MHz operating frequency and carries the same 16-SOIC package.

FAQ

How are the count direction and load functions controlled?

All control functions, including hold, count up, count down, and synchronous load, are managed by two mode pins labeled S0 and S1.

What triggers state changes in the counter?

All state changes are initiated by the rising edge of the clock signal applied to the CP input.

Does the device support cascading?

Yes, the device features built-in carry lookahead capability to facilitate easy cascading with other counters.