Defining fan-out In digital logic specifications, fan-out is usually specified in terms of which quantity?

Introduction / Context:Fan-out indicates how many inputs a single logic output can reliably drive without violating voltage thresholds. It guides safe interconnections and prevents excessive loading.

Given Data / Assumptions:

• Family-dependent input currents and thresholds.
• Fan-out abstracted as the number of “equivalent inputs” (unit loads).

Concept / Approach:Manufacturers define one “unit load” as the input current that corresponds to a standard input of the same logic family. Fan-out equals the ratio of the driver’s guaranteed source/sink capability to one unit load, producing an integer count of inputs that can be driven.

Step-by-Step Solution:Determine family input currents (e.g., TTL high/low input currents).Compute how many such inputs the driver can supply while meeting VOH/VOL specs.Express the result as a count of unit loads, which is the standard fan-out rating.

Verification / Alternative check:Datasheets list fan-out as a number (e.g., “10 LS-TTL loads”), translating electrical limits into an easy design rule.

Why Other Options Are Wrong:Voltage/current/wattage are underlying parameters, but the published fan-out is not directly stated as a voltage, current, or power value—it is a count of unit loads.

Common Pitfalls:Driving mixed-family inputs without recalculating equivalent unit loads; CMOS inputs draw far less current, so the practical fan-out may be much higher.

Final Answer:unit loads