TTL 7400 NAND gate output when HIGH: What is the proper name for the output current capability in the HIGH state for a single 7400 output pin?

Introduction / Context:
Logic datasheets specify separate output-current capabilities for LOW and HIGH states. Correct terminology matters when reading and applying VOH/VOL and fan-out specifications for TTL and CMOS outputs.

Given Data / Assumptions:

• Device: 7400-series TTL NAND gate.
• State of interest: output logic HIGH.
• Industry-standard notation: IOH for HIGH-state output current, IOL for LOW-state output current.

Concept / Approach:
When a TTL output is HIGH, any external load connected to the pin draws current from the output to ground; the gate is “sourcing” current. The maximum guaranteed current in that state is specified as IOH (often a small magnitude compared with IOL). Conversely, in the LOW state the output “sinks” current, specified as IOL.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets list IOH and IOL separately (e.g., IOH ≈ -0.4 mA, IOL ≈ 16 mA for LS-TTL), confirming the naming convention and asymmetry.

Why Other Options Are Wrong:

• “Sink current” applies to the LOW state.
• “source current” alone is descriptive but omits the standard symbol; “IOH” alone omits the verbal description. The most complete, unambiguous phrasing is “source current or IOH.”

Common Pitfalls:
Confusing sourcing with sinking directions; misreading the sign convention for IOH (often negative to indicate current leaving the device).

Final Answer:
source current or IOH.