Multiplexer Enable — Global Control Function On a multiplexer (MUX) chip, what is the function of the enable (EN) input with respect to the device outputs?

Introduction / Context:
Most multiplexers include an enable input that globally turns the device’s data path on or off. This allows hierarchical selection, bus sharing, and power savings. When disabled, the MUX typically forces a defined output state or high-impedance (depending on the family), regardless of select inputs.

Given Data / Assumptions:

• Device: generic MUX with select lines and an enable pin.
• Enable polarity can be active-HIGH or active-LOW, but the functional role is the same.
• When disabled, internal selection logic is effectively gated off.

Concept / Approach:
The enable input acts as a global gate. With EN asserted, the MUX responds to select lines and routes the chosen input to the output. With EN deasserted, the output is disabled or forced to a fixed state, independent of the select code.

Step-by-Step Solution:
Identify EN's role: global permission for data selection.EN asserted → output follows selected input.EN deasserted → output disabled or forced, selection ignored.Therefore, EN activates the entire MUX for normal operation.

Verification / Alternative check:
Datasheets (e.g., 74HC157/158, 74HC151) show enable pins that disable outputs or tri-state them when inactive.

Why Other Options Are Wrong:

• to apply Vcc / connect ground: Power and ground are separate pins, not functions of EN.
• to activate one half of the chip: Some dual MUX packages have separate enables per section, but the generic single MUX chip uses EN for the whole device.

Common Pitfalls:
Assuming EN is optional; if left floating, it may disable the device unintentionally. Always drive EN to a defined logic level.

Final Answer:
to activate (enable) the entire MUX so that selection and data routing occur