In a TTL device operating at 5.0 volts, what range is identified as valid logic high input?

In TTL (Transistor-Transistor Logic) devices operating at 5.0 volts, the valid logic high input range is specifically defined between 2.0 volts and 5.5 volts. This means that any voltage within this range is considered a high logic level, capable of being accurately interpreted as a logical '1' by the TTL device.

The lower end of this range, 2.0 volts, is important because it establishes the threshold above which the device reliably recognizes a high input. Voltages below this threshold may not be interpreted as high, leading to potential signal errors. The upper limit, 5.5 volts, accommodates slight variations in power supply voltage and ensures the input remains within the device's specifications for safe operation.

This range is vital for understanding how TTL logic circuits interpret signals. When designing or troubleshooting circuits, applying signals within this range ensures reliable operation and prevents misinterpretation of the logic states.

In contrast, the other options do not reflect the valid voltage range for a logic high in TTL logic. A range including values below 2.0 volts, or incorrectly exceeding the 5.5 volts limit, would either yield unreliable inputs or exceed the device's functional limits.