Power-up reset generation in digital design: A simple series R–C network can be used to generate an automatic power-up reset pulse that initializes digital logic when supply voltage rises. Evaluate this statement for typical TTL/CMOS systems.

Introduction / Context:
At power-on, digital systems must come up in a known state. A common, low-cost approach is to derive a brief reset pulse from the power ramp using a resistor–capacitor (R–C) network and a buffer or Schmitt trigger. This question checks practical understanding of power-up reset techniques.

Given Data / Assumptions:

• Supply voltage rises from 0 V to its nominal value.
• An R–C network is connected so that the capacitor initially holds a logic level that asserts reset.
• As the capacitor charges through the resistor, the reset signal de-asserts after a delay.
• Downstream logic accepts an asynchronous reset pulse of sufficient width and level.

Concept / Approach:
An R–C differentiates the supply ramp to create a time-limited signal. With proper polarity and thresholding (often via a Schmitt trigger input), the node asserts reset during the early portion of the ramp and then releases reset as the capacitor charges, ensuring a defined initialization interval. The reset width τ is roughly R*C (subject to logic thresholds and VCC ramp rate).

Step-by-Step Solution:
Choose R and C so that τ = R*C comfortably exceeds the minimum reset time of the logic.Connect so that at power-up the capacitor voltage starts near 0 V, producing an active reset.As VCC rises and the capacitor charges, the node crosses the release threshold, de-asserting reset.Optionally pass through a Schmitt trigger for clean edges and immunity to slow ramps.

Verification / Alternative check:
Many microcontroller reference designs show R–C reset or recommend supervisor ICs that formalize this behavior with precise thresholds and timing.

Why Other Options Are Wrong:
“Incorrect” ignores long-standing practice. The AC-only and 15 V restrictions are irrelevant; R–C resets are common at 3.3 V or 5 V with proper component values.

Common Pitfalls:
Using slow ramps without hysteresis; choosing τ too short; failing to ensure reset meets minimum pulse width across temperature and tolerance.

Final Answer:
Correct