Choose the incorrect statement

Question

Choose the incorrect statement

1. A. SMPS is less sensitive to input voltage variations
2. B. SMPS is smaller as compared to rectifiers
3. C. SMPS has low input ripple (Correct answer)
4. D. SMPS is a source of radio interference

Correct Answer

Option C — SMPS has low input ripple

Detailed Solution & Explanation

The correct answer is SMPS has low input ripple.

Key Points

• The question asks for the incorrect statement. SMPS units have high input ripple, not low, because the switching action draws current in sharp pulses.
• The other three statements are all true of a Switched Mode Power Supply:
  • It is less sensitive to input voltage variations, holding regulation over a wide input range.
  • It is smaller and lighter than a linear supply, since high-frequency switching allows a much smaller transformer.
  • It is a source of radio interference, generating EMI through fast switching transitions.

Additional Information

• SMPS efficiency typically reaches 80-90%, against roughly 40-50% for a linear regulator, because the switching transistor is either fully on or fully off and so dissipates little power.
• The EMI drawback is why SMPS designs require careful filtering and shielding — directly relevant in telecommunication equipment.