Switching Power Supplies MCQs December 23, 2025July 12, 2024 by u930973931_answers 50 min Score: 0 Attempted: 0/50 Subscribe 1. What is the main advantage of a switching power supply compared to a linear power supply? (A) Smaller size (B) Lower cost (C) Higher efficiency (D) Lower electromagnetic interference 2. Which component in a switching power supply is responsible for converting DC voltage to high-frequency AC voltage? (A) Capacitor (B) Diode (C) Transformer (D) Inductor 3. The duty cycle of a switching power supply refers to: (A) The maximum current it can supply (B) The ratio of on-time to total period (C) The frequency of the switching waveform (D) The efficiency of the power conversion 4. Which topology is commonly used in low-power switching power supplies due to its simplicity? (A) Half-bridge (B) Push-pull (C) Forward (D) Flyback 5. The term “ripple voltage” in a switching power supply refers to: (A) The AC component superimposed on the DC output (B) The voltage drop across the diode (C) The voltage loss in the inductor (D) The voltage across the switching transistor 6. Which parameter is crucial for determining the maximum current output of a switching power supply? (A) Input voltage range (B) Power transistor rating (C) Output capacitance (D) Output voltage regulation 7. In a forward converter topology, which component is used to store energy during the switching cycle? (A) Transformer (B) Inductor (C) Capacitor (D) Diode 8. The purpose of the snubber circuit in a switching power supply is to: (A) Filter out high-frequency noise (B) Protect the transformer from overcurrent (C) Increase efficiency (D) Prevent voltage spikes 9. Which type of switching power supply topology typically provides galvanic isolation between input and output? (A) Flyback (B) Boost (C) Buck (D) SEPIC 10. Which control method is commonly used in modern switching power supplies to regulate output voltage? (A) Frequency modulation (FM) (B) Phase-locked loop (PLL) (C) Pulse-width modulation (PWM) (D) Amplitude modulation (AM) 11. The switching frequency of a power supply is primarily determined by: (A) The load current (B) The input voltage (C) The power transistor (D) The controller IC 12. A switching power supply operates in discontinuous conduction mode (DCM) when: (A) The load current is very high (B) The inductor current drops to zero during the switching cycle (C) The output voltage is regulated (D) The switching transistor is turned off 13. Which parameter is NOT typically a disadvantage of switching power supplies? (A) EMI generation (B) Complexity (C) Ripple voltage (D) High cost 14. The main advantage of a flyback converter over a forward converter is: (A) Multiple outputs (B) Lower EMI (C) Simpler design (D) Higher efficiency 15. Which component is essential for energy storage and transfer in a boost converter? (A) Transformer (B) Inductor (C) Capacitor (D) Diode 16. The efficiency of a switching power supply is calculated as: (A) (Output power / Input power) × 100% (B) (Output power + Input power) / Input power (C) (Output power – Input power) / Output power (D) (Input power / Output power) × 100% 17. Which topology is known for its bidirectional capability, making it suitable for applications requiring both step-up and step-down conversions? (A) Flyback (B) SEPIC (C) Push-pull (D) Buck-boost 18. In a half-bridge converter, how many switches are used? (A) One (B) Four (C) Three (D) Two 19. The term “soft start” in switching power supplies refers to: (A) Reducing the switching frequency (B) Gradually ramping up the output voltage (C) Adding a snubber circuit (D) Improving the efficiency at low loads 20. Which type of control loop is used to regulate the output voltage of a switching power supply? (A) Voltage feedback (B) Current feedback (C) Phase-locked loop (D) Frequency modulation 21. The main advantage of a resonant converter compared to traditional switching converters is: (A) Higher efficiency (B) Lower output ripple (C) Smaller size (D) Lower cost 22. Which type of switching power supply is typically used in battery-operated devices to step up or step down the voltage? (A) Buck (B) Flyback (C) Boost (D) Push-pull 23. The primary purpose of the input filter in a switching power supply is to: (A) Prevent output voltage spikes (B) Reduce conducted EMI (C) Improve power factor (D) Stabilize the output voltage 24. Which parameter is critical in determining the maximum output power of a switching power supply? (A) Input voltage range (B) Output voltage regulation (C) Output current rating (D) Switching frequency 25. Which component is used to rectify the AC output of the transformer in a flyback converter? (A) Transformer (B) Capacitor (C) Inductor (D) Diode 26. Which topology allows for seamless transition between step-up and step-down conversions without a change in polarity? (A) Buck-boost (B) Boost (C) Buck (D) Flyback 27. The term “load regulation” in a switching power supply refers to: (A) Adjusting the duty cycle of the switching waveform (B) Minimizing electromagnetic interference (C) Maximizing efficiency at full load (D) The ability to maintain constant output voltage despite changes in load 28. Which parameter indicates the ability of a switching power supply to maintain a constant output voltage with varying input voltage? (A) Line regulation (B) Load regulation (C) Efficiency (D) Ripple voltage 29. A buck-boost converter is capable of: (A) Stepping up voltage only (B) Stepping down voltage only (C) Both stepping up and stepping down voltage (D) Generating multiple output voltages simultaneously 30. Which control method is used in resonant converters to achieve high efficiency? (A) Zero voltage switching (ZVS) (B) Phase control (C) PWM (D) Hysteresis control 31. The term “power factor correction (PFC)” in switching power supplies refers to: (A) Reducing harmonic distortion in the input current (B) Maximizing the power output (C) Improving efficiency at light loads (D) Stabilizing the output voltage 32. Which topology is preferred in applications requiring high power output due to its ability to handle large currents? (A) Full-bridge (B) Boost (C) Buck (D) Flyback 33. Which component in a switching power supply stores energy during the on-time of the switching transistor? (A) Transformer (B) Capacitor (C) Inductor (D) Diode 34. The primary advantage of a phase-shifted full-bridge converter is: (A) Higher efficiency (B) Lower EMI (C) Better thermal management (D) Simpler control circuitry 35. Which type of feedback is essential for stable operation in a switching power supply? (A) Voltage feedback (B) Current feedback (C) Phase feedback (D) Frequency feedback 36. The term “duty cycle” in a switching power supply refers to: (A) The frequency of the switching waveform (B) The ratio of inductance to capacitance (C) The percentage of time the switching transistor is on (D) The efficiency of power conversion 37. Which topology is known for its ability to provide both positive and negative output voltages? (A) Cuk (B) Boost (C) Buck (D) SEPIC 38. Which component is used to store energy in a push-pull converter? (A) Inductor (B) Diode (C) Capacitor (D) Transformer 39. The main advantage of a synchronous rectification in a switching power supply is: (A) Lower cost (B) Higher efficiency (C) Smaller size (D) Improved line regulation 40. Which topology is suitable for applications requiring very high step-down ratios? (A) Buck (B) Boost (C) Forward (D) Flyback 41. In a resonant converter, the resonant frequency is primarily determined by: (A) The load resistance (B) The switching frequency (C) The output voltage (D) The inductance and capacitance values 42. Which type of control method is used in LLC resonant converters? (A) PWM (B) Phase-shift control (C) Hysteresis control (D) Frequency modulation 43. The term “dropout voltage” in a switching regulator refers to: (A) The difference between the input and output voltages (B) The voltage loss across the inductor (C) The ripple voltage at the output (D) The maximum load current 44. Which topology is known for its ability to provide high efficiency at a wide range of input voltages? (A) SEPIC (B) Boost (C) Buck (D) Flyback 45. Which component is used to clamp voltage spikes in a switching power supply? (A) MOV (Metal Oxide Varistor) (B) Varistor (C) Zener diode (D) Schottky diode 46. The term “steady-state error” in a switching power supply refers to: (A) The initial voltage overshoot upon power-on (B) The maximum load current the supply can handle (C) The time required for the output voltage to stabilize (D) The difference between actual and desired output voltage after reaching equilibrium 47. Which parameter is most affected by the operating temperature of a switching power supply? (A) Ripple voltage (B) Efficiency (C) Load regulation (D) Line regulation 48. The term “dropout regulator” typically refers to: (A) A switching regulator (B) A linear regulator (C) A resonant converter (D) A buck-boost converter 49. Which topology is commonly used in applications where the input voltage can be higher or lower than the desired output voltage? (A) SEPIC (B) Buck (C) Boost (D) Flyback 50. The term “dead time” in a switching power supply refers to: (A) The time taken for the output voltage to stabilize (B) The interval between two consecutive switching cycles (C) The time period during which the transistor is off (D) The delay in the control loop response