Switch Mode Power Supply (SMPS) Question & Answers June 17, 2023 By Wat Electrical This article lists 75 Switch Mode Power Supply (SMPS) MCQs for engineering students. All the Switch Mode Power Supply (SMPS) Questions & Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of Switch Mode Power Supply (SMPS). A Switch Mode Power Supply (SMPS) is a type of power supply that uses switching devices, such as transistors or MOSFETs, to convert electrical energy efficiently from one voltage level to another. It is commonly used in electronic devices to provide a stable and regulated DC (direct current) output voltage. The main advantage of SMPS over linear power supplies is their higher efficiency. Unlike linear power supplies, which dissipate excess energy as heat, SMPS devices regulate the output voltage by rapidly switching the input voltage on and off. This switching operation allows the SMPS to operate at higher frequencies and achieve higher efficiency levels. The filtered DC voltage is fed into a switching circuit, which includes a power switch (such as a transistor or MOSFET) that rapidly turns on and off. The switching action controls the flow of energy from the input to the output. Switch mode power supplies are widely used in various applications, including computers, telecommunications equipment, consumer electronics, industrial equipment, and more. They offer advantages such as compact size, high efficiency, and the ability to operate over a wide range of input voltages. 1). Which component is primarily responsible for converting the input voltage in a switch mode power supply? Transformer Capacitor Inductor Diode Hint Read more about Inductors 2). Which of the following is an advantage of switch mode power supplies compared to linear power supplies? Higher efficiency Simpler design Lower cost Smaller size Hint 3). Which switching device is commonly used in SMPS for high-frequency operation? Bipolar Junction Transistor Metal-Oxide-Semiconductor Field-Effect Transistor Insulated Gate Bipolar Transistor Thyristor Hint Read more about Metal-Oxide-Semiconductor Field-Effect Transistor 4). Which feedback mechanism is typically used in SMPS to regulate the output voltage? Voltage feedback Current feedback Phase-locked loop (PLL) Frequency modulation Hint Read more about SMPS 5). What is the purpose of a snubber circuit in an SMPS? To regulate the output voltage To filter out high-frequency noise To provide isolation between input and output To suppress voltage spikes and ringing Hint 6). Which component in an SMPS is responsible for rectifying the high-frequency AC voltage? Diode Capacitor Transformer Inductor Hint 7). Which type of SMPS topology provides isolation between the input and output circuits? Buck converter Boost converter Flyback converter Forward converter Hint 8). Which SMPS topology is suitable for stepping up the input voltage? Buck converter Boost converter Flyback converter Forward converter Hint 9). Which SMPS topology is commonly used for voltage step-down applications? Buck converter Boost converter Flyback converter Forward converter Hint 10). Which SMPS topology provides bidirectional power flow? Buck-boost converter Push-pull converter Half-bridge converter Full-bridge converter Hint 11). Which SMPS topology is commonly used in high-power applications? Buck converter Boost converter Flyback converter Full-bridge converter Hint 12). Which SMPS topology is suitable for high-frequency operation? Buck converter Boost converter Flyback converter Resonant converter Hint 13). Which SMPS topology is commonly used for power factor correction (PFC)? Buck converter Boost converter Flyback converter Cuk converter Hint 14). Which SMPS topology provides multiple isolated outputs? Forward converter Half-bridge converter Full-bridge converter Multi-output converter Hint 15). Which type of SMPS provides high efficiency by varying the duty cycle of a high-frequency square wave? Buck converter Boost converter Flyback converter Cuk converter Hint 16). Which SMPS type is suitable for stepping down a higher voltage to a lower voltage? Buck converter Boost converter Flyback converter Forward converter Hint 17). Which SMPS type is suitable for stepping up a lower voltage to a higher voltage? Buck converter Boost converter Flyback converter Forward converter Hint 18). Which SMPS type provides isolation between the input and output? Buck converter Boost converter Flyback converter Forward converter Hint 19). Which SMPS type is commonly used in laptop chargers and mobile phone chargers? Buck converter Boost converter Flyback converter Forward converter Hint 20). Which SMPS type operates at a constant frequency and requires a low-voltage input? Buck converter Boost converter Flyback converter Forward converter Hint 21). Which SMPS type is suitable for applications requiring multiple output voltages? Buck converter Boost converter Flyback converter Multiple-output converter Hint 22). Which SMPS type requires two switches and a center-tapped transformer? Buck converter Boost converter Flyback converter Push-pull converter Hint Read more about Center-Tapped Transformer 23). Which SMPS type is commonly used in automotive applications? Buck converter Boost converter Flyback converter SEPIC converter Hint 24). Which SMPS type provides a regulated output voltage even with variations in the input voltage? Non-isolated converter Isolated converter Resonant converter Non-resonant converter Hint 25). Which component is commonly used to store energy in an SMPS? Capacitor Transformer Diode Resistor Hint Read more about Capacitor Switch Mode Power Supply (SMPS) MCQ for Quiz 26). Which of the following is a disadvantage of switch-mode power supplies? Electromagnetic interference (EMI) Limited output power Short operational lifespan Large size Hint 27). Which of the following is an advantage of SMPS over linear power supplies? Higher output voltage accuracy Lower efficiency Limited input voltage range Lower cost Hint 28). Which switching topology is commonly used in low-power SMPS? Flyback Forward Push-pull Half-bridge Hint 29). Which of the following is a disadvantage of SMPS regarding output voltage noise? Low ripple voltage High voltage stability High output voltage noise Low voltage regulation Hint 30). Which component in an SMPS provides electrical isolation between the input and output? Inductor Capacitor Transformer Diode Hint 31). Which of the following is an advantage of SMPS in terms of size and weight? Larger size Heavier weight Compact size Lightweight Hint 32). Which switching topology is commonly used in high-power SMPS, such as computer power supplies? Flyback Forward Push-pull Half-bridge Hint 33). Which component is responsible for converting AC voltage to DC voltage in an SMPS? Transformer Rectifier Transistor Capacitor Hint 34). What is the typical switching frequency of an SMPS? 50 Hz 60 Hz 100 kHz 1 MHz Hint 35). Which of the following is an advantage of a flyback converter? High voltage output Low voltage output Multiple outputs High efficiency Hint 36). The duty cycle of a PWM signal in an SMPS determines ________________? Output voltage Output current Switching frequency Power transfer efficiency Hint 37). Which component is used to control the duty cycle in an SMPS? Diode Capacitor Transistor Resistor Hint 38). What is the purpose of the feedback loop in an SMPS? Control the input voltage Control the output voltage Provide short-circuit protection Protect against overcurrent Hint 39). Which component is used to isolate the input and output in an SMPS? Diode Capacitor Transformer Resistor Hint 40). Which type of control is commonly used in current-mode SMPS? Voltage mode Current mode Pulse skipping mode Hysteresis mode Hint 41). What is the main function of a switching transistor in an SMPS? To regulate the output voltage To provide isolation between input and output To switch the power supply between on and off states To rectify the AC input voltage Hint 42). Which of the following is commonly used as a control element in SMPS? Voltage regulator Zener diode Microcontroller Thermistor Hint 43). Which type of feedback control is commonly used in SMPS? Voltage feedback Current feedback Phase feedback Frequency feedback Hint 44). Which component is used to regulate the output voltage in an SMPS? Resistor Capacitor Zener diode Voltage reference Hint 45). What is the typical switching frequency range of an SMPS? 1 Hz – 10 Hz 10 Hz – 100 Hz 100 Hz – 1 kHz 1 kHz – 1 MHz Hint 46). Which component is commonly used to rectify the output voltage in an SMPS? Zener diode Capacitor Schottky diode Inductor Hint 47). A switch mode power supply is not providing any output voltage. What could be the possible cause of the problem? Faulty transformer Shorted rectifier diodes Blown fuse Overloaded output Hint 48). An SMPS is producing excessive ripple voltage at the output. Which component is most likely causing this issue? Capacitor Transformer Diode Inductor Hint 49). The output voltage of an SMPS drops significantly when a load is connected. What could be the possible reason? Overheating of the MOSFET Shorted output diode Insufficient feedback compensation Faulty optocoupler Hint 50). An SMPS fails to start up when the power switch is turned on. What could be the likely cause of this problem? Faulty optocoupler Shorted output capacitor Defective startup resistor Overloaded output Hint Switch Mode Power Supply (SMPS) MCQ for Exams 51). An SMPS shuts down immediately after turning on. What is the probable cause? Overheating of the transformer Shorted output diode Overload condition Faulty feedback loop Hint 52). What is the duty cycle of a switch mode power supply? The time duration for which the switch is on The ratio of the on-time to the total switching period The frequency of the switching waveform The difference between the input and output voltage Hint 53). Which equation represents the average output voltage of a boost converter? V_out = V_in / (1 - D) V_out = V_in / D V_out = V_in × (1 - D) V_out = V_in × D Hint 54). What is the formula for calculating the peak inductor current in a buck converter? I_L = (V_in - V_out) / L I_L = (V_out - V_in) / L I_L = V_out × L I_L = V_in × L Hint 55). Which equation represents the switching frequency of a flyback converter? f_s = 1 / (R × C) f_s = 1 / (2 × π × √(L × C)) f_s = V_in × D Hint 56). What is the formula for calculating the output power of an SMPS? P_out = V_out × I_out P_out = V_out × I_out P_out = V_in × I_in P_out = V_out × I_in Hint 57). Which equation represents the average output voltage of a boost converter? Vout = Vin × D/(1 - D) Vout = Vin × (1 - D)/D Vout = Vin × (1 + D)/(1 - D) Vout = Vin × D/(1 + D) Hint 58). Which formula is used to calculate the duty cycle of a buck converter? D = Ton/(Ton + Toff) D = Toff/(Ton + Toff) D = Ton/Toff D = Toff/Ton Hint 59). What is the formula to determine the output current of an SMPS? Iout = Vin × Vout Iout = Vin/Vout Iout = Pout/Vout Iout = Vout/Pout Hint 60). Which equation represents the efficiency of an SMPS? Efficiency = Pout/Pin Efficiency = Pin/Pout Efficiency = Vout/Vin Efficiency = Vin/Vout Hint 61). What is the formula to calculate the ripple voltage in a buck-boost converter? Vripple = (L × ΔI)/Vin Vripple = (L × ΔI)/Vout Vripple = (Vin × ΔI)/L Vripple = (Vout × ΔI)/L Hint 62). What is the typical operating frequency range of a switch mode power supply (SMPS)? 50 Hz – 60 Hz 50 Hz – 60 Hz 1 MHz – 10 MHz 10 MHz – 100 MHz Hint 63). Why are higher frequencies preferred in SMPS designs? To reduce electromagnetic interference (EMI) To increase efficiency To minimize voltage ripple All of the above Hint 64). What happens to the size of transformers used in SMPS as the operating frequency increases? Size increases Size decreases Size remains the same Size is not affected Hint 65). What is the primary advantage of operating an SMPS at higher frequencies? Higher efficiency Smaller size Reduced EMI Faster response time Hint 66). Which parameter defines the maximum frequency at which an SMPS can operate? Duty cycle Ripple voltage Switching speed Switching frequency limit Hint 67). What is the term used to describe the ratio of on-time to off-time for the switching transistor in an SMPS? Duty cycle Pulse width Switching time Frequency modulation Hint 68). How does increasing the operating frequency of an SMPS affect its efficiency? Efficiency increases Efficiency decreases Efficiency remains the same Efficiency is not affected Hint 69). What is the typical range of duty cycle for an SMPS? 0% - 25% 25% - 50% 50% - 75% 75% - 100% Hint 70). What is the typical input voltage range of a universal input SMPS? 5V – 12V 90V – 264V 220V – 240V 500V – 1000V Hint 71). Which of the following is a common switching frequency used in SMPS? 1 Hz 60 Hz 100 kHz 1 MHz Hint 72). What is the typical input voltage range of a universal SMPS? 110-120V 220-240V 100-240V 12-24V Hint 73). Which of the following is a common output voltage range for an SMPS used in computer power supplies? 3-5V 12-24V 48-72V 110-120V Hint 74). What is the typical frequency range of an SMPS? 50-60 Hz 400-500 Hz 1-10 kHz 100-500 kHz Hint 75). Which of the following SMPS types is suitable for applications requiring galvanic isolation? Flyback SMPS Buck-boost SMPS Forward SMPS Half-bridge SMPS Hint Time's up
