Switch Mode Power Supply (SMPS) Question & AnswersJune 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 None HintRead more about Inductors2). 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 None Hint3). 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 None HintRead 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 None HintRead 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 None Hint6). Which component in an SMPS is responsible for rectifying the high-frequency AC voltage? Diode Capacitor Transformer Inductor None Hint7). Which type of SMPS topology provides isolation between the input and output circuits? Buck converter Boost converter Flyback converter Forward converter None Hint8). Which SMPS topology is suitable for stepping up the input voltage? Buck converter Boost converter Flyback converter Forward converter None Hint9). Which SMPS topology is commonly used for voltage step-down applications? Buck converter Boost converter Flyback converter Forward converter None Hint10). Which SMPS topology provides bidirectional power flow? Buck-boost converter Push-pull converter Half-bridge converter Full-bridge converter None Hint11). Which SMPS topology is commonly used in high-power applications? Buck converter Boost converter Flyback converter Full-bridge converter None Hint12). Which SMPS topology is suitable for high-frequency operation? Buck converter Boost converter Flyback converter Resonant converter None Hint13). Which SMPS topology is commonly used for power factor correction (PFC)? Buck converter Boost converter Flyback converter Cuk converter None Hint14). Which SMPS topology provides multiple isolated outputs? Forward converter Half-bridge converter Full-bridge converter Multi-output converter None Hint15). 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 None Hint16). Which SMPS type is suitable for stepping down a higher voltage to a lower voltage? Buck converter Boost converter Flyback converter Forward converter None Hint17). Which SMPS type is suitable for stepping up a lower voltage to a higher voltage? Buck converter Boost converter Flyback converter Forward converter None Hint18). Which SMPS type provides isolation between the input and output? Buck converter Boost converter Flyback converter Forward converter None Hint19). Which SMPS type is commonly used in laptop chargers and mobile phone chargers? Buck converter Boost converter Flyback converter Forward converter None Hint20). Which SMPS type operates at a constant frequency and requires a low-voltage input? Buck converter Boost converter Flyback converter Forward converter None Hint21). Which SMPS type is suitable for applications requiring multiple output voltages? Buck converter Boost converter Flyback converter Multiple-output converter None Hint22). Which SMPS type requires two switches and a center-tapped transformer? Buck converter Boost converter Flyback converter Push-pull converter None HintRead more about Center-Tapped Transformer23). Which SMPS type is commonly used in automotive applications? Buck converter Boost converter Flyback converter SEPIC converter None Hint24). 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 None Hint25). Which component is commonly used to store energy in an SMPS? Capacitor Transformer Diode Resistor None HintRead more about CapacitorSwitch Mode Power Supply (SMPS) MCQ for Quiz26). Which of the following is a disadvantage of switch-mode power supplies? Electromagnetic interference (EMI) Limited output power Short operational lifespan Large size None Hint27). 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 None Hint28). Which switching topology is commonly used in low-power SMPS? Flyback Forward Push-pull Half-bridge None Hint29). 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 None Hint30). Which component in an SMPS provides electrical isolation between the input and output? Inductor Capacitor Transformer Diode None Hint31). Which of the following is an advantage of SMPS in terms of size and weight? Larger size Heavier weight Compact size Lightweight None Hint32). Which switching topology is commonly used in high-power SMPS, such as computer power supplies? Flyback Forward Push-pull Half-bridge None Hint33). Which component is responsible for converting AC voltage to DC voltage in an SMPS? Transformer Rectifier Transistor Capacitor None Hint34). What is the typical switching frequency of an SMPS? 50 Hz 60 Hz 100 kHz 1 MHz None Hint35). Which of the following is an advantage of a flyback converter? High voltage output Low voltage output Multiple outputs High efficiency None Hint36). The duty cycle of a PWM signal in an SMPS determines ________________? Output voltage Output current Switching frequency Power transfer efficiency None Hint37). Which component is used to control the duty cycle in an SMPS? Diode Capacitor Transistor Resistor None Hint38). 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 None Hint39). Which component is used to isolate the input and output in an SMPS? Diode Capacitor Transformer Resistor None Hint40). Which type of control is commonly used in current-mode SMPS? Voltage mode Current mode Pulse skipping mode Hysteresis mode None Hint41). 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 None Hint42). Which of the following is commonly used as a control element in SMPS? Voltage regulator Zener diode Microcontroller Thermistor None Hint43). Which type of feedback control is commonly used in SMPS? Voltage feedback Current feedback Phase feedback Frequency feedback None Hint44). Which component is used to regulate the output voltage in an SMPS? Resistor Capacitor Zener diode Voltage reference None Hint45). 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 None Hint46). Which component is commonly used to rectify the output voltage in an SMPS? Zener diode Capacitor Schottky diode Inductor None Hint47). 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 None Hint48). An SMPS is producing excessive ripple voltage at the output. Which component is most likely causing this issue? Capacitor Transformer Diode Inductor None Hint49). 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 None Hint50). 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 None HintSwitch 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 None Hint52). 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 None Hint53). 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 None Hint54). 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 None Hint55). 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 None Hint56). 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 None Hint57). 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) None Hint58). 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 None Hint59). What is the formula to determine the output current of an SMPS? Iout = Vin × Vout Iout = Vin/Vout Iout = Pout/Vout Iout = Vout/Pout None Hint60). Which equation represents the efficiency of an SMPS? Efficiency = Pout/Pin Efficiency = Pin/Pout Efficiency = Vout/Vin Efficiency = Vin/Vout None Hint61). 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 None Hint62). 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 None Hint63). Why are higher frequencies preferred in SMPS designs? To reduce electromagnetic interference (EMI) To increase efficiency To minimize voltage ripple All of the above None Hint64). 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 None Hint65). What is the primary advantage of operating an SMPS at higher frequencies? Higher efficiency Smaller size Reduced EMI Faster response time None Hint66). Which parameter defines the maximum frequency at which an SMPS can operate? Duty cycle Ripple voltage Switching speed Switching frequency limit None Hint67). 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 None Hint68). How does increasing the operating frequency of an SMPS affect its efficiency? Efficiency increases Efficiency decreases Efficiency remains the same Efficiency is not affected None Hint69). What is the typical range of duty cycle for an SMPS? 0% - 25% 25% - 50% 50% - 75% 75% - 100% None Hint70). What is the typical input voltage range of a universal input SMPS? 5V – 12V 90V – 264V 220V – 240V 500V – 1000V None Hint71). Which of the following is a common switching frequency used in SMPS? 1 Hz 60 Hz 100 kHz 1 MHz None Hint72). What is the typical input voltage range of a universal SMPS? 110-120V 220-240V 100-240V 12-24V None Hint73). 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 None Hint74). What is the typical frequency range of an SMPS? 50-60 Hz 400-500 Hz 1-10 kHz 100-500 kHz None Hint75). Which of the following SMPS types is suitable for applications requiring galvanic isolation? Flyback SMPS Buck-boost SMPS Forward SMPS Half-bridge SMPS None Hint Time's up
