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  • What is a buck converter? What does it look like?

  • How does a buck converter work?

  • What is the difference between a synchronous and asynchronous buck converter?

  • What is a duty cycle?

  • What is the voltage transfer function of a buck converter? Consequently, what determines the output voltage and why? How can you calculate the duty cycle given input and output voltage design requirements?

  • What happens at 100% and 0% duty cycle?

  • What do the waveforms for the inductor voltage and current look like

  • What do the waveforms for the capacitor voltage and current look like

  • What is the purpose of the output inductor?

  • What is the purpose of the output capacitor?

  • What direction does current flow in the inductor and capacitor in the two switching states?

  • Why is the inductor current a linear ramp? (Think back to the fact that buck converters are used for DC-DC conversion)

  • When does the output capacitor charge/discharge

  • Why is input capacitance needed? What happens if it’s removed?

  • What is voltage and current ripple? What parameters control the magnitude of the output voltage and current ripple? (important)

  • What determines the inductor current slope?

  • What is dead-time insertion? Why is it a must have?

  • How does a MOSFET’s parasitic internal body diode play a role in the workings of a buck converter?

  • Where is inductor current sourced from in the off-state?

  • Why do N-channel MOSFETs require additional circuitry to switch on? What are those circuits called? How do they work?

  • What happens to a bootstrap circuit when a half-bridge operates at too high of a duty cycle? What issues arise?

  • What is the difference between a buck converter vs LDO? What are the tradeoffs?

  • When can an LDO be more efficient than a buck converter?

  • What are the sources of power loss in a buck converter? What are they?

  • How can you improve buck converter efficiency?

  • How are Vgs and Rds(on) related?

  • How are Vgs and gate charge (or turn-on/turn-off switching times) related?

  • What are load and line regulation tests? How are they used to characterize buck converters in testing?

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