Analog and electronic circuits

What does the dropout voltage of an LDO (low-dropout linear regulator) mean?

  1. AThe maximum output voltage
  2. BThe change in output voltage when the load is removed
  3. CThe minimum voltage difference between input and output needed to keep the output at its specified voltage
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Answer: C. The minimum voltage difference between input and output needed to keep the output at its specified voltage

The dropout voltage is the minimum difference between input and output voltages at which the regulator can still hold its output. An LDO has a small dropout (for example, about 0.1 to 0.3 V), so it works even when the input is close to the output, making effective use of battery voltage.

  • A. The maximum output voltage is not the dropout voltage.
  • B. The change in output with load is called load regulation.
  • C. Correct. It is the minimum input-output difference needed for regulation.
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