Question
What is the dropout voltage of a linear voltage regulator?
Answer Options
- A) Minimum input voltage for rated power dissipation
- B) Maximum output voltage drop when the input voltage is varied over its specified range
- C) Minimum input-to-output voltage required to maintain regulation
- D) Maximum that the output voltage may decrease at rated load
Correct Answer: C
Explanation
The dropout voltage is a critical specification for a linear voltage regulator, especially when operating on a battery or an input source that may fluctuate close to the required output voltage. It defines the minimum headroom the regulator needs to function correctly.
The dropout voltage is the minimum input-to-output voltage required to maintain regulation. For example, if a 12 \text{ V} regulator has a 3 \text{ V} dropout voltage, the input voltage must be at least 15 \text{ V} to guarantee the 12 \text{ V} output. If the input drops below 15 \text{ V}, the regulator ‘drops out’ of regulation, and the output voltage will fall along with the input voltage.
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