SESK: Stuff Everyone Should Know · sesk.info/hame-linear-regulator-dissipation
How do you calculate the power dissipated by a series linear voltage regulator?
(Vin minus Vout) times output current.
- Input voltage times input current
- Output voltage times output current
- Input-to-output voltage difference times output current ✔
Why: The regulator burns off the extra voltage as heat. Multiply that voltage drop across it by the current flowing through it.
Huh, didn't know that: Dropout voltage is the minimum input-to-output voltage needed to keep a linear regulator in regulation (E7D12).
What do you call a cheap step-down power converter that costs under a dollar? A buck converter.
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References
Answer: Input-to-output voltage difference times output current. The regulator burns off the extra voltage as heat. Multiply that voltage drop across it by the current flowing through it.
- NCVEC 2024-2028 Amateur Extra Question Pool, E7D13 (4th errata, Feb. 4, 2026) www.ncvec.org/downloads/2024-2028%20Extra%20Class%20Question%20Pool%20and%20Syllabus%20Public%20Release%20with%204th%20Errata%20Feb%204%202026.pdf
C. Voltage difference from input to output multiplied by output current
Checked 2026-10-11. - NCVEC 2024-2028 Amateur Extra Question Pool, E7D12 (4th errata, Feb. 4, 2026) www.ncvec.org/downloads/2024-2028%20Extra%20Class%20Question%20Pool%20and%20Syllabus%20Public%20Release%20with%204th%20Errata%20Feb%204%202026.pdf
C. Minimum input-to-output voltage required to maintain regulation
Checked 2026-10-11.
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