PW-14 · Chapter 4 · Power Conversion
Bicycle headlight LED driver
Design a driver for a bicycle headlight: the LED string's Vf is anywhere from 6 V to 13 V (product variants and temperature), at 700 mA, from a 2-cell Li-ion pack (6.0–8.4 V).
| Level | ●● onsite technical |
| Track | Power |
| Really testing | Regulate current, not voltage — and pick a topology that crosses Vin. |
Full worked answer: in the book, page 110 — what to say first, how to explain it, the numbers worth quoting and the follow-ups. About the book →
Going deeper
Extra explanation that is not in the book: worked numbers, where people go wrong, and how to say it in the room.
Going deeper for this question is coming.
Errata
No corrections known for this question. All errata
Ask about this question
Stuck on a step, or think something is wrong? Send it with PW-14 in the subject. Good questions get answered on this page, and corrections go into the next printing.
Related
← PW-13 Software-set bias from −2.5 V to +2.5 VPW-15 −30 V from +5 V →