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Lesson 13
An inductor won't let its current jump, so a switch chopping the input into it makes a triangle of current whose average is the load's. Its volt-seconds balance every cycle, and that sets the output. Commit to predictions, then fire up the scope and see why.
Predict · 1 of 2 · the duty
A buck at 500 kHz: a switch chops 12 V into 10 µH and 22 µF, and a Schottky catch diode carries the current while the switch is off. Open loop: you set the duty and nothing corrects it. What fraction of each period must the switch be on for the output to sit at 5 V with a 5 Ω load? CH1 follows your call.
Result
Waiting on your call.
Make your mark, then lock it in. The answer, your error and the reason behind it land here, and the scope and every view below fire up.
Engine: the in-browser MNA solver, one linear circuit per switch state (on, diode, idle; synchronous; the body diode), restarted consistently at every edge and at the diode's current zero, 300 trapezoidal steps a period. The steady state is found by shooting: Newton on the period map (2 steps here, residual 1e-15), so the inductor's volt-seconds balance to 5e-14 of either area. Switching losses are not modeled. Checked by scripts/buck-lesson-check.mjs. SPICE: its numbers show once you're in the lab (they'd give the answers away).