WOBBLbuck
What is the ripple on this 12 V to 5 V buck at 2 A?
OK
Output ripple 8.56 mV peak to peak on 5.07 V (within the 50 mV limit); inductor ripple 0.604 A, peak 2.33 A.
ripple
8.56 mV
output
5.07 V
inductor ripple
0.604 A
duty
43.7%
Confidence high
- passed hand calculation, steady state, time step convergence
Checks
| status | check | result |
|---|---|---|
| pass | hand calculation | ideal waveform math (triangular inductor ripple dI = 0.583 A through C and ESR) gives 7.95 mV; ngspice 8.56 mV and 0.604 A (8% apart; the math ignores switch and diode drops) |
| pass | steady state | average output moved 0.0069% between the last two 20 cycle windows |
| pass | time step convergence | output ripple 0.00856 with the normal step, 0.00856 with half the step (0.0022% apart) |
Assumptions
- Open loop at the steady state duty cycle 43.7%; real controllers add their own ripple and transients.
- Switch on resistance 0.05 ohm, Schottky catch diode.
- Capacitor ESR 10 mohm, no ESL.