Tag
capacitors
2 articles.
- Your 2.2 µF is 0.68 µF: DC bias and the capacitance you did not buy
Class 2 ceramics lose capacitance when you put voltage across them. Würth measured a 25 V X7R part losing 69 % of its value at its own rated voltage — and the datasheet headline never mentions it.
- Where the buck ripple comes from, and why more capacitance didn't help
The textbook formula ΔV = I/(8Cf) is the special case where ESR is zero. In the regime most real designs sit in, output ripple is I·ESR — independent of capacitance, duty cycle and switching frequency alike.